Verification of a Nondestructive Method for Assessing the Humidity of Saline Brick Walls in Historical Buildings

Abstract

The paper presents the results of the verification of the neural method for assessing the humidity of saline brick walls. The method was previously developed by the authors and can be useful for the nondestructive assessment of the humidity of walls in historic buildings when destructive intervention during testing is not possible due to conservation restrictions. However, before being implemented in construction practice, this method requires validation by verification on other historic buildings, which to date has not been done. The paper presents the results of such verification, which has never been carried out before, and thus extends the scope of knowledge related to the issue. For experimental verification of the artificial neural network (ANN), the results of moisture tests of two selected historic buildings, other than those used for ANN learning and testing processes, were used. An artificial unidirectional multilayer neural network with backward error propagation and the algorithm for learning conjugate gradient (CG) was found to be useful for this purpose. The obtained satisfactory value of the linear correlation coefficient R of 0.807 and low average absolute error |Df| of 1.16% confirms this statement. The values of average relative error |RE| of 19.02%, which were obtained in this research, were not very high for an in-situ study. Moreover, the relative error values |RE| were mostly in the range of 15% to 25%.

Non-Destructive Testing in Civil Engineering

“…Article [11] presents the results of the verification of a method of assessing the moisture content of saline brick walls based on non-destructive measurements and artificial intelligence. The method was formerly developed and can be suitable for the non-destructive identification of the moisture content of walls in historic buildings when destructive interference during the research is not possible because of the conservation limitations.…”

In Situ Monitoring of Drying Process of Masonry Walls

“…The test that was carried out showed that it is possible to reliably identify the moisture content of saline brick walls using the proposed approach without the necessity of interference in the wall structure. Next, the method proposed in [9] was successfully validated by investigating the moisture content in two historic buildings other than those used for the learning and testing of the artificial neural networks [10]. Orr et al [11] evaluated the performance of microwave sensors and radar for monitoring the moisture movement in the masonry walls subjected to wind-driven rain.…”