CREATION OF A POZZOLANIC MATERIAL FROM WASTE CALCIUM HYDROXIDE AND RECYCLED GLASS POWDER

Abstract

The use of consumer and industrial waste as supplementary cementitious materials is one solution to the development of sustainable Portland cement. This research studied the partial replacement of cement with a pozzolanic mixture of recycled soda-lime glass powder (GP) and waste calcium hydroxide (CH). The optimal weight ratio of CH and GP was selected from five ratios between 30/70 to 70/30 (CH/GP), using thermal gravimetric analysis and X-ray diffraction. It was found that CH deficient ratios contained residual glass powder, while CH rich ratios contained residual calcium hydroxide and had undesirable carbonation of the CH. The 60/40 pozzolan was selected due to the large amount of calcium silicate hydrate (C-S-H) gel that was formed, the absence of residual GP and a minimum of excess CH. Portland cement (PC) specimens with 20 to 40 wt.% replacement by the 60/40 pozzolan were characterized for porosity and compressive strength at aging times from 3 to 28 days. The PC with 20 to 40 wt.% pozzolan had slightly increased porosity due to an increased amount of unreacted water from the batch. The porosity decreased with increased aging time. The PC with 30 wt.% pozzolan had a compressive strength equal to the reference PC, but only after 7 days or longer of aging. This was likely due to the slower reaction rate of the pozzolan. The 60/40 CH/GP pozzolan appears to be a viable partial replacement for PC when used at 30 wt.%.