Influence of simulated desuphurised waste on the pore size distribution of cement pastes at 28 days of curing

Abstract

This paper presents some results on pore size distribution of cement paste incorporating simulated desulphurised waste (SDW) at 28 days of curing. The SDW was used in this work due to the wide variability in chemical composition of actual desulphurised waste. The SDW is a mixture (by weight) of 85% of fly ash and 15% gypsum. The cement was replaced (by weight) with 0, 10, 30 and 70% SDW. The water to binder ratio was 0.5. The binder consists of cement and SDW. After the predetermined curing period of 28 days, representative samples were taken, dried and tested for the total pore volume and pore size distribution using the mercury intrusion porosimetry technique. The intruded pore volume increases as the amount of SDW in the paste increases. Also the threshold diameter of pastes containing higher amounts of SDW increases indicating a coarser pore structure. Generally the percentage of small pores decreases with increasing amounts of SDW.