Laboratory Study of Macro Texture and Stone Effectiveness in Skid Resistance of Concrete Pavements

Rapid improvement in vehicle manufacturing technology has caused increases in vehicular speed, thus making ever increasing needs for improvements in vehicle break and skid resistance of road surfaces. International studies have shown increase in average speed, resulted greater damages when accidents occur. Concrete surfaces in general and road surface characteristics in particular have not neen improved in the same manner and wet skid resistance is generally low.The main aim of this research which has been carried out at Tarbiat Modares University is to evaluate the effect of concrete surface macro texture and its type, nominal size and effect of aggregate shape on skid resistance. In this research, the skid resistance is measured by using British portable skid resistance tester, commonly known as British pendulum and macro texture is measured using the sand – patch method.Skid resistance is an important factor for reduction of raod accidents. When this resistance is less than the optimum limit, special provisions should be considered for the surface areas. The best practice for controlling the skid risk is prevention. This means that during construction of the roads, it is necessary to achieve a suitable and long life skid resistance, by taking into account the principal techniques. The present research and its findings showed that the following points are of great importance:1.The diagrams 5 and 7 illustrate the fact that the skid resistance has a direct relationship to the size and shape of aggregates. Aggregates with largest sizes (4.75mm) created the highest resistance.2.Diagram 3 shows that the troweled surfaces (lacking the macro texture) have had the minimum skid resistance.3.It also shows that the macro texture developed on the surface of concrete road through harsh brush and fine aggregates with size 2.6 mm. has had the best skid resistance