Which methods are suitable to assess the effectiveness of chemical injection treatments in the laboratory?

Abstract

Resin injection is a widespread technique to fight rising damp in historic brick masonry buildings, but the evaluation of its drying effectiveness is often hard, also due to the lack of standard procedures to test the different damp-proofing materials. Some testing procedures have been proposed in national guidelines and scientific literature to assess the effectiveness of chemical injection in laboratory, but they reflect very different approaches and are hard to compare.This paper firstly provides a critical overview of the presently available methods to assess the effectiveness of chemical injections in brick masonry at the laboratory scale, highlighting their main advantages and drawbacks. Then, two different experimental test walls are proposed, having large and small size, respectively. The test walls were manufactured and subjected to a continuous capillary rise of water, monitoring the moisture amount by a micro-destructive method based on “permanent sampling holes”. Both test walls allowed to effectively reproduce rising damp occurring in real masonry walls and to monitor the moisture amount during time by an easy and reliable method. Large walls involve a long curing time (more than 1 year in laboratory conditions) and are quite space consuming, but they are less affected by the microclimatic variations. Conversely, small walls are more easy to handle, but also more affected by RH changes. The proposed test walls aim at contributing to the future development of a new testing procedure to evaluate chemical damp-proof courses in laboratory.