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Updated: Apr 18, 2026

Two-way Valorization of Blast Furnace Slag: Synthesis of Precipitated Calcium Carbonate and Zeolitic Heavy Metal Adsorbent
Published on: February 21, 2017
Combined effect of soda residue and dyeing sludge on mechanical properties and microstructural characterization of
Dongyang Tian1, Hua Jiang2, Zedong Qiu2
1School of Civil Engineering, Harbin Institute of Technology, Harbin, 150090, China; Department of Civil Engineering, The University of Hong Kong, Hong Kong, China.
Abstract:
Conventional alkali-activated materials (AAMs) suffer from high alkalinity, which severely limits their sustainability and large-scale application. Meanwhile, industrial by-products like soda residue (SR) and dyeing sludge ash (DS) pose significant environmental risks due to heavy metal leaching and disposal challenges. This study aims to address these dual issues by developing a novel low-alkalinity, ground granulated blast-furnace slag (GGBS)-based AAM through the synergistic utilization of SR and DS. A chloride-alkali-sulfate co-activation system was established, and the effects of SR and DS contents were systematically investigated using multi-scale characterisation techniques, including compressive strength testing, quantitative 29Si MAS-NMR, mercury intrusion porosimetry, and toxicity characteristic leaching procedure. The results reveal that SO2- 4 from SR reacted with Al3+ to form ettringite, while strategic incorporation of Ca(OH)2 stabilised the pH, promoting depolymerization of GGBS and formation of C(-A)-S-H gel with enhanced silicate polymerization. Incorporating 30 wt% SR increased the 56-day compressive strength to 31.8 MPa, representing a 178% enhancement compared to the reference. The hybrid system also refined the pore structure, reducing capillary porosity and water absorption to below 25%. Critically, the formed gels effectively immobilized heavy metals, with leachate concentrations well below regulatory limits. This approach overcomes the high-alkalinity barrier of traditional AAMs, achieves an embodied carbon of only 100-115 kg CO2/m3,which is 60-70% lower than conventional concrete of similar strength, and establishes a high-value waste-to-resource pathway. The clarified synergistic mechanisms provide valuable insights for optimizing low-carbon, eco-friendly cementitious materials.
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