缓凝剂对混凝土性能影响研究

Study on the effect of retarder on concrete performance

缓凝剂作为一种重要的混凝土外加剂,主要被用来延长混凝土的初凝时间,但也会对混凝土的力学性能也会产生很大的影响。分别以木钙与白糖作为缓凝剂,研究其掺量对混凝土凝结时间、坍落度以及抗压强度的影响。结果表明,随着缓凝剂掺量的增加,混凝土的初凝时间先延长后缩短,终凝时间分别延迟6 h和8 h;1 h坍落度损失减小18 mm,2 h坍落度损失减小25 mm,对控制坍落度损失有较好效果;3、7、28、60 d抗压强度均逐渐降低,但对混凝土最终强度无不良影响。

As an important concrete admixture,retarder is mainly used to prolong the initial setting time of concrete,but it will also have a great impact on the mechanical properties of concrete.Wood calcium and white sugar were used as retarders to study the effects of the amount of concrete on concrete setting time,slump and compressive strength.The results show that with the increase of retarder dosage,the initial setting time of concrete is prolonged and then shortened,and the final setting time is delayed by 6 h and 8 h respectively.The 1 h slump loss was reduced by 18 mm,and the 2 h slump loss was reduced by 25 mm.This indicates that the retarder can reduce the concrete temperature to a certain extent but has a limited effect;it has a good effect on controlling the slump loss,and the compressive strength at 3,7,28,60 d is gradually reduced,but has no adverse effect on the final strength of the concrete.