EFFECT OF PRE-IMPREGNATED CARBONIZED AGGREGATE ON CARBONIZATION RESISTANCE OF FULLY RECYCLED CONCRETE

In order to investigate the effect of treated recycled aggregates by pre-soaking calcium hydroxide (CH) combined with CO₂ curing on the carbonation resistance of fully recycled concrete. The carbonation depth of fully recycled concrete was tested at 3, 7, 14 and 28 days using the rapid carbonation method. The experimental results show that with the recycled aggregate replacement rate rising, the carbonation resistance of fully recycled concrete gradually decreases. CH pretreatment combined with CO₂ curing effectively improves the quality of the recycled aggregate, thereby improving the carbonation resistance of fully recycled concrete. The optimum effect of CO₂ curing on fully recycled concrete is achieved with the recycled fine aggregate replacement rate of 70% and the recycled coarse aggregate replacement rate of 100%. In addition, microscopic tests were used to reveal the enhancement mechanism of CH pretreatment combined with CO₂ curing increases the carbonation resistance of fully recycled concrete. Experimental data were used to fit and model the carbonation depth of fully recycled concrete formulated before and after CO₂ curing of recycled aggregates.