Fly ash class F from Thermal Power Plant “Stanari” was used in combination with highly plastic brick clay from Busovača to develop building bricks. The brick clay and fly ash were characterized for chemical and mineralogical composition, grain size distribution, and specific gravity. The fly ash has a higher proportion of larger particles and lower specific gravity than clay. The brick clay was mixed with 20, 40, and 60 wt. % of fly ash, formed in a prismatic shape, dried and then fired at 800, 900, and 1000 °C. The fired prisms were characterized for water absorption, apparent porosity, apparent density, and strength and compared with conventional clay prisms. The addition of fly ash of 20, 40, and 60% reduced the mass of the samples by 14, 23, and 31%, increased apparent porosity by 60, 100, and 160%, and reduced the compressive strength by 50, 80, and 90%, respectively. Conducted tests and comparative studies have shown that the fly ash “Stanari” can be used as an additive to the clay “Čavka” in the maximum amount of 20 % and the optimum firing temperature is 900 °C.

This paper presents the results of an experimental investigation into the effect of nano-silica addition on the mechanical properties and durability of concrete. Three mixes of concrete containing 0%, 2%, and 4% nano-silica by weight of cement were tested. The slump of fresh concrete as well as compressive strength, dynamic modulus of elasticity at 2, 7, 28, 90, and 180 days, and flexural strength at 2, 28, and 90 days of hardened concrete were determined. As for indicators of concrete durability, the total volume of permeable voids, water absorption, the rate of water absorption, and the freeze-thaw scaling resistance were determined. Test results showed that the incorporation of nano-silica in concrete resulted in an improvement of all mechanical properties of concrete, as well as concrete durability parameters that are tested.

Greenhouse gases emission as well as total energy consumption in buildings of public importance, such as schools, municipal buildings, health care centers, can be significantly reduced by increasing buildings? energy efficiency. Buildings? energy consumption adds up to 37% of total energy consumption in the European Union countries. In the Republic of Serbia this amount is significantly higher, about 50%. School buildings are considered as one of the most diverse structures from the point of energy-efficient design and construction. The main aim of this paper is to determine the most appropriate settings for possible improvements in energy efficiency and temperature comfort inside a typical primary school classroom in Serbia. The energy efficiency analysis was performed during the heating season for the naturally ventilated primary school classroom located in the Eastern Serbia region. The analysis was performed using novel computational fluid dynamics model, suggested in this paper. The suggested model was used to solve two hypothetical scenarios. The first scenario simulates the temperature field in classroom with current energy characteristic envelope of the school building. The calculated numerical data from the first scenario were compared with in-situ measurements values of temperature and wall heat fluxes and showed satisfying accuracy. The second scenario was simulated to indicate possible improvements, which would allow energy consumption decrease and thermal quality enhancement. The analyzed results, calculated using the suggested numerical model under the second scenario conditions, showed that using appropriate set of measures, it is possible to obtain desired temperature comfort levels without need for increase in the building energy consumption.

Following the idea of sustainability in food production, a yogurt premix based on beetroot (Beta vulgaris) pomace flour (BPF) was developed. BPF was granulated with lactose solution containing lactic acid bacteria (LAB) by a fluidized bed. Particle size increased ~30%. A decrease in Carr Index from 21.5 to 14.98 and Hausner ratio from 1.27 to 1.18 confirmed improved flowability of granulated BPF, whereas a decrease in water activity implied better storability. Yogurts were produced weekly from neat starters and granulated BPF (3% w/w) that were stored for up to one month (4 °C). High viability of Streptococcus thermophilus was observed. Less pronounced syneresis, higher inhibition of colon cancer cell viability (13.0–24.5%), and anti-Escherichia activity were ascribed to BPF yogurts or their supernatants (i.e., extracted whey). Acceptable palatability for humans and dogs was demonstrated. A survey revealed positive consumers’ attitudes toward the granulated BPF as a premix for yogurts amended to humans and dogs. For the first time, BPF granulated with LAB was used as a premix for a fermented beverage. An initial step in the conceptualization of a novel DIY (do it yourself) formula for obtaining a fresh yogurt fortified with natural dietary fiber and antioxidants has been accomplished.

To provide the quality required for its use, raw kaolin must be subjected to certain processing procedures like delamination which is applied to the layered structure materials. The aim of this research is to determine the possibility of performing delamination in the extruder and to estimate the effects of this process on the physico-chemical properties of kaolin. The results showed that delamination can be efficiently realized in the extruder by shearing densely packed layers under the influence of friction force and added Na2CO3 electrolyte. The crystal structure of the system was thus disrupted. This was confirmed by the Hinckley index (HI) decrease and by the dilatometric characteristics changes during heating. The particle size was reduced and, furthermore, new adsorption centers were formed, which led to an increase in the total cation exchange capacity (CEC). The plasticity of kaolin decreased with the increasing delamination degree, as well as the amount of water required for plastic processing, which is favorable in drying ceramic products.

A method was proposed for the preparation of silica powders using sodium silicate as the silica source and carbon dioxide and hydrochloric acid as precipitating reagents. The effect of reaction temperature (20, 40, 60, and 80 °C) and SiO2 concentration in sodium silicate solutions (4, 6, 8, and 10 %) on silica morphology, dibutyl phthalate absorption, aggregate size distribution, and dispersion ability (agglomerates fragility) were investigated. The best properties of silica powder were achieved at reaction temperature 40 °C and SiO2 concentration 8 %. The properties of the silica sample obtained at optimal conditions were compared with properties of high-quality commercial silica used as rubber reinforcing filler. Also, the vulcanization characteristics and mechanical characteristics of rubber composites containing these two silica fillers were investigated. It was found that silica filler with excellent properties can be produced using the proposed method, while by tuning temperature and precursor concentration, the silica properties that are important for its reinforcing potential may be closely controlled.