Dolgiy V. Creation of high-mobility concrete mixes for pipe concrete of a complex section

The work is devoted to the development of a method for selecting concrete mixes composition with directional regulation of their rheological characteristics using chemical and mineral additives designed to fill continuous pipe structures of complex cross section and long lengths. Object of study. The processes of preparation and injection of concrete mixtures for pipe structures of complex section. The purpose of the study. Development of a method for selecting concrete mixes composition with directional regulation of their rheological characteristics using chemical and mineral additives designed to fill continuous pipe structures of complex section and long lengths. Research Methods. Studies were performed using methods of planning of an experiment. Physical and mechanical studies were carried out in accordance with the regulatory requirements of state standards, as well as according to the developed methods using 6 PAO deflection meters, the relative strains at the control points were determined using IMIG indicators and electronic strain gauges. The rheological properties of concrete mixtures were determined according to current regulatory documents and using a rotational viscometer. The novelty of the work lies in the fact that the methodology for the selection of the composition of multicomponent concrete mixtures for pipe concrete structures of complex section and long length has acquired a further development by changing the rheological properties with varying raw materials. For the first time, compositions of multicomponent highly fluid concrete mixtures for pipe-concrete structures of complex section 1000 m long have been developed. A mechanism has been established for the formation of plugs when injection of light concrete mixtures on porous aggregates into pipe-concrete structures. It is shown that ensuring a high yield strength of concrete mixtures and viscosity at a low shear rate, but with a low flow resistance at a high shear rate, is possible by introducing water-holding additives. The role of finely ground mineral fillers in reducing the separation of highly fluid and cast concrete mixtures is shown. It has been established that filling the rail space with concrete reduces the noise level by 9.6 dB in the frequency range 63 ... 8000 Hz. The technological regulations for the preparation and injection of concrete mixtures into long-length pipe-concrete structures of complex section have been developed. The practical results are in the development of compositions of multicomponent concrete mixtures that can be manufactured in ready-mixed concrete plants. The developed concrete mixes can be used for concreting densely reinforced, distant and inaccessible structures where vehicles cannot be accessed, as well as pipe-concrete structures with a complex configuration. The results of the dissertation were introduced at CJSC String Technologies during the construction of the Ecotechnopark in Maryina Gorka (Republic of Belarus).