Reusing waste glass powder to improve the strength stability of cement at HTHP

Waste glass powder (WGP), as a kind of silicon-rich material, is used to replace 40 wt% oil well cement to inhibit the strength retrogression of hardened cement pastes (HCPs) at high temperature and high pressure (HTHP). The mechanical properties and microstructure of HCPs containing waste glass powder (WGP) of different particle sizes were studied. The results showed that HCPs modified by WGP exhibited greater compressive strength than those modified by silica flour (SF) at 80 degrees C x 0.1 MPa, due to the high activity of amorphous SiO2 in WGP. Compared with neat pastes, the incorporation of 325-mesh WGP or 1000-mesh WGP could effectively improve the compressive strength of HCPs at 260 degrees C x 21 MPa. Microscopic results indicated that the crystalline phases were tobermorite and xonotlite, providing great mechanical properties at HTHP, and xonotlite existed steadily after long-term curing. Mercury intrusion porosimetry results showed that, compared with neat pastes, incorporation of WGP improved the pore structure by stabilizing the total porosity of the cement. Magnesium participated in the transformation of xonotlite phase and change its microstructure. This paper provides a new way to recycle WGP and reduce the carbon dioxide generated in the production of cement.