基于数字图像处理的粗集料接触分布特性

Distribution Characteristics of Coarse Aggregate Contacts Based on Digital Image Processing Technique

为了给抗车辙骨架密实型沥青混合料级配优化设计提供参考,基于沥青混合料车辙试验,对沥青混合料内部粗集料接触分布特性进行了研究。应用二维数字图像处理技术,通过3种不同类型沥青混合料的对比,研究了重复荷载下粗集料接触发展规律、各档粗集料对接触点的贡献率,以及单颗粗集料周边接触点数目分布等沥青混合料内部结构特性。结果表明:由粗集料形成较稳定骨架结构的特征主要包括无接触点的"自由"粗颗粒少、单颗集料周边接触点数目为3个以上的集料数量占总集料数量的比例较大和含有2个接触点的单颗粗集料总数量表现为峰值等;采用PG等级较高的沥青并适量增加4.75mm以上粗集料比例能有效提高沥青混合料的抗车辙性能。

To provide reference for gradation optimization design of anti-rutting skeleton dense asphalt mixture, based on rutting test of asphalt mixture, the distribution characteristics of coarse aggregate contacts in asphalt mixture were studied. By using two-dimensional digital image processing technique, the internal structure characteristics, such as the development rules of coarse aggregate contacts under repeated loads, contribution rates on contact points for every graded aggregates and contact points＇ distribution of single coarse aggregate particle, were studied through the comparison of three different types of asphalt mixtures. The results indicate that the unrestrained coarse aggregate particles are few, the number of single coarse aggregate particles with three or more contact points accounts for a larger proportion of total quantity, and the quantity of single coarse aggregate particles with two contact points is peaked, which are the major characteristics of a stable skeleton structure formed by coarse aggregates. Using high PG grade asphalt and a proper increase in coarse aggregates whose particle sizes are greater than 4.75 mm can effectively increase the rut resistance performance of asphalt mixture.