ADHESION WHEN USING PARTIAL SHOTCRETE WITH MOBILE EQUIPMENT

Abstract

The current methods have been analyzed and materials that are used for the repair and renovation of concrete and reinforced concrete elements of the construction of the future. One of these is the considered method of shotcrete, the use of wet shotcrete, its advantages and disadvantages. Defects that occur during the manufacture, storage, transportation, installation and operation of concrete and reinforced concrete structures are given. The formation of different types of cracks that occur before the operation process and the appearance of cracks during the operation of structures under central tension and along one surface during eccentric tension are considered. The work presents regulation of the technical properties of repair mixtures achieved by the use of special types of cement, additives and aggregates, special laying methods and hardening conditions, as well as appropriate preparation of the surface of old concrete. The study is aimed at determining the adhesion of repair mixtures applied by the shotcreting method. Partial application of the repair mixture was used, using a mobile installation in laboratory conditions, in order to determine the optimal technological parameters of spraying. The methodology of experimental studies for determining the adhesion of fine-grained shotcreting using standardized forms with modernized partitions has been developed. Prepared beam halves with a surface angle of 20°, like old concrete, were used to increase the contact area and reduce swirl during shotcrete. A two-factor, nine-point plan of the experiment was developed, in which the thickness of the layer of fine-grained shotcrete (1 cm, 2 cm, 3 cm) of partial application and the speed of spraying of the shotcrete fiber concrete mixture (0 m/s, 35 m/s, 70 m/s) were varied. An experimental study was conducted and the results of the studies were presented.