PCM Modified Gypsum Hempcrete with Increased Heat Capacity for Nearly Zero Energy Buildings

Abstract

Low energy building materials based on natural and renewable resources have become popular among customers. The natural occurrence of the raw materials and the idea to move closer to nature with its natural products have brought high interest in hempcrete. Hempcrete is a kind of binder-aggregate material where besides mineral binder, hemp shive aggregate act as a filler. A good technical performance of such composites has been reported before, while the term an ‘advanced material’ for traditional hempcrete lacks some superior properties for civil engineers. This research offers advanced hempcrete-type material where gypsum binder and hemp shives are used as the main components. Additionally, phase change material (PCM) was incorporated into the mixture composition to increase their thermal mass. PCM gives additional thermal heat storage for buildings which makes the building envelope more homogenous regarding thermal stability under outer temperature fluctuations. This could give additional comfort during heating and cooling seasons. Up to 20 wt.% of microencapsulated PCM suspension had been added to the hempcrete mixture composition and heat capacity was calculated and validated with differential scanning calorimetry measurements. Physical and mechanical performance was also evaluated. Results indicate that in the temperature interval from 20 to 30 °C, the heat capacity of hempcrete can be increased to 1901 J/(gK) (by 70.4 %) and it correlates well with theoretical thermal mass calculation. This gives promising results for further development of the material and proves the feasibility of PCM integration in hempcrete.

Keywords

• calorimetry
• gypsum
• hempcrete
• hemp shives
• pcm