船闸大体积混凝土抗裂性能提高试验研究

Experimental study on the improvement of cracking resistance of mass concrete in ship locks

为提升船闸大体积混凝土的抗裂性能,探究抗裂剂对混凝土综合性能的影响,研究了复掺矿物掺合料和抗裂剂条件下砂浆的水化放热、混凝土的工作性、力学性能及收缩变形,结合微观试验分析了抗裂剂对混凝土水化的影响,并进行了工程现场试验室应用。结果表明:抗裂剂能够推迟砂浆的水化放热速率峰值,降低砂浆的早期放热量和混凝土的早期强度,但对混凝土后期强度影响不大;抗裂剂能够有效补偿混凝土的收缩,在粉煤灰和矿粉双掺体系中掺入抗裂剂后,混凝土的28 d干燥收缩降低了38%;抗裂剂有效降低了水泥净浆28 d的孔隙率;该抗裂剂在工程现场试验室中应用效果良好。

In order to improve the anti-cracking performance of mass concrete in ship locks and investigate the effect of anti-cracking agent on the comprehensive performance of concrete,the hydration heat release of mortar,workability,mechanical properties and shrinkage deformation of concrete under the conditions of compounding mineral admixture and anti-cracking agent were studied,and the effect of anti-cracking agent on the hydration of concrete was analyzed by combining the paste microscopic test,and the anti-cracking agent was applied in the engineering field laboratory.The results show that the anti-cracking agent can delay the peak rate of hydration heat release of mortar and reduce the early exothermic heat of mortar and early strength of concrete,but it has little effect on the later strength of concrete.The anti-cracking agent can effectively compensate for the shrinkage of concrete.In the fly ash and mineral powder double-mixing system,after mixing anti-cracking agent,the 28 d drying shrinkage of concrete is decreased by 38%.The anti-cracking agent can reduce the 28 d porosity of cement paste.The anti-cracking agent has been applied effectively in the engineering field laboratory.