Project Objectives
The primary objectives of the project are to evaluate the working properties and performance characteristics of injection grouts for the conservation of architectural surfaces, including plasters, wall paintings and mosaics, and to provide reliable tools for conservators and conservation scientists to assess and compare different grouts in the laboratory and field.

Specific objectives of the project are:

• to inform practitioners in the field on the properties and performance of different grouts and grouting materials,
• to correlate scientific research with conservation practice in the field, and
• to disseminate the project results through laboratory and field workshops, publications, and a seminar.

	Giorgio Torraca (left), conservation scientist, and Giacomo Chiari (right), GCI chief scientist, test the injectability device at the GCI Building Materials Laboratory. Photo: Leslie Rainer.

Project Overview
In 2004, the GCI initiated an interdisciplinary study between its Field Projects and Science departments to evaluate injection grouts used in the conservation of architectural surfaces. The project aims to assess the properties of commercially produced and custom-mixed injection grouts widely used in the past twenty-five years to preserve architectural surfaces in situ—a current practice in most of the world. The project aims to combine laboratory testing and field study of these grouts to inform conservators and conservation scientists of the range of injection grouts used in the field, and to improve conservation practice.

Seminal research on injection grouts for the conservation of architectural surfaces was conducted by ICCROM in the early 1980s, coinciding with the movement toward preserving these architectural features in their original context, rather than detaching them, as was previously practiced. Following development of hydraulic lime-based grout formulations at ICCROM in the early 1980s, numerous variations of these injection grouts have been produced and widely used over the past twenty-five years, including a number of commercially produced grout mixtures.

	Conservators and scientists from the Getty Conservation Institute are working with wall paintings conservators from the Herculaneum Conservation Project to evaluate grouts used for conservation of plasters and wall paintings at Herculaneum. Photo: Leslie Rainer.

While manufacturers provide technical data for their products, and testing on custom mixes has been carried out, no single testing method is in use. This makes it difficult to compare and evaluate different injection grouts. Additionally, no limiting-values or criteria to evaluate and compare different grouts have been specifically defined for working properties and they have been defined only in a few studies for performance characteristics. A variety of test methods for the preparation, characterization, and evaluation of grouts has been used—in most cases standardized tests developed for other materials (e.g., mortars, epoxy resins, cement-based binders, etc.) with modifications.

Furthermore, limited systematic research has been done to assess the acceptability and usefulness of these modified laboratory test methods to evaluate injection grouts. At this time there are no standardized tests specifically designed for injection grouts used in the conservation of architectural surfaces, and scant information has been published on field testing.

	Wall paintings such as this one at the archaeological site of Herculaneum require injection grouting to reattach delaminated plaster to the support in order to preserve them in situ. Photo: Leslie Rainer.

In 2005, following the compilation of a bibliography and preliminary literature review on the topic (Component One), the GCI convened a meeting of conservators and conservation scientists to discuss the current state of grouts and grouting practice and to exchange ideas on avenues of further research. As a result of the literature review and specialists meeting, the project has initially focused on the identification, refinement, and development of a suite of tests specific to injection grouts, which can be disseminated to scientists and conservation professionals in the field.

Project activities include:

• compilation of an extensive bibliography and literature review on injection grouts for the conservation of architectural surfaces (Component One)
• modification or development of test methods to evaluate the working properties and performance characteristics of commercial and custom mixed grouts for the conservation of architectural surfaces (Component Two)
• publication of laboratory protocols for a suite of test methods (Component Two)
• design of practical field tests for conservators that can be correlated with laboratory testing (Component Three)
• dissemination of the results of the project to conservators and conservation scientists in the field to improve conservation practice (Component Four).

Last updated: June 2009