Investigation properties of resistance fiber reinforced concrete

Abstract

It is possible to improve the performance of concrete by reinforcing the concrete with chaotically arranged short sections of various fibrous materials (straw, horse hair, graphite, asbestos, polypropylene fibers, etc.). The material thus obtained is referred to as fiber concrete. If we use short sections of steel wire as fibers, we get a composite material called fiber reinforced concrete. Numerous studies show that this material has several advantages over concrete, and partly with reinforced concrete - increased tensile strength, higher fracture toughness, greater resistance to shock and vibration loads, increased frost resistance, abrasion resistance and high temperature action.

Fiber concrete differs significantly from reinforced concrete in that, from a certain limit on the coefficients of volume reinforcement, fibers do not perceive internal forces, but due to the adhesion forces bind the concrete matrix and inhibit its development in microcracks;

With the same reinforcement coefficients, thinner fibers are more effective, as this reduces the critical distance between their centers and, therefore, the likelihood of crack formation.

Steel fibers, crossing the trunk crack, contribute to stabilization of the achieved level of crack formation and restrain the creep deformation of the compressed zone of the steel fiber element. Due to this, the stiffness of the bending steel fiber element decreases more slowly than the rigidity of the same reinforced concrete.

The work of compression steel is less pronounced than tensile. However, the resistance of the steel fiber specimen when compressed by 20 ... 30% exceeds the resistance of the concrete. This is explained by the restraining action of the fibers in the development of tensile stresses on the planes perpendicular to the line of action of the compressive force.

It has been proved that the viscosity of steel-fiber concrete is about 10 ... 12 times higher than the viscosity of concrete and reinforced concrete.