USE OF BIOMASS FLY ASH FOR THE PRODUCTION OF LOW ENERGY BLENDED CALCIUM SULFOALUMINATE CEMENTS

Ordinary Portland cement (OPC) manufacture accounts for about 7% of the global anthropogenic CO2 emissions. This has pushed both cement producers and scientific community to develop new cementitious materials characterized by a production process with a reduced CO2 generation. In this regard, calcium sulfoaluminate (CSA) cements undoubtedly represent an important alternative to OPC; as matter of fact, their peculiar composition can be exploited not only for achieving considerable technical properties but also for giving a more pronounced environmentally friendly feature to their manufacturing process. However, in order to lower the high costs, mainly related to the use of bauxite in the clinker generating raw mix, and further reduce the amount of carbon dioxide associated with their production, CSA cements can be mixed with supplementary cementitious materials (SCMs) such as industrial wastes. In this paper, biomass fly ash (BFA) was employed as SCM in CSA-blended cements; it was preliminarily washed in order to reduce its alkali content (WBFA). The effect of WBFA on both hydration properties and technical behaviour of different CSA blended cements was investigated by means of X-ray diffraction analysis, thermogravimetry and mercury intrusion porosimetry as well as shrinkage/expansion and compressive strength measurements.