Metakaolin Case Study

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The concrete is the second most used product world-wide after water. The construction industry is one of the vital sectors in the nation’s economy. The concrete mainly contains ordinary Portland cement as a primary binder and production of ordinary Portland cement causes 7% of the total greenhouse gases in to the earth’s atmosphere (Malhotra 2002) and production of the ordinary Portland cement produces carbon-di-oxide in mainly two ways , they are burning of fossil fuels and the other is calcination of lime stone into lime. Quarrying of the lime stone is also another environmental degradation. The production of 1 tonne of cement needs about 1.6 tonnes of raw materials and the time taken to form the lime stone is much longer than the …show more content…
They mentioned that Metakaolin alters the pore structure in cement paste mortar and concrete and greatly improves its resistance to transportation of water and diffusion of harmful ions which lead to the degradation of the matrix
Jian-Tong Ding et al (2002) experimentally found out the effects of Metakaolin and Silica Fume on the properties of Concrete. Experimental investigation with seven concrete mixtures of 0, 5, 10, and 15% by mass replacement of cement with highreactivity Metakaolin or Silica fume, at a water cement ratio of 0.35 and a sand-toaggregate ratio of 40% was carried out. The effect of Metakaolin or Silica fume on the workability, strength, shrinkage, and resistance to chloride penetration of concrete was investigated. The incorporation of both Metakaolin and Silica fume in concrete was found to reduce the free drying shrinkage and restrained shrinkage cracking width. It is also reported that the incorporation of Metakaolin or Silica fume in concrete can reduce the chloride diffusion rate significantly. The performance of Silica fume was found to be better
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Eight mix proportions were used to produce high-performance concrete, where Metakaolin replaced either cement or sand of 10% or 20% by weight of the control cement content. The strength development of Metakaolin concrete was evaluated using the efficiency factor (k value). With regard to strength development the poor Greek Metakaolin and commercially obtained Metakaolin yielded the same results. The replacement with cement gave better results than that of sand. When Metakaolin replaced cement, its positive effect on concrete strength generally started after 2 days where as in case of sand it started only after 90 days. Both Metakaolin exhibited very high k-values (close to 3.0 at 28 days) and are characterized as highly reactive pozzolanic materials that can lead to concrete production with excellent

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