Bio-Composites to Tackle UK Built Environment Carbon Emissions: Comparative Analysis on Load-Bearing Capacity, Hygroscopic and Thermal Performance of Compressed Earth Blocks with Addition of Industrial Hemp Waste

Background:

The built environment contributes up to 47% of the UK’s CO₂emissions. Typically, building materials have an energy intensive life cycle. The UK construction industry generated 100 million tonnes of total waste in 2012. Only half of this was diverted from landfill. Facing this scenario, a mainstream transition towards biological materials in the building sector is encouraged to reduce embodied energy and carbon and to divert construction waste from landfill.

Objective:

This research aims to inform UK producers that there are available bio-composite materials for construction that can meet the mainstream requirements.

Method:

This paper analyses the effect of the addition of waste from industrial hemp agriculture to Earth Blocks on the performance of building products. To avoid potentially negative consequences of food displacement, an agricultural by-product from industrial hemp production was used. Hemp was also selected due to its known superior hygrothermal performance.

In the study, fine hemp shiv was added to Compressed Earth Blocks’ mix following three different Earth/Hemp ratios (75/25; 62.5/37.5; 50/50) also a control series. The compressive strength, conductivity and moisture performance were tested, analysed and then compared with the mainstream values.

Results:

The results revealed that blocks’ load-bearing capacity reduced and thermal conductivity also reduced, hence increasing its insulation capacity. The moisture performance also reduced as hemp ratio increased. In comparison with the mainstream products, the results comply with the standard requirements. Thermal capacity overperformed mainstream products.

Conclusion:

A closed loop approach for the construction industry is possible. Bio-composite materials offer the industry an option for the reduction of embodied energy, carbon emissions and construction waste, while meeting industry standards and building regulations.

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