Durham School of Architectural Engineering and Construction


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This article was submitted to the 14th North American Masonry Conference (2023), Omaha, Nebraska, United States


Copyright 2023, the authors. Used by permission


The portland cement concrete industry and the masonry industry are undergoing changes in response to skilled labor shortages and concerns over climate and pollution. There may be interest from parts of the industry in lower carbon footprint and lightweight masonry products. Toward this aim, the use of hemp shiv--the woody core of the hemp plant--in alkali-activated concrete was investigated herein and shown to have a wide range of impacts on the hardened state characteristics of a material suitable for structural concrete masonry units (CMUs) in accordance with ASTM C90 requirements. Hemp shiv is well known for its use in hempcrete, which is a mixture of shiv and lime. However, alkali-activated concrete is a sustainable alternative to portland cement concrete that can be used as a binder for hemp-based concrete. This study investigates the potential of developing hemp-based alkali-activated material to be used in the production of sustainable masonry units. The effects of adding hemp shiv to alkali-activated materials on mechanical characteristics and CO2 emissions are investigated in this study and shown to be a suitable material for CMUs. A parametric study was carried out to define the effects of using different alkali-activator content on the compressive strength and density of the developed sustainable masonry units. In addition, a sustainability study was carried out on the developed CMU-suitable materials to investigate their global warming potential and degree of carbon dioxide sequestration. According to the findings, the final material can have densities and strengths of up to 75 lb/ft3 and 2500 psi, respectively. Furthermore, a carbon dioxide uptake capability up to 126 lbCO2eq/ft3 was measured for the developed masonry units.