骨架型沥青混合料粗集料颗粒接触形态变化规律

Variation of the Contact Form of Coarse Aggregate Particles in Skeleton Type Asphalt Mixture

摘要:

为了揭示骨架型沥青混合料粗集料颗粒接触形态的变化规律，提出了单位截面图像面积颗粒接触数na、单位截面图像面积颗粒接触长度la、单颗颗粒接触数npi和单颗颗粒接触长度与颗粒周长之比rpi以及它们的系统平均值ne，le等颗粒接触参数.采用相邻颗粒中较小颗粒的粒级估计搜索窗半径，并扣除边界颗粒的影响，在此基础上，对13型、20型两类多粒级(热拌沥青)混合料进行大样本接触分析试验.结果表明：随着粗集料中细组分(B)掺量(wB)的增加，13型、20型混合料的na，la均单调递增，na，la值能够反映混合料的骨架组成.newB，lewB曲线峰值位置和VCA(混合料骨架间隙率)wB曲线谷值位置一致，newB，lewB曲线峰值位置对应粗集料颗粒最紧密接触形态.不同混合料的npi分布曲线形状相似.随粗集料细组分掺量的增加，npi分布曲线峰值位置右移.当粗集料细组分掺量达60%时，粗集料颗粒达到最紧密接触形态，npi分布曲线峰值位置开始左移，粗集料粗、细组分的rpi值均达到最高.

Abstract:

Aiming at revealing the variation of the contact form of coarse aggregate particles in skeleton type asphalt mixture, some contact parameters of particles such as contact number(na) of particle per unit area of cross section of image, contact length(la) of particle per unit area of cross section of image, contact number(npi) of single particle and the ratio(rpi) of contact length to circumference of single particle and their system average values(ne, le), etc. were introduced. The radius of search window was determined by the size of smaller particle in adjacent particles, and the influence of boundary particles was excluded. On this basis, the large samples contact analysis experiments about 13 type and 20 type hot asphalt mixture(HMA) were carried out. The results show that na and la can reflect the skeleton composition of 13 type and 20 type HMA, and monotonically increase with the use level(wB) of the fine component(B) in coarse aggregate. The peak positions of curves of ne wB, le wB are consistent with the valley position of curve of VCA wB, the peak positions of curves of ne wB, le wB are closed to the most tight contact state of coarse aggregate particles.The npi distribution curves of different mixtures are similar in shape. With the increase of wB, the peak of npi distribution curve shifts to the right. When the wB is 60%, the coarse aggregate particles reach the most tight contact state, and the peak of npi distribution curve begins to shift left, the rpi values of the coarse component and fine component in coarse aggregate are all to reach the maximum.