INVESTIGATION ON MECHANICAL & THERMAL BEHAVIOR OF HEMPCRETE

Abstract

This was an industrial based project, with main focus on the sustainability development and construction of energy efficient buildings. Inspiration of choosing this project was our seniors, and civil engineering graduates of NUST Institute of Civil Engineering (NICE) from batck-2011 who worked on the same material and presented their research in competition, organized on national level by UNIDO and won a notable position of being in top twenty projects. Research’s main objective was to investigate the mechanical and thermal properties of Hempcrete, and developing a mix design with best possible results. Hempcrete is a low-density, energy and cost efficient concrete with a substantial porous structure resulting in interesting properties related to thermal conductivity and hygrothermal behavior. It has low carbon footprints and contains a renewable bio-based material that can sequester CO2 during its cultivation and keep the environment healthy by not contributing to the global warming. Compressive Strength, Thermal conductivity, Density test results were taken as the performance indicators for all the mixes. Based on these, some deficiencies were recognized to improve the mix design. First mix “Control Mix Design” was developed by keeping 50% water, 18.6% hemp and 31.4% binder content with lime and cement to be 70% and 30% of binder content respectively. Results of specimen for the control mix were quite up to expectations. Density, Thermal Conductivity and Compressive Strength was found out to be 34.72 lb/ft3, 0.0773 W/m.K and 432 psi respectively. All other mixes were formed by varying the percentages of hempcrete contents in Control Mix Design. Problem in some of the mix designs was due excessive amount of lime and cement which increased the density of specimen affecting their thermal insulation results comparative to Control Mix Design. Density is directly related to the thermal performance of hempcrete. Denser specimen showed larger values of thermal conduction, affecting thermal insulation property. A lot more work need to be done in addressing the challenges like climate change and sustainability development by making “Hempcrete” subject of main focus. And future research should focus on establishing methods for formulating consistent specimens and also formulation of specific building element ‘systems’ that would assist in developing design and performance standards. The current research represents a first step towards the development of hempcrete in Pakistan.