Phase evolution and pulverization mechanism of self-pulverizing carbonatable clinkers

This paper investigates the phase evolution and pulverization mechanism of a self-pulverizing carbonatable clinker (SPCC) with a variety of raw material compositions. The particle size, mineral phases, and microstructure of SPCC, produced by sintering at 1400 degrees C for 3 h, were systematically studied by laser particle size testing, XRD/QXRD and SEM/EDS. Results show that clinkers sintered by raw materials with low-Ca/low-Al (Ca/Si < 1.6; Al2O3 < 10 wt.%) or high-Ca/medium-Al (Ca/Si > 2.6; Al2O3 approximate to 10 wt.%) are non-pulverized after cooling. The mineral phases of C(2)AS, CA, and C(12)A(7) are considered to facilitate clinker pulverization at low gamma-C2S contents. With the increase of Al2O3 content in raw materials, SPCC is refined in particle size, accompanied by the significant decrease in the content of calcium silicates. Based on the results, guidelines for producing SPCC are proposed.