Scheduled defect dimensions are provided for guidance purposes only and should not be used in isolation for costing purposes. The processes involved in concrete patch-repair include the preparation of some defects by cutting-out. Cutting-out is undertaken to both prepare the defects to accommodate repair materials and also to ensure that all of the defective concrete is removed and all deteriorated reinforcement is treated. Concrete patch-repairs could, therefore, be significantly different in both size and shape when compared to the defects from which they were derived. Limited exploratory cutting-out may be carried out, on some ‘typical’ defects in order to evaluate potential over-cut, defect to repair, but we would, nevertheless, point out that the only truly and fully accurate measure of repair quantities is that carried out once all defects have been cut-out, ready for repair.
To provide data concerning the likely extent of cutting out required we undertake the visual inspection and hammer testing, described elsewhere with due regard to guidance provided within BS EN 1504 and an array of references from the Concrete Society, CIRIA, Building Research Establishment, the Institution of Civil Engineers and the International Concrete Repair Institute.
Reinforcement at selected, representative existing spalled locations should also be chased back into sound concrete. Exposed and corroded reinforcement will be further exposed in order to assess both the extent of corrosion, in relation to the depth of carbonation and depth of chloride contamination at that location, but also to determine reinforcement bar type/s, which would be identified using the classifications described within CIRIA Special Publication 118. Reinforcement bar diameters and, if applicable, any loss of cross-section will be recorded.
In addition, for guidance, the relative dimensions and form, of potential repairs, compared to the visual defects, will be assessed, to provide, as far as practicable, data for the subsequent preparation of concrete repair bills of quantity, as described within the Concrete Repair Association, Standard Method of Measurement and Concrete Society Technical Report No.38.
In some locations, the reinforcement within selected sound areas, at progressively greater depths of cover, may be exposed and inspected for evidence of deterioration and corrosion in order to assess the likely depth at which the reinforcement is potentially at risk from deterioration and corrosion.
NB: In the case of pre-cast cladding panels, and potentially other forms of construction, an assessment of Form and Fixing may be advisable, or even necessary. Deterioration and distress may focus around particular areas of constructional detail, such as fixings, which should be resolved in order to assess reparability.