Concrete Using Recycled Concrete Aggregates with Rice Husk Ash

Annually a huge amount of construction and demolition (C & D) waste is generated. The negative environmental, social, and economic impacts on waste disposal to landfills, increasing waste generation with the population increase and national waste policies and legislation on recycling waste, have demanded the need for "recycling the C & D waste". Similarly, as cement accounts for up to 10% of global CO2 emissions (commercial aviation industry accounts for 3%), 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 cement replacements (PCRs) to reduce CO2 emissions. This project aims to take a two pronged approach by investigating the effect of PCRs with fixed proportion of recycled aggregates for all the mixes (30% by mass) to evaluate the strength and potential structural applications. The design mix was C32/40. Both GGBS and RHA were substituted for cement at a level of 10, 20, 30, 40 and 50%. All the GGBS mixes and up to 20% RHA replacement satisfied the C32/40 criteria at 90 days.