Freeze-Thaw Resistance of Cement Screed with Various Supplementary Cementitious Materials

This paper describes a study of the effect of partial replacement of ordinary Portland cement (OPC) by various mineral additives in the screed mixtures. Ceramic powder, blast furnace slag and fly ash were gradually employed in increments of 12.5 wt.% up to 50 wt.% to replace OPC. The mixtures were designed to a constant consistency. The influence of mineral additives was evaluated in terms of the air content in the fresh mixtures, the compressive strength, the flexural strength and the freeze-thaw resistance and using non-destructive measurements after 28 and 90 days. The accompanied paste samples were analysed using thermogravimetry to monitor the hydration process by means of total bound water content. The decrease in the mechanical properties and the frost resistance of the mixtures with the mineral additives were recorded, because of the necessity for a larger addition of water. According to the valid standards for concrete screed related to the frost resistance, it could be concluded that maximal suitable cement replacement contents are 12.5, 37.5 and 50 wt.% for ceramic powder, fly ash and blast furnace slag, respectively. The freeze-thaw resistance of the studied materials was found to be strongly related to the content of CSH and CAH hydrates.