Concrete made from fly ash, limestone, clay hold promise as replacements for cement, says IIT Madras study

IIT Madras research shows the promise of fly ash, limestone and clay as replacements for cement in eco-friendly and cheaper concrete. Funded by the Swiss Agency for Development and Cooperation, researchers have provided clarity on the link between micro-structural development and durability performance of concrete through their investigations on concrete with ternary blended (three components) cements. This will help the construction industry produce more eco-friendly concrete than is available now, says a press release from IIT Madras.

Concrete is the most widely used construction material in the world ― 7 cubic kilometres of concrete are manufactured each year, which works to one cubic metre of concrete for every human on earth. Conventional concrete is made out of cement, fine aggregate particles such as sand and coarse aggregate particles from rock, mixed with water; this mixture hardens with time because of the reaction of cement with water.

Modern concrete, however, includes chemical and mineral additives that impart unique properties. It is common today to find cement to be a mixture of two or three different ingredients. The current research study deals with the exploration of properties of a three-component cement. The study unravels the complex nature of interactions of this three-component system involving ordinary cement, limestone powder and calcined clay, called LC3, which leads to the production of highly-durable concrete in aggressive environments such as sea water. The study provides critical insights into the structural development mechanisms with ternary blended ‘cementitious’ systems, and paves the way for effective utilisation of such ‘cementitious’ combinations to produce durable concrete, the release said.