Rehabilitation of reinforced concrete structures #2 Reinforced concrete

Mexico City Earthquake, September 19, 1985. Nuevo Leon fifteen-story reinforced concrete structure. Part of the building was only slightly damaged, while another part of it collapsed. Can this building be rehabilitated?

Before we can start, first we need to know what is a reinforced concrete and how it behave under common loads. This will formed the understanding on why it deteriorates and finally lead us how it can be rehabilitated.

Reinforced concrete is a composite material. Composite materials mean that it is derived from a few materials to form a new engineered material. The few materials have significantly different physical and chemical properties which remains separate at the microscopic or the microscopic level. All these materials in concrete formed a concrete. These materials must be mixed together at a certain composition in order to produce a concrete that is fit for the intended purpose. A variations of mixture may result in difference of strengths. More importantly, an error in the mixtures may lead to structural failures.

The common materials for a reinforced concrete consists of cement, reinforcement bar (or steel - the same thing), aggregates and water. Separately, all these materials work and behave differently. They may not work as intended if one of it is removed even if the proportions were not mixed properly.

Reinforced concrete was derived from a concrete. The difference between these two was the introduction of the steel element (reinforcement bar). When steel is introduced, we called it reinforced. Concrete is strong when being compressed but weak if tensioned while steel behave the exact opposite way. This is the beauty. Hence, reinforced concrete not only resist compression but also tension, which are the two inherent stresses acting on a structures.

Funnily, reinforced concrete was not invented by an engineer but rather a French gardener named Joseph Monier in 1849. Of course, further work after that was carried out by engineers. As I say before, let the professional do the work. You may invent something, but that's it (no bad intention to the original inventor).

Reinforced concrete structures are everywhere. Look around you.

Dr. Ibrisam Akbar