Novel radiographic technique to analyze the porosity and water absorption of bricks

Abstract

Properties of clay brick includes strength, water absorption, durability, expansion, efflorescence and pitting due to lime. Generally these properties are measured using destructive testing methods and as a result sampling errors are inevitable in addition to other considerations such as additional cost for discarding the tested component. Therefore to optimize the costing considerations as well as to reduce the sampling errors an NDT technique such as Radiographic Testing was used to evaluate the properties like water absorption etc. Initially a theoretical model was developed to obtain a relationship between X-ray intensity and the absorbed water volume. From that model it was deduced that the natural log of the intensity changes and the absorbed water volume shows a linear relationship. First to find the appropriate tube voltage and the exposure time, a preliminary experiment was carried out as the first stage and from the results of that, the exposure time and the tube voltages were used for the subsequent second stage to determine whether the experimental findings were in line with the theoretical model For the experimental purpose three sets of samples obtained from different locations were used with five clay bricks in each set. The samples were immersed in water for specified time intervals and the radiographic tests were performed on them. Natural log intensity (index) vs water volume relationship was studied and found to be linear which confirms the theoretical model developed. As per the findings of the research it could be concluded that the Radiographic testing method could be applied to find porosity and water absorption of clay bricks. Radiographic intensity of dry bricks remains constant for a given set. Therefore radiographs can be used to find origin of bricks and hence to sort out bricks of archeological importance.