Determination of humidity level in aerated concrete constructions by non destructive testing methods

Abstract

Abstract. In the time of energy saving it is important to save heating costs. Different methods of thermo insulation are developed and one of them, besides the comprehensive use of thermo insulation materials, is the use of masonry consisting of aerated concrete blocks. In order to determine the contribution of aerated concrete to the total scope of heat insulation it is important to determine the distribution of humidity in the wall construction. As the construction terms are short and usually all tests are done in the habitable buildings, it is difficult to use destructive methods for the determination of humidity level in the wall constructions. This is the reason why the importance and frequency of application of non destructive methods for detection of wall humidity are increasing. One of such methods for non destructive determination of humidity level in aerated concrete constructions is application of electrical impedance spectrometry. In laboratorial test series it is detected that along with the increasing of the humidity level in aerated concrete block the electrical impedance of the construction decreases. Using this method it is possible to detect the distribution of humidity throughout the construction in relative means. If absolute means are important, then calibration work must be performed prior to field testing. In order to increase the accuracy of the results obtained, the frequency analysis must be performed for every type of testing material. In this paper non destructive testing of aerated concrete blocks for determination of the distribution of humidity level as well as frequency analysis for aerated concrete blocks is described.

Frequency Analysis and Measurements of Moisture Content of AAC Masonry Constructions by EIS

“…electrode/water) [3]. The range of frequencies used for the driving signal enables the characterisation of systems comprising more interconnected processes with different kinetics [4], [5].…”

“…It is important to pay attention not only to a single frequency which seems to be suitable for the measurements but also to a range of frequencies around the selected frequency. This is an important fact due to the fact that the moist suitable frequency tend to change its value along with changes of AAC structure changes during its drying process [5].…”

“…These researches display relative correlation between the changes of humidity ratio throughout the cross section of the construction and EIS measurement results [5], [9], [10], [11]. As one of the main fields of research the monitoring of the AAC masonry wall drying process by EIS was performed [10], [11].…”

“…First researches of authors in field of application the EIS measurements on AAC masonry constructions were started with measurements on single masonry block [5].…”

“…This instrument is verified in laboratory experiments and measurements on objects in situ [4], [5], [7]. Z-meter III device consists of an electronic block which performs all measurement procedures.…”