MATERIALS FOR REPAIR OF CONCRETE STRUCTURES

The range of materials for repair of concrete structures to be effectively durable is fairly limited. The materials most widely used are concrete and mortar, which are made as far as practicable with the same type of cement and aggregates as were used in the original structure. When deterioration is due to chemical attack, it may be necessary to use a different cement and or protective coatings. The repaired concrete fail mainly due to the failure or partial failure of the bond between the old and new work.
The standard of bond developed between the old and new concrete is directly related to the care taken in the preparation of the base concrete. In recent years a great deal of attention has been paid to the development of bonding agents. The choice of the repair material is directly related to the function of the repair and the expected service life of the structure after repair. The primary ingredients for most repair materials include one or more of the following:
(i) Ordinary or rapid hardening Portland cement
(ii) Epoxy resins
(iii) Polymer latex
(iv) Polyester resins
(v) Polyvinyl acetate
(vi) Fine and /or coarse aggregate filler

Selection of Concrete Repair Materials:

A variety of repair materials have been formulated to provide a wide range of properties. Since these properties will affect the performance of repair, selecting the correct material for specific application requires careful study. Concrete repair materials have been formulated to provide a wide range of properties. It is likely that more than one type of material will satisfy the design criteria for durable repair of specific structure. In these cases other factors must be taken into consideration which includes:
(i) Ease of application.
(ii) Cost.
(iii) Available labour skills and equipments.
(iv) Shelf life of the material.
(v) Pot life of the material.
A guideline for the selection of repair materials is shown in Table-1.