The effect of metal and polypropylene fiber on technological and physical mechanical properties of activated cement compositions

Increasing physical and mechanical properties of concretes by adding various types of fibers and simultaneously increasing the adhesion strength of "fiber-cement stone" by activating binder is an important scientific problem of modern construction materials science. In this work, the effect of the fiber of various material and size on the rheological properties of concrete mixtures and the physical and mechanical properties of self-compacting concrete and mortar obtained by activation of portland cement in the vortex layer device was investigated. Dependence of impact viscosity on quantitative content of fiber was obtained. Self-compacting concrete with polydisperse reinforcement has been received by optimization of content of investigated types of fibers. In this work, for the first time, a structural analysis of disperse reinforcement of fiber concretes was carried out on the basis of the theory of Schklowskу-De Zhen. It has been shown that steel fibers form nodes of a "star" type mesh, and polypropylene fibers form "tangles" with a high concentration of fibers. In this case, the metal fiber increases the shear stress of the concrete mixture obtained by activation by 1.56 times, which is higher than the polypropylene fiber (up to 1.34 times). A similar effect of the fiber has been observed in determining the viscosity of the concrete mixture. It has been shown that the higher the geometric dimension of the fiber concrete structure the more impact is provided on the resistance to shrinkage development. The developed composition of the fiber concrete obtained by activating the binder in the vortex layer device can find wide application in construction practice.