高效减水剂与缓凝剂复合使用的协同缓凝效应研究

Study on the synergistic retarding effects of the compounding of superplasticizer with retarders

研究了葡萄糖酸钠、糖钙、三聚磷酸钠3种缓凝剂单独使用及其与萘系、氨基磺酸盐系及聚羧酸系3种高效减水剂复合使用对水泥净浆及混凝土拌合物初凝时间和终凝时间的影响。结果表明:固定水灰比时,与单掺缓凝剂相比,缓凝剂与高效减水剂复合使用使水泥净浆、混凝土的初凝时间和终凝时间都进一步延长,存在显著的协同缓凝效应。标准稠度水泥净浆协同缓凝效应明显小于固定水灰比水泥净浆的协同缓凝效应。氨基磺酸盐高效减水剂自身具有一定缓凝性,其与缓凝剂复合时协同缓凝效应最显著。

The synergistic retarding effects of retarders compounded with superplasticizers on the initial and final setting time of cement and concrete was investigated.Three types of retarders were sodium gluconate, sodium tripolyhosphate and calcium sugar.Three types of superplastici-zers used were naphthalene-based, ammonia-based and polycarboxylicate-based superplasticizers.The results showed that a appreciable positive synergistic retarding effect could be seen when the retarder used together superplasticizers, for the fixed water-cement ratio; compared to retarders used separately,if superplasticizers used together with retarders, the initial and final setting time of cement and concrete can be further prolonged. The synergistic retarding effect for paste of normal consistency was smaller than that of fixed water-cement ratio.The ammonia-based super-plasticizers displayed retarding property.The synergistic effect of the ammonia-based superplasticizers/retarder combination was even obvious.