CO2 mineralization in air lime renders incorporating mafic quarry waste

The effect of mafic (dolerite) quarry waste on the carbonation behaviour and the physico-mechanical properties of air lime renders was investigated. Quarry fines obtained from a dolerite quarry in the Troodos Ophiolite Complex, Cyprus, were used as partial replacement to the lime binder at 10, 20, and 30% w/w. The renders were cured under ambient laboratory conditions and evaluated after 28, 56 and 90 days in terms of their physico-mechanical and microstructural characteristics. Open porosity and capillary absorption measurements indicated that the incorporation of quarry waste did not significantly alter the overall physical characteristics of the renders. However, mercury intrusion porosimetry analysis showed a decrease in the average pore diameter with increasing waste content at 90 days of curing, suggesting a refinement of the pore structure. The phenolphthalein indicator test and thermal analyses demonstrated enhanced carbonation in the modified renders compared to the reference mixture, thus suggesting enhanced CO 2 sequestration at ambient conditions. Scanning electron microscopy observations further revealed a denser microstructure in the carbonated areas of the composites with quarry waste. Mechanical testing showed comparable or improved strength values relative to the reference mortar. The mixture containing 20% w/w quarry waste exhibited the highest mechanical strength, whereas the render with 30% w/w waste also showed satisfactory mechanical performance. The findings indicate that dolerite quarry waste can be effectively used as partial replacement to lime in air lime renders, promoting enhanced carbonation and supporting the sustainable use of quarry by-products in lime-based construction materials. The enhancement of the carbonation reactions in air lime renders incorporating mafic quarry waste could contribute to the sequestration of atmospheric CO 2 at ambient conditions, and consequently to the decarbonization of the construction sector, which is a major CO 2 emitter.