Choice of rational parametres of fiber reinforcement

Purpose. One of the ways of improving building material composites is to make composites, while working together dissimilar materials gives an effect equivalent to the creation of a new material whose properties are both quantitatively and qualitatively different from its components. The most promising in this direction is dispersed concrete reinforcement using various types of fibers. Distributing throughout the concrete matrix, fiber provides a three-dimensional reinforcement. The purpose of this article is to conduct a comparative analysis of the strength characteristics of various types of fiber reinforcement for different types of effects, on the basis of which r the price - the strength characteristics of the reinforcement (length and diameter of fiber filaments, or the percentage content by weight fiberglass) are determined. Research is conducted for the basalt, polypropylene and steel fibers. Methods. On the basis of experimental studies by different authors the analysis of the influence of the size and content of the fiberglass on the strength characteristics of the fiber-reinforced concrete for each type of fibers has been given. Results. Basalt fiber is basalt fiber pieces in the form of friable monofilaments length of 3 ... 30 mm, in some cases up to 50 mm, diameter of 13 ... 20 m. The most acceptable from the point of view of strength and processability is length 12 mm, the percentage of 0.2%. Polypropylene fibrovolokno is made from pure polypropylene under continuous process by extrusion and stretching while heating. It is efficient to use fibers of "DІІF" with a diameter of 20 mm and a length of 12 mm and a rate of 1.0 kg / m3. The steel fiber is the most durable and popular material. It can be obtained in various ways: by cutting a steel wire or a thin sheet of turnings, from waste products (for example, from waste cables) and etc. The length of the fibers depends on the technology of its manufacture. Various authors' experimental studies show that the presence of the loops at the ends of the fibers greatly increases the index of adhesion to cement mortar. In this connection, the most suitable anchoring fiber is "Chelyabinka", which has high physical and mechanical characteristics in compared with other types of fibers. It is made of rolled steel (tape, sheet), and a steel strip having at the ends of the anchors in the form of segments of a circle. The ends of the strips are unfolded from each other by an arbitrary angle. Thus, for basalt, polypropylene and steel fibers have been the optimal length, diameter and weight, or the percentage content. Scientific novelty. As a result of the analysis optimal parameters of fiber reinforcement (length, diameter, percent) were selected for various kinds of fibers in order to have a further research of thermal, physical and mechanical properties of concrete on their basis. Practical significance. The increase in the volume of using concrete and structural changes in operating conditions requires continuous improvement of concrete. Based on the analysis of literary sources the information about the most common types of fiberglass has been systematized. This will help to choose the characteristics of fiber-reinforced concrete with optimal price - strength, greatly increasing the strength characteristics of concrete. The study of literature sources also shows that there is practically no data on the strength of fiber-reinforced concrete at temperature influences. This stimulates new experimental and theoretical studies of different types of fiber-reinforced concrete on fire.