Intelligent Replaced of Natural Aggregate and Cement with Recycled Concrete Aggregate, Rice Husk Ash

Abstract

Annually a huge amount of construction and demolition (C&D) waste is generated. It becomes really harmful and posing an adverse effect to the environment, increasing waste generation have demanded the need for recycling the C&D Waste. Similarly, as cement accounts for 10% global CO2 emissions, it is imperative to reduce the embodied CO2 of concrete. Thus, the sustainability of concrete is a major issue which needs to be addressed. Ways of achieving this is to recycle concrete waste back into concrete to reduce waste and use of supplementary cementitious to reduce CO2 emissions. This research aims to take a two-pronged approach by investigating the effect of pozzolanic replacement with fixed proportion of recycle aggregates to evaluate the strength and potential structural application. In this research carried out M40 mix design and rice husk ash were substituted for cement at level of 5, 10, 15, 20% by using a fixed ratio of 10, 20,30% recycle concrete aggregate (RCA). Compression test, Split Tensile Test, Flexural Test and Rapid Chloride penetration test were conducted on specimens of Grade M40, for compression test the cube was cured for 28 days and 90 days for durability (RCPT). All RCA mixes and up to 15% RHA replacement satisfied M40 criteria at 90 days, however the 20% RHA replacement mix was close to achieving this. Thus, the finding of this study indicates the use of concrete containing 30% RCA and 15% RHA can be substantially reduce waste and embodied CO2 without compromising on strength and durability parameters.