Bonding agent and grout: Bonding agent are natural compounded or synthetic materials used to enhance the joining of individual members of a structure without employing mechanical fasteners. These products as the bonding of fresh concrete, sprayed concrete or sand/cement repair mortar to hardened concrete. Two of the critical factors affecting the bonding between new and old concrete, provided sound concrete practices are followed, are (i) the strength and integrity of the old surface and (ii) the cleanliness of the old surface