AFM investigation of cement paste in humid air at different relative humidities

• Published in: Journal of physics. D, Applied physics Applied physics, 2002-04, Vol.35 (8), p.L25-L28
• Main Authors: Yang, Tianhe, Keller, Bruno, Magyari, Eugen
• Format: Article
• Language: English
• Subjects: Applied sciences; Buildings. Public works; Cement concrete constituents; Cements; Exact sciences and technology; Materials; Properties and test methods; Properties of anhydrous and hydrated cement, test methods
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/35/8/101

Some of the most important building materials are porous: concrete and cement, for example. Heat and moisture transport in such materials play an important role for the durability of structures. Condensation damage, mold growth, etc. give rise to sick buildings and costly repairs. These processes have been studied by various experimental methods, but without molecular resolution. Description of these processes is mainly a phenomenological, thermodynamic approach and results in a system of coupled differential equations with some 'material constants' or functions of them (transport coefficients). Here the surface structure of cement paste has been investigated in humid air by contact mode atomic force microscopy (AFM). The samples have been prepared by the novel mica-replication-method (MRM). For relative humidities between 3% and 20%, a structure change from coarse to fine grains has been recognized. Above this range no further significant changes were found.