Suitability evaluation of calcareous fly ash as an active mineral additive to concrete

Abstract

The article presents test results concerning the possibility of applying calcareous fly ash as a II type additive in concrete composition. It has been found that domestic calcareous fly ashes are characterized by not sufficient fineness (too many coarse particles' and by large water demand. These qualities constitute a main cause of calcareous fly ash negative influence on rheological properties of concrete mixture (high wic ratio, rapid loss of consistency' and of a significant reduction of chemical admixtures performance (plasticizers, super-plasticizers and air-entraining agents'. Mechanical activation (grinding' reduces water demand and increases activation of calcareous fly ash. Hardened concrete with an addition of calcareous fly ash is distinguished by large tightness and the compressive strength comparable to the one of concrete produced on Portland cement CEM I. Properly air-entrained concrete with calcareous fly ash addition presents adequate frost resistance.