Performance study of limestone calcined clay cement (LC3) prepared using calcined phosphogypsum as a gypsum substitute

초록

In order to address the carbon emission pressure from the cement industry and the high gypsum consumption of traditional limestone calcined clay cement (LC3), this study used calcined phosphogypsum (CPG) instead of gypsum to prepare LC3. The effects of adding CPG on the macroscopic properties, microstructure, and high-temperature properties of LC3 at different mass fractions (3 %, 5 %, 7 %, and 9 %) were studied. The test results show that the addition of CPG improves the overall strength, especially the early strength. At 1 day, the compressive strength of the sample with 9 % CPG increased by approximately 310.5 % compared to that of the sample without gypsum. The MIP test results show that with the increase of CPG content, the proportion of gel pores (< 10 nm) increases, and the gel pore proportion in the LC3 sample with 9 % CPG is higher than that in the LC3 sample with 3 % CPG. High-temperature tests show that the high-temperature residual strength of the LC3 sample with CPG addition is better than that of the LC3 sample with gypsum addition. At 600 degrees C, the high-temperature residual strength of the LC3 sample with 5 % CPG decreased by 15.3 % compared to the compressive strength at 20 degrees C, while the decrease rate of the LC3 sample with 5 % gypsum was 20.4 %. The use of CPG as a substitute for gypsum in the LC3 system not only promotes the utilization of industrial solid waste but also offers new insights into the application of CPG in LC3.

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