外加剂对矿渣水泥混凝土收缩与早期抗裂的影响

Influence of Additives on Shrinkage and Early-age Crack Resistance of Slag Cement Concrete

选用木钠减水剂、UEA-H膨胀剂、早强剂、柠檬酸缓凝剂以常用掺量外掺入矿粉水泥中,检测其化学收缩和干缩性能,同时将各掺量的外加剂分别引入到矿渣水泥混凝土中,检测其抗压强度以及早期抗裂性能,结果表明:木钠减水剂增加矿渣水泥的早期化学收缩,也增大矿渣水泥胶砂的干缩值;UEA-H膨胀剂增加矿渣水泥的化学收缩,并能降低矿渣水泥胶砂的干缩;早强剂则在早期就大幅度增加矿渣水泥的化学收缩,对胶砂体系干缩性能影响与基准矿渣水泥体系相当;柠檬酸缓凝剂能降低矿渣水泥的化学收缩值,但会提高胶砂体系的干缩值。木钠减水剂、UEA-H膨胀剂和早强剂都能提高矿渣水泥混凝土的早期抗裂性能,其中早强剂在所选用的几种外加剂中效果最好,而缓凝剂对矿渣水泥混凝土早期抗裂性能具有不利影响。

Sodium ligninsulfonate water reducer, UEA-H expansive agent, early strength agent and citric acid retarder could be introduced into slag cement, and then chemical shrinkage and dry shrinkage of system may be tested. After slag concrete with various additives respectively can be prepared, its compressive strength and early crack resistance may be determined. The results can show that： sodium ligninsulfonate water reducer can increase early chemical shrinkage and dry shrinkage of slag cement. UEA-H expansive agent can increase chemical shrinkage and reduce dry shrinkage of slag cement. Early strength agent can substantially increase early chemical shrinkage of slag cement. Influence of early strength agent on dry shrinkage of slag cement may be similar to fundamental slag cement. Citric acid retarder can reduce chemical shrinkage of slag cement, but may improve dry shrinkage of cement system. Sodium ligninsulfonate water reducer, UEA-H expansive agent, early strength agent could improve early cracking resistance of slag concrete. In several additives improved effect of early strength agent on early cracking resistance were preferable. But citric acid retarder may have a negative effect on early cracking resistance of slag concrete.