The problem of the composition optimization of concrete mixes seems to be quite urgent as errors at the composition design stage can lead to problems of concrete at the stage of exploitation such as delamination, cracking etc. Reasonable selection of concrete mix components guarantees the required strength of concrete and reinforced concrete structures in the future. This paper investigates the influence of the concrete mix composition on the strength of concrete. Firstly, typical risks that can occur on the composition design stage have been identified through the experts' interviews. Secondly, this risks were associated with indicators and characteristics that can be tested experimentally. Running of several mathematical models has allowed to outline concrete mix parameters of highest importance and formulate an empirical equation for the dependence of the strength of the concrete mixture on the values of the coarse aggregate quality factor, the fine aggregate fraction and the consumption of the Portland cement has been proposed. As a result, a methodology for controlling the quality of concrete at the stage of the composition design has been formulated. Doi: 10.28991/cej-2021-03091732 Full Text: PDF

The development of modern construction requires the use of environmentally friendly building materials, including insulating materials, to ensure the energy efficiency of buildings and structures. The purpose of the work is relevant and was to develop a methodology for assessing the compliance of extruded polystyrene foam with environmental requirements. The problem is that the certification of such materials includes an examination of their physical and mechanical properties and does not allow assessment of materials’ environmental aspects. A comprehensive approach to assessing the quality of extruded polystyrene foam is proposed, which ensures not only the technical level of material quality, but also compliance with environmental requirements. The research methodology is based on the environmental risks’ identification at all stages of production and the determination of products environmental safety criteria. Each criterion is characterized by a set of indicators, among which a representative indicator is determined. A complex indicator is proposed for assessing the environmental safety of the production of extruded foamed polystyrene. The novelty of the work lies in the algorithm for calculating the material environmental friendliness complex criterion. The process model of the extruded polystyrene foam production analyses made it possible to establish representative indicators according to the products’ environmental safety criteria. As a result of the analysis, critical operations were identified where environmental risks are likely, and representative indicators’ limit values were set in accordance with regulatory documentation. Measures have been developed to minimize the release of harmful substances during each critical operation. To improve environmental management, the system for monitoring and assessing risks in the production of extruded foamed polystyrene has been optimized. As a result, a methodology has been developed for assessing the compliance of the production of extruded polystyrene foam with environmental requirements, which is necessary for product quality certification. Doi: 10.28991/CEJ-2022-08-10-018 Full Text: PDF