Hempcrete a Renewable Material for Green Building: Manufacturing and Properties Optimization

Abstract

The increase in environmental pollution due to large emissions from the cement industry, the need for green materials in construction industry, the increase in the amount of industrial waste that must be recycled for environmental reasons and the need for cost-effective and long-lasting building materials were the reasons to work on hempcrete. Throughout the current work hempcrete mixes are prepared using 25% wt. cement, 75% granulated blast furnace slag as binders and hemp; the natural fiber instead of the expensive synthetic fibers for the purpose of manufacturing cost effective renewable building material. Response Surface Methodology was used as a statistical tool to decrease the number of experiments and raw materials used, and to optimizing and modelling the effect of hemp/binder (0.16-0.44) and alkaline activator/binder ratio (0.41-0.69) on density and compressive strength. The results of the work revealed that the density of hempcrete decreases with increasing hemp/binder ratio and increases with increasing activator/binder ratio. Optimum density 1077.07 kg/m3 was achieved at hemp/binder ratio = 0.16 and activator/binder ratio = 0.65, while optimum compressive strength is estimated at hemp/binder ratio = 0.16 and activator/binder ratio = 0.42. Both compressive strength and density increase steadily with increasing the samples age. However, hempcrete samples cured at dry atmospheric conditions gives a compressive strength comparable with those cured in water but with higher density.