## 2 Research in the Field of Building Materials  
The most popular material that is used in the construction industry is concrete. Its common use is primarily influenced by its high compressive strength, its relatively high durability and resistance to various factors, the ease of forming elements, and the availability of components and their low cost. Concrete is a composite, the basic components of which are a cement matrix and aggregate. In recent years there has been a growing interest in modifying cement composites with finer materials (e.g., various types of fibres or nanoparticles) in order to improve their parameters. Article [1] presents an assessment of the creep of the cement matrix of self-compacting concrete modified with the addition of SiO\({}_{2}\), TiO\({}_{2}\), and Al\({}_{2}\)O\({}_{3}\) nanoparticles using the cavity method. Depending on the type of nanoparticles used, an increase or a decrease in the creep coefficient CIT was found when compared to the reference series. It was found that the addition of SiO\({}_{2}\) and Al\({}_{2}\)O\({}_{3}\) nanoparticles in the amount of 4.0% of the cement mass results in an unfavourably higher value of the creep coefficient (CIT) of the cement matrix. In turn, the use of TiO\({}_{2}\) nanoparticles in the amount of 4.0% of the cement mass results in a favourable reduction in the creep coefficient CIT. The statistical analysis of the obtainedtest results indicates, however, that the addition of nanoparticles does not significantly affect the creep of the cement matrix of self-compacting concrete. Depending on the dimensions of concrete elements, aggregates of different granulation are used in building structures. The properties of the aggregate determine the strength and durability of the concrete. Taking this fact into account, the authors of article [2] examined the influence of the maximum graining of aggregate on the strength properties and modulus of elasticity of concrete. The research showed that the strength properties of the aggregate are not only proportional to the maximum size of the aggregate grain, but also to the aggregate's crushing strength. However, no analogous relationships were found in terms of the modulus of elasticity of the tested concrete. As already mentioned, one of the main requirements for building structures is durability. In reinforced concrete structures, the direct factor that influences the durability of concrete is the corrosion of reinforcing steel. In paper [3], one of the non-destructive methods was used to assess the degree of corrosion of the reinforcement, namely the galvanostatic pulse method (GPM). It is an electrochemical method that uses the physicochemical properties of concrete and steel. Using this method, the influence of the temperature of the tested element on the results of such parameters as: corrosion current density, stationary potential of the reinforcement, and the resistivity of lagging, was investigated. The differences in the values of these parameters, which were measured on the same samples, but at different temperatures, amounted to several dozen percent in some cases. This means that measurements of actual structural elements conducted with the use of the GPM, e.g., at different times of the year, may lead to an incorrect estimation of the probability of corrosion of the reinforcement in the studied area, and also to an incorrect assessment of its corrosive activity over time. According to the authors, it is advisable to define appropriate temperature correction factors for measurements performed with the use of the GPM. It is more and more common to use various fibrous composites that improve the technical parameters of concrete. The use of FRP (Fibre Reinforced Polymers) materials is of particular interest. Paper [4] proposes a new original mathematical formula for predicting the compressive strength of FRP-confined concrete cylinders. The formula was developed on the basis of the output data obtained from a neural network.