Effects of surface modification methods on physical, mechanical, and microstructural properties of sustainable bamboo aggregate subjected to cementitious materials

Abstract

To alleviate the serious loss of gravel resources and improve the sustainability of concrete materials, this study innovatively proposes the development of a new type of bamboo aggregate from green and renewable Phyllostachys edulis (Moso) bamboo to replace traditional gravel aggregates. To realize the direct application of bamboo aggregates, this study proposes the use of epoxy mortar (EM) and polyurethane (PE) adhesives to modify the bamboo surface. Compared to unmodified and PE-modified bamboo, EM-modified bamboo showed significantly improved physical and mechanical properties. Durability tests revealed that the modified bamboo, especially EM-modified bamboo, was less affected by acidic and alkaline corrosion than the unmodified bamboo and the mass loss rate was almost zero. In the early stages of alkaline corrosion, the strength of the bamboo increased, and then began to decrease after 28 d. The removal of the outer green bamboo significantly improved the adhesion of the adhesive to the bamboo surface, as confirmed by pull-out tests. A sufficient bonding area between the EM-modified bamboo and the cement matrix remained after compression damage, whereas obvious debonding behavior between the cement matrix and unmodified and PE-modified bamboo was observed. In summary, EM modification significantly improved the comprehensive performance of bamboo aggregates. This study is expected to help improve the utilization rate of bamboo, promote bamboo concrete, reduce carbon emissions, and develop sustainable materials.