ABSTRACT
Going by the circumstances prevailing in the past, the first generation repair materials were developed on the basis of hydraulic cement alone. Although these materials, such as the dry pack mortar, preplaced aggregate concrete, shotcrete, replacement concrete, etc., are still being used, they suffer from shortcomings of delayed setting and hardening, low tensile strength, unsuitability for thin section repair, injectability difficulties, poor bond strength, etc. These shortcomings led to the extensive introduction of polymeric materials in partial of full replacement of the hydraulic binders. As a result, materials like epoxy-bonded dry pack mortars, organo-hydraulic grout-injected preplaced aggregate concrete, epoxy resin bonded concrete or prepacked polymer concretes came into wider application. Apart from surface or patch repairs, acrylic and epoxy resins, alkyl-alkoxy silane monomers, polymeric siloxane, etc, are being used for hydrophobic treatment of concrete with varying
certain ingredients including solvents. Attempts are being made to develop new reaction processes using green ingredients and solvents. For example, it is possible to eliminate the use of phosgene in the production of urethane; similarly one may look forward to the use of nonpetrochemical solvents like ethyl lactate in the coatings industry.
