Development of high-water-resistance and high-strength alkali- activated foam by using waste brick powder

To enhance the utilization value for waste clay brick, this paper has developed high water resistance and high strength alkali-activated slag-brick powder foam (ASBF) suitable for road foundation backfilling and channel subsoil replacement using waste brick powder (WBP). The long-term physical, mechanical properties, water resistance, and pore structure evolution of ASBF directly exposed to water have been studied. The results show that, under the same dry density level, the compressive strength of ASBF is twice of those in previous studies, showing significant advancement in performance. Water environment caused rough pore boundaries, increased the pore fractal dimension and the pore proportion of 0–100 μm, reducing compressive strength and increasing water absorption. Interestingly, 10 %-30 % WBP significantly improved the water resistance coefficient (consistently above 0.91) of ASBF, and the higher WBP dosage, the smaller the strength deterioration. Compared to conventional cement-based foam, ASBF reduces carbon emissions by about 40 % and embodied energy by about 50 %. This study provides a new perspective for the resource utilization of WBP and expands the application scenarios of alkali-activated foam.