Concrete repair

The 1950s and 1960s saw an enormous growth in new construction and many faults are now becoming evident in some of the structures constructed during these years of peak activity. Today, repair and refurbishment is often preferred to demolition and reconstruction with the result that the maintenance and refurbishment market now represents approximately 50% of the construction industry workload of £37bn per annum. Concrete repair is no exception and currently represents a market of at least £500m annually. A variety of concrete repair methods have been developed many of which rely on adhesion between a repair material and the concrete substrate. The more important aspects of concrete repair will now be discussed under the headings of resin injection, patches, coatings and sealants and finally the implications of property mismatch.

Resin injection

The injection of resin-based materials into cracked concrete is a technique widely employed to either restore structural integrity or to seal the cracks for subsequent durability. However, a necessary preliminary to the consideration of resin injection is an assessment to establish the cause of cracking in the first place. Here it is important to distinguish between inactive cracks which no longer move and live cracks which may continue to move with changing loads or temperatures.

In order to assist in establishing the cause of cracking in concrete it is often helpful to distinguish between intrinsic cracking(l) and that caused by an externally applied stress.