Investigating the structural contribution of patch repairs to reinforced concrete elements

Concrete Materials and Structural Integrity Research Unit, Department of Civil Engineering, University of Cape Town, South Africa

^* Corresponding author: nrgvaf001@myuct.ac.za
⁺ Corresponding author: hans.beushausen@uct.ac.za

Abstract

The patch repair method is one of the most common approaches used by engineers for repairing reinforced concrete structures that have been damaged. Despite its popularity, the knowledge on material properties pertinent to a durable structural repair is still lacking. Most standards and guidelines on concrete repair currently specify arbitrary limits when it comes to the properties of repair materials. In the case of structural patch repairs, these arbitrary limits have led to the development of high-strength cementitious repair mortars, often marketed as “high-performance”, that are tailored to meet the specifications and not the needs on-site. The paper discussed here forms part of a greater study that aims to increase the understanding of patch repairs and inform existing guidelines on designing structural patch repairs. Three commercially available high strength cement-based repair materials were tested for their strength, elastic modulus, shrinkage, and creep properties. These properties were then used as inputs to an analytical model that was developed to determine the distribution of stress in a repaired element over-time. The results from the analytical model suggest that high strength materials do not structurally contribute in the long term, for patch repaired concrete elements under axial compression.