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This study explored the potential of using biomass bamboo aggregates (BAs) developed from bamboo to replace natural aggregates (NAs) in concrete. The use of BAs not only solves the problems of environmental damage and energy depletion caused by NA mining but also improves the toughness of concrete. To address the weak adhesion between bamboo and cement, a method for modifying the surface of the BA with an epoxy mortar coating was proposed. Experimental works have examined the workability, physical, and mechanical properties of bamboo aggregate concrete (BAC) at various BA replacement rates (r =0%∼45%) and modification methods (unmodified, epoxy mortar-modified). The results indicated that BAC with r ≥35% exhibited good workability. As r increased, the water absorption rate increased, and the density decreased. Compared with normal aggregate concrete (NAC), BAC exhibited extended cracking and failure processes, suggesting that it has a postcracking deformation capacity. For BAC, the increase in the early strength growth was slower, but the increase in the strength later was faster, especially with higher BA contents. Despite larger r had negative effects on the mechanical properties, BAC with r ≥35% still met the strength criteria for non-load-bearing and secondary structures. Additionally, BAC exhibited a more pronounced size effect than NAC, but this effect diminished as the BA content reached 25%. Finally, equations for the 28-day strength and size effects of BAC specimens with varying r values were proposed. • Sustainable bamboo aggregates (BAs) were proposed for use in concrete. • Workability, physical and mechanical properties of bamboo aggregate concrete were studied. • Influences of BA replacement levels, curing ages and sizes were examined. • A 28-day strength fitting equation and a size effect formula were proposed. [ABSTRACT FROM AUTHOR]

Bamboo fiber (BF) possesses advantages such as environmental friendliness, renewability, economic viability, and favorable mechanical properties, making it a promising material for improving the brittleness and tensile strength of concrete. Previous investigations have demonstrated a limited exploration of BF-reinforced lightweight aggregate concrete (LWAC). Current study concentrates on investigating the mechanical properties and stress-strain relationship of BF-reinforced LWAC. To achieve this, 7 groups of BF-reinforced LWAC specimens were subjected to compressive tests, splitting tensile tests, and prism compressive tests. The influence of BF content and length on the compressive performance, failure modes and stress-strain curves was studied. BFs effectively suppressed the development of internal cracks in LWAC, playing a role in crack resistance and toughness enhancement. Furthermore, BFs significantly improved the splitting tensile strength of concrete, while the compressive strength slightly decreased with the increase of BF content. After adding BFs, the splitting tensile strength of concrete increased by 8.2∼23.7%, and the compressive strength decreased by 3.6∼11.1%. Moreover, the BF length had almost no effect on the compressive strength of concrete, while when the BF length was 10–30 mm, the tensile strength increased by 5.3∼17.6%. Based on existing researches, strength conversion equations and stress-strain constitutive models of BF-reinforced LWAC were proposed, and the models provide a theoretical basis for the calculation and analysis of BF-reinforced LWAC components and structures. • Bamboo fiber (BF)-reinforced lightweight aggregate concrete (LWAC) was examined. • BFs significantly improved the splitting tensile strength and ductility of LWAC. • The failure modes of specimens were analyzed based on SEM images and DIC technology. • The stress-strain models of BF-reinforced LWAC were established. [ABSTRACT FROM AUTHOR]