The Effect of Alkali Treatment of Date Palm Fiber on Thermal and Mechanical Properties of a New Composite

This study focuses on the development of new eco-composites to be used as an insulating material in building and aims to reduce high-energy consumption. The mass proportions of untreated and treated fibers (0, 2.5, 5, 10 and 20%) were mixed with (cement, water and sand) to prepare the composites. The date palm fibers were treated by sodium hydroxide solutions (10%) and then analyzed by Infrared Fourier transform spectroscopy, and Scanning Electron Microscopy. The thermal conductivity, compressive strength, water absorption and acoustic transmission were also investigated. The results revealed that the incorporation of natural and treated date palm fibers reduces the thermal conductivity and the mechanical resistance of novel composites. The measurement of the thermal properties proved that the loading of fibers in composite decreases the thermal conductivity from 1.38 W m−1 K−1 for reference mortar (0%) to 0.17 W m−1 K−1 for composites with 10% of treated fibers. After applying alkaline treatments to these fibers, the compressive strength raised from 0.022 MPa for natural fibers to 0.53 MPa for treated fibers with 10% of fibers adding. The chemical treatment of fibers had a great influence on the mechanical properties of composite which could be due to an enhancement of the adhesion between fibers and the matrix. For the acoustical analyses, the sound absorption coefficient of composites exceeded 0.8 at high frequencies [1800–200 Hz]. The alkali treatment of palm fibers allowed obtaining a novel material with high acoustic and thermal insulation performances.