Steel Grids, an Efficient Way to Improve the Durability of the Pavement

Abstract

A synthesis of the test results with steel grids in trial road constructions was made in the so called STEELSYNT project. The material for this synthesis has been: the TPPT (Pavement Structures Research Programme) test constructions, the European reinforcement research programme called Reflex and some HVS test projects. HVS (Heavy Vehicle Simulator) is a mobile accelerated loading test facility. All test results both in laboratory and in field conditions showed that rutting can be remarkably reduced by using steel grids in bitumen bound layers or unbound base. In average this reduction lies between 40 - 60 %. The reinforcement works best in the cases where the bearing capacity of the pavement is low. A steel grid prevents the development of longitudinal frost cracks in the reinforced area. The longitudinal cracks usually move to the edges of the road where the grid ends. Steel grid also mitigates the transverse frost cracking by curtailing the width of the cracks and by preventing the development of small cracks. The test results showed also that steel grid delayed fatigue to some extent. The Reflex project prognoses that reflection cracking of the cement bound gravel base can be reduced 35 % by steel grids. The studies so far have not found that longitudinal unevenness could be levelled with reinforcements. Falling Weight Deflectometer is not a suitable measurement tool to quantify the improved performance of a reinforced pavement, so new methods are needed.