Medição do Teor de Humidade em Materiais de Construção

Abstract

The humidity is one of the main causes of pathologies in buildings. This work aims to raise awareness among stakeholders of the construction for the importance of moisture content of building materials and for its experimental determination. The moisture content is an important parameter for civil engineering, requires care in project, implementation and quality control. Its specification in project and its control in the execution are decisive, it is necessary to know the physical and hygrothermal properties of building materials in order to prevent their premature degradation. It is unacceptable that actors involved in construction continue to use materials which properties are unknown. The different forms of expressing moisture content are presented, as well as definitions of different levels of moisture content that a building material can achieved. It was created a table with properties of current building materials (reference values), based on existing bibliographies that reveal themselves scarce, which clearly demonstrated the need for research in this area. It was established the link between the moisture content and numerical simulation, because the automatic calculation programs are essential tools for research on new materials, or simply to simulate the behavior of materials against different requests. The main part of this study presents eleven experimental techniques for the determination of moisture content, each with its advantages and disadvantages. Here is presented the measurement principle (physics), the experimental equipment and its calibration, as well as the experimental procedure and measurement error associated. It is noted that most of the presented equipment is not available at the Laboratory of Building Physics (LFC) FEUP- Engineering Faculty of Oporto's University- and are little known in Portugal. Thus, the work seeks to improve knowledge related to the experimental determination of moisture content. It is emphasized that the choice of appropriate technique depends on the material to be analyzed and the accuracy desired. Having in account the increasing need for the use of equipment for measuring the moisture content, a model for experimental sheets is proposed, which can be applied at work or at laboratory, explaining briefly how to perform the experiment, including the necessary equipment and how to interpret the results. The sheets are organized and written so that any user, regardless of the level of formation, can use the technique described in it. Finally, with some measuring equipment available at the LFC was performed a very simple experiment with limestone samples, which allowed familiarization with the equipment and the difficulty of measuring and handling that these involve, as well as the interpretation of results. Keywords: Experimental techniques, Moisture content.