Abstract
Due to the arid continental climatic conditions, about 37 % of Saudi Arabia is covered by desert sands. These sands are mostly dynamic and cause environmental problems. However, these huge quantities of dune sands are considered important natural resources of fine aggregate construction materials. The studied dune sands are predominantly coarse, medium and fine sands with average percentages of 2.4, 19.97 and 76.28 %, respectively, with scarce percents of silt and clay-size particles (around 1 %). The fineness modulus (FM) values of these sands vary from 0.98 to 1.02. Therefore, it is necessary to improve their gradation and textural characters by adding well-graded, crushed fine aggregates to produce an acceptable level of gradation. Mineralogically, the studied dune sands are mainly composed of quartz (88 %), feldspars (9 %) and a negligible amount of carbonates (2.2 %). The workability and compressive strength values of both cement mortar and concrete of the studied dune sands were found to decrease abruptly at dune sand contents[ 50 %. Finally, the studied dune sands are acceptable as fine aggregates for both concrete and mortar when they do not exceed 50 % of the total volume of fine aggregates at a constant mix ratio of 2: 1: 3 (water: cement: fine aggregates) and 1: 2: 4: 6 (water: cement: fine aggregates: coarse aggregates), respectively, for cement mortar and concrete.