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Brick-concrete demolition residue after the primary recycling is generally discarded due to its low quality. Secondary recycling of the brick-concrete demolition residue is urgently required to be solved at present in China due to the large scale constructions and demolitions, and remains a challenging task. In this work, a brick-concrete demolition residue from an urban-fringe of Hangzhou, China, was secondarily recycled as the fine aggregate to fabricate sustainable pervious concrete after systematic characterization of its physical and chemical properties. In order to improve the engineering properties of the pervious concrete, natural aggregate and sand were used. Multi-scale structure in terms of pore size distribution, skeleton morphology, and matrix-aggregate interfacial transition zone were systematically characterized using X-ray computed tomography and backscattered electron imaging tests. Results show that the increase of the natural aggregate replacement ratio and sand ratio always increases the compressive strength and density, but decrease the water permeability. Incorporation of the secondary brick-concrete demolition residue in concrete increases the total porosity and connected porosity of the pervious concrete, and helps form a Calcium-enriched matrix-aggregate interfacial layer zone. Use of the secondarily recycled brick-concrete demolition residue in pervious concrete manufacture at the optimal mix brings the CO 2 emissions reduction by 107 kg/m3 and costs reduction by 30.3 USD/m3. The findings of this work provide a sustainable route to secondarily recycle low-quality brick-concrete demolition residue for constructions. [Display omitted] • Low-quality brick-concrete waste residue was secondarily recycled for pervious concrete development. • Multi-scale pores, skeletons and interfaces of pervious concrete were characterized. • Relationships between engineering performances and pore structure were discussed. • Optimal pervious concrete mix reduces CO2 emissions by 107 kg/m3 and costs by 30.3 USD/m3. [ABSTRACT FROM AUTHOR]

This work presents a proof-of-concept study of recycling low-quality urban-fringe construction and demolition waste for the development of sustainable cement-free pervious concrete. Waste was in-situ collected from a local construction site of urban-fringe in Hangzhou, China, and elaborately analyzed for quality assessment. Ground brick powder was activated by alkali activators at different (Al+Si)/Na ratios to find the optimal mix ratio. Macro waste solids and alkali-activated recycled brick powder were used as the aggregate and binding material, respectively, to achieve total recycling of the waste. The effects of binder-to-aggregate ratio on the engineering performances and multi-scale structures of the cement-free recycled waste pervious concrete were explored. Results showed that the optimized alkali-activated recycled brick powder paste had high compressive strength up to 50 MPa. The cement-free recycled waste previous concrete showed relatively low compressive strength but high water permeability. Microstructural mechanisms in the aspects of pores, skeletons, and matrix-aggregate interactions were discussed. The replacement of cement by alkali-activated brick powder showed substantial economic and environmental benefits. The findings of this work would provide a promising route towards solving the large-scale construction and demolition waste in China. [Display omitted] • A concept of total recycling of low quality CDW without cement was proposed. • Alkali activated recycled brick powder was used as the binder to replace cement. • Multi-scale structure and engineering properties were investigated. • Cement-free CDW pervious concrete shows lower costs and CO 2 -eq emissions. [ABSTRACT FROM AUTHOR]