Optimization of Composition and Technological Factors for the Lightweight Fiber-Reinforced Concrete Production on a Combined Aggregate with an Increased Coefficient of Structural Quality

Abstract

In recent years, developing lightweight concrete with both the necessary and sufficient strength characteristics is essential in the construction industry. This article studies the influence of the volumetric composition of lightweight fiber-reinforced concrete (LFRC) and the method of its distribution during the preparation of the fiber–concrete mixture on the strength and deformation characteristics of LFRC on a combined aggregate. The optimal grain size of the porous filler was calculated by the mathematical planning method of the experiment. Regression models of the strength and deformation characteristics on the volumetric content of fiber and its distribution method were obtained. The most effective combination of these factors has been determined. The model shows that the increase in compressive strength was 12%, the value of the prismatic strength increased by 25%, the bending tensile strength increased by 34%, and the axial tensile strength increased by 11%. The ultimate strains during axial compression decreased by 10%, axial tension decreased by 12%, and the elasticity modulus increased by 11% compared to the test results of the control composition samples without fiber and pumice. The coefficient of constructive quality (CCQ) of the LFRC on a combined aggregate compared to concrete with the control composition without fiber and pumice showed an increase of more than 32%. It was also found that fiber reinforcement with basalt fibers with a combination of heavy and porous aggregates achieves a synergistic effect together.

Influence of Mechanochemical Activation of Concrete Components on the Properties of Vibro-Centrifugated Heavy Concrete

“…The results of experimental studies of the strength and deformation characteristics of concrete, depending on the type of activation and manufacturing technology, are presented in Table 7 and in Figures 5-12. For the manufacture of vibro-centrifuged samples of annular section, heavy concrete of class B30 was designed in accordance with previously developed recommendations [13,32,37].…”

“…During the research, no additives Portland cement produced by Oskolcement OJSC (Stary Oskol, cement plant site, Russia) [31] was used in accordance with [32].…”

“…Mineralogical and chemical composition of Portland cement is shown in Table 1. Granite crushed stone was used as a coarse dense aggregate (Yug-Nerud, Voronezh region, Russia), and quartz sand (Yuzhny GOK, Rostov region, Russia) was used as a fine aggregate, the mechanical and physical characteristics of which were similar to [32] and are presented in Tables 2 and 3. In addition, activated components were used-cement (mechanical activation) and water (chemical activation).…”

“…For the manufacture of vibro-centrifuged samples, an experimental laboratory vibrocentrifuge was used, a schematic diagram of this installation and a detailed description are presented in [37]. In addition, in [13,32,37] the mode of molding of prototypes of vibro-centrifuged concretes is described.…”

“…For the manufacture of vibro-centrifuged samples of annular section, heavy concrete of class B30 was designed in accordance with previously developed recommendations [13,32,37].…”