Modified Concrete is at the very foundation of the modern world. After water concrete is the second most used material on the planet. Concrete is globally used in the construction industry. According to an estimate, about 30bn tons of concrete are used every year in the world. This figure is increasing day by day due to increasing construction in the world. According to a report by Grand view research global construction size is expected to reach 14.7 trillion $ by 2028, Although concrete is joining the world on one side yet it has some serious emission problems on the other side.
Modified Concrete contributes to almost 8% of global greenhouse emissions. If we are going to limit climate temperature to 1.5C by the end of the century and make the climate resilient infrastructure we need to rethink about the use of concrete formation.
Basically, concrete is made up of stones, sand, cement, water, and some other additives. Production of concrete involves some steps like mixing ingredients, transportation, placement, and curing. China is the largest producer of concrete in the world, accounting for almost 60% of the world’s production. China, India, and the USA are the main producers of concrete in the world. Cement is the major ingredient of concrete. Cement is a friend and foe of concrete at the same time. Carbon dioxide is generated during the calcination of limestone in the production of cement. It is responsible for 70% of concrete emissions. In the formation of cement, clay, and limestone are cooked in a gigantic kiln which is heated up to 1400C. This heating is done with the burning of fossil fuels which is also the source of greenhouse gas emissions.
To replace cement, A Montreal-based company CARBICRETE produced a product steel slag which is a by-product during the steelmaking process. This is a binder like cement but it sequesters carbon. Through this product, they removed 55kg of Co2 per tonne of concrete whereas regular concrete is carbon positive by approximately 200kg. According to an estimate, for 1 kg of cement, there would be 1 kg of Co2. By using 1kg of steel slag, we can avoid carbon emissions by 1 kg. the cost of production is the same for both items. So, according to the claims of the company, steel slag is carbon negative. If this is applicable, then carbon emissions can be reduced to a greater extent.
By using technology, we can make the world carbon-negative. This carbon-negative theme was a highly promising development. One estimate found that decarbonizing cement would have a more profound impact on emissions than decarbonizing aviation and shipping. A study is undergoing at the University of Bradford, where green concrete is under production by using demolished waste. According to an estimate, the UK produces almost 60 to 70 million tonnes of demolished waste every year. By collecting demolish bricks, demolish glass tiles, demolish concrete, and adding certain additives they are converting this to geopolymer binder which will eliminate the use of cement.
Unfortunately, there is no one silver bullet for the concrete carbon problem but with updated technology and modified methods of structural engineering, one can hope for the best results. Sustainable infrastructure and industry are the 9th Sustainable Development Goal (SDGs). Similarly, climate Action is the 13th SDG whose purpose is to create a climate-resilient infrastructure suitable for adaptation to climate change. Modified and updated green concrete production can be helpful in this regard.
