The process of recycling concrete rubble is accompanied by the formation of a large amount of fine fraction, which cannot be reused as aggregate. The results of research on the possibility of using recycled cement mortar (RCM), obtained during concrete recycling, as a cementitious supplementary material, are presented. The experimental research was carried out on the basis of two variables determining the recycling process: X₁—temperature (range of variation 288–712 °C) and X₂—time (range of variation 30–90 min) of thermal treatment of concrete rubble. The experiment included 10 series of new composites made with RCMs subjected to different variants of thermal treatment, and two additional control series. The best treatment parameters were determined based on the assessment of selected physical and mechanical properties of the new cement composites, as well as the analysis of characteristics and microstructure of RCM. The test results showed that proper thermal treatment of concrete rubble makes it possible to obtain a high-quality fine fraction, which has the properties of an active addition and can be used as a partial replacement for cement in mortars and concretes.

The objective of this study was to analyze the physico-mechanical properties of gypsum boards including plastic waste aggregates from cable recycling. The plastic cable waste is incorporated into the gypsum matrix without going through any type of selection and/or treatment, as it is obtained after the cable recycling process. In the experimental process, gypsum boards of different dimensions were manufactured and tested for their Young’s modulus, shock-impact resistance, flexural strength, thermal conductivity, and thermal comfort. The results obtained show a significant increase in the elasticity of the boards with plastic waste (limited cracking), compliance with the minimum value of flexural strength, and a slight improvement in the thermal conductivity coefficient (lower energy demand) and surface comfort (reduced condensation and greater adherence). Therefore, the analyzed material could provide a suitable alternative to currently marketed gypsum boards, contributing to sustainable construction not only in new constructions, but also in building renovations.

Based on experimental results, mathematical models were elaborated to predict the development of compressive strength of concrete with fly ash replacement percentages up to 30 %. Strength of concrete with different types of cement (CEM I 42.5, CEM I 32.5, CEM III 32.5), after 2, 28, 90, 180 days of curing, have been analysed to evaluate the effect of addition content, the time of curing and the type of cement on the compressive strength changes. The adequacy of equations obtained was verified using statistical methods. The test results of selected properties of binders and hardened concrete with fly ash are also included. The analysis showed that concrete with fly ash is characterised by advantageous applicable qualities.

Frost damage is considered to be a typical material deterioration in the concrete structures subjected to external environmental conditions. The effect of different types of steel and polypropylene fibers on the surface scaling resistance of concrete subjected to cyclic freezing and thawing in the presence of deicer salt was analyzed. The test parameters included fiber type and dosage and the type of concrete surface subjected to freezing and thawing. Both the cut and cast surfaces of specimens were tested. The dispersed steel reinforcement was found to improve the scaling resistance significantly. However, the effectiveness of fibers was related to their shape and dimensions. The beneficial effect of polypropylene fibers on salt scaling resistance was apparent only in case of the extruded fibers with treated surface