Long-term leaching test in concretes: An X-ray powder diffraction study

Long-term leaching tests on concretes have been performed to investigate portlandite dissolution by means of X-ray powder diffraction and the Rietveld method, which reveals a promising approach to detect CH content in leached concrete. Several concrete samples have been prepared and immersed in deionised water for 0, 35, 99 and 150 days. The results have been compared with those obtained by DTA/TGA measurements. The Rietveld method provides quantitative determinations of Ca(OH)2 in agreement with thermal analyses. Portlandite dissolution front in a concrete drifts inward upon increasing leaching duration. The distribution of portlandite as a function of the sample depth in the concretes treated for 0, 99 and 150 days show similar trends.