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16 pages, 2424 KiB

Open AccessArticle

Physical Properties and Durability of Lime-Cement Mortars Prepared with Water Containing Micro-Nano Bubbles of Various Gases

by Małgorzata Grzegorczyk-Frańczak, Danuta Barnat-Hunek, Wojciech Andrzejuk, Jacek Zaburko, Monika Zalewska and Grzegorz Łagód

Materials 2021, 14(8), 1902; https://doi.org/10.3390/ma14081902 - 11 Apr 2021

Cited by 10 | Viewed by 2180

Abstract

The paper presents the experimental studies on the effect of the water containing micro-nano bubbles of various gases on the physico-mechanical properties of lime-cement mortars. In total, 7 types of mortars were prepared: with water containing the micro-nano bubbles of O₂, [...] Read more.

The paper presents the experimental studies on the effect of the water containing micro-nano bubbles of various gases on the physico-mechanical properties of lime-cement mortars. In total, 7 types of mortars were prepared: with water containing the micro-nano bubbles of O₂, O₃ or CO₂ as 50% or 100% substitute of ordinary mixing water (tap water) and the reference mortar prepared using tap water. In order to determine the influence of water with micro-nano bubbles of gases, the consistency of fresh mortar and the physical properties of hardened mortar, i.e., specific and apparent density, total porosity, water absorption by weight and capillary absorption, were established. The mechanical strength of the considered mortars was studied as well by conducting the tests for flexural and compressive strengths following 14, 28 and 56 days. Reduced workability and capillary absorption were observed in the modified mortars within the range of 0.9–8.5%. The mortars indicated an increase in the flexural strength after 28 days ranging from 3.4% to 23.5% and improved compressive strength in 1.2–31%, in comparison to the reference mortar. The conducted studies indicated increased flexural and compressive strengths along with the share of micro-nano bubbles of gases in the mixing water. Full article

(This article belongs to the Special Issue Durability of Concrete or Mineral-Asphalt Mixtures with Recycled Aggregates)

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20 pages, 11499 KiB

Open AccessEditor’s ChoiceArticle

Durability of Hydrophobic/Icephobic Coatings in Protection of Lightweight Concrete with Waste Aggregate

by Danuta Barnat-Hunek, Jacek Góra and Marcin K. Widomski

Materials 2021, 14(1), 101; https://doi.org/10.3390/ma14010101 - 29 Dec 2020

Cited by 18 | Viewed by 2933 | Correction

Abstract

The aim of the research presented in this paper is to evaluate the feasibility of using hydrophobic agents based on organosilicon compounds for surface protection of lightweight concrete modified with waste polystyrene. The experimental part pertains to the physical and mechanical properties of [...] Read more.

The aim of the research presented in this paper is to evaluate the feasibility of using hydrophobic agents based on organosilicon compounds for surface protection of lightweight concrete modified with waste polystyrene. The experimental part pertains to the physical and mechanical properties of polystyrene-modified lightweight concrete. The concrete samples were prepared with the following ingredients: CEM I 42.5 R cement, recycled polystyrene (0–2 mm), quartz sand (0–2 mm), coarse river aggregate (2–16 mm), and water. Silane and tetramethoxysilane were employed for surface hydrophobization. Concrete with 20% polystyrene exhibits high porosity (25.22%), which is related to an increase in absorptivity (14.75%) compared to the reference concrete. The hydrophobized concrete is characterized by the lowest surface free energy (SFE) value, which is 7 or 11 times lower than the value of reference concrete, depending on the agents. The test on the contact angle (CA) was performed before and after the frost-resistance test (F–T test). Lower SFE translates into lower adhesive properties, higher resistance of the material to the infiltration of water and corrosive compounds, e.g., salts, and higher resistance to freezing and thawing cycles. Silane and tetramethoxysilane coating raised frost resistance by 54–58% compared to the reference samples. This agent reduced absorptivity by 30%. Recycled polystyrene can be successfully used to produce lightweight concrete (LC) with high durability provided by hydrophobic/icephobic coatings. Full article

(This article belongs to the Special Issue Durability of Concrete or Mineral-Asphalt Mixtures with Recycled Aggregates)

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16 pages, 3320 KiB

Open AccessArticle

Influence of Linseed Oil Varnish Admixture on Glauconite Clay Mortar Properties

by Przemysław Brzyski and Magdalena Grudzińska

Materials 2020, 13(23), 5487; https://doi.org/10.3390/ma13235487 - 2 Dec 2020

Cited by 6 | Viewed by 1886

Abstract

Raw clay is used nowadays in construction as a component of mortars and plasters and as a binder in composites based on straw or shives. It is a material with good sorption properties and vapor permeability, but it is susceptible to shrinkage, is [...] Read more.

Raw clay is used nowadays in construction as a component of mortars and plasters and as a binder in composites based on straw or shives. It is a material with good sorption properties and vapor permeability, but it is susceptible to shrinkage, is not resistant to water, and also is characterized by low mechanical strength, which makes it impossible to be used, for example, in external plasters. Various additives and admixtures are used to improve selected properties of clay mortars. The article presents the research results and assessment of the effect of glauconite clay mortar modification with an admixture of linseed oil varnish on selected properties. Admixtures in the amounts of 1%, 2%, and 3% in relation to clay weight were used. Flexural and compressive strength, water resistance, shrinkage, drying capacity, density, and porosity of mortar, were tested. The admixture of linseed oil varnish in the amounts used in the investigation had a positive effect on some of the tested properties; regardless of the quantity of the admixture, the modified mortars had better parameters concerning flexural strength, shrinkage reduction, and water resistance than the reference mortar, without admixture. Full article

(This article belongs to the Special Issue Durability of Concrete or Mineral-Asphalt Mixtures with Recycled Aggregates)

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20 pages, 2666 KiB

Open AccessArticle

Improvement of the Durability of Recycled Masonry Aggregate Concrete

by Tereza Pavlů, Kristina Fořtová, Jakub Řepka, Diana Mariaková and Jiří Pazderka

Materials 2020, 13(23), 5486; https://doi.org/10.3390/ma13235486 - 1 Dec 2020

Cited by 8 | Viewed by 2234

Abstract

The use of recycled masonry aggregate for concrete is mostly limited by the worse properties in comparison with natural aggregate. For these reasons it is necessary to find ways to improve the quality of recycled masonry aggregate concrete and make it more durable. [...] Read more.

The use of recycled masonry aggregate for concrete is mostly limited by the worse properties in comparison with natural aggregate. For these reasons it is necessary to find ways to improve the quality of recycled masonry aggregate concrete and make it more durable. One possibility is utilization of crystalline admixture which was verified in this study by laboratory measurements of key material properties and durability. The positive influence of mineral admixture was proved for freeze-thaw resistance. The positive impact to carbonation resistance was not unambiguous. In conclusion, the laboratory evaluation shows how to improve the durability of recycled masonry aggregate concrete, however, it is necessary to investigate more about this topic. Full article

(This article belongs to the Special Issue Durability of Concrete or Mineral-Asphalt Mixtures with Recycled Aggregates)

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20 pages, 4810 KiB

Open AccessEditor’s ChoiceArticle

Physico-Mechanical and Rheological Properties of Epoxy Adhesives Modified by Microsilica and Sonication Process

by Andrzej Szewczak and Maciej Szeląg

Materials 2020, 13(23), 5310; https://doi.org/10.3390/ma13235310 - 24 Nov 2020

Cited by 28 | Viewed by 2371

Abstract

Industrial waste from the production of metallic silicon and silicon–iron alloys, which includes silica fumes (microsilica), is subject to numerous applications aiming at its reuse in concrete and polymeric composites. Recycling solves the problem of their storage and adverse environmental impact. Six different [...] Read more.

Industrial waste from the production of metallic silicon and silicon–iron alloys, which includes silica fumes (microsilica), is subject to numerous applications aiming at its reuse in concrete and polymeric composites. Recycling solves the problem of their storage and adverse environmental impact. Six different formulas of epoxy resins were tested, differing in the type of polymer, the mixing process (sonication or not) and the presence of microsilica. The study showed that microsilica added to the epoxy resin changes its viscosity and free surface energy, and these are the parameters that determine the adhesion of the polymer to the concrete surface. Strength tests and SEM analysis have determined how microsilica molecules can penetrate the structure of polymer macromolecules by filling and forming temporary chemical bonds. Mixing the fillers with the adhesive was achieved by using a sonication process. The analysis of the obtained results showed that, depending on the initial composition of the polymer, the addition of microsilica can change the chemical, physical and mechanical properties of the hardened adhesive to varying degrees. In the case of adhesives used in the construction industry to strengthen and glue structural elements, these changes significantly affect the durability of the adhesive joints. Full article

(This article belongs to the Special Issue Durability of Concrete or Mineral-Asphalt Mixtures with Recycled Aggregates)

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18 pages, 4300 KiB

Open AccessArticle

Temperature Influence on Ordinary Concrete Modified with Fly Ashes from Thermally Conversed Municipal Sewage Sludge Strength Parameters

by Gabriela Rutkowska, Paweł Ogrodnik, Joanna Fronczyk and Ayla Bilgin

Materials 2020, 13(22), 5259; https://doi.org/10.3390/ma13225259 - 20 Nov 2020

Cited by 6 | Viewed by 2113

Abstract

Concrete is the most commonly used structural material, without which modern construction could not function. It is a material with a high potential to adapt to specific operating conditions. The use of this potential is made by its material modification. The aim of [...] Read more.

Concrete is the most commonly used structural material, without which modern construction could not function. It is a material with a high potential to adapt to specific operating conditions. The use of this potential is made by its material modification. The aim of the performed investigations was the assessment of rational application possibilities of fly ashes from thermally conversed municipal sewage sludge as an alternative concrete admixture. A concrete mix was designed, based on the Portland cement CEM I 42.5R and containing various quantity of ash, amounting to 0–25% of cement mass. The samples were conditioned and heated in a furnace at the temperature of 300 °C, 500 °C, and 700 °C. Physical and chemical properties of the ashes as well as utility properties of the concrete, i.e., density, compressive strength after 28, 56, and 90 days of maturation, frost resistance, and compressive strength in high temperature were determined. The tests were performed at cubic samples with 10 cm edge. The replacement of a determined cement quantity by the fly ashes enables obtaining a concrete composite having good strength parameters. The concrete modified by the fly ashes constituting 20% of the cement mass achieved its average compressive strength after 28 days of maturation equal to 50.12 MPa, after 56 days 50.61 MPa and after 90 days 50.80 MPa. The temperature growth weakens the composite structure. The obtained results confirm the possibility of waste recycling in the form of fly ashes as a cement substitute in concrete manufacturing. Full article

(This article belongs to the Special Issue Durability of Concrete or Mineral-Asphalt Mixtures with Recycled Aggregates)

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20 pages, 9925 KiB

Open AccessEditor’s ChoiceArticle

Durability of Structural Lightweight Concrete with Sintered Fly Ash Aggregate

by Lucyna Domagała

Materials 2020, 13(20), 4565; https://doi.org/10.3390/ma13204565 - 14 Oct 2020

Cited by 29 | Viewed by 3767

Abstract

The aim of this study was to present the problem of durability of structural lightweight concrete made of a sintered fly ash aggregate. The issue of durability was researched for 12 concrete series in terms of their water absorption, water permeability, and freeze-thaw [...] Read more.

The aim of this study was to present the problem of durability of structural lightweight concrete made of a sintered fly ash aggregate. The issue of durability was researched for 12 concrete series in terms of their water absorption, water permeability, and freeze-thaw resistance. Additionally, the microstructure of several concretes was analyzed with a scanning electron microscope (SEM). In the durability research, the influences of the following parameters were taken into consideration: The initial moisture content of sintered fly ash (mc = 0, 17–18, and 24–25%); the aggregate grading (4/8 and 6/12 mm); and the water-cement ratio (w/c = 0.55 and 0.37). As a result of various compositions, the concretes revealed different properties. The density ranged from 1470 to 1920 kg/m³, and the corresponding strength ranged from 25.0 to 83.5 MPa. The durability research results of tested lightweight concretes showed that, despite considerably higher water absorption, a comparable water permeability and comparable or better freeze-thaw resistance in relation to normal-weight concrete may be present. Nevertheless, the fundamental requirement of lightweight concrete to achieve good durability requires the aggregate’s initial moisture content to be limited and a sufficiently tight cement matrix to be selected. The volume share of the cement matrix and aggregate, the cement content, and even the concrete strength are of secondary importance. Full article

(This article belongs to the Special Issue Durability of Concrete or Mineral-Asphalt Mixtures with Recycled Aggregates)

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15 pages, 6996 KiB

Open AccessArticle

Concrete Repair Durability

by Lech Czarnecki, Robert Geryło and Krzysztof Kuczyński

Materials 2020, 13(20), 4535; https://doi.org/10.3390/ma13204535 - 13 Oct 2020

Cited by 14 | Viewed by 3299

Abstract

The repairs of building structures are inevitable and indispensable. Repairs are used to restore or maintain the usability of existing facilities, often contributing to the extension of their expected service life, increasing the sustainability of building resources. Given that conservation rules are observed, [...] Read more.

The repairs of building structures are inevitable and indispensable. Repairs are used to restore or maintain the usability of existing facilities, often contributing to the extension of their expected service life, increasing the sustainability of building resources. Given that conservation rules are observed, repairs are also used to save monuments. The concept of repair durability brings to the foreground the durability of the repaired structure (after repair): what service life has been obtained/recovered as a result of the repair. Based on the available data (limited set), a generalised distribution function of repair durability was developed, with a disappointing course. This, however, applies (necessarily) to the past. Significant progress was shown to have been achieved in the theoretical and technical fundamentals of technical repair measures. In this situation, a prognostic distribution function was also designed for future repairs according to EN 1504. A rule of thumb called estimating concrete repair durability, CRD was proposed. The risk associated with estimating the durability of repairs was indicated. A reason for optimism is that proactive monitoring of the condition of the structure and, consequently, management of the repair strategy allows to reach the designed life of the structure. Full article

(This article belongs to the Special Issue Durability of Concrete or Mineral-Asphalt Mixtures with Recycled Aggregates)

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18 pages, 4738 KiB

Open AccessArticle

Wettability of Asphalt Concrete with Natural and Recycled Aggregates from Sanitary Ceramics

by Wojciech Andrzejuk, Andrzej Szewczak, Stanisław Fic and Grzegorz Łagód

Materials 2020, 13(17), 3799; https://doi.org/10.3390/ma13173799 - 28 Aug 2020

Cited by 6 | Viewed by 2276

Abstract

In line with the current trend of seeking alternative methods for modification of the existing building composites, such as mineral–asphalt mixtures (MAMs), the materials from concrete and ceramics recycling are being used in increasingly wider applications. When added to MAMs as an aggregate, [...] Read more.

In line with the current trend of seeking alternative methods for modification of the existing building composites, such as mineral–asphalt mixtures (MAMs), the materials from concrete and ceramics recycling are being used in increasingly wider applications. When added to MAMs as an aggregate, ceramic building material, which has different properties than the raw material (clay), may significantly influence the aggregate properties, including the wettability, porosity, asphalt adhesion, and consequently the mixture durability. The material’s microstructure was found using SEM. The wetting properties of mineral–asphalt mixtures were determined by measuring the contact angles (CA) of their surfaces, using water as the measuring liquid. The total surface free energy (SFE) values were determined using the Neumann method. When analyzing the research results, it can be noticed that the chemical composition of the ceramic aggregate has a significant influence on the adhesion of asphalt to its surface due to the chemical affinity. Waste ceramic aggregate, despite its acidic pH value being connected with its elevated silica content, exhibits good adhesive properties. Full article

(This article belongs to the Special Issue Durability of Concrete or Mineral-Asphalt Mixtures with Recycled Aggregates)

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19 pages, 6137 KiB

Open AccessArticle

Effect of Waste Glass Addition as a Replacement for Fine Aggregate on Properties of Mortar

by Marcin Małek, Waldemar Łasica, Mateusz Jackowski and Marta Kadela

Materials 2020, 13(14), 3189; https://doi.org/10.3390/ma13143189 - 17 Jul 2020

Cited by 75 | Viewed by 5813

Abstract

A responsible approach towards sustainable development requires the use of environmentally friendly, low-carbon, and energy-intensive materials. One positive way is to use glass waste as a replacement for fine natural aggregate. For this purpose, the effects of adding glass cullet to the mechanical [...] Read more.

A responsible approach towards sustainable development requires the use of environmentally friendly, low-carbon, and energy-intensive materials. One positive way is to use glass waste as a replacement for fine natural aggregate. For this purpose, the effects of adding glass cullet to the mechanical properties of mortar were carried out. The glass aggregate made from recycled post-consumer waste glass (food, medicine, and cosmetics packaging, including mostly bottles), were used. This experimental work included four different contents of fine glass cullet (5, 10, 15, and 20 wt.% of fine aggregate). The compressive, flexural, and split tensile strengths were evaluated. Moreover, the modulus of elasticity and Poisson coefficient were determined. The addition of glass sand aggregate increases the mechanical properties of mortar. When comparing the strength, the obtained improvement in split tensile strength was the least affected. The obtained effect for the increased analysed properties of the glass sand aggregate content has been rarely reported. Moreover, it was determined that by increasing the recycled glass sand aggregate content, the density of mortar decreased. In addition, the relationships between the properties for mortar containing glass sand aggregate were observed. Full article

(This article belongs to the Special Issue Durability of Concrete or Mineral-Asphalt Mixtures with Recycled Aggregates)

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20 pages, 7277 KiB

Open AccessArticle

Tests of Fiber Cement Materials Containing Recycled Cellulose Fibers

by Tomasz Gorzelańczyk, Krzysztof Schabowicz and Mateusz Szymków

Materials 2020, 13(12), 2758; https://doi.org/10.3390/ma13122758 - 18 Jun 2020

Cited by 5 | Viewed by 3704

Abstract

This paper presents the results of investigations into the effect of the use of recycled waste paper cellulose fibers on the properties of fiber cement boards subjected to contamination by moisture. Four series of fiber cement boards were tested. A reference fiber cement [...] Read more.

This paper presents the results of investigations into the effect of the use of recycled waste paper cellulose fibers on the properties of fiber cement boards subjected to contamination by moisture. Four series of fiber cement boards were tested. A reference fiber cement board manufactured without the use of recycled cellulose fibers constituted as one of the series. The other three series consisted of boards differing in their recycled cellulose fiber content-ranging from 10% to 50% of the total cellulose fiber content. Specimens of the fiber cement boards were subjected to contamination by moisture by storing them in water for 1–96 h. Subsequently, their basic physical and mechanical parameters, i.e., mass moisture content, absorbability, and modulus of rupture (MOR), were tested. Then, the specimens were investigated by means of acoustic emission during three-point bending. Artificial neural networks were employed to analyze the acoustic emission test results. The tests clearly showed the amount of recycled waste paper cellulose fibers and the length of storage in water to have an adverse effect on the boards, contributing to their degradation. This was reflected in the decrease of the acoustic emission (AE) events count recognized by the artificial neural networks, accompanying the rupture of fibers during the three-point bending of the specimens. In order to gain a more detailed insight into the changes taking place in the structure of the tested fiber cement boards, optical examinations were carried out by means of a scanning electron microscope. Interesting findings crucial for building practice were noted. Full article

(This article belongs to the Special Issue Durability of Concrete or Mineral-Asphalt Mixtures with Recycled Aggregates)

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25 pages, 76133 KiB

Open AccessArticle

Properties of Fibrous Concrete Made with Plastic Optical Fibers from E-Waste

by Zbigniew Suchorab, Małgorzata Franus and Danuta Barnat-Hunek

Materials 2020, 13(10), 2414; https://doi.org/10.3390/ma13102414 - 25 May 2020

Cited by 37 | Viewed by 4755

Abstract

This article presents research results relating to the potential for waste utilization in the form of polymer optical fiber (POF) scraps. This material is difficult to recycle due to its diverse construction. Three different volumes of POF were used in concrete in these [...] Read more.

This article presents research results relating to the potential for waste utilization in the form of polymer optical fiber (POF) scraps. This material is difficult to recycle due to its diverse construction. Three different volumes of POF were used in concrete in these tests: 1%, 2%, and 3%. The experimental studies investigated the basic properties of the concrete, the elastic and dynamic moduli, as well as deformation and deflection of reinforced beams. The microstructures, including the interfacial transition zones (ITZs), were recorded and analyzed using a scanning electron microscope. It was observed that 180 freezing–thawing cycles reduced the concrete frost resistance containing 3% POFs by half compared to the control concrete. The resistance to salt crystallization of this concrete decreased by about 55%. POFs have significant effects on the splitting tensile and flexural strengths compared to the compressive strength. The control beams were destroyed during the four-point static bending tests at half the force applied to the beams that were reinforced with POFs. Full article

(This article belongs to the Special Issue Durability of Concrete or Mineral-Asphalt Mixtures with Recycled Aggregates)

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29 pages, 25862 KiB

Open AccessArticle

Intensive Ways of Producing Carbonate Curing Building Materials Based on Lime Secondary Raw Materials

by Nikolai Lyubomirskiy, Aleksandr Bakhtin, Stanisław Fic, Małgorzata Szafraniec and Tamara Bakhtinа

Materials 2020, 13(10), 2304; https://doi.org/10.3390/ma13102304 - 16 May 2020

Cited by 6 | Viewed by 3168 | Correction

Abstract

The article is dedicated to the research and development of intensive methods for curing products by capturing and binding CO₂. It aims to improve and increase the productivity of technologies for the production of artificially carbonated building materials and products. Soda [...] Read more.

The article is dedicated to the research and development of intensive methods for curing products by capturing and binding CO₂. It aims to improve and increase the productivity of technologies for the production of artificially carbonated building materials and products. Soda production wastes, limestone dust and finely dispersed limestone dust were used as the research objects. Secondary raw materials have been investigated using modern methods of phase composition and granulometry test. Intensive methods of production of accelerated carbonation of systems consisting of soda wastes were tested using multi-parameter optimization methods. The effects of recycled lime materials on the strength and hydrophysical properties of the obtained material were determined. The secondary raw materials effect depended on the composition of the raw mixture, molding conditions, CO₂ concentration applied to the carbonate curing chamber, and the duration of exposure to environments with high CO₂ content. It was found that the most effective way of providing accelerated carbonation curing of construction materials and products is a combined carbonation method, combining the principles of dynamic and static methods. It was concluded that the optimal CO₂ concentration in the gas-air mixtures used for carbonate curing is 30%–40%. Full article

(This article belongs to the Special Issue Durability of Concrete or Mineral-Asphalt Mixtures with Recycled Aggregates)

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19 pages, 26795 KiB

Open AccessArticle

Microstructure and Degradation of Mortar Containing Waste Glass Aggregate as Evaluated by Various Microscopic Techniques

by Przemysław Czapik

Materials 2020, 13(9), 2186; https://doi.org/10.3390/ma13092186 - 9 May 2020

Cited by 9 | Viewed by 3332 | Correction

Abstract

The primary aim of this article is to focus on the alkali-silica reaction (ASR) in mortar specimens containing coloured waste glass used as an aggregate. Mortar expansion was measured using the ASTM C 1260 accelerated test procedure until the specimens disintegrated. Special attention [...] Read more.

The primary aim of this article is to focus on the alkali-silica reaction (ASR) in mortar specimens containing coloured waste glass used as an aggregate. Mortar expansion was measured using the ASTM C 1260 accelerated test procedure until the specimens disintegrated. Special attention was paid to the microscopic examination of the damaged mortar. Various methods were used for this purpose, including optical microscopy in reflected and transmitted light with one and two crossed polarizers. The specimens were also subjected to the scanning electron microscopy observations with energy dispersive spectroscopy (SEM-EDS). The data obtained from these techniques provided information on the mechanism of glass-containing mortar degradation due to ASR and also allowed the comparison of different microscopic techniques in terms of the information they can provide on ASR occurrence. Full article

(This article belongs to the Special Issue Durability of Concrete or Mineral-Asphalt Mixtures with Recycled Aggregates)

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18 pages, 6392 KiB

Open AccessArticle

Capillary Uptake Monitoring in Lime-Hemp-Perlite Composite Using the Time Domain Reflectometry Sensing Technique for Moisture Detection in Building Composites

by Przemysław Brzyski and Zbigniew Suchorab

Materials 2020, 13(7), 1677; https://doi.org/10.3390/ma13071677 - 3 Apr 2020

Cited by 18 | Viewed by 2513

Abstract

The use of waste plants in the production of building materials is consistent with the principles of sustainable development. One of the ideas involves using hemp shives as an aggregate for the production of a composite used as a filling of the timber [...] Read more.

The use of waste plants in the production of building materials is consistent with the principles of sustainable development. One of the ideas involves using hemp shives as an aggregate for the production of a composite used as a filling of the timber frame construction of the walls. The most important disadvantage of using the building materials based on organic components is their susceptibility to the water influence. The wall material is exposed to rising groundwater. The research part of the paper presented the preparation method and the investigation of the hemp-perlite-lime composites. Flexural and compressive strength, apparent density, total porosity, thermal conductivity, and mass absorptivity were examined. The main research part pertained to the analysis of capillary uptake occurrence in the composites, being the important phenomenon present in the external walls. The study on this phenomenon was carried out using the technique of indirect moisture evaluation—Time Domain Reflectometry (TDR). The indirect readouts were additionally verified with the traditional evaluation using the gravimetric method based on the PN-EN 1925 standard. The study proved that the tested composites were characterized by low apparent density, thermal conductivity, strength parameters, high total porosity, and mass absorptivity. The partial replacement of hemp shives by expanded perlite had a beneficial effect on the tested properties of composites. Full article

(This article belongs to the Special Issue Durability of Concrete or Mineral-Asphalt Mixtures with Recycled Aggregates)

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21 pages, 4461 KiB

Open AccessArticle

Effect of High Temperatures on the Impact Strength of Concrete Based on Recycled Aggregate Made of Heat-Resistant Cullet

by Aleksandra Powęzka, Jacek Szulej and Paweł Ogrodnik

Materials 2020, 13(2), 465; https://doi.org/10.3390/ma13020465 - 18 Jan 2020

Cited by 15 | Viewed by 3491

Abstract

The article presents results obtained during testing of concrete based on CEM I 42.5R Portland cement, fine and coarse aggregate, glass, volatile ash, and superplastifier. The concrete mixture was modified using filler consisting of bromosilicate heat resistant cullet. Recycled aggregate was added to [...] Read more.

The article presents results obtained during testing of concrete based on CEM I 42.5R Portland cement, fine and coarse aggregate, glass, volatile ash, and superplastifier. The concrete mixture was modified using filler consisting of bromosilicate heat resistant cullet. Recycled aggregate was added to the batch. Samples for the need of testing were produced as (100 × 100 × 100) mm cubes. Before commencing proper tests, samples have been heated within the temperature range of 20–800 °C. Tests carried out during the proper testing procedure included tests of compressive strength, elevated temperature, impact strength, as well as macroscopic tests of the contact area. The obtained test results have provided proof of there being a possibility of producing special concrete, modified by products obtained from heat resistant cullet. This type of is generally characterized by satisfactory performance parameters. The average compressive strength for concrete modified by a 10% of heat resistant cullet was determined as 43.6 MPa and 48.3 MPa respectively after 28 and 180 days of curing. Full article

(This article belongs to the Special Issue Durability of Concrete or Mineral-Asphalt Mixtures with Recycled Aggregates)

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18 pages, 1935 KiB

Open AccessArticle

Influence of Recycled High-Performance Aggregate on Deformation and Load-Carrying Capacity of Reinforced Concrete Beams

by Barbara Sadowska-Buraczewska, Danuta Barnat-Hunek and Małgorzata Szafraniec

Materials 2020, 13(1), 186; https://doi.org/10.3390/ma13010186 - 2 Jan 2020

Cited by 15 | Viewed by 2727

Abstract

The use of recycled concrete aggregates (RCA) in high performance concrete (HPC) was analyzed. The paper presents the experimental studies of model reinforced concrete beams with a rectangular section using high-performance recycled aggregates. Two variable contents of recycled aggregate concrete were used in [...] Read more.

The use of recycled concrete aggregates (RCA) in high performance concrete (HPC) was analyzed. The paper presents the experimental studies of model reinforced concrete beams with a rectangular section using high-performance recycled aggregates. Two variable contents of recycled aggregate concrete were used in this study: 50% and 100%. The experimental analyses conducted as immediate studies concerned the following issues: short time loads-deflection, load-carrying capacity of beams, deformation of concrete, cracks, and long-term loads-deflection. The comparative analysis involves the behavior of beams made of high performance concrete-high strength concrete (HPC-HSC) recycled aggregates with model control elements made of regular concrete based on natural aggregates. The deflection values for the recycled aggregate beams were 20% higher than in the case of the control beams made of HPC-HSC exclusively. Replacement of aggregate with recycled concrete aggregate resulted in a large decrease in the value of these two parameters, i.e., compression strength by about 42% and modulus of elasticity by about 33%. Full article

(This article belongs to the Special Issue Durability of Concrete or Mineral-Asphalt Mixtures with Recycled Aggregates)

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