Abstract
The application of top-grade calcined bauxite to improve the skid resistance of pavement surface coatings increases construction costs and causes excessive tire wear. Therefore, it is necessary to investigate the polishing behavior of different grades of calcined bauxite aggregate. The polished stone value of calcined bauxite was measured after the standard polishing time and the extended polishing time. The Los Angeles (L.A.) abrasion and the crushing value, profile roughness, hardness, X-ray diffraction, and micromorphology were also tested. The results showed that the calcined bauxite above 75# (the ratio of corundum to mullite by weight, C/M > 1) satisfied the requirement of the ultra-thin friction course. Compared with basalt, the calcined bauxite above 80# (C/M > 3) has better long-term skid resistance, even though the pavement surface is subject to heavier traffic. Due to the higher cohesion of lower porosity, more hard minerals to keep the surface roughness, and less soft minerals to smooth the surface roughness, calcined bauxite with a higher corundum content has the better skid resistance. There is a power law relationship between C/M and Polished Stone Value (PSV). Considering the diminishing returns of higher-grade calcined bauxite, it is necessary to accurately select the appropriate C/M of calcined bauxite before use in pavement surface coatings.
Highlights
Adequate skid resistance of pavement is necessary to ensure traffic safety [1]
As coarse aggregates commonly used in pavement surface coatings, basalt and limestone were chosen for a comparison of polishing performance with calcined bauxite
Compared with polishing stone value (PSV) of 90# calcined bauxite, PSV of 85# calcined bauxite is decreased by 6%
Summary
Adequate skid resistance of pavement is necessary to ensure traffic safety [1]. Previously, a lot of studies have been carried out to study new functional surface layers with high skid resistance. According to the specifications in AASHTO PP 79-14, the minimum alumina content in calcined bauxite used for HSFT is 87% [7]. Higher-grade bauxite is more expensive, and excessive skid resistance of pavement can give rise to excessive tire wear. It is neither economical nor environmentally friendly to use only very-high-grade calcined bauxite in pavement engineering. To widen the scope of application in pavement engineering, lower the construction costs, and extend the lives of tires, it is necessary to understand the long-term polishing behavior of calcined bauxite for pavement surface coatings. The polishing behavior of different grades of calcined bauxite aggregate for pavement surface coatings is investigated. The influence of mineral components of calcined bauxite on long-term skid resistance is discussed
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