The particle shape and size of the starting powders represent the most important physical properties, on which the quality of the compacts and final sintered products depends. Two types of powder were analyzed in the paper - electrolytic copper powder with a dendritic particle shape and water-atomized copper powder with an irregular particle shape. The starting powders were sieved through a sieve system with openings of 45 μm, 80 μm, and 120 μm. The characterization of the obtained fractions of both powders was performed by determining the shape and dimensions of the particles using SEM microscopy in combination with ImageJ software, and the apparent density and flow rate were determined using the Hall flowmeter funnel. Pressing of each powder fraction was done using a pressure of 600 MPa. The compacts were further sintered at 1000°C for 2 hours to obtain the final sintered parts. After sintering, their density, hardness, and electrical conductivity were determined and their microstructure was analyzed. The results indicate a great influence of the characteristics of the starting powders on the properties of the final parts obtained by the powder metallurgy route. The particle shape of the powders had a more pronounced influence compared to the particle size.

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 freezethaw 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.

Due to the fast process of urbanization and the increase in the development of transport infrastructure, there is an increase in noise levels caused by road and railway traffic in urban areas, which represents one of the most important today's problems. The goal of this paper is to find out the current noise levels of road and railway traffic. Measuring road traffic noise levels in the area of the city of Zenica and the railway traffic noise in the vicinity of the Railway Station in Kakanj has been done. In the end, the analysis of the obtained results and comparisons with the values regulated by the law as allowed values were performed. Noise level maps were also plotted as one of the contributions to solving the problem of environmental noise.