Effect of steel grids on the durability of the road

The research is a summary of test reports. The summary is based on the the synthesis of the test results of steel grid s in test constructions. The aim of the synthesis was to define the practical benefit of the usage of steel grids concerning following matters: permanent deformations, cracks caused by fatigue, by reflection or by frost heave and longitudinal unevenness. The permanent deformations can be remarkably reduced by using steel grids in bitumen bound layers or unbound base. The depth of the rut is in average 40 - 60 % smaller in the structures with steel grid than without it. The effect of steel grid is small in structures with thich bound layers or otherwise good bearing capacity. A steel grid prevents the development of longitudinal frost cracks. Also the amount of tranverse frost cracks can be reduced by using steel grids. Steel grids delay cracks caused by fatigue or by reflection to some extent. No evidence was found to show that steel grid could mitigate the longitudinal unevenness. The recommendation is that steel grid should be installed in the unbound material.