Study On The Adhesion Of Asphalt To Ceramisite And The Gradation Refinement Of The Asphalt Mixture Containing Ceramisite

Replacing the crushed stone with the ceramsite as aggregate of asphalt concrete can effectively save the stone resources. Ceramsite asphalt concrete pavement has better performance of anti-skid, smooth and comfort driving, low noise, light weight and low elasticity modulus. The adhesion of asphalt to ceramsite can affect the water stability and durability of asphalt concrete is poor. Further, aggregate fragmentation phenomenon will occur in the process of compaction since the incorporation of ceramsite, and result in degradation of gradation, which may affect long-term performance of asphalt concrete. In order to solve these problems, a quantitative method was used to evaluate the adhesion of the asphalt to ceramsite, and then the factors which affect the adhesion were analyzed. Later, the refinement of gradation and compaction characteristics of asphalt concrete with different ceramsite contents and compaction efforts was researched to provide guidance for the engineering practice.Firstly, a circular, gravel-type shale ceramsite and expanded clay were chosen as the research object and the basalt and granite were contrast. The experimental research on the adhesion of 70#,90# and SBS modified asphalt to the five aggregates respectively were carried on by using photoelectric colorimetry, and the adhesion rate was chosen as a quantitative characterization of the asphalt adhesion. The results showed that the adhesion of ceramsite to SBS modified bitumen is best while the adhesion of 90# asphalt is worst; the adhesion of the three asphalt to circular shale ceramsite are poor, but better than granite.Secondly, the viscosity of bitumen, alkali value and surface texture characteristics of aggregates were measured, then the impact of three factors on adhesion were also analyzed. The results showed that bitumen viscosity has important effects on the adhesion, the greater the viscosity of the bitumen is, and the better the adhesion to aggregate; the surface texture characteristics of aggregate have an important influence on the adhesion, but the impact of alkali value is much greater.Thirdly, the mixture design of ceramsite asphalt concrete was performed through Marshall Test method and getting the optimum ratio of the asphalt concrete with different ceramsite contents. The SGC were used to simulated road compaction in construction status. The analysis of aggregate fragmentation of the ceramsite asphalt concrete under different compaction work showed that with increasing ceramsite content, the degree of aggregates fragmentation and fine aggregate content increased. The gyratory compaction times has little effect on the degree of aggregate fragmentation, since the aggregate fragmentation has been completed at the initial compaction period. Fractal dimension was used to characterize the changes in gradation under different ceramsite contents and compaction times. The results showed that with the increase of the compaction times and ceramsite contents, the fractal dimension of the crushed gradation increased and the gradation became much finer.Finally, depended on the densification curve of asphalt concrete, the influence of the incorporation of ceramsite on the compaction characteristics was researched, and the results showed that with the incorporation of ceramsite, the workability and ability to resist permanent deformation of ceramsite asphalt mixture increased at first and then tend to decline, the performances of the ceramsite asphalt mixture containing 10% were the best.