Special Issue "Mechanical, Thermal, and Hygric Properties of Lightweight Composites for Construction Use"

A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: 31 December 2020.

Special Issue Editor

Prof. Zbyšek Pavlík
Website
Guest Editor
Department of Materials Engineering and Chemistry, Faculty of Civil Engineering, Czech Technical University in Prague, Thákurova 7, 166 29 Prague, Czech Republic
Interests: construction materials; building physics; materials testing; materials processing
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Special Issue Information

Dear Colleagues,

Undoubtedly, the thermal performance of construction products has become increasingly important, since it significantly influences the energy associated with buildings’ heating and cooling. Although the buildings share of the world total energy consumption is expected to decrease due to the long-time enhanced demands on quality thermal insulation of building structures, buildings will still account for at least 20% of the total energy demand in coming years, especially due to the increasing demands on the quality of indoor environments. To improve the energy efficiency of buildings, it is necessary to focus on advanced technical and material solutions of building systems, resulting in buildings possessing high thermal resistance and sufficient thermal stability. In this sense, the building envelope, most often constructed as multilayered systems comprising different types of materials, is one of the critical parameters affecting buildings energy performance. Functional properties of these inbuilt materials affect the hygrothermal performance of the building envelope as a whole. Moreover, as the building envelope is in direct contact with the exterior climate, it suffers from different chemical, mechanical, and physical loads, contributing, if inappropriately designed, to the loss of its functional properties.

Several methods for improving the thermal resistance of building materials have been adopted; most of them are based on the use of lightweight fillers, foaming agents, low-density plastics, organic and inorganic-based fibers, etc. Although many of the construction composites possessing high thermal resistance have been already developed, there is still an open field for the design and development of new advanced types of materials that are more effective, both from economic and environmental points of view. In this respect, the application of secondary raw materials looks like a promising solution.

Besides the effective thermal performance of construction materials, they must meet other functional requirements (service life, hygric performance, durability, mechanical resistance, aesthetic appearance, etc.), which makes their design and testing complex. This Special Issue of Materials welcomes papers from all areas of materials research aimed at the design, development, and assessment of new lightweight composites for construction use, in which papers of high quality and originality with regard to the studied topic will be accepted.

Prof. Dr. Zbyšek Pavlík
Guest Editor

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Keywords

  • building energy performance
  • lightweight construction composites
  • hygrothermal performance
  • thermal properties
  • durability

Published Papers (5 papers)

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Research

Open AccessArticle
Magnesium Oxychloride Cement Composites with Silica Filler and Coal Fly Ash Admixture
Materials 2020, 13(11), 2537; https://doi.org/10.3390/ma13112537 - 03 Jun 2020
Cited by 2
Abstract
Worldwide, Portland cement-based materials are the most commonly used construction materials. As the Portland cement industry negatively affects the environment due to the excessive emission of carbon dioxide and depletion of natural resources, new alternative materials are being searched. Therefore, the goal of [...] Read more.
Worldwide, Portland cement-based materials are the most commonly used construction materials. As the Portland cement industry negatively affects the environment due to the excessive emission of carbon dioxide and depletion of natural resources, new alternative materials are being searched. Therefore, the goal of the paper was to design and develop eco-friendly, low-cost, and sustainable magnesium oxychloride cement (MOC)-based building material with a low carbon footprint, which is characterized by reduced porosity, high mechanical resistance, and durability in terms of water damage. To make new material eco-efficient and functional, silica sand which was used in the composition of the control composite mixture was partially replaced with coal fly ash (FA), a byproduct of coal combustion. The chemical and mineralogical composition, morphology, and particle morphology of FA were characterized. For silica sand, FA, and MgO, specific density, loose bulk density, and particle size distribution were measured. Additionally, Blaine specific surface was for FA and MgO powder assessed. The workability of fresh mixtures was characterized by spread diameter. For the hardened MOC composites, basic structural, mechanical, hygric, and thermal properties were measured. Moreover, the phase composition of precipitated MOC phases and their thermal stability were investigated for MOC-FA pastes. The use of FA led to the great decrease in porosity and pore size compared to the control material with silica sand as only filler which was in agreement with the workability of fresh composite mixtures. The compressive strength increased with the replacement of silica sand with FA. On the contrary, the flexural strength slightly decreased with silica sand substitution ratio. It clearly proved the assumption of the filler function of FA, whereas its assumed reactivity with MOC cement components was not proven. The water transport and storage were significantly reduced by the use of FA in composites, which greatly improved their resistance against moisture damage. The heat transport and storage parameters were only slightly affected by FA incorporation in composite mixtures. Full article
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Open AccessArticle
Cost Analysis of Prefabricated Elements of the Ordinary and Lightweight Concrete Walls in Residential Construction
Materials 2019, 12(21), 3629; https://doi.org/10.3390/ma12213629 - 04 Nov 2019
Cited by 3
Abstract
Global economic growth causes an increase in natural resources exploitation, particularly in construction branch. The growing use of electricity contributes to climate change. Therefore, it is necessary to search the solutions, which will allow for reducing natural resources exploitation. One of the many [...] Read more.
Global economic growth causes an increase in natural resources exploitation, particularly in construction branch. The growing use of electricity contributes to climate change. Therefore, it is necessary to search the solutions, which will allow for reducing natural resources exploitation. One of the many opportunities to do that is the application of the recycled materials. The authors of the given article have analyzed three variants of construction solutions. One of them was the production of the walls of a building from reinforced concrete prefabricates with styrofoam insulation layer. The second variant for analysis were prefabricated walls from lightweight concrete, made of sintered clay aggregate with a foam core. The third proposed variant was a system of multi-layered walls, which was made of lightweight concrete with granulated expanded glass aggregate (GEGA). The main objective of the research was to assess the use of lightweight GEGA prefabricates, focusing on economic and technological aspects of the solution. The authors have analyzed the entire construction costs; ceilings and stairs were assumed as reinforced concrete elements. In calculations, the weight of the elements was taken into account, as well as transportation and mounting costs. On the basis of this cost analysis, it was concluded that the use of prefabricated element, made of lightweight concrete with GEGA, could be a replacement for the solutions, widely applied until these days. The analysis has also shown that the use of prefabricates with GEGA is sensible from the economic viewpoint, as it allows for saving construction time. Moreover, the solutions, proposed here, allow for saving natural resources and assuming a more environmentally friendly and caring attitude. Full article
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Open AccessFeature PaperArticle
Mortars with Crushed Lava Granulate for Repair of Damp Historical Buildings
Materials 2019, 12(21), 3557; https://doi.org/10.3390/ma12213557 - 30 Oct 2019
Cited by 6
Abstract
In this paper, crushed lava granulate was used as full silica sand replacement in composition of repair mortars based on hydrated lime, natural hydraulic lime, or cement-lime binder. Lava granules were analyzed by X-ray fluorescence analysis (XRF), X-ray diffraction (XRD), and scanning electron [...] Read more.
In this paper, crushed lava granulate was used as full silica sand replacement in composition of repair mortars based on hydrated lime, natural hydraulic lime, or cement-lime binder. Lava granules were analyzed by X-ray fluorescence analysis (XRF), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Particle size distribution of both silica and lava aggregates was assessed using standard sieve analysis. Hygrothermal function of the developed lightweight materials was characterized by the measurement of complete set of hygric, thermal, and structural parameters of the hardened mortar samples that were tested for both 28 days and 90 days cured specimens. As the repair mortars must also meet requirements on mechanical performance, their compressive strength, flexural strength, and dynamic Young’s modulus were tested. The newly developed mortars composed of lava aggregate and hydrated lime or natural hydraulic lime met technical, functional, compatibility, and performance criteria on masonry and rendering materials, and were found well applicable for repair of historically valuable buildings. Full article
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Open AccessArticle
Comparison of Concrete Creep in Compression, Tension, and Bending under Drying Condition
Materials 2019, 12(20), 3357; https://doi.org/10.3390/ma12203357 - 15 Oct 2019
Abstract
Three types of creep experiments of compression, tension, and bending were implemented to identify quantitative relations among the three types of creep under drying atmospheric conditions. In case of the bending creep experiment, two types of unreinforced concrete beams with similar dimensions were [...] Read more.
Three types of creep experiments of compression, tension, and bending were implemented to identify quantitative relations among the three types of creep under drying atmospheric conditions. In case of the bending creep experiment, two types of unreinforced concrete beams with similar dimensions were cast for use in the beam creep and shrinkage tests. The variations in the shrinkage strain within the beam depth were measured to evaluate the effect of the shrinkage variations on the bending creep strain. The beam creep strain measured within the beam depth was composed of uniform and skewed parts. The skewed parts of the creep strain were found to be dominant whereas the uniform parts were small enough to be neglected in the bending creep evaluation. This indicated that the compressive bending creep at the top surface was close to the tensile bending creep at the bottom surface. The ratios of tensile and bending creep strains to compressive creep strain were approximately 2.9 and 2.3, respectively, and the ratio of bending creep strain to tensile creep strain was approximately 0.8. Particular attention is laid on the close agreement between tensile and compressive bending creep strains even if the creep in tension is 2.9 times larger than the creep strain in compression. Full article
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Open AccessArticle
Influence of Wood-Based Biomass Ash Admixing on the Structural, Mechanical, Hygric, and Thermal Properties of Air Lime Mortars
Materials 2019, 12(14), 2227; https://doi.org/10.3390/ma12142227 - 10 Jul 2019
Cited by 5
Abstract
Mechanically-activated wood-based biomass ash (WBA) was studied as a potential active admixture for design of a novel lime-pozzolan-based mortar for renovation purposes. The replacement ratio of lime hydrate in a mortar mix composition was 5%, 10%, and 15% by mass. The water/binder ratio [...] Read more.
Mechanically-activated wood-based biomass ash (WBA) was studied as a potential active admixture for design of a novel lime-pozzolan-based mortar for renovation purposes. The replacement ratio of lime hydrate in a mortar mix composition was 5%, 10%, and 15% by mass. The water/binder ratio and the sand/binder ratio were kept constant for all examined mortar mixes. Both binder constituents were characterized by their powder density, specific density, BET (Brunauer–Emmett–Teller), and Blaine specific surfaces. Their chemical composition was measured by X-ray fluorescence analysis (XRF) and mineralogical analysis was performed using X-ray diffraction (XRD). Morphology of WBA was investigated by scanning electron microscopy (SEM) and element mapping was performed using an energy dispersive spectroscopy (EDS) analyzer. The pozzolanic activity of WBA was tested by the Chapelle test and assessment of the Portlandite content used simultaneous thermal analysis (STA). For the hardened mortar samples, a complete set of structural, mechanical, hygric, and thermal parameters was experimentally determined. The mortars with WBA admixing yielded similar or better functional properties than those obtained for traditional pure lime-based plaster, pointing to their presumed application as rendering and walling renovation mortars. As the Chapelle test, STA, and mechanical test proved high pozzolanity of WBA, it was classified as an alternative eco-efficient low-cost pozzolan for use in lime blend-based building materials. The savings in CO2 emissions and energy by the use of WBA as a partial lime hydrate substitute in mortar composition were also highly appreciated with respect to the sustainability of the construction industry. Full article
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