USE OF SELF-SEALING CONCRETE WITH POLYCARBOXYLATE-TYPE ADDITIVES IN THE PRODUCTION OF LONG-LASTING ZBK

Abstract

In modern conditions, in order to ensure high standards in monolithic construction, as well as in the production of complex heavily reinforced or long-dimension structures, self-compacting concrete has become widely used. Self-sealing concrete is two-phase (solid and liquid) suspension and has high fluidity. Fluid maintenance and avoidance phase segregation is a difficult task, the main mechanisms for control is the surface chemistry of particles of small fractions, as well as quality cement dough and the amount of coarse aggregate. The basis of self-compacting concrete is ultra-thin free-flowing cement dough. The mobility of the dough increases along with the thickness of the water film solid particles. However, the water shell is formed only around grains, when the spaces between the grains were previously filled. The amount of water that necessary to obtain a certain fluidity of the dough directly depends on values of the specific surface of wetted particles. The unevenness and shape of grains, surface energy, pozzolanic and hydraulic properties of ultrathin of mineral applications directly affects the thickness of the water film that acts as a lubricant In addition to high fluidity, the dough must also have high viscosity in order to avoid delamination. With the help of appropriate super precise control of flow behavior is achieved without plasticizers noticeable changes in quality Such concretes have a number of advantages: the ability to densely fill the form or formwork and penetrate into hard-to-reach places without using vibration; maintains the homogeneity of the structure, even in the presence of densely located fittings and has the ability to independently release entrained air. Such properties are achieved as a result of the correct selection of the composition of the concrete mixture with the use of fine aggregate fractions, as well as the use of appropriate plasticizing additives.