有机缓凝剂对水泥改性乳化沥青胶浆的改善效果研究

Study on the Effect of Organic Retarder on the Performance of Cement Modified Emulsified Asphalt Mastic

将适量的萘系减水剂(Naphthalene superplasticizer,NSP)加入到改性乳化沥青(Modified asphalt emulsified,MAE)中能够实现水泥和改性乳化沥青的直接拌和。当NSP的掺量为4%(质量分数,下同)时,水泥沥青胶浆(Cement asphalt mastic,CAM)工作性能不佳。本试验所使用的沥青和三种有机缓凝剂分别为:改性乳化沥青、海菜粉、聚丙烯酰胺(PAM)、葡萄糖酸钠。试验结果表明:海菜粉对CAM的改善效果最好。当海菜粉掺量为0.03%时,CAM 7 d内的强度增量比较大;28 d的抗拉强度和抗压强度最高,凝结时间最短,干缩变化幅度较小。随着海菜粉掺量的增加,CAM的抗拉强度和抗压强度有所降低。PAM由于其自身有很强的粘稠度和絮凝作用,因而对CAM的粘弹性有很大影响;当PAM掺量为0.02%时,CAM的粘度最大,坍流度最小;当PAM掺量由0.01%增加到0.03%时,CAM的粘度、干缩量和抗压强度呈现先增大后减小的规律,坍流度和凝结时间呈现先减小后增大的规律,而抗拉强度随掺量的增加而增大。葡萄糖酸钠对CAM的改善效果最差,虽然加入葡萄糖酸钠能改善CAM的流动性、粘度等非力学性质,但会引起CAM试块较大幅度的体积收缩和干缩,抗拉强度和抗压强度明显降低,凝结时间过长,试件表面出现裂缝等不良现象。

The addition of an appropriate amount of naphthalene superplasticizer(NSP)to modified asphalt emulsified(MAE)enables direct mixing of cement and modified emulsified asphalt.When the NSP content is 4%,cement asphalt mastic(CAM)does not work well.The asphalt and three organic retarders used in this test are:modified emulsified asphalt,seaweed powder,polyacrylamide(PAM),sodium gluconate.The test results show that seaweed powder has the best effect on CAM.When the dosage of seaweed powder is 0.03%,the 28 d tensile strength and compressive strength of CAM are the highest,the setting time is the shortest,the variation of dry shrinkage is small,and the intensity increment within 7 d is relatively large;with the amount of seaweed powder increased,tensile strength and compressive strength decreased.PAM has a great influence on the viscoelasticity of CAM because of its strong viscosity and flocculation.When the PAM content is 0.02%,the viscosity of CAM is the largest and the turbulence is the smallest.In the process of increasing 0.01% to 0.03%,the viscosity,dry shrinkage and compressive strength of CAM showed a first increase and then decrease,and the turbulence and condensation time showed a first change and then an increase.The tensile strength increases as the amount of the addition increases.Sodium gluconate has the worst improvement effect on CAM.Although the addition of sodium gluconate can improve the non-mechanical properties such as fluidity and viscosity of CAM,it will cause large vo-lume shrinkage and shrinkage,tensile strength and resistance of CAM test pieces.The pressure strength is obviously lowered,the setting time is too long,and cracks appear on the surface of the test piece.