Environmental-Friendly Concrete with Industrial and Post-Consumer By-Products

摘要

Concrete is one of the most widely used construction materials in the world. However, the production of Portland cement, an essential constituent of concrete, leads to the release of significant amount of CO_2 a greenhouse gas; one ton of Portland cement clinker production creates one ton of CO_2 and greenhouse gases (GHGs). Environmental issues will play a leading role in the sustainable development of the cement and concrete industry in this century. For example, is we run out of limestone, as it is predicted to happen in some places, then we cannot produce Portland cement and, therefore, we cannot produce concrete and all the employment associated with the concrete industry goes out-of-business. Ground limestone is sometimes interground with clinker to produce cement, reducing the needs for clinker making and calcinations. This reduces energy use in the kiln and CO_2 emissions from calcinations. A sustainable concrete structure is one that is constructed so that the total environmental impact during the entire life cycle, including during its use, is minimum. Concrete is a sustainable material because it has a very low inherent energy requirement, is produced to order with very little waste, is made from some of the most plentiful resources on earth produces on as-needed basis, has very high thermal mass, can be made with recycled materials, and is completely recyclable. Sustainable design and construction of structures have a small impact on the environment, use "green" materials embody low energy costs, have high durability and low maintenance, contain a large proportion of recycled or recyclable materials, and use less energy and resources. High performance cements and concrete can reduce the amount of cementitious materials and total volume of concrete required. Concrete must keep evolving to satisfy the increasing demands of all its users. Reuse of post-consumer wastes and industrial by-products in concrete is necessary to produce even "greener" concrete. Use of coal ash, rice-husk ash, wood ash, GGBFS, silica fume, and other similar pozzolanic materials can reduce the use of manufactured Portland cement clinker, and at the same time produce concrete that is more durable. "Greener" concrete also improves air quality, minimizes solid wastes, and leads to sustainable cement and concrete industry.