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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

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The article is devoted to questions of identification of the factors influencing the establishment of high-quality intercompany relationships between stakeholders within the framework of the investment and building project. The problems arising at the developer by the transfer of part of construction works to the contractor. As the major factors influencing the establishment of high-quality intercompany relationship we consider the specificity of capital of the developer, the size of the enterprise, the level of uncertainty and the trust of the developer to other participants. In each group of factors the analysis is using the components' method to allocate those which exert the greatest impact. A logit-model was constructed and the calculation for it was carried out allowing to estimate a contribution of each component to results. The model integrates a concept of trust with the main variables of the transaction cost theory. It is estimated on the selection basis of the construction organizations from the Ural Federal District of Russia. As a result, the authors conclude that the trust influences the developer's decisions about transfers of part of construction works to the contractor within the framework of an investment project.