Adherent hardened cement paste attached to recycled concrete aggregates (RCA) generally presents a higher porosity than natural aggregates, which induces a lower porosity in the properties of RCA. The characterization of the adherent hardened cement paste content () in the fine RCA would promote better applications of RCA in concrete, but the determination of in fine RCA is not well established. A simple method based on salicylic acid dissolution was specifically developed to quantify the in RCA, especially for RCA containing limestone aggregates. The results demonstrated that the soluble fraction in salicylic acid () was equal to the for white cement and slightly lower for grey Portland cement, which was also confirmed by a theoretical approach using modelling the hydration of cement paste with the chemical equations and the stoichiometric ratios. The physical and mechanical properties of RCA (e.g., water absorption) were strongly correlated to the . For industrial RCA, did not give the exact value of , but it was sufficient to correlate with the other properties of RCA. The water absorption could be estimated with good accuracy for very fine RCA (laboratory-manufactured RCA or industrial RCA) by extrapolating the relationship between water absorption and , which is very important for concrete formulation.
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| http://dx.doi.org/10.3390/ma15093384 | DOI Listing |
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