This work focuses on comparing the effect of ten different types of pozzolans on the strength of lime pastes in relation to their pozzolanic activities as determined by the Chapelle test and monitoring the reactivity of these pozzolans using the thermogravimetric method. It was found that the Chapelle test can in some cases overestimate the reactivity of the pozzolan due to differences between the conditions during the test and in reality. The strengths of lime-pozzolan pastes did not correlate well with the pozzolanic activity values of the pozzolans used. On the contrary, the amount of reacted lime in the pastes, determined by the thermogravimetric method, correlated very well with the compressive strengths of the pastes.

In view of the increasing number of natural and man-made disasters and the increasing economic and social problems, it is necessary to adapt the existing principles and methods of structural design, the corresponding construction techniques, and the operation of buildings to make them more sustainable, resilient, and adaptable to new situations in changing natural and socio-economic conditions in the world. Recent research and development of concrete composition, production technology, and development of concrete constructions, intensified over the last 20 years, have led to the improvement of technical parameters while reducing environmental impacts. Due to the optimization of the mixture, new types of concrete have significantly better characteristics from the perspective of strength, mechanical resistance, durability, and resistance to extreme loads.The paper presents examples and results of research focused on the use of new types of silicate composites and their effective combinations in the case study. It is generally necessary to apply new silicate composites in such a way that their potential is used to the maximum. The aim is to present the possibility of new practical and effective application of modern materials with an emphasis on reducing environmental impacts and at the same time increasing the resilience of structures. It covers the utilization of high-performance concrete as a protective and load-bearing thin skin with textile reinforcement using carbon textiles tube in combination with recycled concrete aggregate core.Developed technical solutions could contribute to addressing the Sustainable Development Goals (SDGs), which the United Nations set out in 2015 as a 2030 action plan.

In general, one of the possible future paths of the building construction industry is the development of robotization and prefabrication of individual building components. Presented article continues the development of prefabrication using traditional effective ombination of two often used materials in construction – timber and concrete in the form of a slabs. The traditional concept of combining these materials is used for ceiling structures – slabs, panels, floor panels, where timber is most often in the form of beams and a concrete slab is applied over the beams as a material transmitting compressive stress. The key to functionality for this system is the shear connection of both materials. The presented study presents a thin concrete layer made of high-performance concrete, which is connected to a wooden board from glulam using an adhesive bridge. The aim of this presented study is to improve the bending load-bearing capacity and bending stiffness of the glulam slab with a small amount of high-performance concrete and thus achieve a more favorable environmental profile of the ceiling panel. The individual variants differ in thickness, the presence and number of ribs. These variants are compared with a variant of the same thickness of glulam slab without the layer of concrete.

The resistance of structures to explosive impacts is a highly relevant issue in modern engineering. During an explosion, structures are subjected to extreme dynamic loads, which necessitate advanced materials and reinforcement strategies. UHPFRC, with its evenly distributed steel fibres, exhibits exceptional mechanical properties that make it well-suited for blast-resistant applications. Combining UHPFRC with steel reinforcement is expected to significantly mitigate structural damage under explosive loading.This article focuses on the process of production of testing steel-concrete column specimens under axial compressive load for evaluating their blast resistance. The initial section describes the test elements and the objectives of the experiment. The following section outlines the design and material properties of the concrete mixtures used. Subsequently, the production process, including formwork preparation and casting, is detailed. Finally, the results achieved from ongoing testing are briefly introduced.

Portland cement is traditional binding material which is applicable for various modern technologies in these days – the 3D printing is one of them. The development of 3D printers using cement-based materials for the manufacturing of structural elements and moreover entire building is novel concept of structural engineering, which combines advanced material solution and high level ofautomation. This paper is focused on the study of properties of fresh mixture in order to control its consistency and regime of setting time to achieve continual process of 3D printing. The properties of fresh mortar were modified by the admixture accelerating the process of hardening and stabilizing agent. The performed experimental program showed that both applied admixtures could be used for the control of the consistency of fresh mortar to achieve optimal shape of mortar layer after its extrusion.

Timber-concrete composite systems have emerged as a promising building technique, leveraging the strengths of both materials to improve load capacity, stiffness, and overall performance. In the presented study, high-performance concrete with perfect mechanical performance and durability is used in timber-concrete composite systems to further reduce the environmental footprint and optimize structural efficiency. The weakest point in general of these constructions is the interface between the concrete material and the wood. The focus in this study is on shear strength, specifically examining the combination of adhesive bonding with notch shear connections. Experimental results, by a push-off test, reveal that the inclusion of shear connectors is essential for effective and secure bonding, with adhesive application methods significantly influencing shear strength. The findings highlight the potential of timber-concrete composite systems high-performance concrete to achieve high shear strength and structural integrity through optimized adhesive and rib configurations. The goal is to make maximum use of the material’s mechanical potential and significantly reduce the primary sources of raw materials. The presented article is based on the diploma thesis of Nick Vanheeswijck.

The need to determine the bond strength of concrete layers in structural modeling is quite frequent and often encounters a lack of relevant experimental data due to the large number of variables which affect the bond strength. This article describes an experimental method that makes it possible to obtain the experimental data necessary for subsequent modeling of multi-layered concrete composite structures. The experiment is designed to be applicable both to laboratory specimens with defined properties and to samples taken from existing structures. The advantage of this method is its simplicity, minimal equipment requirements, and repeatability. The three-layer specimens, representing a sandwich wall, allow the study of the influence of the age and quality of the concrete on the bond strength, and through image analysis, provide valuable information on deformation, interlayer slip, and crack formation. The results of the experiment may contribute to the determination of a bond strength diagram for multi-layered walls, which can be integrated into software tools for comprehensive structural analyses.

The main objective of this paper is to propose an improvement and automation of the current mechanical testing procedure of concrete and rock samples in hot cells, i.e. in laboratories designed for radioactive sample testing. The paper describes the effect of radiation on the different components of concrete and consequently on the concrete itself. To give a general idea of sample handling and hot cell operations, safety precautions are prescribed which significantly prolong and complicate the handling of a radioactive rock sample. Video recordings of the tests were used to analyse the progress of the tests. The main issues were the placement of samples off the axis of the compression test machine, sample curvature, compression test machine design and poor recording of sample deformation. New centring stops were introduced to improve the handling of the specimen when placed in the test machine. Additionally, the use of image processing was proposed to evaluate the correct placement of the sample in the test machine. These improvements should lead to easier sample handling and correct results which will serve as a good basis for subsequent numerical analyses.

Alkali-activated materials play an important role in the current industry, because they offer alternative way towards low carbon technologies. However, their crucial utilization still lays in the field of composites resistant to high temperatures, especially in the heavy machinery and chemical industry. The current paper documents rheological properties of set of pastes on the basis of Czech metakaolin as precursor, which was activated by lithium water glass exhibiting various silicate modulus. The rheological properties were studied in terms of standard flow test and optimized composition exhibiting similar workability were subsequently investigated by using rotary rheometer. The rheology was monitored in time to document performed changes during the geopolymerization. The attained flow curves were fitted by Herschel-Bulkley model and basic rheological characteristics of optimized pastes were derived. The research confirmed prolonged workability of the studied paste activated by lithium water glass and better. The pastes activated by lithium water glass of lower silicate modulus exhibited lower values of yield stress.

This study aims to verify and independently compare the functionality of waterproofing screeds against the effect of radon with the influence of freezing cycles. The effect of freezing cycles on the sealing ability against radon was investigated on polymer, silicate (mineral), and bituminous screeds. The measured values correspond to commonly used insulation materials, confirming the correctness of the measurement and evaluation methodology. Waterproofing screeds are shown to be suitable materials for substructure applications. Unlike waterproofing made from strips such as bitumen membrane or PVC membrane, they do not contain joints and can thus offer a more reliable solution. The measured values show minimal differences between the tested waterproofing screeds after freeze-thaw exposure. Especially in the case of silicate (mineral) screed and polymer screed, the effect is negligible. The greatest effect of freeze-thaw cycles on the ability to seal against radon was observed for bitumen screeds.