低温养护下硫铝酸盐水泥的水化进程及强度发展

Hydration Characteristics and Strength Development of Sulphoaluminate Cement Cured at Low Temperature

研究了0、5℃和20℃养护下硫铝酸盐水泥的水化产物、水化程度及强度发展。结果表明:低温(0℃和5℃)养护延缓了硫铝酸盐水泥的水化,早期水化程度大幅减小,并出现二水石膏结晶;但2~3 d期间水化程度出现显著增长,二水石膏也被完全消耗。低温养护未阻碍水化反应的持续快速进行,也未改变水化产物的种类,但对其数量产生影响。抗压强度的发展规律与水化程度基本一致,低温养护下1 d的抗压强度显著降低,但后期增长明显,5℃养护28 d的抗压强度甚至超过20℃的。早期抗压强度的发展主要受制于水泥的水化速率和水化程度,后期的增长则更多地取决于主要水化产物的量变和微观结构的发展。

The hydrate assemblage, hydration degree and compressive strength development of calcium sulphoaluminate cement pastes cured at 0, 5 ℃ and 20 ℃ were investigated. The results indicate that the hydration process is significantly delayed by the low temperature （0 ℃ and 5 ℃） curing, decreasing the degree of hydration in the early ages. Meanwhile, formation of gypsum is detected. However, the hydration degree increases significantly during 2-3 d, along with the completely consumption of gypsum. Neither the rapid hydration process is hindered nor the hydration products are changed by low temperature curing, but the amount of hydrates is affected. Compressive strength development is basically the same with the hydration degree evolution. The compressive strength at 1 d decreases sharply at 0 ℃ and 5 ℃, but increase significantly in the later ages. The 28 d compressive strength of pastes curing at 5 ℃ even exceed that at 20 ℃. It is revealed that the development of compressive strength mainly depends on the hydration rate and degree of cement paste in the early ages, while the growth of it in the later ages more depends on the quantitative change of main hydration products and the evolution of microstructure.