Thesis: Qunxi Wang

Performance Evaluation of Chemical Poultice Removal of Silane & Siloxane Water-Based Water-Repellent Treatments on Hand-Molded Brick

This research proposed to assess the effectiveness of chemical poultice in removing water-repellent coatings from hand-made brick substrates. This investigation is imperative due to the history of unintended consequences caused by the widespread inappropriate application of hydrophobic treatments and subsequent damage caused by said treatments, which has necessitated a method for removal. Additionally, there is a growing need to ascertain if penetrating water repellent treatments are retreatable and compatible, particularly for their continued use in preservation treatments for historical buildings.

Furthermore, the industry currently lacks research on the removal of penetrating water repellent treatments. This represents a critical knowledge gap that must be addressed. More thorough discussion and investigation are necessary to develop effective methods for the safe and complete removal of these treatments, particularly in the context of historic preservation.

A performance-based evaluation was conducted to assess the effectiveness of select chemical removers used in conjunction with poultices. Both solvent-based and alkaline-based chemical removers were tested on modern hand-molded bricks. The test samples comprised untreated bricks, bricks treated with water repellent, and bricks treated with water repellent followed by chemical cleaning. Each brick sample was divided into three parts to accommodate different segments of the testing program. The evaluation encompassed two key aspects: the performance of the bricks in terms of water absorption and water vapor transmission, and an analysis of the chemical components present on the brick surface. This analysis was conducted through surface photomicrography and reflectance (FT-) IR spectroscopy. By conducting all test programs on three segments of each sample, the results could be compared.