Design of steel fiber-reinforced concrete for slip forming

Introduction. Slip forming is one of the effective and promising methods of concrete mix casting. Development of slip forming technologies largely depends on accumulated experience and tools, one of which is the composition design methodology. The use of special types of concrete, such as fiber-reinforced concrete, requires additional knowledge and the creation of special technological tools. The purpose of the study: to develop a methodology for designing steel fiber-reinforced concrete composition for slip forming. Methods and materials. Known methods for designing concrete and steel fiber-reinforced concrete compositions are used. A methodology for designing steel fiber-reinforced concrete composition for slip forming has been developed, consisting of two stages: designing the matrix composition to ensure a given ultimate extensibility of the mixture; designing steel fiber-reinforced concrete based on a pre-obtained matrix composition. Cement CEM I 42.5N, medium-sized sand, crushed stone with particles size 5-10 mm and 36 mm length steel milling fiber are used. Results and discussion. According to the proposed methodology, the composition of steel fiber-reinforced concrete with specified properties was designed (ultimate extensibility not less than 100 mm/m; cone slump 1...4 cm; compressive strength not less than 40 MPa; flexural strength not less than 6.5 MPa). The results of laboratory tests of the obtained composition are presented. In terms of strength, workability and ultimate extensibility, the composition meets the technical specifications. Conclusions. The proposed methodology of designing the composition of steel fiber-reinforced concrete for slip forming has been successfully tested in laboratory and can be recommended for use in production.