振动对水泥稳定碎石搅拌过程和性能的影响

为了研究振动对水泥稳定碎石搅拌过程及其性能的影响规律,通过对不同搅拌方式搅拌功率曲线的测试,结合水泥稳定碎石在搅拌过程中不同阶段的流变状态,分析振动对水泥稳定碎石搅拌过程的影响。在此基础上采用不同水泥掺量的C-B-1型和C-B-3型水泥稳定碎石混合料,开展振动搅拌与常规搅拌的对比试验,分析振动对水泥稳定碎石抗压强度、微观结构、干缩性能的影响。结果表明:水泥稳定碎石搅拌过程可根据搅拌功率变化趋势的拐点分为干拌阶段、弥散阶段、裹覆阶段和均匀阶段,混合料逐渐从弹性体转变为具有一定塑性的黏-弹性体;振动能量能减小混合料各组分间的内摩擦力,搅拌功率比常规搅拌方式低9.1%～15.2%,振动加快了各组分弥散阶段的搅拌过程,湿拌时间缩短了37.5%;与常规搅拌相比振动搅拌改善了水泥稳定碎石混合填充料的均匀性,微观结构均匀且致密,有更多的C-S-H凝胶使其抗压强度更高且强度变异系数更小;同强度标准时不同搅拌方式混合料水泥用量呈线性正相关,水泥节约量与水泥用量呈线性正相关,水泥节约率与水泥用量成反比例函数关系;振动搅拌混合料节约的水泥量随水泥用量的增加而增多;振动搅拌水泥掺量为5%的C-B-1型混合料时其平均最大干缩应变量要比常规搅拌的少20.4%,平均干缩系数少18.7%,且干缩系数变异性更小。

Influence of Vibration on Mixing Process of Cement Stabilized Macadam and Its Performance

In order to study the influence of vibration on the mixing process and performance of cement stabilized macadam, the mixing power curves of different mixing methods were tested based on the rheological behavior of cement stabilized macadam at different stages in the mixing process. On this basis, comparative tests of vibration mixing and conventional mixing were carried out using C-B-1 and C-B-3 cement stabilized macadam mixtures with different cement dosage, and the effects of vibration on the compressive strength, microstructure, and dry shrinkage properties of cement stabilized macadam were analyzed. The results show the following:The mixing process of cement stabilized macadam can be divided into the dry mixing stage, homogeneous dispersion stage of each component, coarse aggregate coating stage, and homogeneous mixing stage according to the inflection point of the changing trend of mixing power; the mixtures change from elastomer to visco-elastic body with some plasticity; the vibration force can reduce the internal friction between the components of the mixture; the mixing power is 9.1%-15.2% lower; the vibration mixing accelerates the mixing process of each component in the uniform dispersion stage; and the wet mixing time is 37.5% shorter. Compared with conventional mixing, vibration mixing improves the uniformity of the cement stabilized macadam mixture. The microstructure is uniform and dense, which causes the material to have higher compressive strength and smaller strength variability. It is concluded that there is a linear positive correlation between the cement dosage of the mixtures in different mixing methods at the same strength standard, the cement savings are linearly and positively correlated with the cement dosage, and the cement savings rate is inversely proportional to the cement dosage. The cement savings achieved by vibration mixing increases with increase in cement content in the mixture. With vibration mixing, the average maximum dry shrinkage strain of C-B-1 mixtures with 5.0% cement dosage is 20.4% less, the average dry shrinkage coefficient is 18.7% less, and the variability of dry shrinkage coefficient is smaller, compared to conventional mixing.