Geopolymer Cements and Their Properties: A Review

Abstract

Abstract Concrete is the world's most versatile, durable and reliable construction material. Next to water, concrete is the second most used substance on earth and it requires large quantities of Portland cement. The industrial sector is the third largest source of man-made carbon dioxide emissions after the transportation sector as the major generator of carbon dioxide, which pollutes the atmosphere. Ordinary Portland cement (OPC) production produces the largest amount of carbon dioxide amongst all industrial processes. In addition to that a large amount of energy is also consumed for the cement production. The production of OPC not only consumes a huge amount of the natural resources i.e. limestone and fossil fuels but also produces almost 0.9 t of CO2 for 1t of cement clinker production. Thus, the world cement production generates 2.8 billion tons of manmade greenhouse gas annually. Hence, it is inevitable to find an alternative material to the existing most expensive, most resource and energy consuming Portland cement. Geopolymer cements are innovative binders which can be produced by the chemical action of aluminosilicate materials plenty available worldwide. They are rich in silica and alumina reacting with alkaline solution and producing aluminosilicate gel that acts as the binding material for the concrete. Geopolymers are synthesized by polycondensation reaction of geopolymeric precursor and alkali polysilicates. The paper presents data on the important engineering properties of geopolymer cements showing that these cements offer an alternative to, and potential replacement for, OPC. Geopolymer technology also has the potential to reduce global greenhouse emissions caused by OPC production. Due to the high level of mechanical properties of geopolymer cements and their environmentally beneficial technology they appear as a prospective construction material for the future.