Investigation of the changes in aggregate morphology during different aggregate abrasion/degradation tests using image analysis

Abstract

There are different tests for measuring aggregate abrasion/degradation resistance, which simulated the destruction conditions in various applications of aggregate. Although these tests have been used for a long time, the process of changing the aggregate shape after the test is still not well known. These changes could be an essential factor in the quality of aggregate materials during their life cycle and play a vital role in the simulated model of aggregate degradation. In this study, the aggregate shape properties in terms of form, angularity, and surface texture are investigated and compared before and after the AAD tests by image analysis techniques. Two common types of coarse aggregates were selected, i.e., limestone and andesite. The AAD tests include different standard test methods, i.e., Micro-Deval (MD), Los Angeles abrasion losses (LAAL), aggregate crushing value (ACV), and aggregate impact value (AIV) were conducted. The results indicated that the change of aggregate shape is based on AAD tests and rock type. The heterogeneity in the mechanism of AAD tests led to the different changes in aggregate morphology and also to opposite behavior due to rock type in texture. The changes in surface texture and angularity are very different, although changes in form have the same trend after LAAL, ACV, and AIV tests. The results showed that the shape changes of the aggregates are affected by both the test type and rock type. The behavior of ACV, AIV, and LAAL in shape changes is similar and is different from MD. The knowledge obtained from this research presents a primary step concerning the numerical modeling and quantitative evaluation of the AAD tests.