Computerised prediction of the deterioration of concrete building facades caused by moisture and changes in temperature

Abstract

Environmental conditions, mainly temperature and relative humidity, are the major factors in the physical, chemical, and biological deterioration of concrete building facades. The purpose of this thesis is to investigate the effect of the environmental conditions on the deterioration of concrete building facades, develop a system for monitoring these conditions, and predict the deterioration and remaining service life of these facades on the basis of the monitoring data. The thesis consists of a literature review, laboratory and field investigation, the development of a hygrothermal monitoring and deterioration predicting system, and its application to concrete building facades. The literature review covered the concrete deterioration caused by moisture and changes in temperature. Special attention was given to the corrosion of steel reinforcement as a result of carbonation, damage caused by repeated freezing and thawing, and mould growth. The laboratory investigation and field monitoring of relative humidity and temperature were carried out to assess the impact of environmental factors on the performance of the structure under concern. The laboratory and field measurement data were used to validate the concrete deterioration prediction models. The results confirm that the hygrothermal field monitoring is significant for: (i) collecting real relative humidity and temperature data within the concrete facades and the surrounding environmental conditions; (ii) integrating the effects of the measured data into different indicators for calculating the potential for deterioration, and (iii) working as an early warning alarm to ensure appropriate renovation and maintenance measures by comparing the predicted deterioration levels with different threshold values of deterioration indicators. Based on the monitoring data, the environmental factors that affect the deterioration of concrete building facades are characterized. The result of the research will improve the building construction industry by providing methodologies and systems for monitoring and predicting the performance of structures. A scientific relevance of this research will be the improved understanding between the results received in laboratory studies and observations of deterioration in practice. The implementation of the RHT-MAPS monitoring system developed can be carried out cost-effectively in comparison to the construction and maintenance expenses of concrete facades. The maintenance costs can also be optimized by the monitoring results.