On the Influence of Cross-Section and Reinforcement of Reinforced Concrete Constructions on the Concentration of Coarse Aggregate in Concrete with Frame Structure

Abstract

Concretes with frame structure produced by using the technology of separate concreting by immersing a coarse aggregate in a low-viscosity mortar matrix due to an increased concentration of coarse aggregate have an increased E-modulus, reduced creep coefficient and cement volume in concrete compared to traditional vibrational compaction concretes. Production concrete using separate concreting technology by immersing a coarse aggregate in a mortar matrix with low-viscosity allows to obtain a frame structure of concrete with a concentration of coarse aggregate up to 0.7 when a voidness of coarse aggregate is equal 0.28. The real concentration of coarse aggregate in a concrete structure depends on the particle size of the coarse aggregate, the cross-section dimensions of the structure, and the reinforcement coefficient. The influence of geometric dimensions and the coefficient of reinforcement on the concentration of coarse aggregate in the concrete with frame structure is studied. The concentration of coarse aggregate decreases with the growth of the S/V modulus (S – area, m2, V – volume, m3) and the reinforcement coefficient, but the decrease in the E-modulus does not exceed 5%. Conclusion: regardless of the type of construction and reinforcement, the concrete of the frame structure must have a sufficiently high uniformity of deformation properties.

Improving the Structural Characteristics of Heavy Concrete by Combined Disperse Reinforcement

“…The addition of synthetic fibers to the concrete mixture does not lead to a noticeable increase in the strength of the composite for axial tension, elongation in bending, and compression under the action of static loads, since concrete cannot transfer static forces to fibers, which have a lower modulus of elasticity compared to concrete. However, despite the low values of elastic characteristics, in comparison with steel, polypropylene fibers are still of great interest in terms of their use for dispersed reinforcement [37][38][39][40][41][42].…”

Analysis of up-to-date methods of non-destructive testing of performance properties of reinforced concrete building structures

“…The basic principle for each of the above-mentioned methods of impact action is the principle of interaction of pulse being delivered by the impact of the device's striker and the structure's material. For example, rebounding velocity is higher in concretes of higher density and lower content of cavities in the structure [6,7]. The conversion of the striker's kinetic energy into potential energy allows us to make calculations and build calibration dependencies between the readings of the device and the strength of concrete.…”

The Influence of the E-Modulus of Coarse Aggregate on the Stress-Strain Diagram of the Concrete with Frame Structure

“…The stress-strain diagram was obtained under central axial compression of concrete samples. Concretes of two series with various coarse aggregate were tested: crushed granite with E-modulus 71 GPa and strength of the initial rock more than 120 MPa [11] and crushed siliceous sandstone with E-modulus 42 GPa and strength of the initial rock more than 100 MPa [10]. In the first series mortar matrix with ratio cement: sand C:S = 1:1.3 were used (sand with 2.7 size modulus).…”

“…Due to the low concentration of the mortar matrix and, consequently, the cement stone in the structure of concrete, such concretes are characterized by a low indicator of specific cement content from 4 to 6 kg/(m 3 •MPa) [8]. Due to the high concentration of coarse aggregate, its properties have a significant impact on the deformation properties and the stress-strain diagram of the concrete with frame structure under loading [10,11]. The results of studies of the effect of coarse aggregates with various E-modulus on the stress-strain diagram of the concrete with frame structure in comparison with ordinary concrete are presented.…”