Track 1: DOCUMENTATION AND DIAGNOSTICS – UNDERSTANDING HISTORIC PLACES / Volet 1 : Documentation et diagnostic – Comprendre les lieux historiques

Testing and Evaluation of Soil Based Grouts for the Adhesion of Consolidated and Un-Consolidated Painted Lime Plaster at the Mission San José de Tumacácori

Friday, October 13
10:30 AM - 12:15 PM

The interior decorative painting at Mission San Jose de Tumacácori is a rare survival of late 18th century-early 19th century artistic traditions of northern Sonora and the Kino mission churches. Despite earlier attempts to stabilize these finishes, the original painted lime plaster has continued to detach from the adobe substrate. Previous techniques to stabilize the paintings began with research by J. Rutherford Gettens in 1949-1952 and subsequent attempts in 1984 to reattach detached plaster have proven ineffective. Furthermore, the last time exhaustive work was done in the interior nave was in 1984. The current research evaluates soil-based injection grouting in order to adhere the loose plaster on the nave and sanctuary walls. Earthen grouts were chosen over the more commonly used hydraulic lime grouts in order to consider a more compatible system with the original construction materials. A well-designed earthen grout must be fluid enough to insure full penetration, exhibit low shrinkage and strong bond strength equal to its own cohesive strength for successful repair. Samples of the original adobe, mortar, and plaster were analyzed and local soils were sampled and tested in order to design a grout displaying optimal properties. The test grout was subjected to several geo-technical tests including viscosity, density, shrinkage, and expansion/ bleeding; as well as its hardened properties such as splitting tensile strength, capillary water absorption, water retention and permeability. The selected grout’s performance was finally analyzed within a mock-up assembly composed of friable plaster facsimiles and adobe, simulating 1/2" and 1/4" gaps. Half of the plaster facsimiles were consolidated with nanolime due to their friable nature based on recent parallel research. The research expands current knowledge on the use of earthen grouts for reattachment of earthen and lime plasters on earthen substrates.

Learning Objectives:

Nicole M. Declet

University of Pennsilvania

Nicole Mariel Declet Díaz received a Master of Science in Historic Preservation, with a focus in Building Conservation Science, from the University of Pennsylvania. She received her bachelor degree from the School of Architecture at the University of Puerto Rico. Declet has primarily focused on the conservation of earthen buildings. Recently, Declet and a team of conservators worked on the Mission San José de Tumacácori stabilizing the lime plaster and adobe, as well as applying the soil grout tested as part of her thesis. Currently, Declet is completing a fellowship at the Getty Conservation Institute in the Building and Sites Department.


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Stephen J. Kelley, FAIA, SE, FAPT, FUSICOMOS

Stephen J Kelley, Inc.

Stephen J. Kelley is a registered architect and structural engineer in private practice who has devoted these two skills to the preservation of our built cultural heritage. With 35 years of experience, his projects range from small to immense, simple to sophisticated and cover a wide range of building materials and systems. His award-winning projects are located throughout the United States but he has also worked on significant projects in Asia, Europe, Africa, South America and the Caribbean basin. He has published widely on various aspects of preservation and is an educator who has taught at the university level thus sharing his experience with the next generation of preservation professionals. He has served on the Board of Directors of both the US Committee of the International Council on Monuments and Sites (US/ICOMOS) and the Association for Preservation Technology (APT) and was elevated to Fellowship in both organizations. He is a UNESCO Tangible Heritage Expert and is Vice President of the International Scientific Committee on the Analysis and Restoration of Structures of Architectural Heritage (ISCARSAH).


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Testing and Evaluation of Soil Based Grouts for the Adhesion of Consolidated and Un-Consolidated Painted Lime Plaster at the Mission San José de Tumacácori

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