Since depletion of natural resources and the amount of construction and demolition waste have overcome the socially and environmentally acceptable level, the construction industry must address this issue and reduce its impact on the environment. A step towards sustainability in the construction industry is the application of recycled aggregates and supplementary cementitious materials as integral components of concretes, which provides conserving natural aggregates and waste reduction. This study adopts a holistic approach to producing green self-compacting concrete with the highest portion of recycled aggregate as a replacement for natural aggregate and fly ash as filler. Based on the particle packing density method, four series of self-compacting concrete were prepared: the first series was made with natural fine and coarse aggregate, the second series was made with fine natural aggregate and recycled coarse aggregate, the third with 50 % (by mass) of fine natural aggregate replaced by recycled fine aggregate and recycled coarse aggregate, and the fourth series completely with recycled fine and coarse aggregate. The content of fly ash remained constant. Regardless of the expected decrease of workability in a fresh state with the increase of the recycled aggregate content, all series exceeded the requirements set for the hardened structural concrete.

Thermal shock stability plays a great role in the selection of optimal refractory material. Different methods of characterization were developed for this purpose, including the implementation of nondestructive testing. Image analysis is a very well method for characterization of different materials structures, as well as changes and occurred defects in structure caused by different influences. In this paper, possible application of image analysis will be presented related to the monitoring thermal shock behavior of selected refractory materials. Different parameters such are R parameter, level of destruction, as well as determination of morphological descriptors (area, perimeter, diameter, roundness) using Image analysis, will be presented.

Concrete is a material that has been used for centuries and is often modified using polymers. In the last fifty years, synthetic polymers have been used for the modification of concrete, but also for the production of concrete. In recent decades, sulfur concrete has been an interesting product that can be used mainly in low-rise construction due to its characteristics. In this work, we used the starting mixture for the preparation of sulfur concrete (sand, elemental sulfur with the addition of modified sulfur and fillers) heated to a temperature of 120 ºC to 170 ºC and homogenized. The results of previous research on the production of sulfur concrete showed that the density of the obtained product changes depending on the type as well as the amount of filler added to the basic mixture based on raw materials. Talc, microsilicon, plate alumina and fly ash were used as fillers. The amounts of fillers were 0%, 1%, 3%, 5%, 7% and 10%.

The paper presents the results of the research cavitation erosion behavior of samples based on talc with addition of domestic zeolite from the Zlatokop deposit. Samples based on talc with 15 % of zeolite, from Zlatokop (Vranjska Banja), sintered at 1200ºC were used in this investigation. Resistance to cavitation was monitored by the ultrasonic vibratory cavitation set up with a stationary specimen and measuring respectively determining the specimens' mass loss. Image analysis and Young's modulus of elasticity were used to determine the level of degradation of the sample surface and sample's volume. Obtained results showed good resistance of the refractory samples based on talc and zeolite to the cavitation erosion, which indicates the possibility of application ceramic samples based on talc and zeolite in various areas of industry where the presence of destruction due to the effect of cavitation is expected.

The majority of refractories used today are associated with the iron and steel industries. Typically, the refractory lining of a blast furnace consists of a combination of different refractory materials chosen for different portions of the furnace, as well as distinct process conditions and temperature ranges. Knowledge and requirements for the iron manufacturing system in conjunction with the physical, mechanical, and chemical qualities of the proposed refractories determine the choice of refractory combination. Inadequate understanding of the aforementioned components frequently results in refractory failure, which then becomes a difficult problem to tackle. A blast furnace's refractory liner typically fails owing to any number or combination of these variables. To facilitate comprehension, we will explain the types of refractory lining required in a blast furnace by region, as well as the observed trend in refractory lining patterns over the past few decades.

During mechanical activation, qualitative changes that can produce various phenomena occur in the material. In this study, anhydrous sodium carbonate was mechanically activated for 2, 7, 14, and 28 minutes in a vibro mill at a frequency of 3000 oscillations per minute. After activation, four series of activated samples were stored in the air at room conditions for 31 days (relaxation period). To monitor the kinetics of the transformation process of activated sodium carbonate samples, i.e. the mechanism of sodium bicarbonate formation during relaxation, Fourier-transform infrared (FTIR) spectroscopy analysis was used. FTIR testing was performed as a function of relaxation time for all four series of samples, with characteristic groups observed: CO32-, HCO3- and OH-. The obtained results provided kinetics parameters for the transformation of sodium carbonate into sodium bicarbonate due to the chemisorption of moisture and carbon dioxide from the atmosphere.

The effect of the partial replacement of natural filler by ground waste sulfur originating from the oil refining process on the fresh and hardened properties of self-compacting concrete was investigated. Properties investigated were slump flow, V-funnel, L-box, and sieve segregation of fresh concrete mixes; compressive, flexural, and bond (pull off) strengths, dynamic modulus of elasticity, ultrasonic pulse velocity, dynamic Poisson’s ratio, specific electrical resistance, density, and microstructure of hardened concrete. Results showed a slight decline in compressive, flexural, and bond strengths and dynamic elasticity modulus with increased addition of sulfur. Specific electrical resistance and density were higher for samples containing sulfur. Also, scanning electron microscopy indicated a slight porosity increase in the samples containing sulfur. Having in mind that, in the case of waste valorization in concrete, all properties of self-placing concrete should remain within acceptable levels or improve, this study proved that mixtures containing ground sulfur as a partial replacement for filler could be used for structural applications.