Applicability of Biochar in Concrete for Landscape Paving† - Workability and Mechanical Properties of Mortar Partially Replacing Cement with Wood-Based Biochar -

This paper describes a replacing cement with high carbon content biochar among construction materials used in landscape paving for the purpose of carbon neutral in response to climate change. Based on the cement mortar of paving concrete, a mixture was performed in which up to 6% of the cement usage was replaced with wood-based biochar with high carbon content and porous structure, and the workability through flow tests and the mechanical properties through test specimen strength tests were identified. In addition, the porous structure of wood-based biochar was confirmed through SEM image analysis, and it was confirmed that the cement matrix was filled inside the porous structure of the biochar and attached to the outer surface. The workability of cement mortar mixed with wood-based biochar according to the flow test was no different from that of ordinary mortar regardless of the replacement rate and the time elapsed after mixing, and the workability increased at some replacement rates. The mechanical properties through strength tests showed that all strengths increased with age, and the increase rate of flexural strength was the largest depending on the cement replacement ratio, while the increase rate of compressive strength was relatively low. In particular, regardless of the replacement rate, it was found that the design standard compressive strength and flexural strength specified in the Korea design standard or mixing design guidelines were both more than doubled. Therefore, since the mortar that replaced cement with wood-based biochar has both workability and mechanical properties, there will be no problem in applying biochar to concrete for landscape paving.