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Deficits in quarry gravels in some regions initiated the present study to examine the feasibility of using dune sand, obtained from the Sahara region, for road construction. Dune sand was used to produce compacted sand concrete, which serves as a base layer in pavement structures. An investigation of the potential sands was carried out and their physical characteristics were then evaluated. A proportioning study was developed to find the best mixture of compacted dune sand concrete with a minimum 28 day compressive strength of 15 MPa. The paper summarises the steps followed to validate the use of this new material and describes the results of all performed mechanical tests. Furthermore, the paper provides the results of fatigue tests for the retained mixture, reports its fatigue parameters, presents the results of the free shrinkage test, and finally proposes the spacing of sawn joints for compacted dune sand concrete slabs to avoid shrinkage cracking.

Rehabilitation and repair of flexible pavements produce huge amounts of reclaimed asphalt pavement (RAP) material. Using RAP in the formulation of portland cement concrete (PCC) is a technique that is part of a sustainable development approach since it reduces on the consumption of new aggregates and reuses a material that is considered as waste. This paper describes the semi-adiabatic calorimetry test performed on a concrete mix incorporating RAP material as aggregate. Results showed that the cement hydration process is not affected by the presence of asphalt coated on the surface of RAP material. Classical tests (compressive strength, flexural and indirect-tensile strengths, elastic modulus, and free-shrinkage) were also performed on PCC mixes incorporating different percentages of RAP. It was found that as the percentage of RAP increases, the PCC mechanical properties decrease. This is mainly attributed to the presence of voids in the transition zone between the asphalt-coated aggregates and the hydrated cement paste as confirmed by scanning-electron microscope images. Unrestrained shrinkage testing showed statistically insignificant change in shrinkage strain with RAP content. The strength and shrinkage results lead to conclude that as much as 40% of RAP could be incorporated into the formulation of PCC and achieve properties that are acceptable for the construction of rigid pavements.

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