Sustainability of concrete
Sustainability can be defined as meeting the present development without depleting natural resources and without compromising the ability of future generations to meet their need. Sustainability is not limited to the construction field. It involves all aspects of life, such as civil infrastructure, energy, environment, health, and life cycle. The production of the concrete mixture will required cement, aggregates, water, and admixture. The production of these ingredients means the consumption of natural resources. The concrete mix contains about 16–20 percent cementitious materials, 6–8 percent mixing water, 60–70 percent aggregate, and 2–3 percent of admixtures by mass. Concrete is used almost in every structure built above the earth. Therefore it is considered one of the largest used materials worldwide.
The estimation of the amount of produced concrete over the globe can be done by the estimation of the amount of cement produced. Then by the knowing the approximate ratio of each ingredient of a concrete mixture, we can estimate the approximate produced amount of each ingredient over the globe. In 2007, the amount of produced cement estimated to be 2.5 billion tonnes, 1 billion tonnes of water, 10 billion tonnes of aggregates and 400 million tonnes of admixtures annually. In total, 14 billion tonnes of concrete consumed globally, which makes it a huge industry. The mining, processing, and transportation of the raw material to manufacture various concrete ingredients will consume a tremendous amount of energy, natural resources, and it will produce large quantities of co2 emissions. Therefore control measures should be taken to reduce the depletion of natural resources and the emission of co2. The sustainability of concrete can be enhanced by reducing the emission of co2, reducing the consumption of raw materials, and increasing the durability of concrete structures. Using waste material and by-products such as GGBS, micro silica, and other pozzolans will reduce the amount of cement in a concrete mixture. The reduction of cement in a concrete mixture will save the raw materials and reduce the emission of co2 resulted during the manufacturing of cement. Prolonging the service life of a concrete structure is another approach in improving the sustainability of concrete. Prolonging the service life of concrete structures will save the resources required to replace the weak structures, and it will reduce the construction waste resulted from the demolitions of old concrete structures.