Mechanical characterisation and modelling of bamboo bio-concrete with residue aggregates

The use of industrial bamboo residues as bio-aggregates in cementitious composites offers a sustainable approach to reducing the environmental impact of conventional concrete. However, there is still limited knowledge regarding the compressive behaviour of mixtures in which bamboo particles fully replace traditional coarse aggregates. This study investigates the mechanical performance of bamboo bio-concretes (BBCs) with total replacement of coarse aggregates, using bio-aggregate volume fractions of 15%, 20%, 25%, and 30%. After 28 days, compressive strength decreased from 31.5 MPa (BBC-15) to 17.9 MPa (BBC-30), while the elastic modulus declined from 15.08 GPa to 8.57 GPa. Higher bamboo contents improved post-peak ductility, with BBC-30 sustaining up to 52% of the peak load at 8000 με, compared to 39% for BBC-15. Poisson’s ratio values (0.36–0.43) indicated significantly greater lateral deformability than that of conventional concretes, and statistical analysis showed that this parameter is governed mainly by the low stiffness of bamboo particles rather than by the bio-aggregate fraction itself. Existing theoretical models (Model Code 2010 and Eurocode 5) did not accurately represent the ductile post-peak behaviour, whereas Popovics’ equation produced better fits. The results highlight the distinct mechanical features of bamboo bio-concretes and support their suitability for low-load-bearing structural elements.