Carbon sequestration and environmental impacts in ternary blended cements using dyeing sludge and papermaking sludge

Abstract

This research delves into the hydration processes and ecological repercussions of cement blended with papermaking sludge (PS) and dyeing sludge ash (DS). It targets the alleviation of detrimental environmental impacts from solid waste, alongside evaluating their prospective utilization in cement product fabrication. Low-temperature roasting DS is rich in phosphates, which impose a hindering effect on the initial hydration of cement clinker, and displays superior pozzolanic activity when juxtaposed with PS. Meanwhile, the incorporation of PS heightens the malleability of the cement paste blend, consequently modulating the pore size distribution within the cement matrix, resulting in amplified compressive resilience of the amalgamated cement samples. Additionally, the inclusion of DS and PS presents an augmented surface area, promoting the nucleation of hydration by-products. The infusion of a greater quantity of hydration by-products within the mixed cement matrix fosters pore refinement and advances strength development. Furthermore, the blended cement proficiently constrains heavy metals inherent in the sludge and curtails ecological implications during cement product fabrication. Furthermore, compared with conventional Portland cement, the ternary blended cement employs un-calcined PS and low-temperature activation DS. This approach facilitates enhanced carbonation and CO2 sequestration from industrial waste streams, thereby achieving carbon reduction at the source.