Analysis of biochar-mortar composite as a humidity control material to improve the building energy and hygrothermal performance

This study suggests a new perspective of biochar as a building material that improve not only for the strength but also hygrothermal properties. Biochar has a high porosity and surface area created by pyrolysis. It can be suitably used as a porous material because porous materials are used by incorporating into building materials for improving hygrothermal performance in the construction sector. To analyze whether biochar can be used as a functional building material to improve the hygrothermal performance, two types of biochar, made from oilseed rape (OSB) and mixed softwood (SWB), were prepared. A biochar-mortar composite was prepared according to the mixing ratio of the biochar from 2 wt% to 8 wt%, and the compressive strength and hygrothermal performance of them were analyzed. The compressive strength is the highest when 4 wt% of biochar into the mortar was mixed regardless of the type of biochar. Thermal conductivity of biochar-mortar composites was decreased as the biochar addition increased, and the value of biochar-mortar composites with 8 wt% OSB decreases by maximum 57.6% compared to the conventional cement mortar. The water vapor resistance factor of biochar-mortar composites increases, and biochar-mortar composites with 8 wt% SWB increases by maximum 50.9% compared to the reference. WUFI simulation shows that the biochar-mortar composites can contribute to a humidity control and no mold growth. The biochar-mortar composites can also contribute to energy savings although the amount of savings is insignificant. As a result, this study proved that when the mortar with biochar addition was possible to improve not only strength but also hygrothermal properties of mortar. This approach will be a new perspective that biochar can apply to the building material in practice. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study demonstrates that adding biochar to mortar can improve both the strength and hygrothermal properties of the mortar. The thermal conductivity of biochar-mortar composites decreases with increasing biochar addition, leading to improved water vapor resistance and humidity control. Overall, the incorporation of biochar into mortar shows potential for enhancing building materials' performance in practice.