Performance Evaluation of Patch Repairs on Historic Concrete Structures

A component of Concrete Conservation
A concrete, multi-story building with shrubs on each floor's balconies sits behind a walkway

Example of a heritage building in which exposed concrete contributes to the site’s cultural significance: Alexandra Road Estate and Park, 1972-1978. Neave Brown, Camden Architects Department, England

Participants in the Conserving Concrete Heritage Experts meeting identified lack of knowledge on the efficacy and durability of existing concrete repair solutions and the scarcity of technical resources on concrete conservation as critical challenges confronting the field.

In response, the Conservation Institute has partnered with Historic England and Laboratoire de Recherche des Monuments Historiques, France, to develop research to evaluate the performance of patch repairs executed in concrete conservation projects. “Patch repair” is used in this research to refer to nonstructural repair, both full-depth and partial-depth, where partial replacement of original deteriorated or damaged concrete is conducted.

The research focuses on repairs designed for and executed on culturally significant buildings and structures that aimed to follow typical conservation principles—such as minimizing loss of original material and retaining original profile, texture, and color of the parent concrete—in addition to meeting the usual requirements of concrete repair, such as adhesion and compatibility with the substrate material. The research involves the evaluation of concrete repairs on a selection of historic concrete structures in England, France, and the United States.

Outcomes

  • Better understanding of repair methods and practices, patch repair deterioration, and efficacy and durability of patch repairs
  • Identification of professional resources, such as existing guidance and craftsmanship skills, available in each country and how that context influences concrete repair in historic buildings
  • Methodology for recording, monitoring, and evaluating repairs to historic reinforced concrete
  • Identification of future research needs

Methodology

Phase I

  • Development of evaluation methodology and identification of survey and assessment techniques
  • Selection of case studies in England, France, and the United States

Phase II

  • Background research on each case study’s original building specifications and repair history
  • Field assessment and documentation of current conditions of the repairs based on visual inspection and nondestructive evaluation techniques

Phase III

  • Selection of a smaller number of case studies for in-depth evaluation
  • Complementary in-situ testing and sample collection for laboratory analysis

Phase IV

  • Dissemination of results through reports and papers
  • Development of events for discussion of results with practitioners

Team Members

Conservation Institute

  • Susan Macdonald, Project Director, Head, Buildings and Sites
  • Ana Paula Arato Gonçalves, Project Manager, Associate Project Specialist
  • Simeon Wilkie, Associate Scientist

Historic England

  • Nicola Lauder

Laboratoire de Recherche des Monuments Historiques

  • Élisabeth Marie-Victoire
  • Myriam Bouichou
  • Jean Ducasse-Lapeyrusse

Consultants

  • Rowan Technologies Ltd: David Farrell
  • Simpson, Gumpertz & Heger: Matthew Bronski
  • Wiss, Janney, Elstner Associates: Paul Gaudette, Ann Harrer
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