High-volume fly ash system: Concrete solution for sustainable development

The challenge for the civil engineering community in the near future will h e to realize projects in harmony with the concept of sustainable developmen t, and this involves the use of high-performance materials produced at reas onable cost with the lowest possible environmental impact. Portland cement concrete is a major construction material worldwide. Unfort unately, the production of portland cement releases large amounts of CO2 in to the atmosphere, and because this gas is a major contributor to the green house effect and the global warming of the planet, the developed countries are considering very severe regulations and limitations on the CO2 emission s. In view of the global sustainable development, if is imperative that supple mentary cementing materials be used to replace large proportions of cement in the concrete industry, and the mob available supplementary cementing mat erial worldwide is fly ash, a by-product of thermal power stations. To cons iderably increase the utilization of fly ash that ts otherwise being wasted , and to have a significant impact on the production of cement, it is neces sary to advocate the use of concrete that will incorporate large amounts of fly ash as a replacement for cement. Such concrete, however, must demonstr ate performance comparable to that of conventional portland cement concrete , and must be cost effective. In 1985, CANMET developed a concrete incorporating large volumes of fly ash that has all the attributes of high-performance concrete, that is, one tha t has excellent mechanical properties, low permeability superior durability , and that is environmentally friendly. This paper gives an overview of the properties of this type of concrete that is believed to be a very promisin g alternative for the industry seeking to meet the sustainable development objectives.