The study presents results of calorimetric tests of three different cements. Two Ordinary Portland cements, CEM I 52.5 R and CEM I 42.5 R, and one Blastfurnace cement, CEM III/A 42.5 N LH/HSR/NA, were analysed. The analysis has shown that the empirical formulas derived based on the results can successfully replace the Arrhenius formula in determination of the hydration rate in relation to curing temperature. It was proven that the hydration rate in relation to the curing temperature changes with the progression of hydration. The study introduces an E_n coefficient which determines the influence of curing temperature on generation of heat. Results of the study have shown that the value of E_n is not constant and changes with the progression of hydration process. Proposed method of numerical modelling of the total heat generated and generation rate based on obtained results allows for the calculation of those two parameters for any curing conditions.

Using the waste materials in the production of the building materials limits the storage of the wastes, burdensome for the environment and landscape, and makes possible to manufacture the materials and products with the use of the less volume of the raw materials. Cement concretes and mortars as the basic building materials offer the broad prospects of utilization of the recyclable or waste materials. The wastes from the iron ore processing are the solid wastes resulting from the process of enrichment of the ore concentrate. The paper presents the results of testing three mortars, in which a part of fine aggregate was replaced with the iron oxide concentrate (IOC) resulting from such a process. IOC has been used as a substitute of 10%, 20% and 30% (by mass) of the fine aggregate. The effect of the concentrate on the mechanical performance of the mortars at the high temperature (up to 600 °C) was also investigated. The IOC is a neutral material, not affecting chemically the process of cement hydration. The addition of IOC slightly improves the strength of the cement mortars (by 5% to 10%). In the case of the larger amount (20–30%) of the addition, the use of superplasticizer is necessary. The IOC significantly improves the high temperature resistance of the cement mortars (300 °C). The cement mortars containing 30% of the IOC addition keep 80% of the initial flexural and compressive strength when exposed to the temperature 450 °C.

The paper presents a comprehensive analysis of cement-based composites incorporating both fine recycled concrete aggregates (fRAs) and recycled concrete powder (RCP), which were used for 3D concrete printing. The study evaluates properties ranging from fresh-state behaviour to hardened properties, durability, and microstructural characteristics. In the final stage, a life cycle assessment (LCA) was conducted. A study found that it is feasible to print a composite containing up to 100% fRA as a replacement for natural river sand. Notably, an increase in fRA content enhances the buildability of the mix, as confirmed by green strength tests. However, the open time of mixes containing fRA and RCP was shortened. Incorporation of RCP and fRA led to a decrease in shrinkage within the first 24 h of hydration. Mechanical studies reported a significant reduction in compressive strength (up to 55%) when RCP and fRA were introduced to the mix. Despite the reduction in mechanical properties in specific configurations, all mixes—including 100% fRA and 10% RCP—exhibited compressive strengths above 30 MPa, demonstrating their potential suitability for use in the construction industry. The durability properties of mixes modified with fRA show that there is a statistically significant reduction in flexural strength after 25 and 50 freeze–thaw cycles. In terms of compressive strength, cast specimens did not exhibit any notable reduction in mechanical performance after freezing and thawing cycles. The LCA results demonstrate the high potential for using fRA and RCP derived from concrete waste in the additive manufacturing industry.

Non-metallic reinforcement such as fiber-reinforced polymer (FRP) is now being increasingly used in construction. Despite numerous similarities, elements reinforced with non-metallic bars work differently from the ones reinforced with steel bars, including cracking and failure mode. The examination of the stress state in these elements, so important for their proper design, raises many difficulties. The article presents the results of tests of bended beams reinforced with GFRP bars. The results of the experimental tests were compared with calculations based on selected design instructions. The results have shown that beams reinforced with GFRP exhibit increased cracking, higher deflection, and often mode of failure through crushing of concrete. The results have shown that in bended elements reinforced with the GFRP bars, the rebar often does not achieve the strength declared by the manufacturer. The study has shown that theoretical values of load-bearing capacity of beams reinforced with composite rebar differ greatly between different guidelines and instruction. The analysis showed that the use of GFRP bars as a replacement for steel bars is possible in demanding environmental conditions. However, excessive deflections and cracks may result in limited application due to overall serviceability requirements of the element.

This steel hall was built at the turn of the 1980s and 1990s. The main building consists of 5 naves with a span of 20 m. The hall was built in a rarely seen structure. The columns and beams are made of openwork columns based on [140 profiles with a round bar grating of 16 mm. After the decision was made to modernize the hall, its structure had to be adapted to current standards, particularly with regard to snow and wind loads. Analysis of the bar model revealed significant exceedances in the load-bearing capacity of both the steel structure and the foundations – despite the fact that the facility had been operating without failure for over 30 years. The excavations and additional tests revealed a number of surprising construction irregularities, forcing the designer to use unusual design methods. First, the foundation condition was thoroughly verified, showing that the static scheme adopted in previous opinions does not correspond to the actual one, and the design dimensions of the foundation are selected in such a way that they have a positive impact on the statics of the frame under high stress. Advanced calculations using the FEM/FEA method allowed for a significant reduction of the initially planned reinforcements while meeting the standard requirements

The article presents a methodology for determining the minimum thickness of screed in ground-floor slabs, taking into account the buoyant force of water in the event of possible flooding. The calculations assume typical material properties of the screed, including its weight, to determine a thickness that ensures floor stability and resistance to uplift caused by water. The analysis also considers the effect of thermal insulation layer thickness on the buoyant force and includes the necessary safety margin for floor design.The theoretical calculations were verified based on a real case of ground-floor floor failure. This failure, caused by improper installation of insulation layers and flooding of the screed, resulted in the lifting and damage of the floor. Analysis of this event allowed identification of practical principles for designing floors resistant to buoyant forces.The article provides a simple method for selecting the minimum screed thickness depending on the material type and layer arrangement. The results indicate that proper installation, with adequately thick screed and tight layering, is essential to prevent damage in case of flooding. The work highlights the often overlooked principle of buoyancy and provides practical design recommendations that can be applied to new buildings as well as the renovation of existing floor slabs.