Assessment the polishing of local aggregates by means of skid resistance for surface pavement layer

الملخص EN

: During the entire life cycle of a pavement, highway agencies are expected to monitor and preserve an appropriate surface roughness (i.e.

texture) to facilitate friction between pavement surface and vehicle tires.

The resistance of pavement surface to sliding and skidding of the traveling vehicles is measured by skid resistance.

There is a prime importance to provide skid resistance to preserve adequate surface roughness for pavement and prove resistance to polishing due to the traffic effects.

The skidding resistance of an asphalt pavement is essentially depends on aggregate properties in the surface wearing course.

Depending on the shape, size, and gradation of aggregate in the paving mixture of the wearing surface, the skid resistance performance of the road surface varies differently with environmental and traffic operating conditions.

Field experience in Iraq has indicated that wearing surface with different aggregates differed in their skid resistance at different stages of their service life.

This research reports the findings of an experimental study for investigating the effects of aggregate properties on skidding resistance for three common types of local aggregates used in Baghdad for road construction, they are brought from Al-Nebae quarry in Salahdin governorate, Al-Sedoor quarry in Diala governorate and Chlatt quarry in Misan governorate.

However, this study was designed to characterize the polishing properties of the three types of aggregates in an attempt to explain their different skid resistance performance.

To achieve the objective of this research, Accelerated Polishing Machine is used (which it has been operated by the researcher as the first test conducted in Iraq) to produce aggregates samples of polished stone used in roads surface and to simulate actual roads conditions, and British pendulum test was employed for the study for determining the Polished Stone Value (PSV) for tested samples.

The tests are conducted at temperatures of 60±1° C (140±2° F), 40 ±1° C (104±2° F) and 20±1° C (68±2° F) and at a rotation wheel speed of 320 rpm and applied loading of 400 N.

The dry and wet conditions are employed for Pendulum test, with three traffic volume (in terms of time of testing) (1 hr, 2 hr, and 3 hr) for a nominal total of 54 tests are performed.

Finally, a set of recommendations are presented for promoting the skidding resistance performance of Iraqi pavements including changes and adding to current construction quality assurance procedures