机场SMA高温变形中集料倾角变化规律

为探究机场重载下SMA(沥青玛蹄脂碎石混合料)的车辙变形特性,同时为建立沥青混合料细观模型提供数据支持,针对SMA高温变形过程中集料倾角的变化规律开展研究.采用车辙试件取芯方式,研究沥青混合料在高温及高荷载作用下集料倾角随碾压次数的变化规律.基于X-射线CT技术获取并重构了碾压前后沥青混合料的三维数字图像,提取了数字试件沿轮迹方向和垂直轮迹方向的二维图像,采用MATLAB编写图像的批量处理程序,获取二值化图像,进行集料倾角的计算和统计.结果表明:沥青混合料集料倾角的累计分布概率符合三参数威布尔分布;混合料集料倾角在0°~20°分布最多;碾压后,沿轮迹方向0°~20°区间集料倾角概率保持增大,垂直轮迹方向40°~60°区间集料倾角概率保持增大;沿轮迹方向集料倾角变化与车辙变形线性相关;掺加70#沥青的SMA集料较掺加SBS改性沥青的SMA集料倾角更易偏转.

Aggregate Angle Changes of Airport SMA Mixtures in High Temperature Deformation Process

In order to explore rut deformation characteristics of airport SMA (stone mastic asphalt) under overload, and provide data support for asphalt mixture of mesoscopic models establishing, the angle changes of aggregates in high temperature deformation process of airport SMA asphalt mixture was studied. Angle changes of aggregates in asphalt mixture under high temperature and high load was studied by the method of coring from rutting specimens. 3D digital images of asphalt mixture before and after the rolling was recorded and reconstructed based on X ray CT technology. 2D images along and vertical to the wheel track were extracted from digital specimens. MATLAB image batch processing procedure was taken to obtain binary images. Angles of aggregates were calculated statistically. Results show that the cumulative distribution of asphalt mixture aggregate angle obeys to three parameters Weibull distribution. Angles of aggregates are most in 0°20° intervals. After rolling, aggregate angles along the direction of the wheel track keep increasing in 0°20° interval, aggregate angles vertical to the direction of the wheel track keep increasing in 40°60° range. The angle changes of aggregates along the wheel track have linear relationship with rut deformation. SMA with 70# asphalt is more likely to deflect than SBS modified asphalt SMA mixture.