Optimization of metakaolin in concrete

Abstract

In present era the development of a nation is symbolized by presence of its infrastructure. There is a huge demand for sustainable development of infrastructure in developing as well as in developed countries. Concrete which is the most versatile and used construction material on earth. Cement as one of the most important ingredients of concrete has limited raw material resources. Use of only cement as a binding material not only imposes limitation on compressive strength of concrete but also leads to excessive heat of hydration, increases potential chloride attacks, adds to cost, reduces durability of concrete and structure as a whole. The use of Portland cement (PC) in concrete has significant greenhouse gas (GHG) implications, where the manufacture of each tonne of PC generates approximately 0.9 tonnes of CO2 emissions. Along with the reduction of green house gases generation by concrete, many mechanical and physical properties of concrete can be improved by partial replacement of PC with supplementary cementing materials (SCM). Typical SCMs include fly ash, ground granulated blast furnace slag, Silica fume, ground limestone, natural pozzolans and metakaolin. Sometimes agricultural wastes such as rice husk ash, wheat straw ash and bagasse ash which are pozzolanic in nature are also used. Metakaolin is a calcined product of the clay mineral kaolinite. The experimental work carried out by replacing cementitious material with Metakaolin by 5, 10, 15 and 20 percent. The observations and behaviour of concrete mix is recorded at every stage. Important changes were noticed in workability and compressive strength of concrete at various stages (3, 7, 28 and 56 days).The results are very encouraging for using metakaolin in concrete for higher gain of strength (early age strength as well as final strength) and durability. From experiments it is clear that optimization of metakaolin produces better results in concrete.