Moisture in concrete - transport forms, measurement methods and economic and environmental significance

The need to understand water transport and other humidity related behaviour of concrete arises from many practical reasons. In floor constructions, the necessary drying time before surface coating is of vital importance in preventing deterioration and loo sening of coatings. High humidity may give rise to health problems as well as aesthetic and durability problems during the service life of the structure. In controlling and estimating the existing humidity in concrete, reliable and easy-to-use measureme nt methods are essential. However, practical experiences have shown that reliable humidity measurements in concrete are very difficult to perform, especially at the construction site. Further, existing guidelines regarding necessary drying time before sur face coating are old, and not valid for modern floor constructions. Similarly, modern Swedish software for predicting drying times is not applicable on Norwegian concrete constructions. In this situation, the strategic institute program will focus on the following work packages (WP): 1) WP1 shall sum up national and international experiences from earlier moisture measurements projects. 2) WP2 shall measure moisture transport and drying times for a number of modern Norwegian concrete floor constructions. In addition, WP2 shall document the reliability of various measurement techniques. 3) Based on the measurements in WP2, WP3 shall prepare tools for predicting drying times and moisture transport in concrete constructions. 4) WP4 shall evaluate test meth ods for alkali-sensitive floor coatings, and prepare basic data for new guidelines concerning maximum moisture content in the concrete before surface coating. The program will be carried out at SINTEF Byggforsk AS in close co-operation with the Norwegian University of Science and Technology, NTNU.