Structural performance and optimization strategies of hempcrete composites: a comprehensive review

The growing demand for sustainable construction materials has increased interest in improving the performance of bio-based composites such as hempcrete. Although hempcrete is recognised for its thermal insulation, hygrothermal regulation, and carbon sequestration capacity, its relatively low compressive strength limits structural applications. This review evaluates recent advances in high-strength hempcrete to assess its potential as a load-bearing construction material. Particular emphasis is placed on identifying mix design strategies required to achieve or exceed a compressive strength of 5 MPa. The review examines mix design, constituent materials, mechanical properties, durability, structural performance, and life cycle environmental impacts, with particular attention to binders and performance-enhancing additives. The findings indicate that alternative binders, including geopolymers and magnesium-based cements, can increase compressive strength to approximately 5 MPa, while additives such as metakaolin can improve strength by 50–90%. Mechanical performance is strongly influenced by binder–additive combinations. Life cycle assessments show that hempcrete generally has a lower, and sometimes negative, carbon footprint than conventional construction materials. Overall, optimised formulations demonstrate considerable potential for structural applications. Future research should prioritise standardised mix design methods, long-term durability evaluation under diverse environmental conditions, and reliable structural design models compatible with building codes.