Krzysztof Ostrowski

The influence of the shape of coarse aggregate on the properties of fresh concrete mixes, and the strength of high-performance self-compacting concrete (hPsCC) is important issue. In this study, irregular and regular grains were separated from the basalt, porphyry and granite coarse aggregate. The shape of these grains was determining using digital image analysis and was in accordance with the european standard [19]. The aspect ratio (ar) and roundness (r) were ascertained in order to highlight the differences in the coarse aggregate shape used the design hPsCC. The study indicates that using the same crushing system, varied parameters of the shape of coarse aggregates were obtained. It was determined that the best fitting distribution for aspect ratio and roundness at a 95% confidence level is the generalised extreme value distribution. 

Due to their numerous advantages, epoxy resin coatings are a common way to finish industrial floors. Obtaining coating strength at the level declared by the manufacturer requires preparation of the cement substrate through mechanical treatment, for example, in the form of sandblasting. The next step is the thorough cleaning and vacuuming of the surface and the application of the adhesives. The aim of this research was to improve the strength parameters of a coating in which no adhesive were used. Materials which have a potentially positive effect on epoxy resins are mineral additives. This paper presents the results of tests aimed at improving the adhesion between a concrete foundation and an epoxy resin coating modified with waste glass powder obtained from the production of glass microspheres.

This article presents the influence of carbon fibre reinforced polymer sheets (CFRP) on the strength of normal and fibre concrete columns determined in uniaxial compression. Fibre reinforced concrete (FRC) belongs to a special concrete group which is characterised by special properties without strength [12]. By using CFRP, we can modify the process of work of these composites, which are adhered to a prepared surface using a high performance resin, especially as is shown in this article. This composite material works in an elastic-plastic range with strengthening.

This article presents the results of an experimental investigation on the influence of carbon-fibre-reinforced polymer (CFRP) sheets on the strength of short concrete columns constructed from normal concrete (NC) and high-performance concrete (HPC). The results show that external confinement can significantly improve the ultimate strength and strain of the specimens. The stress-strain response of confined concrete depends largely on the type of concrete with regard to its compressive strength. The results demonstrate that composite columns constructed from normal concrete work in an elastic-plastic range with strengthening, whereas strengthening of columns constructed from high-performance concrete did not occur. The study indicates that the confinement .

High-performance, self-compacting concrete (HPSCC) represents a very significant step in the development of concrete technology. The most important features of SCC are specific rheological properties which include flowability, segregation resistance and passing ability. Therefore, a crucial requirement is to maintain an appropriate balance between the slump flow and plastic viscosity of concrete mixtures. In general, the rheological properties are modified by effective superplasticisers and a proper ratio of water to binder. The aim of this study is to focus on the important aspect of the impact of shape of the coarse aggregate on fresh concrete mixture properties and the strength of high-performance, self-compacting concrete (HPSCC).

The purpose of the article is to determine the effect of the addition of polypropylene fibres on the properties of concrete mixtures and hardened concrete. To this end, both destructive and non-destructive tests were conducted. The concrete mixture tests included the testing of the consistency, air content and bulk density of the concrete mixture. Investigations of hardened concrete were based on the determination of compressive strength by destructive tests, sclerometer and ultrasonic methods and tensile strength in bending tests. All tests were performed for seven series of concrete mixtures, differing in their fibre content. The results showed that the addition of polypropylene fibres to the concrete mixture causes changes in consistency, increases air content, and does not increase the compressive and tensile strength of concrete. It was also observed that the addition of polypropylene fibres does not cause significant changes in the bulk density of the concrete mix.