Granite is a well-known building and decorative material, and, therefore, the amount of produced waste in the form of granite powder is a problem. Granite powder affects the health of people living near landfills. Dust particles floating in the air, which are blown by gusts of wind, can lead to lung silicosis and eye infections, and can also affect the immune system. To find an application for this kind of waste material, it was decided to study the effect of partially replacing cement with waste granite powder on the properties of fresh and hardened mortars intended for masonry applications. The authors planned to replace 5%, 10%, and 15% of cement with waste material. Series of mortar with the addition of granite powder achieved 50% to 70% of the compressive strength of the reference series, and 60% to 76% of the bending strength of the reference series. The partial replacement of cement with the granite powder significantly increased the water sorption coefficient. The consistency of the fresh mortar, and its density and water absorption also increased when compared to the reference series. Therefore, Granite powder can be used as a partial replacement of cement in masonry mortars.
Bleeding is a common problem in concrete slabs, and may lead to serious damage. The goal of this article is to understand the impact of alternative binders and their properties on the bleeding of concrete. Therefore, the impact of the type of binder on the bleeding process is investigated. The results show that the addition of granite powder or fly ash allows for the increased control of the bleeding process. It was found that a finer particle size distribution (PSD), an increased specific surface area (SSA), and a higher bulk density may reduce the amount of dispensed water in the concrete mix. Furthermore, the use of additives with an increased SSA leads to even a 30% reduction of the bleeding rate of mixes. The utilization of additives with a finer PSD than cement enables a 37% reduction of the bleeding rate of mixes. The influence of bleeding on compressive strength was assessed using destructive and non-destructive tests: Replacing 30% of cement with granite powder leads to a 30% reduction of concrete strength after 28 days of curing; on the other hand, replacing 30% of cement with siliceous fly ash leads to an 18% reduction of strength. Importantly, bleeding was also found to lead to the heterogeneity of the physical and mechanical properties across the concrete section. Consequently, the proper control of the bleeding process leads to more homogeneous properties of concrete across its cross-section.
This article proposes a methodology for classifying occupational accidents involving scaffolding based on the knowledge of the causes that led to their occurrence. Each occupational accident is caused by several causes belonging to three generic groups (technical, organizational, human) occurring in a different configuration. The aim of this research was to determine the qualitative and quantitative structure of the causes of accidents caused by falling from scaffolding. Significant causes were selected from the set of all the causes identified in the analyzed set of accidents. For this purpose, Pareto–Lorenz analysis and the ABC classification were used. Then, a set of significant causes containing technical, organizational and human causes was created, which was the basis for determining the subsets of accidents caused by similar causes. The hierarchical cluster analysis method, the agglomeration clustering technique and the binding of objects using the Ward method were proposed to determine the number of characteristic clusters. Three subsets of accidents with a similar set of causes were obtained. Information on the quality and number of causes in individual subsets was used to estimate the probability of an accident caused by a given set of causes and to assess occupational risk in construction. Calculations were performed using Statistica software.
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