Keywords: composite

INCREASING IN IMPACT VISCOSITY OF FIBER-ASH-CONCRETE

https://doi.org/10.34031/2618-7183-2020-3-6-5-16
Abstract
The trend in building materials science is to replace the different proportions of Portland cement in the binder. Therefore, the paper proposes the principles of controlling the static and dynamic strength of fiber-reinforced concrete, consisting in the complex effect of the hydro-removed ash and slag mix and basalt fiber on the processes of structure formation of the cement composite. A four-stage purification system for the hydro-removed ash and slag mixture has been developed, including disintegration, flotation and two-stage magnetic separation. It was found that the density of the fresh mix from the dose behaves naturally, and the density of solid samples at low doses slightly decreases. High early strength of the developed composites is noted, in particular, for specimens with ASM, one and a half increase in compressive strength is traced in comparison with non-additive specimens. Combinations of "fiber + ASM" with a quadrupling of strength have a significant effect on bending strength. Successful approximations of the compressive strength and bending strength on the ASM dose for different ages (1, 7, 28 days) are traced with the regular behavior of the coefficients in the power dependences. Revealed a multiple increase in the impact strength of the developed compositions. The use of the results will lead to the possibility of designing high-strength concretes, including for special structures.
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EFFECT OF WOLLASTONITE ON THE MECHANICAL CHARACTERISTICS OF CONCRETE

https://doi.org/10.34031/2618-7183-2020-3-5-34-42
Abstract
Improvement of the physical and mechanical properties of cement composites should be accompanied by the disposal of industrial waste of various generation. Therefore, the paper proposes the principles of con-trolling the strength properties of concrete, which consist in the complex effect of wollastonite obtained from boron production waste on the processes of structure formation of the cement matrix. When this introduced in an amount of 2-8 wt. % wollastonite has a dual function as a mineral filler and a reinforcing fiber. It has been proven that in the presence of wollastonite, the concrete mix becomes lighter without reducing its physical and mechanical properties. It was revealed that the early strength for all the developed compositions with the addition of wollastonite increases due to the acceleration of hydration processes. Calcium silicate, which is wollastonite CaSiO3, has a close chemical composition with cement clinker, especially with Ca2SiO4 belite and Ca3SiO5 alite. This leads to the formation of a chemically homogeneous and, as a result, hardened microstructure. Elongated wollastonite fibers with good adhesion to the cement stone provide effective micro-reinforcement of the concrete composite. Using the results will lead to the possibility of designing high-strength concretes, including for special structures.
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