Исследование свойств двухслойных бетонно-фибробетонных конструкций при различных соотношениях толщины слоев

Abstract

Introduction. The article presents the results of a study of the strength properties of concrete, fiber-reinforced concrete and combined structures (two-layer concrete-fiber-reinforced concrete structures, where one layer is made of concrete without reinforcement, the second is made of fiber-reinforced concrete). Materials and Methods. Two types of concrete mixture were prepared, differing only in that polypropylene fiber was added to one (dosage 5 kg/m3), and to the other not. From these mixtures 4 series of samples were made, three pieces in each one with dimensions of 100×100×400 mm of various compositions: 1st series is completely made of a mixture with fiber; 2nd series is completely without fiber; 3rd series is made of two layers: the first half (50 mm in height of the sample) consists of a mixture with fiber, and the second half without it; 4th series is one third (33 mm in height of the sample) from a mixture with fiber, and two thirds part without fiber. Results. After the standard hardening period all specimens were tested for tensile flexural strength (three-point bending). On the basis of these tests, conclusions were drawn about the possibility of using fiber reinforcement of structures not for the entire volume, but only within the stretched zone. Discussion. Based on these tests, conclusions were drawn about the possibility of using fiber reinforcement structures not for the entire volume, but only within the stretched zone. Conclusion. The results of laboratory studies have shown that samples with fibroblast have residual strength, while samples without fibroblast have a sharp decrease in strength after reaching a peak value, and the processes of changing the limit of proportionality (strength) when testing combined samples of concrete and fibroblast structures are described. Resume. The results can be used in the design of fiber-reinforced concrete structures experiencing tensile loads, as well as in the development of research in this area. The principal possibility of using combined (two-layer) structures in the design of sprayed concrete supports with a complex geometry of the production contour is proved. The further development of this research topic is relevant when considering multilayer concrete and fiber-reinforced concrete structures. For practical purposes, these results can be useful, especially when designing sprayed concrete supports of mine workings.