A Study on Polymer Modified High Volume GGBFS Concrete
Abstract
This technical investigation represents a study on polymer modified high volume GGBFS concrete on providing durable and stable constructional material and increasing in utilisation of high volume of GGBFS in concrete and reduction of usage of portland cement and reduction of CO2 in the atmosphere. There was the many number of studies done on the polymer concrete, the polymer concrete is introduced in 1960’s based on the technical and practical situation in the construction industry. As considering the past history of polymer concrete and present situation of modern methods of strengthening, reparing and increasing in stability and life span civil engineering structure the technique of polymer concrete is introduced.
The high volume GGBFS concrete is one of the specific type of GGBFS concrete with lower water cementitious material ratio and at least 50% of Portland cement by mass is replaced by GGBFS. Due to lower water content, superplasticizer is essential in order to achieve the desired workability. GGBFS is used to improve workability of fresh concrete to reduce the heat of hydration, to increase durability and the strength of concrete, due to its pozzolanic activity.
In this study the GGBFS of 50% and 60% is used as the cement replacing material, SBR latex polymer, Super plasticizer of conplast-430 is used. This work is conducted to study the polymer modified high volume GGBFS concrete. Mix design is as per the high volume fly ash concrete technology best practice guidelines was used. The M30 grade concrete mix was prepared. The total number of specimens were casted 330. The 165 specimens as 50% and 165 specimens as 60% GGBFS replacement were casted. Polymer added to the concrete in the percentage of 0% to 5% in a 0.5% increment. The polymer added to the concrete with weight of the cementitious materials. The super plasticizer is added 1.2% throught the mix with weight of the cementitious materials. The higher workability is found at the 2.5% of polymer addition to the concrete. The strength of concrete is calculated at different percentages of polymers addition to the concrete. After the 28days of curing the test results shows the 2.5% of polymer and 50% of GGBFS replacement has the increase in strength as compared to 60% of GGBFS replacement for all strengths, i.e compressive strength, split tensile strength, flexural strength, shear strength, impact strength. Along with this the near surface characteristics such as water absorption and sorptivity are studied. By this study shows the percentages addition of polymer in concrete increases the strengths as compared to conventional concrete.
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Introduction
Polymer-modified concrete is the concrete made up off combining two or more materials with polymer composites, Polymermodified or polymer cement mortar (PCM) and concrete (PCC) are a category of concrete-polymer composites. Polymer modified concrete are made by partially replacing the cement in concrete by different pozzolona materials and there by hydrating binders of conventional cement mortar or concrete with polymers, i.e., polymeric admixtures, superplasticizers or cement modifiers, thereby strengthening the binding agent with the polymers. Polymer- modified or polymer cement paste, which is prepared without any aggregate, is sometimes used. Polymer concrete (PC) is a type of composite where thermoset resins binds inorganic fine aggregates or coarse aggregates instead of the water and cement binder mostly used in Portland cement concrete (PCC). Polymer concrete includes the matrix of polymers and strengthening phases having a dispersed particles. The properties of polymer determines the composites behavior of polymers, which are dependent on time, structure and temperature. These composites have some advantages compared to ordinary cement concrete such as: fast hardening, high mechanical strength and high chemical resistance. The features of polymeric concrete depend on the polymer properties, type of filler and aggregates, and the component concentrations. Its applications are continuously diversifying including the building cladding dating from 1958. Polymer concrete applications construction and repair of structures, highway pavements, bridge decks, waste water pipes and even structural and decorative construction panels. In recent years the applications include: cultured marble for counter tops, as repair material, overlays for bridge and floors, sport arenas and stadiums, laboratories, hospitals, factories; also precast polymer concrete is used for drains, underground boxes, manholes, acid tanks and cells, tunnel lining, shells, floor tiles, architectural moldings and machine tools and bases.
The blast furnace slag is a by-product of the iron manufacturing industry. Iron ore, coke and limestone are fed into the furnace and the resulting molten slag floats above the molten iron at a temperature of about 1500oC to 1600oC. The molten slag has a composition of about 30% to 40% SiO2 and about 40% CaO, which is close to the chemical composition of Portland cement. The hydraulic potential of blast furnace slag was first discovered in Germany in 1862.
Conclusion
Following conclusions may be drawn based on experimentations conducted on polymer modified high volume GGBFS concrete.
1. Higher workability may be achieved by adding 2.5% polymer in polymer modified high volume GGBFS concrete. Also the polymer concrete produced by replacing 50% cement by GGBFS show higher workability as compared to 60% replacement.
2. Better water absorption and sorptivity values may be achieved by adding 2.5% polymer in polymer modified high volume GGBFS concrete. Beyond 2.5% addition, the water absorption and soroptivity values increases. Also the polymer concrete produced by replacing 50% cement by GGBFS show better water absorption and sorptivity values as compared to 60% replacement.
3. Compressive strength of polymer modified high volume GGBFS concrete is higher at 2.5% addition of polymer. Beyond 2.5% addition, the compressive strength starts decreasing. Also it can be concluded that the compressive strength of polymer modified high volume GGBFS concrete with 50% replacement of cement by GGBFS is higher as compared to 60% replacement.
4. Tensile strength of polymer modified high volume GGBFS concrete is higher at 2.5% addition of polymer. Beyond 2.5% addition, the tensile strength starts decreasing. Also it can be concluded that the tensile strength of polymer modified high volume GGBFS concrete with 50% replacement of cement by GGBFS is higher as compared to 60% replacement.
5. Flexural strength of polymer modified high volume GGBFS concrete is higher at 2.5% addition of polymer. Beyond 2.5% addition, the flexural strength starts decreasing. Also it can be concluded that the flexural strength of polymer modified high volume GGBFS concrete with 50% replacement of cement by GGBFS is higher as compared to 60%replacement.
6. Shear strength of polymer modified high volume GGBFS concrete is higher at 2.5% addition of polymer. Beyond 2.5% addition, the shear strength starts decreasing. Also it can be concluded that the shear strength of polymer modified high volume GGBFS concrete with 50% replacement of cement by GGBFS is higher as compared to 60% replacement.
7. Impact strength of polymer modified high volume GGBFS concrete is higher at 2.5% addition of polymer. Beyond 2.5% addition, the impact strength starts decreasing. Also it can be concluded that the impact strength of polymer modified high volume GGBFS concrete with 50% replacement of cement by GGBFS is higher as compared to 60% replacement.