Effects of dune sand on reduction of reflection cracking in double-layered paving systems for roads: a laboratory investigation

摘要

Many parts of Algeria are covered with windblown dune sand which is characterised as poorly-graded soil with relatively high permeability. Also, the coupling of asphalt concrete and cement bound layer is often used in pavement construction. The main purpose of this study, made of several stages, was the valorisation of dune sand in such road construction technique. Double layered samples were prepared in the laboratory with a compacted gravel cement concrete (GC) base course and an asphalt concrete (BB) surface course. GC was made by compacting a mixture of gravel, dune sand, cement and water: the cement percentage ranging from 4 to 12%. The Marshall method was used to design the upper bituminous layer. A thick anti-reflective cracking interlayer made of dune sand mixed with emulsion was also used. Twenty-five samples were prepared and tested by dynamic three-point bending tests on beams. Subsequently, results analysis was performed to quantify the influence of the dune sand interlayer on the mechanical behaviour of the system. The obtained results showed that the samples with as much as 30% of dune sand in the interlayer have sufficient mechanical performances to be used in road layers.