水泥基材料中高效减水剂应用效果的检测方法

采用水泥浆体流动度、混凝土减水率、坍落度及强度增长率等指标确定了2种萘系高效减水剂的掺量，研究了二者在此掺量下对相同配比砂浆的流动度及经时损失、开裂敏感性及干湿变形的影响。结果表明：与水泥适应性均较好的2种萘系高效减水剂在各自掺量下，所配制的砂浆具有相同的初始流动度及流动度经时损失变化，但其初始开裂时间与干湿变形却存在差异，说明在评价高效减水剂的应用效果时除了检测与水泥的相容性外还应考虑其对水泥基材料收缩变形性能的影响；不同外加剂对水泥基材料体系碱度的适应能力不同，较高的碱度会增加材料的开裂敏感性。

Investigation on Appraisal Methods for Application Effect of Superplasticizer in Cement-based Materials

The dosages of two different polynaphthalene sulphonate superplasticizers(PNS) were selected according to the adaptability index including fluidity of cement paste,water-reducing ratio,and slump and strength development of concrete.On this base,it was experimental studied that the effect of two PNS on fluidity,cracking sensitivity,dry and wetting deformation of the same cement mortars.The results showed that cement mortars mixed with the two PNS had the same initial fluidity and fluidity change vs time,but took on different initial cracking time and linear deformation.This indicated that the effect of PNS on shrinkage beformation of cement-based materials should be considered when selecting high range water reducing admixtures.The results also demonstrated that the higher content of Na2SO4 in PNS(or cement) would increase the cracking sensitivity of cement-based materials besides affect the application of PNS.