Concrete Repairs in “Rehabilitation Works Sample Clauses

Concrete Repairs in “Rehabilitation Works. Many factors can lead to defects in old concrete structures which will manifest themselves sooner /or/ later depending on the agressivity of the environment. The visible manifestation of the defects is commonly referred to a damage. − A defect exists where a structure, member, or building material is permanently subjected to stresses or aggressive conditions which exceed its load bearing capacity or resistance. − The damage is the consequence of that defect and normally manifests itself at the surface of the concrete, it may however lie concealed beneath the undisturbed surface of the concrete. The Contractor is invited not to simply repair the damage because this does not by itself suffice to eradicate the defect which caused it. Precautions must therefore be taken by the Contractor to prevent a recurrence of damage caused by the same defect. In most cases this is achieved by treating the surface of the concrete with an additional form of protective treatment: Repair protection: is the formula for successful remedial actions. The Contractor must visit all the site and for each structure: − Identify the various stress factors that can cause damage to concrete structure. − Give guidance in the diagnosis and assessment of such damage. − Suggest “method of treatment” aiming to eradicate the primary cause or defect. The Contractor must obtain full agreement from the Engineer for each of these steps. The Contractor must obtain also previous approval from the Engineer for: − The products. − The remedial treatment of concrete. N.B.: Repairs systems designed to render concrete and reinforced concrete impermeable to water, in existing water retaining structure may be used by the Contractor applying these same procedures. The main zones to be assessed by the diagnosis can be resumed to: 1) Corrosion of steel reinforcement: a) Carbonation b) Infiltration of harmful substances. c) Thickness of concrete cover to the steel reinforcement 2) Mechanical influences on concrete: a) Abrasion 3) Chemical influences: a) Erosion by dissolution of the material. b) Disruption caused by internal expansion 4) Physical influences.