缓凝剂对混凝土膨胀剂效能的影响

Effects of retarding agent on the performance of concrete expansive agent

本文研究了多糖类、有机酸及其盐类、磷酸盐3类常用缓凝剂对混凝土膨胀剂的限制膨胀率、抗压强度的影响,并研究了其对混凝土坍落度变化和拆模时间的影响。结果表明:3类缓凝剂对胶砂28d抗压强度均略有提高,多糖类缓凝剂对混凝土膨胀剂的胶砂限制膨胀率有明显降低,强度达10%~25%;有机酸类中葡萄糖酸钠、磷酸盐类缓凝剂对混凝土限制膨胀率、抗压强度均略有提高;掺0.07%葡萄糖酸钠混凝土14d限制膨胀率提高了10.7%,抗压强度提高了9.2%,对混凝土1h坍落度损失降低20mm,拆模时间影响不大,是与膨胀剂复合使用较理想的缓凝剂。

This paper mainly research three types of commonly use dretarding agent's(glucide, organic acidsand their salts, phosphate) impact of limit expansion ratio, compressive strength, and the changes of concrete slump and form removal time. The experiment results show that: Three types of the retarding agent can slightly increase the 28 days' mortar compressive strength. But glucide significantly reduce the mortar limit expansion ratio from 10% to 25%; The sodium gluconateof organic acids and phosphate not only increase concrete limite expansion ratio, but also can increase the concrete compression strength. The sodium gluconate mix in concrete by 0.07% canimprove 14 days concrete limit expansion ratio by 10.7%, concrete compressive strength by 9.2%, the one hour's loss of concrete slump reduceless than 20 mm, and with little impact on removal time. So, sodium gluconate is an appropriate retarding agent used with concrete expansive agent in concrete.