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Abstract Aiming at the problems of difficult control of setting time, uncoordinated development of strength and unstable volume in the later period when sulphoaluminate cement (CSA) and Portland cement (PC) are compounded. In order to explore the effect of aluminum phase composition in silicate on the hydration of PC-CSA composite system, the effects of C3A content and sulfur-aluminum ratio on the volume stability and mechanical properties of PC-CSA composite system and its mechanism were studied by adding different proportions of C3A single ore. The results show that with the increase of C3A content, the setting time of PC-CSA increases, the mechanical strength decreases and the free expansion rate increases. When the content of C3A increased by 8 %, the initial setting time and final setting time of PC-CSA system were prolonged by 36 min and 66 min respectively, the compressive strength of 28 d decreased by 8.45 MPa, and the free expansion rate of 28 d increased by 0.17 %. There is a competitive hydration relationship between C3A and C4A3S. The content of C3A will inhibit the hydration of C4A3S, increase the content of AFm, and delay the early hydration of C3S. When the hydration product AFt / C-S-H of the system is 0.15, the ratio of the two is moderate, and AFt is short and thick, with high strength and good volume stability.
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Published: 31 July 2024
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2024, Vol. 0 
