It is shown that thermal analysis and XRD data can identify the component of RPCCA which may be hydrated cement or slag (generally considered as an aggregate component). The other coarse aggregates present may be gravel or limestone. The fine aggregate often referred to as sand may be quartz or limestone in origin. The limestone may be dolomite and/or calcite in nature. The TG reveals the extent of the hydration product portlandite [Ca(OH)(2)] in the sample, the amount of CaCO3 present, and the amount of dolomite, XRD studies confirm the presence of these materials. In old concrete samples, the portlandite may be partially carbonated. TG data in CO2 allows the presence of dolomite to be identified.