Дисперсное армирование - способ повышения прочности изделий

There is a question of optimum choice of type, length and quantitative content of fibers for achievement of high strength of compositions made on the basis of cement of various activities, construction sand and reinforcing components as a part of dry building mixes. Analysis of publications. The role of fibers is that they take a part of load, interfere with development of cracks and displacement of blocks, according to numerous researches which results are generalized in works of Desov A. E., Akhverdov I. N., Solomatov V. P., Vyrovoy V.N., etc. According to existing theories, destruction of composition is carried out due to breaking and stretching of fibers. There are different types of models and theories of destruction of materials on the basis of mineral binders. According to researchers, material is not isotropic environment, and deformation and destruction of concrete is caused by the influence of external forces. In case of introduction of discrete fibers, the mechanism of tension can be presented to the following. One part of fibers works for stretching and the other one interferes with shift of particles, increasing connectivity of the system. Mineral and metal fibers, located parallel to the operating external load, increase rigidity of the system. As organic fibers have low module of elasticity, they most likely interfere with shift of the particles and reduce arising secondary tension. Therefore, the effect of reinforcing depends on structure, matrix strength and also on parameters of fibers and their properties. The purpose of the article. Development of a method of determination of the minimum length and content of components in cement and fibrous composition. Conclusions. Thus, the made analysis of the research results shows that the most effective length of polypropylene fibers with a diameter up to 15 -17 µm in compositions of cement and sand mortars is in limits of 5 7 mm. The fibers content in mortars, at which compression strength increases by 1530%, and bending strength by 40-70%, does not exceed 0.2% of the binder mass. It is typical that reinforcing is more effective for compositions in which a lowbranded binder is applied. It testifies that it is possible with disperse reinforcing to eliminate partially decreasing of cement binder activity that is a result of its storage. So, strength gain due to reinforcing of mortars with binder activity 20 MPa is 50 60% whereas strength of mortars, in which Portland cement with activity of 49 MPa is applied increased, only for 25 30%.