Rrestoration (Repair) Methods of the Lower Surfaces of Reinforced Concrete Structures by Forming a Mixture into a Formwork

Abstract

The article presents technological solutions that can be used to restore and strengthen significant areas of the lower surfaces of span reinforced concrete structures, as well as minor deep damage of the lower surface of reinforced concrete structures. This method is used to repair fragmentary damage of the lower surfaces of structures. The presented methods consist in preparation of the base, arrangement of the formwork, and feeding repair mixture into the shuttering through the holes in the structure or in the shuttering. 
 The method of restoring large surfaces consists in feeding a high-mobility non-shrinkable concrete mixture into the gap between the restored structure and the previously arranged formwork. After preparing the base, at the highest points of the damaged structure through-holes are drilled to supply the concrete mixture, release air and control the filling of the cavity with the mixture. The fixed formwork panels must completely cover the restored part of the structure and partially extend onto the undamaged surface of the structure. The prepared concrete mixture is fed through a funnel into the hole until the cavity and holes are completely filled up with it and vibrate. After a day, the formwork is removed and moistened for 3 days.
 To repair minor deep damage to the lower surfaces of reinforced concrete structures is performed by feeding a highly mobile non-shrinkable mixture into the space between the structure and pre-mounted formwork is performed using a syringe for soluble mixtures. Holes are drilled in the formwork to release air and supply the mortar. Flexible tubes are installed in the holes. A syringe with the prepared solution is connected to the rubber tube and filled the cavity. After the mixture begins to come out through the air release tube, it is removed, and a plug is installed in the hole. When the cavity of the damaged fragment is completely filled, the rubber hose is bent and fixed in this position, and the syringe for the solution is disconnected. After 5 hours, the restored fragment is stripped and looked after.
 The proposed methods make it possible to carry out high-quality repair work on the lower surfaces of spans without using special complex equipment, which reduces the cost of repair work.