CSIR researchers have found that fly ash, a by-product of the South African pulp and paper industry, can be used as a supplementary cementitious material in the production of cement concrete.
The South African pulp and paper industry is under pressure to find alternative options for managing fly ash generated by the power plants in their mills. It is estimated that fly ashly the use of FAd sludge, ls. fly ash generated in South African pulp and paper mills is as high as 1 million tons a year. These by-products are traditionally stock-piled on site, landfilled, or burned.
Fly ash disposal has major environmental and financial implications due to the increasingly stringent environmental regulations, uncertainty over disposal costs and future availability of land for waste disposal.
The conversion of fly ash into valuable products such as heat resistant geo-polymers could help the pulp and paper industry to reduce its environmental footprint and waste management costs. A typical example of heat-resistant materials is refractories used to protect metal surfaces against high temperatures in furnaces or kilns. Fly ash can be used to replacemined natural resources such as clay, which is currently being used in the manufacturing of refractories.
In investigating the valorisation of fly ash into heat-resistant geo-polymers, CSIR researchers found that it can be used in supplementary cementitious materials in the production of Portland cement concrete and in the synthesis of zeolites (often used as molecular filters in a range of industrial processes). Researchers concluded that only the use of fly ash as supplementary cementitious materials in the production of Portland cement concrete/bricks is technically and economically viable.