Study on the macroscopic properties of phosphorus slag composite cementitious materials based on hydration perspective

Phosphorus slag (PS) is a kind of industrial waste residue, and the reuse of PS as a mineral admixture is a sustainable and efficient treatment method. In this paper, the reaction process of PS in composite paste is systematically analyzed by studying the workability, hydration kinetics, microstructure and macroscopic properties. The results show that the initial fluidity of PS composite paste decreases with the increase of PS content, and the fluidity increases in the first 2 h. Compared with inert quartz powder of the same particle size, incorporating PS delays the appearance of the exothermic hydration peak and reduces the peak value. By XRD and TGA, PS did not cause the paste to produce new hydration products. The Ca(OH)2 content of PS composite paste was always smaller than that of the quartz powder composite paste, and the content of 3 d and 28 d gel was higher than that of quartz composite paste. The pore size distribution showed that the gel pores of PS composite paste were significantly higher than the pure cement paste and the quartz powder composite paste, and the capillary pores were smaller than those of quartz powder composite paste. So, to sum up, a pozzolanic reaction followed the inhibition by PS in the early stage in the system, which promoted the hydration of the cement and promoted the densification of the microstructure and the development of strength. As a result, the strength of PS composite paste increased rapidly in the age of 3-28 d, and the resistance of chloride ion penetration was significantly improved with the increase of PS. This study provides theoretical basis and technical guidance for the application of phosphorus slag as mineral admixture in cementitious system.

Automated summary

Phosphorus slag (PS) is a sustainable and efficient treatment method as a mineral admixture in cementitious systems. In this study, the reaction process of PS in composite paste was systematically analyzed, and the results showed that incorporating PS delayed the appearance of exothermic hydration peak and increased the strength of the paste. Overall, this study provides theoretical basis and technical guidance for the application of phosphorus slag as a mineral admixture in cementitious systems.