IMPROVEMENT OF MARL AND DUNE SAND FOR HIGHWAY CONSTRUCTION IN ARID AREAS

Major parts of the Eastern Province of Saudi Arabia are covered with w indblown dune sand which is characterized as poorly-graded soil with h igh permeability. Also, marl, which is available in abundance in this region, has poor strength. It is usually required to use these materia ls as subgrade layers or as a backfill in base and subbase lavers of r oads and highways. Because of the low strength characteristics of thes e materials and the high water table in the region, some sort of stabi lization is needed to improve the characteristics of these materials. In this research, slow-setting emulsified asphalt and medium-curing cu tback asphalt were used to stabilize both marl and dune sand. Lime and Portland cement (2% and 4%) were added to the stabilized soils to acc elerate the curing process and to reduce stability loss due to water d amage. It was found that the stabilizing agents improved both shear st rength and resistance of the analyzed soils to water damage. It was ob served that Portland cement was more effective than lime. (C) 1997 Els evier Science Ltd.