Learning From Failure: Biosphere Ii Essay

Biosphere II was a project done in Arizona received recognition on 26th September 1991. Eight people; four men and four women were used in the experiment. Biosphere 2 was an air tight structure with its base made of steel pan and surrounded by an above ground structure that was made of glass and steel. Inside the biosphere was all that could be found in the real world. There was a desert, a marsh, a rain forest, a savannah, an agricultural land, an ocean and human Habitat. This was in an effort of creating something close to the earth’s ecosystem. These people were to live on air, water and food produced by plants (Allen & Blake, 2007). The goals of the experiment were to determine the possibility of building an artificial biosphere and the potential of such biosphere surviving. Also incase the biosphere didn’t thrive then the causes would have been established. However, Biosphere II proved to be a great failure which had consumed a lot of resources in its establishment. Trouble started soon as the crew got into biosphere II. First, they experienced a shortage in oxygen supply hindering them from functioning well. The oxygen decreased to low levels such that more of it had to be injected into the system. When the crew were forced to pump in more oxygen into the system in order to sustain them, this indicated that biosphere II was not self reliant. At first they did not figure out what the problem was but they later discovered that was caused by carbon dioxide which had accumulated in the system. The carbon dioxide accumulated at a very high rate especially in the savanna and rain forest regions. This was associated with the presence of high organic matter which the microbes metabolized and in the process consumed a lot of oxygen resulting to high levels of carbon dioxide. It was also expected that the trees would play a very crucial role in regulating amount of carbon dioxide in the air and would have been able to supply the crew with sufficient oxygen through the process of photosynthesis. However, the plants did not seem to accomplish this role instead the level of oxygen kept on decreasing while carbon dioxide kept on increasing a phenomenon that was later discovered to have been caused by concrete that was used to build the biosphere II. Instead of carbon dioxide being used up by plants it reacted with calcium hydroxide a major component of concrete which resulted to formation of water and calcium carbonate. This was confirmed by the scientists after testing the walls and realizing that the inner surface of the walls had calcium carbonate levels which were ten times the level of the outer walls (Alling, Nelson &Silverstone, 1993). While making their selection, the scientists had chosen different species of animals, insects and plants that they thought would survive best in the biosphere II. However, by the end of the project only a few species had managed to survive. The rate of extinction was higher than predicted and most insect species got extinct which had a negative impact on the plants since they were no longer pollinated and thus were unable to propagate themselves. Statistics show that of the 25 species of small vertebrates present in Biosphere II only 6 survived by the end of the mission. However some species were favored by the environment in biosphere II. While others got extinct; ants, cockroaches and katydids flourished together with some plant species such as the morning glory. The morning glory grew vigorously that it almost choked the other plants. The crew had no alternative but invested most of their time working to get food. They experienced a shortage in food supply and faced hunger most of the time. Before the two year period ended the crew had grown 85 percent of the food they consumed and got the remaining15 percent food from their emergency supplies. Since they relied on sunlight which came through the glass to grow food, the winters of 1991 and 1992 affected the amount of food they could grow (Marino, Odum &Thomas, 1999). This proved that the project was incapable of sustaining an ecosystem that was balanced. They also faced various challenges some of which included shortage in clean water. This was as a result of pollution experienced in the water system. Many nutrients accumulated in the water systems therefore polluting it. They had to clean their water using algae mats. Other atmospheric imbalances followed suit where by levels of dinitrogen oxide in the air increased in an alarming rate such that the crew risked brain damage because vitamin B12was synthesized at an extremely slow rate (Allen & Blake, 2007). The experiments shortcomings were also seen when the crew quarreled. The members were supposed to work together as a group in order to bring out the best results but this never happened. Instead they split into groups comprising four members each and got to the point of not talking to each other except when it was necessary to run the biosphere. The lessons that can be learnt from this failed experiment come from the mistakes committed by the scientists. First we learn the importance of taking time to plan whatever we intend to do. Before attempting any thing one should take all measures required for proper functioning of the project. Also another critical factor to consider is the reliability of the materials and equipment to be used in the project (Alling, Nelson &Silverstone, 1993). If proper materials had been used in construction of the biosphere II then the problem of insufficient oxygen could not have occurred. The importance of using qualified personnel also arises. They used an architect who was incompetent this resulted to designing biosphere II with many faults. However what can be learnt from this experiment in general is the importance of relating well with each other. For any thing to succeed then there should be cooperation among people concerned this translates to excellent working conditions which leads to better outcome. References Allen J. & Blake A. (2007) Biosphere 2: the human experiment . New York: Viking publishers. Alling A. , Nelson M. & Silverstone S. (1993) Life under Glass: The Inside Story of Biosphere 2. Oracle: Biosphere Press. Marino B. D. , Odum H. & Thomas M. (1999) Biosphere 2: Research Past and Present Amsterdam: Elsevier publishers.

Interview questions for capital market & NSE Essay

What is capital Market? Capital market is a market of securities. Where a company and government raise long term funds. it is a market where money invested more them one year. In this we include the stock market and bond market Definition of ‘Debt’ An amount of money borrowed by one party from another. Many corporations/individuals use debt as a method for making large purchases that they could not afford under normal circumstances. A debt arrangement gives the borrowing party permission to borrow money under the condition that it is to be paid back at a later date, usually with interest. Definition of ‘Primary Market’ A market that issues new securities on an exchange. Companies, governments and other groups obtain financing through debt or equity based securities. Primary markets are facilitated by underwriting groups, which consist of investment banks that will set a beginning price range for a given security and then oversee its sale directly to investors Definition of ‘Secondary Market’ A market where investors purchase securities or assets from other investors, rather than from issuing companies themselves. The national exchanges – such as the New York Stock Exchange and the NASDAQ are secondary markets. Secondary markets exist for other securities as well, such as when funds, investment banks, or entities such as Fannie Mae purchase mortgages from issuing lenders. In any secondary market trade, the cash proceeds go to an investor rather than to the underlying company/entity directly. What do you mean by Equity investment? Answer: An equity investment generally refers to the buying and holding of shares of stock on a stock market by individuals and firms in anticipation of income from dividends and capital gains, as the value of the stock rises. It may also refer to the acquisition of equity (ownership) participation in a private (unlisted) company or a startup company What do you mean by stock market or equity market? Answer: A stock market or equity market is a public entity (a loose network of economic transactions, not a physical facility or discrete entity) for the trading of company stock (shares) and derivatives at an agreed price; these are securities listed on a stock exchange as well as those only traded privately. What do you mean by money market? Answer: The money market is a component of the financial markets for assets involved in short-term borrowing and lending with original maturities of one year or shorter time frames. What do you mean by stock exchange? Answer: A stock exchange is an entity that provides services for stock brokers and traders to trade stocks, bonds, and other securities. Stock exchanges also provide facilities for issue and redemption of securities and other financial instruments, and capital events including the payment of income and dividends. Securities traded on a stock exchange include shares issued by companies, unit trusts, derivatives, pooled investment products and bonds. What do you mean by Financial regulation? Answer: Financial regulation is a form of regulation or supervision, which subjects financial institutions to certain requirements, restrictions and guidelines, aiming to maintain the integrity of the financial system. This may be handled by either a government or non-government organization What are the Aims of financial regulation? Answer: Aims of regulation The aims of financial regulators are usually: * To enforce applicable laws * To prevent cases of market manipulation, such as insider trading * To ensure competence of providers of financial services * To protect clients, and investigate complaints * To maintain confidence in the financial system * To reduce violations under laws List some financial regulatory authorities * Commodity Futures Trading Commission (CFTC) * National Credit Union Administration (NCUA) * Financial Services Authority (FSA), United Kingdom What do you mean by NSE? Answer: The National Stock Exchange was incorporated in 1992 by Industrial Development Bank of India, Industrial Credit and Investment Corporation of India, Industrial Finance Corporation of India, all Insurance Corporations, selected commercial banks and others. Trading at NSE can be classified under two broad categories: (a) Wholesale debt market and (b) Capital market. What are the advantages of NSE? (National Stock Exchange) NSE has several advantages over the traditional trading exchanges. They are as follows: * NSE brings an integrated stock market trading network across the nation. * Investors can trade at the same price from anywhere in the country since inter-market operations are streamlined coupled with the countrywide access to the securities. * Delays in communication, late payments and the malpractice’s prevailing in the traditional trading mechanism can be done away with greater operational efficiency and informational transparency in the stock market operations, with the support of total computerized network. Why India needs economic planning? One of the major objective of planning in India is to increase the rate of economic development, implying that increasing the rate of capital formation by raising the levels of income, saving and investment. However, increasing the rate of capital formation in India is beset with a number of difficulties. People are poverty ridden. Their capacity to save is extremely low due to low levels of income and high propensity to consume. Therefor, the rate of investment is low which leads to capital deficiency and low productivity. Low productivity means low income and the vicious circle continues. Thus, to break this vicious economic circle, planning is inevitable for India. What are general objectives of Indian Planning? The long-term general objectives of Indian Planning are as follows : * Increasing National Income * Reducing inequalities in the distribution of income and wealth * Elimination of poverty * Providing additional employment; and * Alleviating bottlenecks in the areas of : agricultural production, manufacturing capacity for producer’s goods and balance of payments. *

Polymer Concrete

POLYMER COCNCRETE 1. Introduction Despite being thought of as a modern material, concrete has been in use for hundreds of years. The word concrete comes from the Latin concretus, which means â€Å"mixed together† or compounded. Concrete is an extremely popular structural material due to its low cost and easy fabrication. Concrete is made up of sand or stone, known as aggregate, combined with cement paste to bind it. Aggregate can be of various sizes. It is broadly categorized as fine (commonly sand) and coarse (typically crushed stone or gravel).The greater proportion of concrete is aggregate which is bulky and relatively cheaper than the cement. As much of the constituents of concrete come from stone, it is often thought that concrete has the same qualities and will last forever. Concrete has been called artificial stone, cast stone, reconstructed stone and reconstituted stone. However, concrete must be thought of as a distinct material to stone. It has its own characteristic s in terms of durability, weathering and repair. Concrete is a relatively durable and robust building material, but it can be severely weakened by poor manufacture or a very aggressive environment.A number of historic concrete structures exhibit problems that are related to their date of origin. It is referred that the concrete is porous. The porosity is due to air-voids, water voids or due to the inherent porosity of gel structure itself. On account of the porosity, the strength of concrete is naturally reduced. It is conceived by many research workers that reduction of porosity results in increase of strength of concrete. Therefore, process like vibration, pressure application spinning etc. , have been practiced mainly to reduce porosity.All these methods have been found to be helpful to a great extent, but none of these methods could really help to reduce the water voids and the inherent porosity of gel which is estimated to be about 28%. The impregnation of monomer and subsequen t polymerization is the latest technique adopted to reduce the inherent porosity of the concrete to improve the strength and other properties of concrete. These problems can be solved by application of polymer in concrete construction. A polymer is a large molecule containing hundreds or thousands of atoms formed by combining one, two or occasionally more kinds of small molecule (monomers) into chain r network structures. The main polymer material used in concrete construction are polymer modified concrete and polymer concrete. Polymer modified concrete may be divided into two classes: polymer impregnated concrete and polymer cement concrete. The first is produced by impregnation of pre-cast hardened Portland cement concrete with a monomer that is subsequently converted to solid polymer. To produce the second, part of the cement binder of the concrete mix is replaced by polymer (often in latex form).Both have higher strength, lower water permeability, better resistance to chemicals, and greater freeze-thaw stability than conventional concrete. Polymer concrete (PC), or resin concrete, consists of a polymer binder which may be a thermoplastic but more frequently is a thermosetting polymer, and a mineral filler such as aggregate, gravel and crushed stone. PC has higher strength, greater resistance to chemicals and corrosive agents, lower water absorption and higher freeze-thaw stability than conventional Portland cement concrete.The pioneering work for the development of polymer concrete was taken up by United States Bureau of Reclamation (USBR). The initial exploratory works carried out at the Brookhaven National Laboratory (BNL) in cooperation with USBR and US in Atomic Energy Commission (AEC) revealed great improvement in compressive strength, permeability, impact resistance and abrasion resistance. The development of concrete-polymer composite material is directed at producing a new material by combining the ancient technology of cement concrete with the mod ern technology of polymer chemistry. 2.Types of Polymer Concrete Four types of polymer concrete materials are being developed presently. They are: a) Polymer Concrete (PC) b) Polymer Cement Concrete (PCC) c) Polymer impregnated Concrete (PIC) d) Partially Impregnated and surface coated polymer concrete The composites using polymer can be: polymer concrete (PC), when the binder is a polymer that replaces the cement paste, polymer modified concrete (PMC/ PCC), when the polymer is used near cement, polymer impregnated concrete (PIC), when the cement concrete is treated by soaking and polymerization.These composites have some advantages compared to ordinary cement concrete such as,rapid hardening, high mechanical strengths, chemical resistance, etc. Among the disadvantages is their high cost. The utilization domain of polymer concrete is continuously diversifying: PMC is widely used for floor and bridge overlays; acrylic latex has been used to produce mortars which can be sprayed on arc hitectural finish ; PIC was first widely used in bridge decks, pipes and conduits for aggressive fluids, floor tiles, building cladding, hazardous waste containment, post-tensioned beams and slabs, and stay-in place formwork.Polymer concrete is similar to ordinary cement concrete because it contains fine and coarse aggregates, but the hydraulic binder is totally substituted with a polymer material. The aggregates are bounded together by the polymer matrix. Polymer concrete contains no cement or water. The performances of polymeric concrete depend on the polymer properties, type of filler and aggregates, reinforcing fiber type, curing temperature, components dosage, etc. Polymer binder can be a thermoplastic, but more frequently a thermosetting polymer.The polymers most frequently used are based on four types of monomers or pre polymer system: methyl methacrylate, polyester prepolymerstyrene, epoxyde prepolymer hardener and furfuryl alcohol . The aggregates used in dry state can be s ilicates, quartz, crushed stone, gravel, limestone, calcareous, granite, clay, etc. In the composition can be used also the filler. Different types of fine materials can be used such as: fly ash, silica fume, phosphogyps, cinder, etc. Filler, especially fly ash, can improve the properties of polymer concrete . 3. History †¢ PC was used as early as 1958 in the USA to produce building cladding. Both PC and PCC have been in commercial use since the 1950s †¢ PIC was developed and has been in use since the 1970s †¢ Polymer concrete products have been used for decades in engineering construction like machine foundations, in the building industry for facade products and sanitary parts, in electrical engineering for isolation devices and especially in the chemical industry for all types of ducts due to its favourable properties, especially its corrosion resistance as well as its strength and elasticity †¢ The development of polymer concrete products, mostly pipe, dates b ack to the early 1960`s.The objective was to achieve a substantial increase in resistance to chemical attack †¢ With the development of trenchless technologies (micro-tunneling and pipe jacking) in 1970`s, polymer concrete pipes became popular in sewer systems.As such over the past years, the process of production and manufacturing of polymer concrete products like pipes, manholes and structures have been fundamentally improved †¢ Today it is used for cultured marble for counter tops, lavatories, as repair material, overlays for bridge and floors in sport arenas and stadiums, laboratories, hospitals, factories; also precast PC was used for drains, underground boxes, manholes, acid tanks and cells, tunnel lining, shells, floor tiles, architectural mouldings and machine tools and bases 4.Significance †¢ Depending on the materials employed, PC can develop compressive strengths of the order of 140 MPa within hours or even minutes and is therefore suitable for emergency co ncreting jobs in mines, tunnels, and highways †¢ PCC possess excellent bonding ability to old concrete, and high durability to aggressive solutions; it has therefore been used mainly for overlays in industrial floors, and for rehabilitation of deteriorated bridge decks. In the case of PIC, by effectively sealing the micro-cracks and capillary pores, it is possible to produce a virtually impermeable product which gives an ultimate strength of the same order as that of PC. PIC has been used for the production of high-strength pre-cast products and for improving the durability of bridge deck surfaces †¢ PCC possess excellent bonding ability to old concrete, and high durability to aggressive solutions; it has therefore been used mainly for overlays in industrial floors, and for rehabilitation of deteriorated bridge decks. In the case of PIC, by effectively sealing the micro-cracks and capillary pores, it is possible to produce a virtually impermeable product which gives an ult imate strength of the same order as that of PC. PIC has been used for the production of high-strength pre-cast products and for improving the durability of bridge deck surfaces †¢ Polymer concrete (PC) is a mixture of aggregates with a polymer as the sole binder. To minimize the amount of the expensive binder, it is very important to achieve the maximum possible dry packed density of the aggregate. . Polymer Concrete (PC) Polymer concrete is an aggregate bound with a polymer binder instead of Portland Cement as in conventional concrete. The main technique in producing PC is to minimize void volume in the aggregate mass so as to reduce the quantity of polymer needed for binding the aggregates. This is achieved by properly grading and mixing the aggregates to attain the maximum density and minimum void volume. The graded aggregates are prepacked and vibrated in a mould.Monomer is then diffused up through the aggregates and polymerization is initiated by radiation or chemical mean s. A silane coupling agent is added to the monomer to improve the bond strength between the polymer and the aggregate. In case polyester resins are used no polymerization is required. An important reason for the development of this material is the advantage it offers over conventional concrete where the alkaline Portland cement on curing, forms internal voids. Water can be entrapped in these voids which on freezing can readily cracks the concrete.Also the alkaline Portland cement is easily attacked by chemically aggressive materials which results in rapid deterioration, whereas polymers can be made compact with minimum voids and are hydrophobic and resistant to chemical attack. The strength obtained with PC can be as high as 140 MPa with a short curing period. However, such polymer concretes tend to be brittle and it is reported that dispersion of fiber reinforcement would improve the toughness and tensile strength of the material.The use of fibrous polyester concrete (FPC) in the c ompressive region of reinforced concrete beams provides a high strength, ductile concrete at reasonable cost. Also polyester concretes are visco-elastic in nature and will fail under sustained compressive loading at stress levels greater than 50 per cent of the ultimate strength. Therefore polyester concrete should be considered for structures with a high ratio of live load to dead load and for composite structures in which the polymer concrete may relax during long-term loading.Experiments conducted on FPC composite beams have indicated that they are performance effective when compared to reinforced concrete beam of equal steel reinforcement percentage. Such beams utilize steel in the region of high tensile stress, fibrous polyester concrete (FPC) with its favourable compressive behavior, in the regions of high compressive stress and Portland cement concrete in the regions of relatively low flexural stress. Properties of Polymer Concrete: †¢ Due to good chemical resistance and high initial strength and modulus of elasticity, industrial use of PC has been mainly in overlays and repair jobs. Thermal and creep characteristics of the material are usually not favorable for structural applications of PC. †¢ Polyester concretes are visco-elastic and will fail under a sustained compressive loading at stress levels greater than 50 percent of the ultimate strength. Sustained loadings at a stress level of 25 percent did not reduce ultimate strength capacity for a loading period of 1000 hr. 6. Polymer Cement Concrete (PCC) Polymer cement concrete is made by mixing cement, aggregates, water and monomer, such plastic mixture is cast in moulds.Cured, dried and polymerized. The monomers that are used in PCC are: a) Polyster-styrene. b) Epoxy-styrene c) Furans d) Vinylidene Chloride However, the results obtained by the production of PCC in this way have been disappointing and have shown relatively modest improvement of strength and durability. In many cases material s poorer than ordinary concrete are obtained. This behavior is explained by the fact that organic materials (monomers) are incompatible with aqueous systems and sometimes interfere with the alkaline cement hydration process.Recently Russian authors have reported the production of a superior Polymer cement concrete by the incorporation of furfural alcohol and aniline hydrochloride in the wet mix. This material is claimed to be specially dense and non-shrinking and to have high corrosion resistance, low permeability and high resistance to vibrations and axial extension. Washington State University in cooperation with Bureau of Reclamation tested the incorporation of several monomers into Wet Concrete for preparing PCC for fabrication of distillation units for water desalination plants.However, it is reported that only epoxy resin produced a concrete that showed some superior characteristics over ordinary concrete. †¢ The materials and the production technology for concrete in PCC are the same as those used in normal Portland Cement concrete except that latex, which is a colloidal suspension of polymer in water, is used as an admixture. †¢ Earlier latexes were based on polyvinyl acetate or polyvinylidene chloride, but these are seldom used now because of the risk of corrosion of steel in concrete in the latter case, and low wet strengths in the former. Elasto-meric or rubberlike polymers based on styrenebutadiene and polyacrylate copolymers are more commonly used now. Latex: †¢ A latex generally contains about 50 % by weight of spherical and very small (0. 01 to 1 m in diameter) polymer articles held in suspension in water by surface-active agents. †¢ The presence of surface-active agents in the latex tends to incorporate large amounts of entrained air in concrete; therefore, air detraining agents are usually added to commercial latexes. 10 to 25 percent polymer (solid basis) by weight of cement is used in typical PCC formulations †¢ The addition of latex provides a large quantity of the needed mixing water in concrete. †¢ The application of PCC is limited to overlays where durability to severe environmental conditions is of primary concern. †¢ PCC is made with as low an addition of extra mixing water as possible; the spherical polymer molecules and the entrained air associated with the latex usually provide excellent workability. Concrete Mix and Curing: †¢ Typically, water-cement ratios are in the range0. 40 to 0. 5, and cement contents are on the order of 390 to 420 kg/m3. †¢ The hardening of a latex takes place by drying or loss of water. †¢ Dry curing is mandatory for PCC; the material cured in air is believed to form a continuous and coherent polymer film which coats the cement hydration products, aggregate particles, and even the capillary pores. Properties: †¢ The most impressive characteristics of PCC are its ability to bond strongly with old concrete, and to resist the entry o f water and aggressive solutions. †¢ It is believed that the polymer film lining the capillary pores and micro-cracks does an excellent job in impeding the fluid flow in PCC. These characteristics have made the PCC a popular material for rehabilitation of deteriorated floors, pavements, and bridge decks. 7. Polymer Impregnated Concrete (PIC) Polymer impregnated concrete is one of the widely used polymer composite. It is nothing but a pre-cast conventional concrete, cured and dried in oven, or by dielectric heating from which the air in the open cell is removed by vacuum. Then a low viscosity monomer is diffused through the open cell and polymerized by using radiation, application of heat or by chemical initiation. Mainly the following types of monomer are used: a) Methylmethacrylate (MMA) ) Styrene c) Acrylonitrile d) T-butyl styrene e) Other thermoplastic monomers The amount of monomer that can be loaded into a concrete specimen is limited by the amount of water and air that h as occupied the total void space. It is necessary to know the concentration of water and air void in the system to determine the rate of monomer penetration. However, the main research effort has been towards obtaining a maximum monomer loading in concrete by the removal of water and air from the concrete by vacuum or thermal drying, the latter being more practicable for water removal because of its rapidity.Another parameter to consider is evacuation of the specimen prior to soaking in monomer. This eliminates the entrapment of air towards the centre of the specimen during soaking which might otherwise prevent total or maximum monomer loading. The application of pressure is another technique to reduce monomer loading time. 8. Partially Impregnated (or Coated in Depth CID) and Surface Coated (SC) Concrete Partial impregnation may be sufficient in situations where the major requirement is surface resistance against chemical and mechanical attack in addition to strength increase.Even with only partial impregnation, significant increase in the strength of original concrete has been obtained. The partially impregnated concrete could be produced by initially soaking the dried specimens in liquid monomer like methyl methacrylate, then sealing them by keeping them under hot water at 70 C to prevent or minimize loss due to evaporation. The polymerization can be done by using thermal catalytic method in which three per cent by weight of benzoyl peroxide is added to the monomer as a catalyst. It is seen that the depth of monomer penetration is dependent upon following: a) Pore structure of hardened and dried concrete ) The duration of soaking, and c) The viscosity of the monomer The potential application of polymer impregnated concrete surface treatment (surface coated concrete, SC) is in improving the durability of concrete bridge decks. Bridge deck deterioration is a serious problem everywhere, particularly due to an abrasive wear, freeze-thaw deterioration, spalling and corrosion of reinforcement. Excellent penetration has been achieved by ponding the monomer on the concrete surface. Due care should be taken to prevent evaporation of monomer when ponded on concrete surface.A 5 cms thick slab, on being soaked by MMA for 25 hours produced a polymer surface coated depth of 2. 5 cms. Significant increases in the tensile and compressive strengths, modulus of elasticity and resistance to acid attack have been achieved. The application of monomer for field application like in bridge decks poses more problems than laboratory application. A typical surface treatment in the field can be done in the following manner. a) The surface is dried for several days with electrical heating blanket. b) Remove the heating blanket and cover the slab with 0. 4 cum oven-dried light-weight aggregate per 100 sqm. c) Apply initially 2,000 to 3,000 ml of the monomer system per square meter. d) Cover the surface with polyethylene to retard evaporation. e) Shade the surface to prevent temperature increase which might initiate polymerization prematurely, that may reduce penetration into the concrete. f) Add periodically additional monomer to keep the aggregate moist for minimum soak time of 8 hours. g) Apply heat to polymerize the monometer: Heating blanket, steam or hot water can be used for this purpose. Some of the promising monomer systems for this purpose are: ) Methylmethacrystalate (MMA), 1% Benzoyl peroxide (BP), 10% Trimethylopropane thimethacrylate (TMPTMA). b) Isodecyl methacrystalate (IDMA), 1% BP, 10% TMPTMA c) Isobutylmethacrystalate (IBMA), 1% BP, 10% TMPTMA BP acts as a catalyst and TMPTMA is a cross linking agent which helps in polymerization at low temperature of 52%C. 9. Properties of Polymer Impregnated Concrete Since polymer impregnated concrete (PIC) is one of the most important category of polymer concrete, the properties of PIC are discussed below. Stress – Strain Relationship The stress strain curve for MMA –impreg nated concrete tested to failure is shown in fig. elow.. PIC has a nearly linear stress strain relationship to failure. There is very little departure from linearity upto 90% of ultimate strength and there is no abrupt change at the proportional limit. The stress strain curves for Styrene TMTMPTMA impregnated concrete also show the same characteristics as for MMA impregnated concrete. The modulus of elasticity increased from 27 GPa for un-impregnated specimen to 49 GPa for MMA impregnated specimens. [pic] Compressive Strength The effect of polymer loading on the compressive strength in PIC is given in the following figure.Using methylemethacrystalate as monomer and with a polymer loading of 6. 4%, strength of the order of 144 MPa have been obtained using radiation technique of polymerization. (The control specimen had compressive strength of 38 MPa). The compressive strength obtained with thermal catalytic process was 130 MPa. [pic] [pic] Styrene impregnated specimens exhibit simila r trends, except that the strength levels were somewhat lower. The polymerization by radiation method produced a concrete of higher strength than the produced by thermal catalytic method.Perlite concrete impregnated with MMA and polyester styrene have also shown considerable increases in compressive strengths. It is found the higher strengths are obtained with MMA impregnated sample than with polyester styrene. The average compressive strength for a 1:8 non-air entrained perlite concrete samples, impregnated with MMA was 56 MPa for polymer loading of 63% compared to control specimen of compressive strength 1. 2 MPa. Tensile Strength The increase in tensile strength in the case of PIC has been observed to be as high as 3. times that of the control specimen for polymer loading of 6. 4% MMA i. e. impregnated concrete have shown tensile strength of the order of 11. 6 MPa compared to the strength of control specimen of 3 MPa using radiation process of polymerization. Thermal catalyticall y initiated polymerization, produced concrete with tensile strength 3. 6 times that of the control specimen and 7. 3% less than that of radiation produced concrete. Polymer Concrete : Polyester resin concrete with binder continent varying from 20 to 25% have shown tensile strengths in the range of 9 to 10 MPa at 7 days.Polymer Cement Concrete: Polymer cement concrete using latex has given tensile strength of 5. 8 MPa with a latex / cement ratio of 0. 25; compared to the control specimen of 4. 4 MPa strength. The increase in tensile strength is very modest. Flexural Strength Polymer impregnated concrete with polymer loading of 5. 6% MMA and polymerized by radiation have shown flexural strength 3. 6 times more than that of the control specimen, i. e. the flexural strength was increased to 18. 8 MPa from 5. 2 MPa. Polymer Concrete (PC) Polymer resin concrete has been reported to give flexural strength of the order of 15 MPa at 7 days.Creep Compressive Creep deformation of MMA impregnat ed concrete and styrene-impregnated concrete has been observed to be in direction opposite to that of the applied road i. e, Negative Creep. After the typical initial movement during load application, these concretes expand under sustained compression. The reason for this negative creep in PIC is not very clear though it may be possible that it is due to residual stresses generated in the concrete after polymerization of monomers. The increased volume may also be due to phase changes induced by pressure. This behaviour has been noticed at a relatively loiw loading of 5. MPa. Otherwise creep deformation of PIC concrete is generally one-tenth of conventional concrete, when compared on a basis of deformation per unit load. Creep deformation generally stabilizes after two to three months. Shrinking due to Polymerisation Shrinkage occurs through two stages of impregnation treatment i. e. , through initial drying and through polymerisation. The shrinkage through polymerisation is peculiar to PIC and could be several times greater than the normal drying shrinkage. It has been seen that for the same base material, different monomer systems cause different amounts of shrinkage.It is expected that the shrinkage due to polymerisation will be less for a base that has higher modulus of elasticity. Durability The saturation of the hydrated cement with corrosion resistant polymer probably acts as a protective coating and results in excellent improvement in durability. a) Frees Thaw Resistance: Polymer impregnated concrete has shown excellent resistance to freeze-thaw MMA impregnated and radiation polymerized specimens have withstood 8110 cyclens of freeze-thaw compared to 740 cycles in case of unimpregnated concrete. Even partially impregnated concrete withstood 2310 cycles. ) Resistance to Sulphate Attack: Keeping a failure criteria of 0. 5% expansion, it has been observed that there is atleast 200 percent improvement in the resistance of polymer impregnated concrete and 89 % improvement in the case of partially impregnated concrete over the conventional concrete. c) Acid Resistance: The acid resistance of PIC has been observed to improve by 1200 percent when exposed to 15% HCI for 1395 days. Water Absorption A maximum reduction of 95 percent in water absorption has been observed with concrete containing 5. 9 percent polymer loading. Co-efficient of Thermal Expansion:Polymer impregnated concrete has higher co-efficient of thermal expansion compared to conventional concrete. Compared to the unimpregnated concrete having a value of 4. 02 X 10-6, a 5. 5% MMA, radiation polymerized concrete has a co-efficient of thermal expansion of 5. 63 X 10-6, and styrene impregnated specimens have shown a value of 5. 10 X 10-6. Resistance to Abrasion Polymer impregnated concrete has shown appreciable improvement in resistance to abrasion. A 5. 5% MMA impregnated concrete has been found to be 50 to 80 per cent more resistance to abrasion than the control specimen.Even s urface impregnated concrete slabs have shown an improvement of 20 to 50%. Wear and Skid Resistance. Though there may be apprehension that polymer filled voids in polymer concrete might produce a slippery surface, on actual wear track test, it was found that the treated surfaces show excellent skid resistance compared to the unimpregnated surfaces. The wear after 50,000 simlated vehicular passes has been less than 0. 025cm. Fracture of Polymer impregnated Concrete Polymer impregnation of concrete changes its microstructure radically resulting in a change in the cracking behaviour of the impregnated concrete under load.Impregnation improves the strength of the mortar matrix and also the strength of the paste-aggregate interface by elimination of microcracks. Polymer probably enters the aggregates also and forms a network of polymer fibres across the interface, thus strengthening it. Radiographic studies have shown that micro cracking starts first around 70 to 80% of the ultimate load, very often in the mortar phase. When an advancing crack reaches an aggregate, it does not follow the aggregate boundary as in ordinary concrete, but usually propagates through the aggregate.This indicates that the paste aggregate interface bond is significantly improved by polymer impregnation. It has been observed that PIC indicates nearly linear behaviour to failure, which is typical of brittle material. The brittle nature of PIC presents a severe design limitation. It would be ideal to produce a material with the slow failure mode of normal concrete while retaining the high strength and modulus of elasticity of PIC. One method to achieve this ideal is to adjust the past aggregate bond so that the failure mode is through the interface like in ordinary concrete.In principle, this can be achieved by using a very strong and tough aggregate, so that the advancing crack is diverted round to the paste-aggregate interface. The fracture mode of PIC can also be altered by incorporating a small quantity (1% by volume) of fibres in the matrix. The fibres do not affect the modulus of elasticity of concrete due to their low concentration, but serve to inhibit crack propagation through the mortar by acting as crack arrestors. 10. Sequence of Operations Drying and evacuation:The time and temperature needed for removal of free water from the capillary pores of moist-cured products depend on the thickness of the elements. At the drying temperatures ordinarily used (i. e. , 105 C), it may require 3 to 7 days before free water has been completely removed from a 150- by 300-mm concrete cylinder. Temperatures on the order of 150 C can accelerate the drying process so that it is complete in 1 to 2 days. Soaking the dried concrete in a monomer: The in situ penetration of concrete in the field may be achieved by surface ponding, but precast elements are directly immersed in the monomercatalyst mixture.Commercial monomers contain inhibitors that prevent premature polymerization dur ing storage; the catalyst serves to overcome the effect of the inhibitor. Sealing the monomer: To prevent loss of monomer by evaporation during handling and polymerization, the impregnated elements must be effectively sealed in steel containers or several layers of aluminum foil; In the rehabilitation of bridge decks this has been achieved by covering the surface with sand. Polymerizing the monomer: Thermal – catalytical polymerization is the preferred technique.The time for complete polymerization of the monomer in the sealed elements exposed to steam, hot water or air, or infrared heat at 70 to C may vary from a few to several hours. In the case of a MMA-benzoyl peroxide mixture, no differences in strength were found between specimens polymerized at C with hot air for 16 hr or with hot water for 4 hr. 11. Application of Polymer Impregnated Concrete Keeping in view the numerous beneficial properties of the PIC, it is found useful in a large number of applications, some of wh ich have been listed and discussed below: a) Pre-fabricated structural elements. ) Pre-stressed Concrete c) Marine works d) Desalination Plants e) Nuclear Power plants f) Sewage works-pipe and disposal works. g) Ferro cement products h) For water proofing of structures i) Industrial applications a) Pre-fabricated Structural Elements: For solving the tremendous problem of Urban Housing shortage, maintaining quality, economy and speed, builders had to fall back on pre-fabricated techniques of construction. At present due to the low strength of conventional concrete, the pre-fabricated sections are large and heavy, resulting in costly handling and erection.These reasons have prevented wide adoption of pre-fabrication in many countries. At present, the technique of polymer impregnation is ideally suited for pre cast concrete, it will find unquestionable use in industrialization of building components. Owning to higher strength, much thinner and lighter sections could be used which enabl es easy handling and erection. They can be even used in high rise building without much difficulties. b) Pre-stressed Concrete: Further development in pre-stressed concrete is hindered by the inability to produce high strength concrete, compactable with the high tensile steel available for pre-stressing.Since PIC provides a high compressive strength of the order of 100 to 140 MPa, it will be possible to use it for larger spans and for heavier loads. Low creep properties of PIC will also make it a good material for pre-stressed concrete. c) Marine Works: Aggressive nature of sea water, abrasive and leaching action of waves and inherent porosity, impair the durability of conventional concrete in marine works. PIC possessing high surface hardness, very low permeability and greatly increased resistance to chemical attack, is a suitable material for marine works. ) Desalination Plants: Desalination of sea water is being resorted to augment the shortage of surface and ground water in many countries. The material used in construction of flash distillation vessels in such works has to withstand the corrosive effects of disilted water, brine and vapour at temperature up to 1430 C. Carbon steel vessels which are currently in use are comparatively costly and deteriorate after prolonged use. Preliminary economic evaluation has indicated a savings in construction cost over that of conventional concrete by the use of PIC. ) Nuclear Power Plants: To cope up with the growing power requirements for industrial purposes, many countries are resorting to nuclear power generation. The Nuclear contained vessel (Pressure vessel) is a major element, which is required to withstand high temperatures and provide shield against radiations. Another attendant problem of nuclear power generation is the containment of spent fuel rods which are radioactive over long period of time to avoid radiation hazards. At present heavy weight concrete is being used for this purpose, which is not very eff ective.PIC having high impermeability coupled with high strength and marked durability provides an answer to these problems. f) Sewage Disposal Works: It is common experience that concrete sewer pipes deteriorate due to the attack of effluents and when buried in sulphate infested soils. Further in the sewage treatment plant, concrete structures are subjected to severe attack from corrosive gases particularly in sludge digestion tanks. Polymer-impregnated concrete due to its high sulphate and acid resistance, will prove to be a suitable material in these situations. ) Impregnation of Ferro-cement products: The ferro-cement techniques of construction is being extensively used in the manufacture of boats, fishing trawlers, domestic water tanks, grain storage tanks, man hole cover, etc. , Ferro cement products are generally this (1 to 4 cms) and as such are liable to corrode. Application of polymer impregnation techniques should improve the functional efficiency of ferro-cement products . h) Water Proofing of Structures: Seepage and leakage of water through roof and bathroom slabs, it a nagging problem and has not been fully over come by the use of conventional water proofing methods.The use of polymer impregnated mortar should solve this problem. i) Industrial Applications: Concrete has been used for floor in tanneries, Chemical Factories, dairy farms and in similar situations for withstanding the chemical attack, but performance has not been very satisfactory. The newly developed PIC will provide a permanent solution for durable flooring in such situations. 12. Case Studies: Two case studies are presented as follows: 1. Properties of Fiber Reinforced Polymer Concrete studied by Marinela Barbuta and Maria Harja 2. Polymer Concrete for Structural Restoration and Corrosion Protection of Concrete Support Columns.I. Properties of Fiber Reinforced Polymer Concrete studied by Marinela Barbuta and Maria Harja The experimental results of studies regarding polymer concrete with cellulose fibers are presented. The compositions used in the present study derive from a previous one which investigated a large number of compositions using different dosages of resin and filler. The mechanical characteristics such as: compressive strength, flexural strength and split tensile strength were investigated on fiber reinforced polymer concrete made with different dosages of resin and filler, the fiber dosage being constant for all mixtures.Materials The experimental researches on polymer concrete were made by using the following materials: polymer, fly ash as filler, crushed aggregates and fiber type ARBOCEL. The polymer was type epoxy resin, called ROPOXID, made in Romania by POLICOLOR Bucharest . The hardener was type ROMANID 407, also made by POLICOLOR Bucharest. The fly ash (FA) from the power plant CET Holboca, Jassy, was added to the fine aggregates. The fly ash is an inorganic waste produced by burning pulverized coal in power stations. Fly ash consists of many small, glass-like particles ranging in size from 0. 01 to 100 ? m.Chemically FA contains oxides, hydroxides, carbonates, silicates, and sulphates of calcium, iron and aluminum. The content in carbon is given from loss ignition. FA is a heterogeneous mixture of amorphous and crystalline phases and is generally considered to be a ferroaluminosilicate element. The mineralogical, physical and chemical properties of FA depend on the nature and composition of the coal, conditions of combustion, type of emission control devices, storage and evacuation methods. Storage methods may affect weathering rates, especially under humid conditions where soluble constituents may be leached.The principal characteristics of FA are: colour gray to black, function of carbon unburned, particles sizes between 0. 01 to 100 ? m; the shape of particles is spherical, specific surface is between 4,800. . . 5,200, the density is between 2,400 and 2,550 kg/m3 [ The aggregates were used in two sorts: 0. . . 4 mm and 4. . . 8 mm, with continuous granulosity, obtained from crushed river gravel by S. C. EMBERON SRL Jassy. The ARBOCEL fibers are natural cellulose fibers, produced by J. Rettenmaier & S? ohne GMBH. ARBOCEL is produced from cellulose in various qualities (fiber lengths, thicknesses, purities, etc. The properties of ARBOCEL cellulose fibers are: mean fiber length of 10 ? m, completely safe, insoluble in water and organic solvents, resistant to dilute acids and bases. The fiber was used in proportion of 3% from the mass of resin plus the hardener. Experimental Samples For the study of polymer concrete properties nine compositions (BPFF) were prepared in the experimental program (Table 1). [pic] The polymer concrete with different compositions as is given in Table 1, was prepared by mixing firstly the resin with hardener, then after complete homogenization the fibers were introduced in the mixture as shown in fig below [pic] Fig 1. Cellulose fiber mixing with resin. The fly ash w as added to the mix of aggregates and the resin and aggregates were mixed by the mechanical mixer. After complete mixing, the polymer concrete was poured in formworks. For each composition the density was determined. The following mechanical characteristics were experimentally tested: compressive strength on cube sample of 70. 7 mm sizes, flexural strength and split tensile strength on prismatic samples of sizes 210? 70? 70 mm, according to standard prescriptions. [pic] Fig. 2. – Samples of polymer concrete with fibers. Results and DiscussionsAccording to EN 12390/2001 the mechanical characteristics of polymer concrete with cellulose fiber, experimentally determined namely: compressivestrength (fc), flexural strength (fti) and split tensile strength (ftd) are given in Table below . [pic] From the experimental results the following observations can be made: a) The values of compressive strengths for polymer concrete with fibers (Fig. 3) vary between 62. 62 MPa (for BPFF7) and 46. 41 MPa (for BPFF2). Fig. 3. – Variation of compressive strength for polymer concrete with fiber. [pic] Fig. 3. – Variation of compressive strength for polymer concrete with fiber. ) With the increasing of resin and fly ash dosage the compressive strengths increase (Figs. 4 and 5). [pic] Compressive strength, MPa Fig. 4. – Variation of compressive strength for polymer concrete with fiber vs. the resin content, for 6. 4% FA. [pic] Fig. 5. – Variation of compressive strength for polymer concrete with fiber vs. the FA content, for 12. 4% resin. d) The values of flexure strengths for polymer concrete with fibers (Fig. 6)vary between 17. 57 MPa (for BPFF9) and 13. 55 MPa (for BPFF8), so, the decrease of resin dosage results in the increase of flexure strength. pic] Fig. 6. – Variation of flexural strength for polymer concrete with fiber. [pic] [pic] Fig. 7. – Variation of split tensile strength for polymer concrete with fiber: a – vs. t he resin content; b – vs. the sample number. d) The values of split tensile strengths for polymer concrete with fibers (Fig. 7) vary between 6. 94 MPa (for BPFF9) and 4. 29 N/mm2 (for BFF7); the increase of resin dosage results in the increase of split tensile strength. The experimental researches lead to the following observations: a) For the maximum epoxy resin dosage (16. %) compressive strength is reduced near minimum value, the flexure strength is medium, but the split tensile strength has high value. b) For the minimum epoxy resin dosage (12. 4%) compressive strength is reduced under the medium value, the flexure strength is also reduced, and the split tensile strength has value over the medium. c) For the maximum fly ash dosage (12. 8%) compressive strength and flexurestrength are medium, but the split tensile strength is near the highest value. d) For the minimum fly ash dosage (6. 4%) compressive strength and flexure strength are under the medium and the split tensil e strength is near medium value. ) For the same dosage of epoxy resin the maximum compressive strength and flexure strength were obtained for maximum fly ash dosage. It results that for increasing the compressive strength and flexure strength at same dosage of resin and fiber, it must be used the maximum dosage of fly ash. f) For the split tensile strength it must be used a medium fly ash dosage; The values of mechanical characteristics of polymer concrete are smaller then those of mechanical characteristics obtained for polymer concrete with silica fume and polymer concrete with fly ash . The author concluded that The experimental researches concerning the polymer concrete had investigatedthe mechanical characteristics of epoxy polymer concrete prepared with cellulose fibers and fly ash as filler. †¢ When the same dosage of cellulose fibers is used, the content of resin must be increased. Also for obtaining good mechanical properties the filler is used with higher dosages. â⠂¬ ¢ The experimental values of mechanical strengths for polymer concrete with cellulose fibers were smaller then that for polymer concrete without fibers. This type of fibers is not a good choice for polymer concrete reinforcement. II.Polymer Concrete for Structural Restoration and Corrosion Protection of Concrete Support Columns by David E. Snider and Heather M. Ramsey of Sauereisen Inc. A large copper mine and refinery in the western United States had a dilemma. Their cell house, which contains over 1,500 cells, each holding more than 20,000 gallons of electrolyte, had experienced severe corrosion and structural degradation of the support columns for the tanks. These columns support the cells in their solvent extraction and electrowinning process. This process entails immersion of a stainless steel cathode or â€Å"starter plate† into the electrolyte.Pure copper is deposited onto the starter plate during this 10-day digestion process. The collected copper is then further r efined at a separate location. Over time, highly acidic leakage from the cells had corroded the support columns to the point that their ability to adequately withstand the imposed load was in doubt. Additionally, the refinery desired to upgrade the facility’s ability to withstand seismic activity. The leakage, primarily copper sulfate and 25% sulfuric acid at a pH of 1. 0 or less, corroded not only the concrete but more significantly the reinforcement bar (rebar) encased in the concrete.Corrosion of the rebar resulted in an increase of internal pressure due to expansion of the corrosion products, therefore putting the concrete in high tensile stress. The direct effect of this stress was cracking and spalling of the concrete. Figure 1 shows a typical degradated column requiring restoration. [pic] The original construction of the columns used the rebar spaced 6-inches on center vertically and 18-inches on center horizontally. The refinery’s standard repair procedure was to remove corrosion products from the concrete and steel and then to top them with a polymer-modified portland-cement mortar.This standard repair method requires two (2) to three (3) days per column, and although temporarily affective, did not meet the company’s desire for a long-term solution. They decided upon a new approach using a polymer concrete (PC), which is a bisphenol A based-epoxy. This material is designed for maximum flowability, mechanical properties and chemical resistance. The PC repair system utilizes the polymer concrete for encapsulation, chemical protection, mechanical support and resistance to physical abuse. Figures 2 illustrates the method by which the stainless steel rebar was attached to the columns after surface-preparation.Stainless steel rebar was imbedded into the concrete floor using an epoxy mortar. Channels were saw-cut vertically in the concrete column. These channels provided a recess into which the rebar was bent and then secured into place with the epoxy mortar. Grouting of the rebar with this high strength epoxy mortar also served to provide tensile stress relief. By lowering stress relief, corrosion rates are reduced. [pic] Figure 2. Stainless steel rebar bent and grouted into the channels. To further ensure structural integrity and to upgrade seismic capabilities, the company chose to use fiberglass reinforcement (FRP) strips and wraps nder the PC. The strips were installed vertically on the columns and a fiberglass fabric was wrapped around the columns horizontally. The columns were formed and the polymer concrete was poured into place completely encapsulating the columns, the rebar and the FRP. This method required two (2) days per column. To date, 75 columns have been repaired using this method. Figures 3 and 4 show the forming and pouring of the PC. Figure 5 shows the PC after the form has been removed and the FRP that was applied to the columns. [pic] Figure 3. The forms placed around the column. . [pic] As me ntioned earlier, an important property of the PC is the flowability. The test for this property is ASTM C-143 and measures the â€Å"slump† of the polymer concrete. (Figure 6). A slump of 6 inches is considered to be flowable. This particular polymer concrete exhibits a slump of 8-inches, which is very flowable. Figures 6, 7 and 8 illustrate the flowability of the polymer concrete mixture. Table 1 lists some of the other physical properties of the polymer concrete used on this repair that were important considerations. [pic] Property at 7-days Value Property at 7- Days | Value | |Density |135 pounds/cft (2. 2gm/sq. cm) | |Compressive Strength |12,000 psi (84. 4 N/sq mm) | |Flexural Strength |3,000 psi (21. 1 N/ Sq. mm) | |Modulus of Elasticity |1. 08x 10(6)psi 7600 N/Sq mm | |Shrinkage` |0. 9 % | |Tensile Strength |2,400 psi (16. 9 N/Sq. mm) | The PC is roughly three times as strong as a portland cement mix (about 4,000 psi (281 kg / sq. cm. 28. 1 N/sq mm)) and is not chemic ally affected by the electrolyte. These properties make it an ideal product for the column restoration. As expected, none of the 75 columns repaired to date have exhibited any signs of failure and have required no maintenance since the repair program commenced in early 2007.Coatings will typically have a service life of 8 to 15 years depending upon the exposure and physical abuse. However, in this case, typical service life of coatings was six months. Their service life is also affected and somewhat limited as a result of application thickness. Coatings are generally applied at thicknesses ranging from a few mils up to a few hundred mils. Polymer concretes, however, are applied at a minimum thickness of 1 inch and may be applied as thick as 18 inches. The thickness of barrier coatings determines the overall permeability, which is a measure of water vapor’s ability to pass through a material.If the coating is less than 250 mils, the method used to determine permeability is bas ed on the water-vapor transmission (WVT) test ASTM E-96 or ASTM D-1653. Permeance is calculated from WVT. Permeability is obtained by multiplying permeance by thickness. A permeability of 10-8 (1. 49 x 10- 17 grams/Pa†¢s†¢m) or less is generally considered to provide a good barrier coating. Also due to the thickness, and other considerations, the service life of a polymer concrete is longer and requires far less maintenance. Experience with PCs by this manufacturer has shown no failures after 15 years of service.Laboratory evaluations coupled with field observations indicate the service life of PCs to be typically greater than 25 years. Figure 9 illustrates the completed column, including a protective topcoat for the FRP reinforced concrete. Although not needed for functionality, the topcoat was extended over the PC for aesthetics and coating integrity. [pic] Figure 9. Completed column repair. Many users of polymer concretes will entirely replace portland concrete with a f ull thickness of the polymer concrete. This is particularly true when extended downtimes are prohibitive. The lengthy cure time for standard portland based ement prior to receiving a protective coating is unacceptable for many facilities. After placement, polymer concretes may be placed into full chemical service after a 24-hour cure. Furthermore, with the strengths achieved with PC, it is usually possible to reduce the overall thickness to about ? of that commonly used with portland concretes. Typical thicknesses for PCs range from 1-inch to 4-inches. Polymer concretes may be engineered, formed and placed in the same manner that one would employ with a portland concrete structure. They also are reinforced in the same manner as portland concretes.Polymer concrete thicknesses are typically much less than that of the Portland concrete, therefore smaller diameter rebar is often used. At a thickness of 1 inch, one would use lesser thick rebar instead of a reasonably higher thick rebar c ommonly found with portland concrete constructions. Due to the ease of installation, the facility’s local preferred contractor was able to perform the work. The author concluded that Polymer concretes, which do not contain portland cement, have demonstrated tenacity as a protective barrier material in this difficult application and many others.This application required corrosion protection from a severely aggressive electrolyte, as well as protection from physical abuse. Other essential requirements were a system affording both ease of use and a quick turnaround time. Polymer concretes are also proving to be cost effective alternatives to using portland cement-based concretes with chemical-resistant topcoats for corrosion protection. The cost of maintenance for polymer concretes per year of service life is significantly less than that of concrete with applied barrier coatings, which may require multiple re-applications over the same number of years of service.Conclusion: 1. T he major factor that has been responsible for the extensive use of polymer-based materials in civil engineering is their advantages, viz . increased tensile strength, compressive strength, freeze-thaw durability, and decreased water permeability to a negligible value. 2. Owing to its excellent resistance to chemical attack i. e sulphate attack, acidic attack, saline water, radiation from nuclear substances polymer concrete has great potential over Portland cement for the design of structures in such industries, desalination plants, nuclear plants, underwater structures, overlays in bridge decks. . There are many type of application of repairing material available such as grout, motar, concrete, sprayed concrete and cement based material. Among these, resin based materials are performed much better than the others. 4. The cost of maintenance for polymer concretes per year of service life is significantly less than that of concrete with applied barrier coatings, which may require mult iple re-applications over the same number of years of service. 5. Extended use of pre stressed elements could be permitted with the reduced permeability possible. 6.The incorporation of dyes with the plastics used for polymerization opens another aesthetic aspect of concern to civil engineers and architects, as does the potential size decrease for greater span/depth ratios. 7. The only barrier to be focussed on is its higher cost in comparison to OPC and further research for economic production of polymer concrete would help to overcome this problem. References 1. â€Å"Properties of Fiber Reinforced Polymner Concrete†, Msrinela Barbuta and Maria Harja, Univerisity Technica, Tomul LIV(LVIII) Fasc,3, 2008, Constructii Architectura. . Muttukumar M. , Mohan D. J. , Polymer Res. 12, (2004) 3. â€Å"Polymer Concrete for Structural Restoration and corrosion protection of Concrete Support Columns† of David E. Snider and Heather M. Samsey of Sauereisen Inc. , 4. â€Å"Polymer concrete and its potential in the Construction industry†, Luke M. Snell,1 H. Aldridge Gillespie, and Robert Y. Nelson, Department of Civil Engineering, West Virginia University, Morgantown, West Virginia, and School of Civil Engineering and Environmental Science, University of Oklahoma Norman

Examine, analyze and explain violent childrens programming from a Research Paper

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EU law - Essay Example All of these rights were previously established in the EC Treaty. Also relevant in relation to citizens’ rights is article of the European Charter of Fundamental Rights, which binds the institutions, bodies and the Member States when they implement EU law. This paper examines the effects of Lisbon treaty. An overview of other treaties Before the signing the Lisbon treaty, the European Union entered into different treaties that lead to the Lisbon one. This section outlines these treaties. The European Coal and Steel Community treaty (ECSC) (Treaty of Paris): this treaty was signed in 1951 in Paris creating regional institutions meant to manage trade of coal and steel. Members who signed this treat included France, Italy, West Germany, Netherlands, Belgium and Luxembourg (Chalmers, 2006). European Economic Community (EEC) Treaty (treaty of Rome): This was signed in 1957 by the same countries that formed treaty of Paris. On the same day, another treaty European Atomic Energy Comm unity (the EURATOM Treaty), was signed by the six countries. Other important treaties that followed included. European Communities (the Merger Treaty of 1965): This treaty merged the three previous treaties (ECSC, EURATOM and EEC) to create the European Communities, as known as the community Market, which was signed in 1967 (Chalmers, 2006). Upon the signing of this treaty, key institutions of the European Union were formed; this included the European Commission, the European Parliament, the Council of Ministers and the European Court of Justice. Single European Act: this important treaty was reached in 1987, which amended the previous three founding treaties, thus creating an â€Å"internal market† for member states; the market was implemented in 1992. The goals of this treaty included forming a single currency and creating a free market. The Treaty on European Union (the Maastricht Treaty): this was reached in 1992 but was enforced in 1993, creating the European Union, whic h was based on the European Communities. This particularly treat founded a â€Å"three pillar† system. The last treaty signed before the Lisbon treaty was the Treaty of Amsterdam, signed in 1997 that was enforced in 1999.this treaty amended and also renumbered the European Union and the European Community (Chalmers, 2006). Lisbon Treaty: provisions on Democratic Principles Democratic principles provided in the Lisbon Treaty fundamentally purposed to enhance the democratic authority of the Union in the Preamble. These new reforms mainly strengthened the role of the European Parliament, country parliaments, as well as providing for citizen’s initiatives, with an aim of increasing democratic legitimacy of the European Union. The Treaties contained provisions focused at cementing democracy in its representatives as well as their participatory dimensions by founding new participatory mechanisms, like the European citizens’ initiative, and new guides of communication and information with the European civil society. The European Parliament (EP): The Lisbon Treaty moved one step ahead in regard to the idea of representation by establishing that the European Parliament should be composed of representatives of the Union’s citizens, appointed for five years through direct universal suffrage in a free and fair secret election. According to these regulations, the European Council had to determine through accord, on the initiative of its Parliament, future composition of the latter

Presentist History Essay Example | Topics and Well Written Essays - 2500 words

Presentist History - Essay Example Even those who were already born during this period may not remember much about it. Despite this, it is clear that Americans cannot escape the foundational legacy left by the Great. At the very least, it is known that during that period, times were really bad because the Great depression is the standard by which economists, historians and journalists measure most of other potentially bad times that followed. Liberal and Conservative economists still argue over the cause of the depression but the fact remains that it happened and in the process scarred the lives of millions of Americans while at the same time changed the course of United States politics. The parallels between the Economic Crisis of 2008 and the Great Depression have been subject to many comments. The current economic crisis is believed by some economists to be as bad as the Great Depression but this point highly disputable. As economists and historians continue with their debates, the effects of the 2008 recession are still felt all around the globe. Introduction Depressions lead to large and persistent declines in economic activities of a nation. They feature a major crime whereby an economy is leveled. There are always a number suspects who possibly contributed to the depression. The most fascinating aspect of depressions is that they manage to remain a mystery. They are mysterious when looked at from the perspective of standard economics. This is so particularly in countries that are highly developed such as the United States, Britain, Australia that ideally should not have them because of their relatively efficient institutions and well functioning economies.1 This then begs the question as to what makes such economies go bad. This paper will assess the features of crises and depressions, with a focus on the Great Depression and the recent economic recession of 2008. Though these crises initially occurred in the United States, their magnitude was felt all over the world. In the United States , the effects of the systemic crisis are easily seen due to the recent political, economic, and ideological developments. Output and employment levels in the U.S. gradually fell at a great speed that had never been seen for many decades with the situation getting worse to a point that forced the government to introduce bailout plans to rescue some of the economic sectors. General Motors and Citigroup which were two of the largest corporations in the US, one a symbol of the manufacturing prowess of the US and the other the largest bank became insolvent. Policies that had previously been effective in overcoming past financial recessions and crises such as institutional bailouts and expansionary monetary policies were not capable in stemming the 2008 crisis.2 Comparisons: The Similarities It is important to note that in terms of real economic decline as measured by unemployment, real GDP or Industrial Production, the Great Recession was relatively minor. In the period between 1929 and 1933, the real GDP of the US fell by close to 30 percent. On the other hand, between 2007 and 2009 the real GDP fell by slightly over 5 percent. In 1933, unemployment in the U.S. peaked at 25 percent whereas in 2009 it was slightly above 10 percent.3 The United States Bureau of Labor Statistics places the unemployment rate at 8.2 percent as of March 2012.4 Though this rate is still high, it cannot be compared to the rate that prevailed during the 1930s. Secondly,

Non Profit Leadership Research Paper Example | Topics and Well Written Essays - 1500 words

Non Profit Leadership - Research Paper Example As per the nonprofit trend survey of 2013, nearly 69% of demand lacks to overcome the requirement of senior nonprofit leaders. There has been constant demand for the nonprofit leaders in order to provide proper staffing for the welfare of the society and to increase the source of funding. Since, the nonprofit sector have no profit generation capability and its available resources are limited thus, it is vital that leaders in this sector are more competent towards making the best possible use of the available resources with minimum wastage. Concurrently, the demand for effective resource planning, and motivating these individual engaged in the sector is extremely essential. Correspondingly, it can be argued that there is greater demand for leaders who are eligible and competent to fulfill the various requirements of the nonprofit sector. Moreover, fundraising is essential element for the successful performance of nonprofit sector. However, fundraising requires efficient planning and t heir execution in the most effective manner. Hence, it requires competent leaders who have planning as well as problem solving skills. Strategizing new initiates for the welfare of the society, educating children, assisting in eradication of poverty are general motive of nonprofit sector. Consequently, meeting those goals and objectives seeks for leaders who are capable of guiding and directing the activities of the non-profit organization. Staff retention, providing a flexible work environment, hiring staff also forms key elements for the success of non-profit sector. It can be argued without efficient and competent leaders, it is quite difficult for attaining requisite... Non Profit Leadership The leaders in any organization have significant influence on the performance of the organization as well as on its objectives. Correspondingly, the need for leaders is also ascertained to be extremely vital in the non-profit sector due to several reasons. More specifically, the non-profit sector is concerned with the welfare of the society and has limited resources. Thus, it requires efficient utilization of the available resource which seeks for competent leaders. The role of leaders in the non-profit sector can be identified to be diverse and more complex than the role of leaders in the commercial sector. Leaders in the non-profit sector are required to possess certain personality traits such as problem solving skills, planning and organizing skills, team management skills and relationship building skills among other for successful execution of various function required to meet the objectives of the non-profit organization. Furthermore, it has been identified that there are relati vely less diversity concerning with leaders in the non-profit sector as compared to business leaders. To sum up, it can be asserted that leaders in the non-profit sector are required to display proactive role in order to encourage young leaders. It is equally important to develop approach that would provide financial support to young leaders as well as to implement innovative ideas that would radically promote the goals and objectives of the non-profit organization.

Country Report Essay Example | Topics and Well Written Essays - 1750 words

Country Report - Essay Example After Japan suffered defeat in World War II, Korea was liberated and Soviet-American agreements exploited the divisions that had sprung up during the previous decades. Aggravated by old resentments, nationalistic attitudes, and the politics of the new Cold War, the Soviet-American actions further divided North and South Korea, precipitated the Korean War, and erected a lasting wall dividing a country that 50 years earlier had been united. The story of Korea is the story of a once deeply unified people that have been profoundly distanced in a world apart. The divisions that existed in Korea after Japan's defeat in World War II were the result of Japan's occupational tyranny. Divisions between the left and the political right, between capitalism and Chinese communism, the nationalists and the Japanese sympathizers, only further disappointed those that expected immediate independence after Japan's defeat. Even with these disagreements across the country, Korea may have been able to heal its wounds, find some common ground and engage in a program of unification and independence. However, the Soviets and the Americans had already dashed any hope that the Korean's may have had for unification and they were unwittingly being setup for even greater division (Gourevitch). The initial plans to turn Korea into an American-Soviet trusteeship had fallen through. In the days after the atomic bombs had been dropped, but before Japan surrendered, America already was planning out the future for Korea. While the Russians occupied the Northern Provinces and the US forces occupied the South, they were forming coalitions and governments that would be sympathetic to their respective ideologies. The Northern Provinces were primarily revolutionaries and communists led by Kim Il Sung, an anti-Japanese revolutionary (Gourevitch). By 1946, the communists were able to form a cohesive political party in the North and were able to man a small army. The South, with Seoul, had the ruling seat of government but was staffed by bureaucratic positions that were more often perceived as Japanese collaborators left behind after the occupation. Late in 1945, Dr. Syngman Rhee returned to Korea after residing outside the country during the period of Japanese imperialism. Many U.S. officials favored Rhee, a staunch anti-Communist, to form the new government. Rhee and US Occupation forces made plans to establish a separate government administration in South Korea by organizing the bureaucracy left behind by the Japanese. Rhee's newly established government set out to cripple his political opponents and destroy any possibility of a leftist uprising in anticipation of overpowering the North and gaining complete control of the unified Korea. By 1949, Rhee had imprisoned 30,000 of his political enemies, had another 70,000 imprisoned in "Guidance Camps", and by December 1949 he was arresting as many as 1,000 suspected communists per day (Cumings, 223). These dictatorial tactics were designed to maintain his power while he eliminated any remaining resistance in the South for a planned invasion of the Northern Provinces. Who started the war, and who took the first offensive action

Expropiation of Assets in Venezuela Essay Example | Topics and Well Written Essays - 1250 words

Expropiation of Assets in Venezuela - Essay Example The legal definition of expropriation is the taking away of private property in favor of the government for public use in the greater interest of the public. Any vital industry could be subject to expropriation whenever the government sees it fit to do so but this move is also very highly controversial since it runs against the sanctity and protection of private property. It runs counter to an economic principle that business enterprises is better left to investors and that government's business is to support and stay out of the way of business enterprises. It is always a subject of contention because of another issue, which is just compensation. Private property could be taken away by force of government edict, without or very little form of just compensation to the previous owners. The question of proper and correct valuation is also a very serious issue during expropriation as the investors need to get their money back. The compulsory seizure of private property could be applied to any property or to an industry considered as vital to the national interests. The state has always exercised three very important powers for it to govern effectively: police power, the power to impose taxes and the power of imminent domain. The last pertains to the right of the government to take away any property in the greater interest of public benefit, such as taking away privately-owned land to expand a road network, for example, or force people to move to a different location because of plans to create a dam and the place would soon be underwater. It is done all in the name of economic progress or for public safety. However, in the case of expropriation, it is an entirely different matter altogether. This paper argues that expropriation is clearly a wrong step. Discussion There are instances when expropriation is justified, such as during wartime condition in which the government needs to act quickly in the exigency of the situation. In this case, it is clearly justifiable to do so because the national interest is at stake. Failure to act would be the equivalent of gross negligence or the abdication to perform a public and civic duty. History is also replete with instances in which expropriation took place with most of them falling under this justifiable classification of protecting the national interest for the greater public good. An industry considered as vital to the national interests' such as the transport industry, the mining industry, the communications industry or the health industry could be expropriated but a move to do so must be justified to the public and to the investing community. Any expropriation will surely send shivers to investors who now would think twice about committing their money. The difference between the power of imminent domain and expropriation, when it is exercised by the government, is that the former is seen as lawful while the latter is unlawful. The first in stance involves a certain process to be followed, such as proper notification of the party involved and providing for just compensation. The second instance is often very abrupt and does not require the government to justify its actions of expropriating private properties. In other words, it is simply just an act of confiscation and seizure by the government. When people started living in organized society, there is an implicit agreement in the people giving up certain rights in favor of the State for the right of being government by that State for their benefit. This is necessary because without this social contract, societies would be chaotic as no one will be able to enforce laws designed for an orderly existence. However, there are also limits imposed on the State and one of the most sacred principles in the modern society is the right to own private property. It is always protected by the laws of any nation. Expropriation is controversial in the sense

Drug Abuse Essay Example for Free

Drug Abuse Essay Drug abuse has an effect on all aspects of life; overall health and wellness, family life, and the community. With there being so many different kinds of drugs the effects are endless. The effect of drug abuse does not discriminate or focus on any one person. Drug abuse can be found in any area of the world and the overall effects can be devastating to anyone involved. A person’s choice to use any kind of illegal drug or abusing prescribed medicines can have a damaging impact on their overall health and wellness. This damaging effect on addicts overall health and wellness can be both short and long term. An active addict can face many health changes and challenges throughout the time that they choose to use. There can be many short term effects that depend on exactly what drug is being abused. There are drugs that can raise your heart rate, make you hallucinate, and even dehydrate you badly. â€Å"The impact of addiction can be far reaching. Cardiovascular disease, stroke, cancer, HIV/AIDS, hepatitis, and lung disease can all be affected by drug abuse. Some of these effects occur when drugs are used at high doses or after prolonged use; however, some may occur after just one use.† An addict can face many mental health issues during their addiction that can have a devastating effect on their own life. Women substance abusers are more likely than men to have poor self-concepts (low self-esteem, guilt, self-blame) and high rates of mental health problems, such as depression, anxiety, bipolar affective disorder, suicidal ideation, psychosexual disorders, eating disorders, and Post traumatic stress disorder.† â€Å"Chronic use of some drugs of abuse can cause long-lasting changes in the brain, which may lead to paranoia, depression, aggression, and hallucinations.† The addict has a giant effect on their family and home environment. There can be many issues that a family must face when an addict is living in the home. There can be many forms of abuse in a home where there is an addict. There can be sexual abuse, financial abuse, physical abuse and emotional abuse in any home. The addiction is not responsible for the violence but can intensify and make it more common. When an addict is deep in their addiction they will often put financial responsibilities of the home off to get high instead. This can cause child neglect by no food being in home, no  electricity or heat. There can be consequences for the children living in a home with an active addict. These consequences may not show up for years until the child of the addict is grown. â€Å"The disturbed home and family setup, the inter-parental and parent-child conflict, parental neglect in large families, defective disciplinary techniques (too lax or too strict) and family disorganization ar e considered as some of the causes of drug abuse.† There is a higher risk of children of an addict growing up to become addicts themselves An addict has an effect on the community in which they live. This effect from an addict can cause problems for the entire community There is more possibility of crime and erratic behavior in the community where an active addict is living. A defining characteristic of addictive behavior is that they involve in the pursuit of short-term gratification at the expense of long-term harm When a person is under the influence of any drug they may not be fully conscious of the choices that they are making. When there is an active drug area in the community there is usually more violence and less desired living situations. When there are drugs in a common area that area becomes more prone to violence and could actually desensitize the people in the community When you have shootings, robberies, rapes, and murders in any area there will be less of a desire for anybody to want to live there. Conclusion In conclusion with their being so much drug abuse in today’s society where do we begin to help break the cycle? We have seen that the problem is a mental health issue that begins with the addict; however drug abuse has an effect on all aspects of life; overall health and wellness, family life, and the community. If we stop judging the addicts and making them feel so much shame and embarrassment, we can lift them up, encourage them and support them to better then it can change the overall hurt and damage that is being inflicted on our people and society.

Private School vs Public School Essay Example for Free

Private School vs Public School Essay Many public school facilities are impressive others are mediocre. The same is true of private schools. In the public school system, the twin engines of political support and economic revenue base are critical. In private schools the ability to attract endowments and other forms of financial support are just as critical. Private school facilities reflect the success of the schools development team and that of the school to continue to generate alumni support. Some private K-12 schools have facilities and amenities which surpass those found at many colleges and universities. Hotchkiss and Andover, for example, have libraries and athletic facilities on a par with those at Brown and Cornell. They also offer academic and sports programs which make full use of all those resources. It is hard to find comparable facilities in the public sector. They are few and far between. Public schools also reflect the economic realities of their location. Wealthy suburban schools will have more amenities than inner city schools as a rule. Think Greenwich, Connecticut versus Detroit, Michigan, for example. So, who has the edge? Lets call it a draw, all things considered. Class Size: According to the NCES report Private Schools: A Brief Portrait private schools win out on this issue. Why? Most private schools have small class sizes. One of the key points of private education is individual attention. You need student to teacher ratios of 15:1 or better to achieve that goal of individual attention. On the other hand a public system has to take almost anyone who lives within its boundaries. In public schools you will generally find much larger class sizes, sometimes exceeding 35-40 students in some inner city schools. At that point teaching rapidly degenerates into babysitting. Teaching: Public sector teachers are generally better paid. Naturally compensation varies widely depending on the local economic situation. Put another way, its cheaper living in Duluth, Minnesota than it is in San Francisco. Unfortunately low starting salaries and small annual salary increases result in low teacher retention in many public school districts. Public sector benefits have historically been excellent; however, health and pension costs have risen so dramatically since 2000 that public educators will be forced to pay or pay more for their benefits. Private school compensation tends to be somewhat lower than public. Again, much depends on the school and its financial resources. One private school benefit found especially in boarding schools is housing and meals. Private school pension schemes vary widely. Many schools use major pension providers such as TIAA-CREF Both public and private schools require their teachers to be credentialed. This usually means a degree and a teaching certificate. Private schools tend to hire teachers with advanced degrees in their subject over teachers who have an education degree. Put another way, a private school hiring a Spanish teacher will want that teacher to have a degree in Spanish language and literature as opposed to an education degree with a minor in Spanish. Budgets: Since local property taxes support the bulk of public education, the annual school budget exercise is a serious fiscal and political business. In poor communities or communities which have many voters living on fixed incomes, there is precious little room to respond to budget requests within the framework of projected tax revenue. Grants from foundations and the business community are essential to creative funding. Private schools on the other hand can raise tuition, and they also can raise significant amounts of money from a variety of development activities, including annual appeals, cultivation of alumni and alumnae, and solicitation of grants from foundations and corporations. The strong allegiance to private schools by their alumni makes the chances of fund-raising success a real possibility in most cases. Administrative Support: The bigger the bureaucracy, the harder it is to get decisions made at all, much less get them made quickly. The public education system is notorious for having antiquated work rules and bloated bureaucracies. This is as a result of union contracts and host of political considerations. Private schools on the other hand generally have a lean management structure. Every dollar spent has to come from operating income and endowment income. Those resources are finite. The other difference is that private schools rarely have teacher unions to deal with. Advantages and disadvantages: There are many advantages and disadvantages to both public and private schools. As a parent, both options must be explored and the choice must be based on what is right for each particular child. Public schools often have a larger variety of subjects available, especially when it comes to electives. However, what is learned is somewhat decided by the state because public schools need to do well on standardized testing. Private schools, on the other hand, whether parochial or private have much more freedom of choice in curriculum and can choose to make their own assessments. Because of the individualized instruction, private schools tend to do generally better on standardized testing, that is, if they choose to use it. Private schools, many times, have more demanding curricula and have a higher rate of students who go on to attend college. Public schools are larger and also have larger class sizes. Public schools also have larger student-teacher ratios. According to a web site called Public School Review, Private schools average 13 students per teacher, compared with an average of 16 students per teacher in public schools (public school review). However, public schools have certified teachers. Private schools typically have teachers who are not state-certified and who may not have expertise in their subject matter. The biggest difference between public and private schools probably is that public schools are required to educate all students. They cannot deny any student admission. On the other hand, private schools have complete control about which they accept and can kick students out much more easily. Public schools are funded by tax revenue whereas private schools are funded privately. That means private schools cost money to attend called tuition. Taxpayers pay for public schools so the payment is included in what people pay. However in private schools, the payment is upfront for students to attend. Overall, there is no one right answer for which kind of school a student attends-public or private. The decision must be made for each individual student as there are advantages and disadvantages of both. Comparisons: Private school can be more beneficial than going to a public school. Private schools focus on preparing students for the next level of education; public schools are focused on test preparations sessions. Choosing the right school system for your child has a repercussion towards their future education. In the public school system the classrooms are overcrowded with students. Each class has an average of 27 to 30 students to it, which can limit the ability of one on one interaction with the teacher. A lot of the bullying issues come from the unstructured dress codes. This can create social divide to the less fortunate kids that can’t afford all the name brand items. In public school teachers are quick to say your child needs to be on medication if they are high strung, without knowing what other forms of issues might be occurring in the home. When parents try to discipline their child at home the school seems to always try to step in. Some things should be up to the parents to handle without haven to worry about the school stepping in. In the private school system when a child enters the school for the first time he or she will start out with a minimal class size with no more than 20 students. This allows more one on one time with the teacher, it also opens up more time for activities. The private school has a very strictly enforced dress code to eliminate animosity between the students. The schools are very family oriented with parents and students being involved with school activities. Teachers and parents are held to higher standards from the private schools. Teachers are expected to continue to grow and parents are obligated to maintain discipline of their children even in their absence. The testing that takes place at private schools is called Terra Nova, and kids are tested two or three times a year. Conclusion So, who comes out on top? Public schools or private schools As you can see, there are no clear-cut answers or conclusions. Public schools have their advantages and disadvantages. Private schools offer an alternative. Which works best for you? Thats the real question which you have to answer.