Influence of Mixing Methods on Performance of Compressive Strength for Cement Stabilized Macadam Mixture

To improve mixing uniformity of cement stabilized macadam and its compressive strength, for suspended dense mixture with 4% cement content, 7 d unconfined compressive strength and its variation coefficient from different locations in the same batch under vibratory mixing (VM) conditions were analyzed to get the reasonable mixing time, wet-mixing time, vibration frequency and mixing speed by orthogonal test method. On this bases, the comparative test of VM and conventional compulsory mixing (CM) was conducted on unconfined compressive strength of suspended dense mixture and skeleton dense mixture with the cement content of 3%, 4%, 5%, respectively. The influence of VM on compressive strength of cement stabilized macadam was analyzed. The results show that mixing parameters affect the compressive strength under vibratory condition. The most influence factor is mixing time, followed by vibration frequency and mixing speed, whilst the least effect factor is wet-mixing time. The compressive strength of the mixture increases, and its variation coefficient decreases with the increase of the mixing parameters. VM can significantly improve the strength of the mixture based on the reasonable parameters, but the strength gets less promotion by VM with the increase of cement content. The compressive strength of suspended dense mixture and skeleton dense mixture under vibratory conditions increase by 20.7% and 16.1% respectively, on average. And the variation coefficient decreases by 40%, compared with CM. The compressive strength of skeleton dense mixture under VM and CM is significantly higher than that of suspended dense mixture with the same amount of cement, but VM is more sensitive to the suspended dense type with greater promotion. © 2018, Editorial Department of China Journal of Highway and Transport. All right reserved.