This paper presents the results of laboratory tests on the properties of cement concrete containing various types of aggregate. The purpose of the tests was to determine the effect of aggregate on compressive strength, indirect tensile strength, air pore characteristics, frost resistance and the modulus of elasticity of concrete for road surfaces. The aggregate that meets the requirements for road concrete was determined on the basis of the tests. Keywords: road concrete, frost resistance of aggregate, frost resistance of road concrete.

The paper presents an analysis of the technical condition of a railway bridge structure with a span structure in the form of welded girders. Static diagram of the structure consists of two simply supported beams. The theoretical span of the spans is 2 x 14.50 m, their overall length is 14.90 m, and the total length of the crossing is 30.6 m. The reasons for the formation and development of bridge degradation were analysed. In addition, the actual load capacity of the structure was determined and the possibility of its further operation was evaluated. Particular attention was given to the quality of workmanship and the degradation progress of welded joints, which led to the exclusion of the object from use. The main purpose of the presented analyses is to formulate general recommendations, whose implementation in a direct or indirect form may contribute to reducing the degradation process of railway steel bridge structures. When inspecting welded railway bridges, particular attention should be paid to the condition of welds and to control and prevent the structure from cracking.

The presented article concentrates on the influence of various concrete additives in the form of fibers on the mechanical parameters of concrete so as to obtain the effect of gradual changes in these parameters, which is very important in the transition zone of the railway track. Steel, polymer and glass fibers, as well as concrete without additives, were accepted for the study. The effect of additives on the consistency of the mixture, compressive strength, frost resistance and elastic modulus was studied. The research concerned concrete samples and models of elements of the ballastless railway surface, i.e., track slab and concrete block supports. The track slab model was made of concrete without additives, while the models of supports were made both without and with additives. The studies were carried out in laboratory conditions. As a result, the tested concrete samples with various additives were ranked so that they could be used as a material for elements of the railway surface in the transition zones of engineering facilities on railway roads, which is important from the point of view of reducing the threshold effect occurring in these zones. Detailed laboratory tests were presented, the results of these studies were discussed, and final conclusions were drawn regarding the technology of materials and the methodology of constructing the transition zones of the railway surface in order to avoid or at least reduce the threshold effect existing in such zones.

The paper presents the results of experimental research that is the continuation of the research conducted as a part of a Ph.D. dissertation. The experimental research consisted in measuring the temperature at various depths inside a concrete slab, including its surface, and measuring the air temperature. The temperature distribution was measured on a concrete slab with dimensions similar to real road slab dimensions. The aim of the research was to determine the temperature gradient in the concrete slab in Polish climatic conditions and to verify the available analytical methods. Keywords: temperature gradient, concrete pavement, thermal stress in concrete pavement.