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To solve heat energy storage of building enclosure systems, phase change materials (PCMs) were implemented into magnesium oxychloride cement (MOC) to form a MOC-PCM composite. Such composites possess sufficient mechanical strength for specific usage and high heat storage efficiency. The chemical and physical properties of raw materials were investigated as well as fresh composite mixture rheology. On matured samples, structural, mechanical, hygric, and thermal properties were tested. The results suggest that the enrichment of MOC with PCM particles causes an increase in porosity, hence a decrease in the specific density of the composites. With each addition of PCM the reduction of mechanical properties of the composite material occurs, where the maximum reduction in flexural and compressive strength for the sample with 40 wt % of PCM is around 80%. The low strength of the composite is compensated by excellent thermal properties that are required for its intended application. The enthalpies of phase changes increased linearly with the dosage of PCM and can contribute to the passive moderation of temperature fluctuations. The developed composites can find use in building engineering in the form of indoor cladding panels, facing slabs ceiling boards, etc. Which can be beneficially applied for example in the passive cooling of attic rooms and retrofitting of the present building stock.

In the steel industry, a large amount of diverse waste is generated, including carbon-bonded magnesia-rich waste originating from refractories. This study focused on the development and characterization of composite material based on magnesium oxychloride cement (MOC), with an emphasis on incorporating MgO-C-based refractory waste (CBMW) as a sustainable filler. To reach the best possible material properties, two different size fractions were applied in various ratios, completely replacing quartz sand. A comprehensive analysis of all composite material samples was conducted utilizing various analytical techniques, XRD, SEM, EDS or STA-MS. Mechanical properties such as compressive strength, flexural strength, and Young's modulus of elasticity were evaluated. Even though even the best sample did not surpass the mechanical properties for the reference, compressive strength 78.1 MPa was achieved, which is a more than sufficient value for most indoor applications.

In past years, the study of magnesium oxychloride cement became fairly widespread, because of its good mechanical properties and environmental sustainability. One of its biggest advantages is its ability to work well with different types of fillers and aggregates. This paper deals with the synthesis and analysis of such material, namely the composite of magnesium oxychloride with diatomite. Three different phases varying in the amount of diatomite were prepared and analyzed using various analytical methods, namely X-ray diffraction, X-ray fluorescence, simultaneous thermal analysis, scanning electron microscopy and energy dispersive spectroscopy. The phase and chemical composition, morphology and thermal behavior were studied as well as the structural, mechanical, hygric, and thermal properties of the hardened materials. This sort of novel and alternative material shows wide-ranging application potential while being eco-friendly and providing great mechanical properties applicable in the extreme conditions.

The Portland cement (PC) industry is a big producer of CO2– a major contributor to the global warming. As the world tends to reduce the CO2emissions because of its negative effect, a sustainable and efficient PC alternative is needed to be found. One of the most promising substitute is based on reactive magnesia – magnesium oxychloride cement (MOC). This paper deals with the design, development, and characterization of environmentally friendly composites based on MOC. In addition to the standard quartz sand filler, carbon spheres-based waste produced by polypropylene treatment via plasma gasification was used as a nanoadditive. Before the preparation of the composites themselves, the carbon spheres (CS) were analysed with a wide range of analytical methods in order to determine their microstructure and composition. The CS were used in the amount of 0.5, 1.0, and 3.0 wt% related to the weight of the pure MOC paste. The prepared composite samples were tested for their microstructure, phase and chemical composition, micro- and macrostructural parameters, and mechanical properties after 28 days of maturing. Furthermore, the influence of CS on the hygric properties and the water resistance of the MOC-based composites were studied after 24 h-long immersion in water. It has been shown, that with the increasing amount of CS, the mechanical parameters improve quite rapidly, making CS an enhancing eco-friendly nanoadditive. It was also shown, that CS helps to slow down water transport in MOC-based composites, which is a key aspect in the improvement of their water resistance and overall durability after exposure to humidity. The incorporation of carbon spheres-based waste as a nanoadditive in MOC-based composites shows promising improvements in mechanical properties and water resistance, contributing to the development of environmentally friendly construction materials.

The excellent technical parameters of magnesium oxychloride cement (MOC) and its ability to sequester CO2from the environment predestine its use as an alternative to Portland cement. However, its main shortcomings, low water resistance, and excessive water absorption need to be addressed to enable its wider application in construction. For this reason, the improvement of the water resistance of MOC-based composites through the use of nanosized molybdenum disulfide (MoS2) is the subject of this case study. The MOC-based composites were subjected to experimental testing of their chemical, structural and physical parameters using a wide range of advanced laboratory techniques. The composites enriched by MoS2nanoadditive exhibited a densified and compact structure with improved mechanical parameters and stiffness. Water transport and storage were significantly decelerated and reduced by the incorporation of MoS2nanoparticles, resulting in an improvement of water resistance, characterized by the softening coefficient, which was 66.1 % after 24 h of immersion in water, which is about 13.8 % higher than that of the reference MOC-based composite.

The article presents the laboratory investigations of the basic thermal and hygric parameters of standard lightweight aggregate-concrete and lightweight aggregate-concrete supplemented with municipal sewage sludge. Both types of concrete are based on light aggregates, commonly used in the Polish building market. In order to improve the hygric parameters of the material, such as water absorptivity, the admixture of water emulsion of reactive polisiloxanes was applied. Within the presented research, together with basic moisture parameters estimation, capillary rise process was monitored using Time Domain Reflectometry (TDR) modified sensors. Hygric parameters were supplemented with the estimation of thermal conductivity coefficient λdetermined using stationary method. The analysis of thermal and hygric properties of concrete confirmed the applicability of lightweight aggregate-concrete with sewage sludge supplementation for further production.

As part of the development and research of UHPC materials, the broad professional public deals mainly with the determination of the basic physical and mechanical parameters, in particular the compressive strength, that is considered as a determining parameter for these cement-based composites. The strength of the composite material is determined under normal laboratory conditions. Fine cement-based composite materials are increasingly used not only for academic purposes but also for practical applications. Therefore, it is necessary to focus on other parameters that determine these new Hi-Tech materials. The mechanical properties of materials at elevated temperatures belong to an area that is not properly defined not only in the Czech Republic but also in the world. Research into the behavior of these composite materials and their thermal loading can provide additional information and basics to expand these building materials such as France, USA, Japan and other countries around the world. In the Czech standards applicable to the design of concrete structures subjected to thermal stress, the values of the reduction coefficient Kc, θ are used only for commonly used dense concrete and also for expanded concrete. It is clear that these values cannot be used for fine-grained composite materials with cement binder reinforced hybrid reinforcements. The aim of the paper is to determine and describe the behavior of these materials in the temperature range of 20 ° C to 1000 ° C for two test modes that affect residual strength and high temperature strength.

High Performance Fiber Reinforced Concrete (HPFRC) became very popular material for its high mechanical strength, elastic modulus and corrosion resistance. However, also its high-temperature resistance is of a particular importance because of the fire safety. Therefore, the effect of high-temperature exposure on UHPC reinforced by combination of steel and PVA fibers was studied in the paper. PVA fibers were used to moderate concrete damage induced by water vapor evaporation from dense UHPC matrix. The UHPFRC samples were exposed to the temperatures of 200 °C, 400 °C, 600 °C, 800 °C, and 1 000 °C respectively. Concrete structural changes induced by high temperature action were described by the measurement of basic physical and mechanical properties. The realized experiments provide information on the changes of concrete porosity and loss of mechanical resistivity.

This paper deals with determination of basic physical, mechanical, thermal and water transport properties of lime–based plasters whose composition was modified by the addition of diatomaceous earth. To eliminate possible deterioration of original lime plaster by natural weathering, the hydrophobic admixtures on the stearate and oleate basis were added into the plaster mixtures and boiled linseed oil as a painting was applied. All studied material parameters were tested after 28 days of wet curing and after exposition to accelerated carbonation. The results of examined properties of developed plasters gave promising outcomes for the use of hydrophobised materials in renewal of historical buildings. Based on the obtained data, plaster made of lime hydrate, diatomite, and combination of water repellent agents can be recommended for renovation purposes.

Residual parameters of Ultra High Performance Concrete (UHPC) exposed to high temperatures were experimentally accessed. The UHPC was provided by hybrid fibre reinforcement based on polyvinyl alcohol (PVA) and steel fibres. Among the studied material properties, bulk density, matrix density, total open porosity, pore size distribution, water vapour transmission and liquid water transport properties were examined. The UHPC samples were exposed to the temperatures 400 °C, 600 °C, 800 °C, and 1000 °C respectively. For comparative purposes, the reference UHPC samples cured at laboratory temperature were tested as well. Based on the obtained results, correlation between concrete structural changes and tested parameters was found out. The applied temperature load highly affected the concrete porosity, pore size, and thus both liquid and gaseous moisture transport parameters. Disintegration of concrete structure, colour change, cracking, damage of steel fibres (melting), and failure of their cohesion was apparent from optical microscopy analysis.

This paper is focused on the research of material characteristics of high performance concrete reinforced with a combination of steel and hybrid fibers exposed to the extreme temperatures. In the performed experiments it was examined several types of mixtures (HPFRC, UHPFRC) exposed to the extreme temperatures up to 200-1200 °C. Outside residual parameters of each examined mixtures (tensile bending strength, compression strength, fracture parameters) was investigated the dependence of porosity of the matrix, sample damage and chemical analysis of samples exposed to extreme temperatures, to the resulting mechanical parameters. Part of the initial results of the research described base material and physical properties of the examined mixes and shows the effect of high temperatures on these properties. The results presented in the current paper are the basis for further research and the preparation of numerical models for the design of HPC exposed to extreme temperatures.

Nowadays, many researchers are intensively trying to develop novel environmentally friendly composite materials for construction with a view to replace widely used Portland cement (PC). Current hopes are pinned on the use of materials based on reactive magnesia. In this case study, composites prepared from magnesium oxychloride cement (MOC), ground waste glass, and either quartz sand or foam glass were prepared and analyzed in detail. The main aim was to design and develop novel composites with low unit weight, good thermal insulation performance, and high water damage resistance. In addition, the application of secondary-raw materials as a partial substitution for common fillers was accented. The properties of fresh and matured composites were studied and analyzed within the framework of a complex experimental campaign involving phase composition assessment, structural, textural, mechanical, hygric, thermal, and durability parameters testing, as well as the identification of main chemical bonds in the formed hardened materials. The usage of ground waste glass led to a significant drop in porosity, densified microstructure, enhanced compressive strength, reduced water ingress, and improved durability. In general, the prepared composites provide properties and performance, which make them promising eco-efficient alternatives to PC-based construction composites.