Enhancement of compressive strength of high-volume fly ash cement paste by wet grinded cement: Towards low carbon cementitious materials

Abstract

The use of high-volume fly ash (HVFA) in cement-based materials can significantly reduce the CO2 emissions. Nevertheless, slow strength development becomes the barrier for HVFA system, and the main reason is because the low alkalinity offered by Portland cement (PC) cannot efficiently activate the pozzolanic reaction of FA. In this study, wet grinding was used to process PC and obtain superfine particles, with intention to promote the hydration of PC and offer more CH for FA activation. HVFA (50% PC and 50% FA) system was designed, and 0–15% wet grinded cement (WGC) was used to replace PC. The effects of WGC on HVFA system were investigated; the CO2 emissions and costs of WGC-HVFA system were calculated. Results showed that the superfine cement with D50 = 3.17 μm was obtained by wet grinding. The compressive strength of HVFA mortars without WGC was 14.3 MPa and 33.5 MPa at 3 d and 28 d age, while 15% WGC enhanced the compressive strength of the mortars to 22.0 MPa and 46.6 MPa, respectively. In addition, CO2 emissions and costs of the HVFA system containing 15% WGC were 477 kg/t and 347.5 RMB/t, which were much lower than that of PC system. Such results proposed an innovative approach to enhance the compressive strength of HVFA system, with great potential in low carbon cementitious materials.