Influence of styrene-butadiene rubber and pretreated hemp fibers on the properties of cement-based repair mortars

This paper examines fresh performance (spreading and wet density), mechanical (adhesion, flexural and compressive strength), transfer properties (total shrinkage and water absorption), and thermogravimetric analysis of repair mortars based on cement modified by 5% of Styrene-Butadiene Rubber (SBR) by weight of cement. These mortars were reinforced with vegetable and glass fibers at rates of 0.1%, 0.3%, and 0.5% relative to the total volume. The vegetable fiber used in this work (hemp) has been previously treated with 5% of NaOH for 2 hours. Silica fumes as a cement addition were used at 10% by weight of cement in all mixtures. The results obtained by this work show that the polymer mortar reinforced with fibers of 0.5% hemp increased by 14% and 9.5% in flexural and compressive strength at 28 days respectively compared to polymer mortars without fibers. Regarding the total shrinkage, the mortars containing 0.3% or 0.5% hemp fibers had good long-term dimensional stability compared to the mortars with glass fibers. The results obtained by this present work suggest that there would be a promising future for the use of plant fibers in cement materials modified by a polymer (SBR).