新型触变剂对新拌混凝土性能影响的试验研究

Experimental study on the effect of new thixotropic agent on the performance of fresh concrete

为改善混凝土的触变性能,使新拌混凝土满足经抹坡后能较好保持抹坡形态的特殊工况和功能要求,试验研究了触变剂对新拌混凝土拌合物性能、泵送性能和屈服应力的影响。结果表明:与基准混凝土相比,掺0.5%触变剂后新拌混凝土的含气量由3.0%增大至6.1%,坍落度降低了35 mm,拌合物包裹性好,尽管坍落度有一定程度的降低,但混凝土工作性较好,未出现扒底情况;新拌混凝土拌合物的流动性、抗分层离析性能均满足泵送要求,触变剂未对新拌混凝土的泵送性能产生较大的影响;触变剂明显提高了新拌混凝土的屈服应力,这主要与在浆体中绕曲纤维状分布的触变剂形成杂乱网格,对浆体或骨料均起到束缚、限位效果有关。

In order to improve the thixotropic properties of concrete and make fresh concrete meet the special working conditions and functional requirements of the slope-slurry shape after the slope applied,the effect of the thixotropic agent on the properties,pumping performance and yield stress of the fresh concrete mixture was studied.Results showed after the addition of the thixotropic agent,the gas content of the fresh concrete was increased from 3.0%to 6.1%,the slump was reduced by 35 mm,although the slump had a certain degree of reduction,the concrete workability was better,there is no bottoming situation;the fluidity of the fresh concrete mix and the ability to resist delamination and segregation met the pumping requirements.The thixotropic agent does not have a major impact on the pumping performance of the fresh concrete.The thixotropic agent significantly increased the yield stress of the fresh concrete,which was mainly related to the formation of a chaotic grid of the thixotropic agent that is distributed in the shape of a curved fiber in the slurry.The grid is related to the binding and limiting effect on the slurry or aggregate.