Abstract: In order to evaluate the angularity of coarse aggregate and study its influence on the performance of the mixture, Image-pro plus digital image processing software was used to analyze the rationality of the number of aggregate samples and the placement surface. The angularity of coarse aggregate with different material sources and different processing techniques was evaluated, and on this basis, the road performance test of asphalt mixture was carried out. The results show that the angularity of coarse aggregate is closely related to the processing characteristics and material source characteristics of stone. High-strength stone can better resist crushing and wear and maintain good angularity. The multi-stage crushing process can increase the crushing surfaces of the aggregate particles and form more edges, thereby improving the angularity of the coarse aggregate. The angularity of coarse aggregate has a significant effect on the performance of AC-20 asphalt mixture. With the increase of the average angular parameters from 1.076 4 to 1.082 5,1.083 2 and 1.129 1, the dynamic stability of the mixture is increased by 12.9%, 15.8% and 55.6% respectively, and the bending strain is increased by 6.3%, 8.5% and 17.5% respectively. Improving the angularity of coarse aggregates is beneficial for enhancing the high-temperature and low-temperature performance of the mixture. However, under the same compaction work, aggregates with strong angular properties are more difficult to compact, resulting in the increase of voids and reduction of water stability of the mixture. Therefore, for asphalt mixtures with high angularity of coarse aggregates, the compaction process should be optimized during construction to achieve good compaction.

Key words: highway engineering; road performance; digital image processing technology; coarse aggregate; angularity

摘要： 为评价粗集料的棱角性并研究其对混合料性能的影响规律，利用Image-pro plus数字图像处理软件分析了集料样本数量和摆放面的合理性，对不同料源和不同加工工艺的粗集料进行了棱角性评价，并在此基础上开展了沥青混合料路用性能试验。结果表明：粗集料的棱角性与石料的加工特性和料源特性密切相关。高强度石料能更好地抵抗破碎和磨损，保持良好的棱角性；多级破碎工艺可增加集料颗粒的破碎面，形成更多棱角，从而提高粗集料的棱角性；粗集料的棱角性对AC-20沥青混合料性能有显著影响。随着平均棱角参数由1.076 4增加到1.082 5、1.083 2、 1.129 1，混合料的动稳定度分别提高了12.9%、15.8%、 55.6%，弯拉应变则分别增加了6.3%、8.5%、 17.5%；提高粗集料棱角性有利于提升混合料高温和低温性能，但相同压实功下，棱角性强的集料更难压密，导致空隙增大，降低混合料的水稳定性，因此对于粗集料棱角性较高的沥青混合料，施工中应优化压实工艺，以获得良好的压实。

关键词: 道路工程；路用性能；数字图像处理技术；粗集料；棱角性