The effect of aggregate type, size and polishing levels to skid resistance of chip seals

The objective of this study was to investigate skid resistance performance of chip seal samples, which were produced at laboratory conditions, with different aggregate types, sizes and polishing levels. Three different origins such as limestone, basalt and boulder and four by-products including electric arc furnace and Ferrochrome slags were supplied to prepare chip seals. Physical, mechanical and chemical properties of each aggregate were determined. Micro-Deval test device was utilized to obtain polished aggregates at different levels with five different revolutions changing from 5250 to 52,500. Following the polishing process, aggregates were sieved into four different particle sizes ranged from 4.00 to 12.50 mm to manufacture single size chip seals. The aggregate surface at certain polishing levels was monitored via scanning electron microscope. Sand patch method and British Pendulum Test method were used to measure the surface macro-textures and skid resistance performance of each chip seal sample according to ASTM E 965 and ASTM E 303, respectively. In this study, skid resistance performance of each chip seal sample was evaluated with macro and micro textures. The results showed that micro-texture is more significant feature than the macro-texture in skid resistance. The chip seal samples produced with slags show better skid resistance than those produced with natural aggregates. Dependently, utilizing slags in surface coating applications does not only ensure environmental and economic benefits, but also provides high skid resistant pavement.