Effect of Organic Compounds on the Special Properties and the Microstructure of Autoclaved Brick.

After a long decomposition process, organic matter turns into humic substances. In humus, carbon dioxide (CO2) bound in photosynthesis is brought back to the soil, where it should be used by its ecosystem. This is important because similar relationships are found in modern concretes and concretes designed with the use of geochemical modeling (possibility of the C-S-H phase for storing harmful substances). The aim of the article was to investigate the possibility of using humus (Humus Active-HA) and vermicompost (Biohumus Extra Universal-BEU), i.e., organic matter resulting from a long process of biological decomposition in the production of autoclaved bricks containing only ecological materials, i.e., sand, lime, and water. Tests of compressive strength, density, microstructure based on SEM, XRD, and micro-CT analysis were performed. The results of the research indicate that humus and vermicompost can be successfully used in their production. The paper compares traditional products and products made of raw material mass containing 3%, 7%, and 11% of humus and vermicompost, using the apparatus of mathematical experiment planning. Compressive strength, volumetric density, water absorption, and wicking, porosity, and material microstructure were tested. The best results were obtained for samples with the addition of 7% humus and 3% vermicompost. The compressive strength increased to 42.04 MPa (compared to standard bricks, whose strength is 15-20 MPa), and the bulk density increased by about 55%, to the value of 2.11 kg/dm3, which indicates the densification of the material's microstructure. They were characterized by the highest compressive strength, moderate water absorption, and a high proportion of closed pores in the sample.

Influence of Waste Basalt Powder Addition on the Microstructure and Mechanical Properties of Autoclave Brick.

In the production of building materials, there has been an increased interest in the use of by-products and industrial waste in recent years. Such modifications make it possible to solve not only technical and economic problems, but also environmental problems. This article describes the use of basalt powder waste in sand-lime products (silicates). The aim of the study was to manage basalt powder waste and to investigate the changes it causes in sand-lime products. The article describes the planning of the experiment, which directly determines the number of samples and their composition, which was necessary to conducting a full analysis and correctly illustrating the relationships occurring in the samples. Basic tests were carried out: compressive strength, density and water absorption, as well as optical tests and scanning microscopy. Based on the research conducted, it was concluded that the use of basalt powder as a component of sand-lime products has positive effects. Studies show that the best results are achieved with a proportion of powder in the raw material mass of about 10%-the compressive strength reaches almost 30 MPa, which is almost twice that of traditional silicate.

Onboarding in Polish Enterprises in the Perspective of HR Specialists.

The article discusses onboarding in Polish enterprises analyzed from the perspective of HR specialists. The subject of consideration in the article falls within the area of broadly understood concern for the sustainable development and well-being of employees adjusting to a new work environment during their adaptation period. Actions taken by HR specialists have a significant impact on the behavior of employees and their well-being and satisfaction in the new workplace, including commitment and care for all stakeholders involved in building a positive psychological climate at the time of starting work. The aim of the article was to identify onboarding practices implemented in selected types of Polish enterprises and selected factors determining the choice of specific practices, such as analyzing the dependencies between the type of an enterprise and the implementation of onboarding practices in it, identifying the perception of these practices by HR male and female specialists at a given age and with given seniority, and determining whether the practice of assigning a buddy to new employees depends on the type of enterprise. The study described in the article was conducted in 178 medium-sized Polish enterprises, of which, 25 were manufacturing companies, 34 were trading companies, and 119 were service companies. In each enterprise, an HR specialist completed a questionnaire on onboarding. The analysis of the dependencies between the type of company and the type of onboarding implemented in it (general, position, or team onboarding) revealed no statistically significant differences between the types of companies participating in the study and the type of onboarding implemented in them. The discrepancies between preferences for particular onboarding practices and the gender, age, and seniority of HR specialists participating in the study turned out to be statistically significant and indicate that manufacturing companies more often assign a buddy to new employees in their onboarding process than trading and service companies. The conclusions obtained from the research, apart from the cognitive value, have an application value, e.g., regarding the recruitment of HR specialists.

Experiencing Stress among Different Professional Groups in the Context of Their Age.

The subject of this article is the identification of coping with stress and experiencing stress in three groups of the same number of people, different in terms of their occupation: professional soldiers of the Polish Army with the rank of an officer, people employed in managerial positions, and specialists working in independent positions in the context of their age. The analysis of the literature and the research carried out refer to the concept of sustainable development. This indicates the need to take care of limiting excessive stress and improving the mental well-being of all employees, regardless of the demographic characteristics and nature of the work performed. In order to identify possible differences, three types of questionnaires meeting the criteria of psychometric correctness were used (CISS, KPS, PSS-10). The obtained results were subjected to statistical analysis using the FUZZY TOPSIS method based on multi-criteria decision-making and the fuzzy logic, which was first applied in the social science. The obtained data confirmed some differentiation within the three studied groups, as well as the modifying role of age in coping and experiencing stress.

Cement Bypass Dust as an Ecological Binder Substitute in Autoclaved Silica-Lime Products.

The cement industry is one of the most developed industries in the world. However, it consumes excessive amounts of natural resources and can negatively impact the environment through its by-products: carbon dioxide (CO2), cement clinker dust (CKD) and cement bypass dust (CBPD). The amount of dust generated in the cement clinker production process depends largely on the technology used. It typically ranges from 0 to 25% by weight of the clinker, and a single cement plant is capable of producing 1000 tons of CBPD per day. Despite practical applications in many areas, such as soil stabilisation, concrete mix production, chemical processing or ceramic and brick production, the dust is still stored in heaps. This poses an environmental challenge, so new ways of managing it are being sought. Due to the significant content of free lime (>30%) in CBPD, this paper uses cement bypass dust as a binder replacement in autoclaved silica−lime products. Indeed, the basic composition of silicate bricks includes 92% sand, 8% lime and water. The investigation shows that it is possible to completely replace the binder with CBPD dust in the autoclaved products. The obtained results showed that all properties of produced bricks were satisfactory. The study concluded that many benefits could be achieved by using cement bypass dust in the production of bricks, including economic bricks for building, reducing the dependency on natural resources, reducing pollution and reducing negative impacts on the environment.

The Influence of Hydrated Lime and Cellulose Ether Admixture on Water Retention, Rheology and Application Properties of Cement Plastering Mortars.

In this article, the effect of hydrated lime and cellulose ether on the water retention, rheology, and application properties of plasters was studied. For mortars, the consistency, bulk density, and water retention were tested. Rheological measurements of pastes included yield stress and plastic viscosity. In addition to standard tests of mortars and examining the rheological properties of the pastes, a proprietary method for testing the application properties was proposed. The obtained research results made it possible to evaluate the performance of the tested plasters. An attempt was also made to correlate the rheological properties of pastes (plastic viscosity) to the water retention value. The influence of hydrated lime and cellulose ether on selected properties of pastes and plasters was also presented using the statistical Box-Behnken method. The subjective rating of an expert plasterer confirmed the necessity of the modification of plastering mortars with hydrated lime and cellulose ether. As shown, modification of cement plastering mortar with hydrated lime and cellulose ether at the same time allows obtaining a material with favorable technical and technological properties, especially mortars applied by machine.

Thermal Conductivity of Sand-Lime Products Modified with Foam Glass Granulate.

Waste glass constitutes a significant part of general waste worldwide. Unfortunately, only a small percentage is recycled. It is, therefore, quite important that it can be applied in the production of construction materials. The main aim of this article is to determine the thermal conductivity of the products modified with granulated foam glass (GFG) (recycled product) of the 0.25-0.5 mm fraction, as well as to indicate dependence of the change in volume density of samples caused by the use of GFG and the change of the thermal conductivity coefficient compared to reference samples. For the purpose of this research, various parameters were examined i.a. volume density, water absorption, determination of the pore size distribution by mercury porosimetry and determination of the heat conduction coefficient with the use of a plate apparatus. The test results were developed on the basis of a mathematical model that determined the influence of the filler on the functional properties of the product. The research has shown that the use of GFG in the sand-lime products will contribute to lowering their thermal conductivity by more than 50% compared to traditional products.

Recycled Glass as a Substitute for Quartz Sand in Silicate Products.

In 2016, an average of 5.0 tons of waste per household was generated in the European Union (including waste glass). In the same year, 45.7% of the waste glass in the EU was recycled. The incorporation of recycled waste glass in building materials, i.e., concrete, cements, or ceramics, is very popular around the world because of the environmental problems and costs connected with their disposal and recycling. A less known solution, however, is using the waste glass in composite products, including sand-lime. The aim of this work was to assess the role of recycled container waste glass in a sand-lime mix. The waste was used as a substitute for the quartz sand. To verify the suitability of recycled glass for the production of sand-lime products, the physical and mechanical properties of sand-lime specimens were examined. Four series of specimens were made: 0%, 33%, 66%, and 100% of recycled waste glass (RG) as a sand (FA) replacement. The binder mass did not change (8%). The research results showed that ternary mixtures of lime, sand, and recycled waste glass had a higher compressive strength and lower density compared to the reference specimen. The sand-lime specimen containing 100% (RG) increased the compressive strength by 287% compared to that of the control specimen. The increase in the parameters was proportional to the amount of the replacement in the mixtures.