Ceramics-Silikáty

To realise the resource-oriented utilisation of poly-aluminium chloride (PAC) residue rich in SiO₂ and Al₂O₃, the residue was dechlorinated, dried, and used to partially replace cement by mass to fabricate static-press concrete bricks. The compressive and flexural strengths at 28 days and durability after 50 freeze-thaw cycles were tested, and a microstructural characterisation was performed by X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results show that, after pre-treatment, the cumulative content of SiO₂ and Al₂O₃ in the PAC residue reaches 73.52%, confirming its potential as a reactive pozzolanic material. When the replacement ratio is ≤20%, the 28-day compressive strength remains 85%-95% of the control, and the strength loss after 50 cycles is below 20%, meeting specific standards. At replacement ratios ˃20%, both the mechanical and durability performances decline markedly. The microstructural analysis suggests that, at low replacement ratios, the residue refines the pore structure via microaggregate effects and secondary hydration, whereas at high levels, dilution effects and residue morphology increase the porosity. This verifies the feasibility of PAC residue (≤15% replacement) in static-press bricks and provides guidance for its industrial valorisation in green building materials.