Reinforced concrete repair - Part 1

The main problems involved in the design and execution of civil engineering structures and buildings are well known and, in general, carefully studied. The standards used as a reference provide sufficient security, and calculation assumptions are prudent.

As a result, the collapse of a structure, except in the case of an accident during construction, is an extremely rare event.

Nevertheless, many structures, although perfectly suited to the loads they carry, are bound to pose serious maintenance problems during their service life.

In addition, recurring problems appear on structures of the same nature, period or design. Damage can result from the repeated, unintentional use of inappropriate construction devices, poorly adapted design or execution methods, or inadequate materials.

This repeated use of unsatisfactory devices, materials or methods also stems from the fact that the engineer who designs, and the contractor who executes, are unaware of the difficulties they create, and therefore fail to make the necessary rectifications for subsequent work. This state of affairs is explicable, even if not excusable: the design, construction and maintenance of structures or buildings are generally entrusted to different departments or companies. Contacts between trades are often poorly organized or simply non-existent.

Whatever the case, one thing is certain: concrete, like all other materials, is subject to the ravages of time. It cracks, disintegrates or bursts under physical, mechanical and chemical stress. It therefore needs to be maintained and repaired, or even demolished if the damage is incurable.

It's clear that a thorough study of the environment in which the material will be used, and the conditions under which it will be installed, are the first precautions to be taken. Care and maintenance are the second stage of "good housekeeping". Repair" represents a more substantial intervention in the structure or material.

The repair of reinforced concrete structures, buildings, roads, etc. has become a routine operation. Concrete remains a high-performance, long-lasting material, but the explosion in construction after the Second World War has been such that the number of damaged buildings and infrastructures requiring repair is increasing exponentially.

At the interface between materials science and engineering, repair systems and techniques have to be chosen with a short-term view – to restoring a structure to its original capacity – but also, in the longer term, to ensuring it has a new lease of life. Achieving these objectives depends on a fair and sufficiently precise assessment of the condition of the elements....