Investigation of fiber length distribution on crack resistance mechanism of basalt fiber asphalt mixture based on digital image processing technology

Abstract

Basalt fiber has been widely used to enhance the crack resistance performance of asphalt mixtures. The length of the fiber is an essential parameter to affect the reinforcement effect. However, the research on fiber length distribution (FLD) on the anti-cracking mechanism of asphalt mixtures is still limited.This study aims to present an efficient methodology considering the FLD effect for investigating the crack resistance mechanism of basalt fiber asphalt mixture (BFAM). The X-ray computed tomography (CT) and discrete element (DE) simulation techniques are used to obtain morphological parameters of the BFAM correlated with the FLD (i.e. aggregate skeleton gap size parameters). Then, three indoor cracking tests of the BFAM at low and medium temperatures (i.e. trabecular bending test, IDEAL-CT test and SCB test) are conducted to investigate the relationship between crack resistance performance and morphological parameters. Influences of FLD on the fracture property indexes of the BFAM are discussed.Results indicate that the optimal FLD for the best anti-cracking performance of the BFAM with a specific dense-graded gradation can be found by using digital image processing technology. The morphological parameter of the longest axis of the aggregate skeleton gap is identified as the optimal FLD, which can significantly improve the fracture energy and fracture property indices of the BFAM compared with other FLDs. Under the same fiber content, the fracture energy enhancement of BFAM with different FLDs varies from 7.63% to 106.87%. As for the fracture property indices, the enhancement of the εB in trabecular bending test, CTindex in IDEAL-CT test, and FI in SCB test varies from 17.42% to 39.30%, 13.00% to 162.99%, and 7.46% to 77.61%, respectively. The results demonstrate that fiber length distribution indeed impacts the cracking resistance of the BFAM. The X-ray CT and DE simulation techniques are proved to be both highly efficient approaches for seeking the optimal FLD in the BFAM.