Mechanics and permeability properties of ecological concrete mixed with recycled engineering muck particles

The excavation of construction foundation pits, tunnels, channels, and other projects generates a significant volume of engineering muck, posing challenges in management. Prolonged accumulation of this muck can lead to environmental pollution. The effective recycling of this type of construction waste is crucial for the advancement of a circular economy, necessitating immediate attention to research and solutions. In this study, a novel method is introduced for the preparation of low-carbon and environmentally friendly ecological concrete. This method involves the utilization of recycled engineering muck particles to substitute a portion of the natural aggregate and enables the comprehensive recycling of engineering muck. Subsequently, the mechanical and permeability properties of ecological concrete under varying muck particle content and porosity conditions are analyzed through experiments, taking into account the impact of relative average pore diameter and pore tortuosity. A predictive model has been developed for the tortuosity of pore channels in ecological concrete, taking into account effective porosity and average pore diameter. The enhanced Kozney-Carman model is employed to describe the correlation between pore properties and hydraulic conductivity. The findings indicate that a composite curing agent is formed by combining ordinary Portland cement with a hydrophilic polyurethane solution. This composite curing agent demonstrates superior performance compared to pure cement in the solidification of engineering muck. As the replacement rate of unsintered recycled residue particles increases, the porosity of concrete may increase by up to 29.7%. This results in enhanced permeability characteristics but a decrease in compressive strength. In contrast to lightweight aggregates manufactured through the sintering process, the carbon emissions of unsintered recycled residue particles are reduced by 57.7%. This study provides suggestions for the repurposing of construction waste and contributes to the advancement of sustainable practices within the concrete production sector.