工程现场自密实混凝土配比设计研究

Research on Proportion Design of Self-compacting Concrete(SCC) in Actual Production

针对工程现场自密实混凝土生产时工作性能降低的问题,通过坍落扩展度、混凝土搅拌等试验探讨分析了环境温度、搅拌时间、外加剂以及原材料堆放对自密实混凝土的影响。综合考察影响因素后,通过现场配制对不满足要求的自密实混凝土提出了配比调整方案,并对自密实混凝土质量控制提出了措施。研究结果表明,温度越高自密实混凝土坍落扩展度损失越快,掺入适量的缓凝剂可以阻止坍损;搅拌时间存在一临界值,需根据现场实际情况作具体调整;自密实混凝土拌合物出现离析泌水现象时,应优先调整高效减水剂的用量;露天堆放会导致砂石含水率和含泥量发生变化,从而影响混凝土拌合物的流动性能,应实行封闭式材料管理。

In order to solve the problems that the working performance of self-compacting concrete （SCC） decreased in actual production, the main affect factors including ambient temperature, mixing time, admixtures and raw material stacking on SCC were analyzed by slump spread test and mixing test. According to the actual situation of mixing, the ad-justment aiming at working performance was raised. The measures for the quality control of SCC were put forward. The re-search results indicated that the slump spread would lose quickly with the increase of temperature, which could be effec-tively prevented by the retarder. There was a critical value of the mixing time which should be adjusted according to actu-al situation. The dosage of super plasticizer needed to be adjusted to avoid segregation or bleeding. Stacking of sand and stone in open-air would make water content and mud content change which influenced the fluidity of SCC. Closed mate-rial management should be implemented.