Evaluation of Consolidation Treatments for the San José Convento Column, San Antonio Missions National Historic Park, San Antonio, Texas

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drill resistance
Historic Preservation and Conservation
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McNabb, Kalen Daniel

The retreatment of previously consolidated stone has become a common occurrence and an important area of research in the field of architectural conservation. The San José Convento Column within the San Antonio Missions National Historical Park in San Antonio, Texas is a prime example for consideration. Initially analyzed, tested, and treated in 1993 by the Architectural Conservation Laboratory at the University of Pennsylvania, the limestone column is in need of additional treatment. Recent analysis has determined that while the 1993 treatment had been largely successful, microcracks originally present have advanced and surface detachment has worsened, largely due to clay swelling deterioration. Over the past 19 years, further research has been performed on modified ethyl silicates that inhibit clay swelling while restoring the grain-to-grain cohesion of argillaceous stone. In order to determine the most appropriate consolidation treatment for the column, several consolidants including a modified ethyl silicate were tested to determine the most appropriate method for in situ application. Samples, consisting of 2-inch square cubes and 2-inch x 2-inch x 0.2-inch coupons were treated with three different consolidants including a pre-treatment with an anti-swelling agent. Samples were then subjected to physico-mechanical testing to evaluate the effect of these treatments on stone strength, water absorption, and permeability. New methods of assessing the consolidation effects involving resistance drill testing were used to measure depth of penetration and efficacy of application. The information and data obtained from this study will inform the future retreatment of the column needed to resolve the microcracking visible today.

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<p>Suggested Citation:</p> <p>McNabb, Kalen Daniel (2012). <em>Evaluation of Consolidation Treatments for the San José Convento Column, San Antonio Missions National Historic Park, San Antonio, Texas</em>. (Masters Thesis). University of Pennsylvania, Philadelphia, PA.</p>
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