Synergistic modification of bamboo aggregates by sodium alginate-CaCl2: optimization and performance evaluation of sustainable lightweight concrete

In the context of global climate change, the demand for green building materials has grown increasingly urgent. This study has made significant advancements in sustainable construction materials by developing all-bamboo aggregate concrete (BAC) enhanced with a sodium alginate-CaCl₂ synergy through an environmentally friendly process. Using response surface methodology optimization, the 28-day compressive strength was increased to 8.10 MPa. Scanning electron microscope (SEM) analysis indicates that the alginate gel forms a cross-linked network within bamboo micro-cracks, substantially improving interfacial bonding. A novel bamboo aggregate mass index (BAMI) has been introduced to quantify particle shape, allowing precise control over aggregate quality, thus offering a new solution for lightweight pavement materials. While fly ash reduces short-term strength, its low alkalinity and secondary hydration effects positively influence long-term durability. This research provides a scientific basis for utilizing BAC in pedestrian pavements and advancing sustainable construction materials.