ALKALI ACTIVATION OF INDUSTRIAL BY-PRODUCTS TO DEVELOP NEW EARTH-FRIENDLY CEMENTS

Portland cement-based products (primarily concretes) are the world's most commonly used building materials. Due to its huge production world-wide, the Portland cement industry is faced economic, energy and environmental problems (7 % of total world-wide CO2 emissions). Major international concern over how to reduce CO2 emissions has given rise, within the scientific community, to a growing interest in the development of materials and technologies able to reduce the impact of Portland cement and make construction a more sustainable industry. One of the possible alternative materials whose study and use have intensified in recent years are the so-called alkaline cements, produced by alkali activating silico-aluminous materials (natural prime materials or industrial waste (blast furnace slag, fly ash…). The aim of such research is to develop new cementitious materials similar to, or in certain respects (strength and durability) even better than, Portland cement-based concretes, i.e., more energetically and environmentally sustainable cements for use in civil engineering. Specifically, the present paper discusses the technological fundamentals for producing high quality cement using industrial by- products as prime materials (fly ash from a steam power plant, and granulated blast furnace slag). These new cements are particularly suitable for the precast industry: manufacture of railway sleepers, concrete blocks, and so on.