The Influence Law and Mechanism of C-S-H Seed on the Strength of Steam Curing Cement-based Materials

The steam curing process commonly used in the precast concrete industry has some disadvantages such as high energy consumption and easy cracking of concrete. The incorporation of seed crystals can accelerate the development of early strength of concrete and reduce the negative impact of steam curing. In this work, the effects of C-S-H seeds on the early performance of steam-cured cement materials were studied through flowability and strength tests, and then the influence mechanism was explored through hydration heat analysis, XRD characterization, and pore structure evaluation. The results show that the appropriate amount of C-S-H seed crystal can increase the fluidity of mortar by 56. 7%, shorten the final setting time of cement by 40.1%, accelerate the early hydration of cement, and significantly improve the early strength of mortar. The 12 h compressive strength increases by 125. 4%. However, it may cause an increase of gel pores at later stages. Steam curing reduces the strength-enhancing effects of C-S-H seeds, with higher curing temperatures causing greater reductions. At early stages, steam curing provides stronger early-strength effects than C-S-H seeds. Additionally, steam curing increases capillary pores, with 60 Ό steam curing causing more damage to later-stage strength than 40 Ό curing. Incorporating moderate amounts of C-S-H seeds and lowering curing temperatures can promote early strength while minimizing long-term strength loss. The findings offer valuable insights for optimizing the performance and production of cement-based materials.