Mesoscopic model of volume changes due to moisture variations in porous materials

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Vol. 327; no. 1; pp. 34 - 43
• Main Authors: Schiller, P., Bier, Th, Wahab, M., Mögel, H.-J.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15-09-2008; Elsevier
• Subjects: Adsorption; Capillary forces; Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Porous materials; Porous solids; Surface physical chemistry; Swelling; Capillary forces; Adsorption; Swelling; Porous solids; Experimental data; Force; Theory; Glass; Laplace equation; Porous material; Solid; Porous solids;Adsorption;Swelling;Capillary forces; Pore size; Pore; Capillarity; Distribution; Vycor; Models; Air humidity
• ISSN: 0927-7757; 1873-4359
• DOI: 10.1016/j.colsurfa.2008.05.046

Porous solids swell and shrink in dependence on air humidity. Based on the independent pore model, the extended theory of capillarity based on the augmented Young–Laplace equation is used to evaluate the swelling and shrinkage of porous solids. Assuming cylindrical pores, theoretical results on the volume changes are in a fairly good agreement with experimental data for vycor glass, but they do not describe the behaviour of hardened cement paste. Comparing experimental data and the theoretical evaluations, we suggest that the discrepancies result from a very broad pore size distribution and the occurrence of a large amount of slit pores in cementitious materials.