Mortar Based on Dune Sand and Substitute Wood Sawdust: Physico-Mechanical Characterization and Relationship Between Properties in Young Age Assia Aidoud 1* , Messaouda Bencheikh 1 , Nacera Khaldi 1 , Ilyess Mouhamed Ahmed Herga 2 1 Laboratory and Department of Civil Engineering and Hydraulics, University 8 May 1945 of Guelma, BP 401, Guelma 24000, Algeria 2 Department of Civil Engineering and Hydraulics, University 8 May 1945 of Guelma, BP 401, Guelma 24000, Algeria Corresponding Author Email: aidoud.assia@univ-guelma.dz https://doi.org/10.18280/acsm.450603 ABSTRACT Received: 2 December 2021 Accepted: 27 December 2021 The South of Algeria is known for these immense sand dunes, which cover part of its territory (Sahara). The main objective of this study is the recovery of sands dune and wood waste (sawdust). The latter, which constitutes a potential source of several environmental and economic problems. The objective of this present work is to characterize the physico-mechanical properties at a young age of a dune sand-based mortar lightened by wood waste and to examine the suitability of using it for various applications in the construction of buildings. The improvement of the characteristics of these sands, which essentially formed of sand untapped to date and with the sole aim of enhancing this national sand wealth. The formulation of the mixtures is based on the substitution of dune sand by sawdust, at different weight contents 0, 10, 20 and 30%. The quantity of cement is fixed at 450 g. The results obtained show firstly that the introduction of sawdust improves the characteristics of the mixture (grain size tends to be spread out, reduction in densities), and secondly the physico-mechanical characteristics, especially at 30% substitution (reduction absorption by total immersion of 20.50%, porosity of 28.32%, wet density of 1.73% and dry density of 14.94% and increase in tensile strength of 61.43% and in compression of 63.87%). The effect of sawdust on the relationships between the properties of mortars was clearly noted either for the relationships between early strengths or between compressive and tensile strengths. Keywords: sawdust, mortar, absorption, porosity, resistance 1. INTRODUCTION The evolution of the current world forces us to rethink construction methods. Indeed, today, the construction sector consumes a significant amount of energy. It is responsible for about a quarter of carbon dioxide emissions, not to mention the depletion of non-renewable resources. This sector must therefore innovate to limit its impact on the environment while guaranteeing user comfort [1]. Several investigations have been attempted with the aim of using overabundant sand from the dunes in the construction sector, particularly in Algeria and Africa, which have been the subject of research [2]. The universal need to protect the environment and manage natural resources well requires establishing new laws and adapting new concepts. The recovery of natural materials and the recycling of waste are an effective means in the face of the economic and ecological constraints of recent years [3]. Faced with the context of environmental protection and like all industrial and household waste, waste from wood processing industries will have to be recovered and valued [4]. Many products already exist on the market, but knowledge in this field is still limited and studies must be carried out in order to better understand certain mechanisms and improve the properties of these materials [5]. 2. EXPERIMENTAL DETAILS The materials used for the preparation of the mixtures and the making of the various mortars are of local origin, whose preliminary characteristics are presented in Table 1. A witness sand mortar and three mortars composed in a manner substituted dune sand (DS) with different percentages of sawdust (0, 10, 20 and 30%) respectively. With a stabilization treatment of sawdust before mixing the mortar pastes. This treatment consists of soaking the wood residues in water for 24 hours before use, for each composition Table 2 were the subject of this comparative study at young age (7, 14, 21 and 28 days). The tests concerned the determination of some physico-mechanical properties of early-age mortars (porosity, absorption, wet and dry densities, compressive strength, tensile strength). All the tests were carried out on prismatic specimens (4 x 4 x 16) cm 3 . Keep in water after stripping until the days of the test. The compression and tensile tests (by three-point bending) were carried out respectively by a press of 2000 kN capacity with speeds of 0.5 MPa/s and by a digital universal mechanical strength testing machine of 50 kN of capacity, load and controlled displacement. The measurements of the physical properties were carried out by a hydrostatic balance precision of 0.01 g. Annales de Chimie - Science des Matériaux Vol. 45, No. 6, December, 2021, pp. 447-453 Journal homepage: http://iieta.org/journals/acsm 447