Swelling inhibitors for Clay Materials : comparison of Industrial and Natural Surfactants. In : Monument future : Decay and Conservation of Stone
Résumé
Humidity variations due to the climate of Western Europe induce many problems in clay-rich building material. Indeed, the repetition of wet/dry cycles leads to swelling and shrinkage phenomenons. Thus, cracks and material loss may appear. A solution to limit the volume change of bulk material consists of using surfactants. This study focused on the behavior of swelling montmorillonitic clay mixed with a series of 9 surfactants: 3 diaminoalkanes with different carbon chain lengths, polyethylenimine and triton X-100 (industrial surfactants) were compared to natural products (bio-inspired/ bio-sourced) such as lawsone, pork gelatin, saponin and dopamine. The swelling at the clay sheet scale before and after treatment was observed on powders using X-ray diffraction analyses after conditioning at low and high relative humidity, while the swelling deformation at macroscopic scale was assessed on specimens submitted to imposed hygric conditions via the continuous measurement of axial deformation. In complement, the microstructure was investigated by mercury intrusion porosimetry. Diaminoalkanes appeared to be the more efficient swelling inhibitors for the crystalline swelling, in particular, those with long carbon chains. Nevertheless, some of natural additives also showed a high capacity to reduce swelling at both macroscopic and microscopic scales which would suggest the possible use of less toxic additives/natural as swelling reducer.
Origine : Fichiers produits par l'(les) auteur(s)