EROSION OF SUBBASE MATERIALS UNDER RIGID PAVEMENTS

Abstract

Pumping is the major cause of rigid pavement failure. Pumping has been a problem since the 1940s. Stabilized materials have been used in an attempt to prevent pumping. However, these materials did not eliminate pumping or faulting, since they are subject to surface erosion. An understanding and characterization of the sur­face erosion of subbase and shoulder materials are important in pavement design, rehabilita­tion, and economic evaluation. Limited research has been conducted to investigate the erosion of subbase and shoulder materials. Most of the erosion tests used only provide relative ero­sion values and can not be correlated with shear stresses induced by the water in the pavement. However, the shear stresses that cause erosion can be measured in the rotational shear device. These shear stresses can be used to determine a critical shear stress for each material tested. The experimentally obtained shear stresses can be compared with the actual shear stress present underneath the pavement, The paper discusses the importance of erosion in pavement design and rehabilitation, as well as the attempts that have been made to include erosion in the design. Research in the testing of erosion of subbase and shoulder materials is further described with special emphasis on the rotational shear device.