Effects of construction-related factors on chip seal performance

Chip seal is an economical type of asphalt pavement that is widely used in countries such as Turkey, Australia, South Africa and New Zealand. However, unlike hot mix asphalt pavements, the performance of this type of pavement can be affected by many different parameters. Although these parameters have been identified in the literature, the extent to which each of these parameters affects the performance of chip seal has not yet been determined. The leading parameters affecting chip seal performance are those related to construction, including the adhesion capability of the aggregate used in construction, natural dust amount of the aggregate, ambient temperature during construction, bitumen temperature in the bitumen distributor tanks, time between bitumen spraying and aggregate spreading, time between aggregate spreading and rolling, time between construction stages, surface temperature during construction, aggregate and bitumen designs, in situ plate test values and per cent embedment of the aggregates. To determine the effect of these construction parameters on pavement performance, they were observed and measured on five test roads. The chip-sealed test roads were monitored for 1 year with nondestructive tests and observations to determine which construction-related parameters affect the performance of the pavement. The study results indicated that macrotexture loss is the most important deterioration factor in chip-sealed pavements; initial texture depth is also important with respect to the long-term performance of chip-sealed pavements. Rolling operations is another important factor for the performance of chip seal. If rolling operations are performed at high ambient temperatures, the per cent embedment of the aggregate will increase, causing the chip seal to deteriorate more rapidly. Consequently, the ambient temperature during the construction of chip seal is important; thus, chip seal should not be constructed at ambient temperatures lower than 30 °C or higher than 43.5 °C.

Highlight
► The paper research subject about chip seals on unbound pavements and their performances under traffic.
► Especially, construction related parameters how does affect on chip sealed pavement performance was investigated.
► Principle of the research based on nondestructive test in situ, measurements and observations.
► In this research, important construction stages were indicated for long life serviceability of chip seals on unbound pavement.