Development and characterization of a new sustainable composite reinforced with date palm stems for rehabilitation and reconstruction of earthen built heritage

Abstract

In rural, arid, and desert areas such as in southern Algeria, constructions are generally based on the use of raw earth due to its availability, abundance, and low price. In addition, raw earth-based constructions require continuous repairs and restorations. Therefore, this work aims to develop a new eco-friendly, low-cost, and sustainable composite, which is adapted to the local climate and meets the structural requirements of earthen constructions. The new composite blocks are made from compressed raw earth and reinforced with date palm stems (DPS), moistened, and then statically compacted. The use of DPS is part of the recovery process of date palm waste that can be used as reinforcement in blocks and can also lead to the improvement of the mechanical and thermal performance. The chemical and mineralogical composition of the raw earth is first determined by X-ray fluorescence and X-ray diffraction, while its physical, chemical and mechanical properties are also determined using different international standards. Two varieties of DPS, namely the Teggaza and Telemso ones are tested under tensile loading, where the latter shows better mechanical properties compared to classical reinforcements in compressed earth blocks (CEB). Thirty reinforced CEB formulations have been here developed, with different weight content of DPS fibres (0.5, 1, 1.5 and 2 wt%), length (1, 2 and 3 cm), morphology (smooth, rough, and mixed) and DPS with four types of treatments (immersion, boiling, autoclaving and hornification). This work also provides an analysis of the mechanical characteristics of the composite blocks by highlighting the influence of the different parameters (i.e., percentage, length, morphology, and treatment of the DPS) on the bending and compressive strengths after drying for 7 and 28 days.