Rainfall Effect on the Erosion of Unsealed Roads

This book aims to investigate the effect of weather change on the erosion of unsealed roads through simulations of rainfall conditions in the laboratory and producing a design graph for the generated stresses under cyclic loading. 18 large load plate tests took place where two different road samples were prepared one of the sub-bases samples was quarry fines and the other was gravel with a Kaolin clay subgrade. The soil samples were compacted in a ∅230mm 409mm height apparatus then a 3000 7000 and 10000 cyclic loading were applied at 3Hz simulating the expected traffic load. Different rainfall intensities were simulated by adding water to the samples. It has been noted that a polynomial relation developed between the percentage of fines and number of loading cycles for poorly graded sand; whereas a linear relation developed for gravelly sub-base. Not only fines were pumped from the subgrade; but also fines were developed due to the friction between the loading plate and the road surface. Finally an early model had been developed relating the deformation and percentage of generated fines to the number of loading cycles.