Improvement of Marl and Dune Sand for Highway Construction in Arid Areas

Major paris of the Easlern Protʹince of Saudi Arabia are covered with windblown dune sand which is characterized as poorly-waded soil with high permeabilitr. Also. marl. which is available in abundance in this region. has poor strength. It is usually required [0 use these materials as subgrade layers or as a backfill in base and subbase lavers o(roads and highways. Because olthe low strength characteristics of these materials and the high water table in the region. some sort of stabilization is needed to improve the characteris[ics of these materials. In this research. slow-selling emulsified asphal[ and medium-curing cutback asphalt were used [0 stabilize both marl and dune sand. Lime and Portland cement (2% and 4%) were added [0 the stabilized soils to accelera[e the curing process and [0 reduce stability loss due to water damage. It was found thaI [he stabilizing agents improlʹed ho[h shear strength and resis[ance ol the analr:ed soils to water damage. I[ was observed [hat Portland cement was more etl"Clilʹ£ʹ than lime