Abstract
The inclusion of natural rubber latex into the Metakaoline blended concrete improves the performance properties of the concrete. Metakaoline in concrete reduces the porosity in the concrete on account of its pozzolanic reactions. Natural rubber latex modifies the concrete by improving the workability of concrete through ball bearing actions. The polymer latexes present in the natural rubber gets filled up in the pores in the paste structure thus forming a bond between the cement and aggregates in the concrete. This paper aims in presenting the optimum percentage weight natural rubber latex with Metakaoline to be made use in achieving the strengths at different water binder ratios to produce High Performance concrete. Keywords: Natural rubber latex, High performance concrete, Metakaoline, water binder ratio, Aggregate binder ratio, compressive strength, flexure strengt.. I. Introduction Use of pozzolana and polymers in concrete is in practice from long periods. The pozzolana like Metakaoline is used to replace cement to improve the concrete properties. The highly reactive Metakaoline is replaced cement in this investigation by various percentages of 5%, 10%, 15%, 20% and 30%. Along with metakaoline, the various percentage weights of natural rubber latex has also been made use. The water to binder ratio adopted is 0.3%, 0.325%, 0.35%, 0.375%, 0.4%. The use of super plasticizer is made to achieve the workability. The concept of using water binder ratio and compacting the concrete to minimize voids, making use of mineral admixtures will result in the type of concrete called High Performance Concrete. This paper presents the details of experimental results, incorporating natural rubber latex and Metakaoline based high performance concrete. High performance concrete now a day is essential in the construction of high rise buildings and the type of construction like nuclear power plants. The inclusion of natural rubber latex in the concrete makes the concrete workable under lower water to binder ratios .This is interpreted in terms of improved consistency due to the ball bearing action of polymer particles.Tateyashiki, et al (1) proved by Zeta- potential that the consistency or fluidity is due to the ball bearing action of the polymer particles among cement particles. Ohama, Yashiko (2) in their literature opined that there is a noticeable increase in the tensile and flexure strengths but not many improvements in the compressive strengths of latex modified concrete. Metakaoline is an artificial pozzolana produced by burning kaolinite clay with in a specific temperature range between 650⁰-800⁰C.The production processes is controlled to obtain higher purity and reactivity. Metakaoline comprises of Silica and alumina that react with calcium hydroxide formed during hydration of cement. Metakaoline reduces the Ca (OH) 2 from the cement. Thus results in the formation of Calcium hydro Silicate and calcium alumino silicate which in turn is responsible in improving the strength. Wild et al (3) reported the results on strength development of concrete, where cement was partially replaced with Metakaoline. According to Wild the relative strength of concrete containing Metakaoline was found to increase with the increase in curing time. S.Wild, J.M.Khatib (4) in their report has mentioned that partial replacement by ultra-fine solids results in a reduction in the strength of pastes but an increase in the strength of concrete due to an improved transition zone. Considering the useful properties of MK (Metakaoline) and NRL (natural rubber latex) it has been planned to make use of these materials in this investigation.
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