Composition of Concrete Surfaces after Demoulding and Coating: Comparative Study by XPS, FTIR and Raman Spectroscopies

Hardened concretes were studied by several spectroscopic techniques (FTIR, Raman and XPS) to determine the surface composition after demoulding and after coating. After demoulding, most of the paste was constituted of calcite but some areas were identified by µRaman as portlandite, ettringite, belite, alite and ferrite phases. The FTIR (in ATR mode) allowed detecting portlandite and C-S-H but it highlighted also organic residues from the demoulding oil. XPS allowed recording interesting atomic ratios to study the extreme surface and the presence of contamination. After post-treatments, the main organic units were determined by FTIR and XPS at the concrete’ surface. Raman was also interesting: no vibration modes of organic species were detected but mineral/hydrated phases were clearly characterized under a thick organic layer. Due to their own specificities, these complementary techniques allowed identifying the mineral/hydrated phases and organic residues/coating at the concrete surfaces.