Investigations concerning the processes of plugging stone structure formation, using X-ray diffraction, electronic microscopy and differential thermal analyses, were implemented. Influence of active mineral additives of metakaolin and zeolite on the properties of plugging mortar and their interaction with Portland cement minerals with the aid of the model systems were established.

Abstract. This article presents the results of experimental investigation of reinforced concrete beams without transverse reinforcement on the shear. In researching, the variable parameter was relative span to effective depth ratio, which acquired the values a/d=2, 1.5, 1. The testing program involves testing of each beams samples twice. Beams were tested by the static loading of applied force at two points. Experimental results have shown the difference between the experiments of twin beams above 5 -9%. The obtained results indicate an increase of the bearing capacity with a decrease of relative span to the effective depth ratio. The first inclined crack disclosed in mid-height cross section, at the load 50 kN at an angle equal to 45. With increasing loading, the width of crack increased and the crack propagation occurred to the top surface of the testing sample. On occurrence of limit width of crack wmax=0.4 mm, another crack was opened in the direction from the loading point to the edge of beam support. The limit values of the crack opening width are fixed at 71 -84% of the load carrying capacity of the samples. The effect of increasing the shear strength, according to the serviceability, is similar to the increasing of the bearing capacity and close by the value.

The composite materials as FRP (Fiber Reinforced Polymers), which are characterized by benefits resulting from the combination of high strength reinforcement (as carbon, glass, steel or aramid fibers) with synthetic matrix are increasingly used to reinforce existing structures. Reinforcing System as FRCM (Fibre Reinforced Cementitious Matrix), which includes, among others, Ruredil X Mesh Gold System, is much less commonly used. However, the uniform and practical methods for calculating composite reinforced structures are not determined. Especially when considering the real conditions of structure exploitation, which requires further research in this field. In the paper the initial loading level influence on the efficiency of reinforced concrete beams strengthen using system Ruredil X Mesh Gold was investigated.

The article is devoted to an experimental research of the strength of reinforced concrete beams, and its dependence on a simultaneous influence of a corrosion environment and a loading factor. The tests have been carried out upon reinforced concrete specimens of 2100×200×100 mm size, with a regular reinforcement. The beams are of a span equaling to 1,9m with different reinforcing ratio of beams. The acid environment, namely 10 % H2SO4, was taken as a model of an aggressive environment. Reinforced concrete beams have been tested with and without the co-action of the aggressive environment and loading factor. Beams, which underwent a simultaneous action of the corrosive environment and loading, were loaded to a level 0.7 of its load-carrying capacity. The load-carrying capacity in aggressive environment in all the beams of all the series was achieved in 46-60 days. The influence of the simultaneous action of the aggressive environment and loading on the strength of reinforced-concrete beams has been described in the following work. It is necessary to note that the design code of Ukraine does not allow determining load carrying capacity of the beams affected by corrosion with simultaneous influence of loading with adequate accuracy. The analysis of experimental data has been done and the main directions of the design code's correction have been formulated.

This research paper present the experimental study of reinforce concrete beams strengthened by FRCM system in the shear area. All samples are without transverse reinforcement at the shear distance. First beams tested as control sample, with shear distance a/d=2. Another three beams tested with strengthening by FRCM system. Variable parameter is the level of initial load, before strengthening. The initial load values were 0, 0.3, 0.5 from carrying capacity of control samples. All RC beams were designed to fail in shear, even strengthened samples. In the result of this research we determined that fracture toughness of RC beams increases with a decrease of span to the effective depth ratio. Results are comparable with the increasing of bearing capacity. The first inclined crack opend in mid-height cross section at the load 50 kN at an angle equal to 45 0 and it does not depend on the shear span. The maximum width of inclined cracks decrease with decreasing of shear span. The maximum width of inclined cracks decrease with decreasing of the shear span. The maximum values of width of inclined cracks are fixed at the value of 0.55 -0.85 mm. Using the limit crack opening width as criteria of exhaustion of serviceability (SLS) we saw that about 16 -29% of bearing capacity still remains before the danger of shear failure of the beam. * Corresponding author: Pavlo.I.Vehera@lpnu.ua