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31 pages, 11063 KiB

Open AccessArticle

The Role of Ceramics in the Configuration of a New Solar Thermal Collection System for Domestic Hot Water and Heating

by Jordi Roviras Miñana and Vicente Sarrablo Moreno

Materials 2025, 18(9), 1907; https://doi.org/10.3390/ma18091907 - 23 Apr 2025

Viewed by 347

Abstract

The work presented in this study aims to demonstrate the capacity of ceramic materials in the configuration of solar thermal collectors (CSTs) for the production of domestic hot water (DHW) and heating in buildings. Currently, the ceramic tile and panel manufacturing sector presents [...] Read more.

The work presented in this study aims to demonstrate the capacity of ceramic materials in the configuration of solar thermal collectors (CSTs) for the production of domestic hot water (DHW) and heating in buildings. Currently, the ceramic tile and panel manufacturing sector presents very advanced manufacturing systems at a technological level that allows the generation of pieces with high physical and mechanical performances. Especially, their high resistances to extreme temperatures and good thermal conductivities position these materials as great candidates in the field of CSTs. In addition, ceramic materials tend to be durable and corrosion resistant, which makes them a very reliable option in the long term. The results obtained in the test campaign and presented in the article confirm the capacity of ceramics to meet the basic requirements of a CST system for buildings in terms of absorption, energy performance, watertightness, and resistance to water pressure, among other aspects, and make it possible to advance new research to improve the behaviors, performances, and architectural integration of ceramic collectors. Full article

(This article belongs to the Special Issue Advance in Sustainable Construction Materials, Second Volume)

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31 pages, 7292 KiB

Open AccessArticle

Eco-Efficient Fiber-Reinforced Concrete: From Mix Design to Fresh and Hardened State Behavior

by Ana Bergmann, Mohammed Nabil Eid, Mayra T. de Grazia, Sergio R. A. Dantas and Leandro F. M. Sanchez

Materials 2025, 18(6), 1245; https://doi.org/10.3390/ma18061245 - 11 Mar 2025

Viewed by 467

Abstract

Fiber-reinforced concrete (FRC) mixtures often face challenges in the fresh state, which are typically addressed using high Portland cement (PC) content or chemical admixtures, obstructing sustainability efforts in the construction industry. Therefore, this study employs advanced mixed design techniques, specifically particle packing models [...] Read more.

Fiber-reinforced concrete (FRC) mixtures often face challenges in the fresh state, which are typically addressed using high Portland cement (PC) content or chemical admixtures, obstructing sustainability efforts in the construction industry. Therefore, this study employs advanced mixed design techniques, specifically particle packing models (PPMs), to proportion eco-efficient FRC mixtures with reduced cement content (<300 kg/m³) while achieving desirable fresh and hardened state properties. Twelve low-cement (LC) FRC mixtures, containing limestone filler (LF) as an inert material and a partial replacement for PC, were designed with a water-to-cement ratio of 0.64, incorporating two fiber types (polypropylene and steel) at varying contents (0.5% and 1.0% by volume) and lengths (38 mm and 50 mm). PPM-designed mixtures used two coefficients of distribution (q-factors: 0.21 and 0.26) and were evaluated for fresh (VeBe time, slump, and rheology) and hardened (compressive strength and flexural performance) state properties. Results show that PPM-designed FRC mixtures achieved up to 70% higher compressive strength and up to 64% greater flexural capacity compared to conventional mixes (i.e., American Concrete Institute—ACI), despite using 20% less cement. Additionally, PPM mixtures exhibited higher VeBe times (up to 24 s) and yield stress, reflecting improved packing density, while demonstrating shear-thinning behavior for practical applications (i.e., pumped or vibrated concrete). Finally, the findings demonstrate that PPMs enable the development of eco-efficient, low-cement FRC mixtures with similar or improved hardened state performance and reduced environmental impact. Full article

(This article belongs to the Special Issue Advance in Sustainable Construction Materials, Second Volume)

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24 pages, 11564 KiB

Open AccessArticle

Effects of Granulated Cork with Bark on the Microstructure and Resistance to Extreme Environmental Conditions of Concrete for Non-Structural Precast Elements

by María Concepción Pacheco Menor, María José Arévalo Caballero, Antonio Macías García and Pedro Serna Ros

Materials 2025, 18(5), 933; https://doi.org/10.3390/ma18050933 - 21 Feb 2025

Viewed by 505

Abstract

The building sector is responsible for major environmental impacts. Utilising bio-based raw materials, such as bio-aggregates, in concrete production could address to this environmental challenge. While the physical and mechanical properties of various bio-based concretes have been explored, research on their microstructure and [...] Read more.

The building sector is responsible for major environmental impacts. Utilising bio-based raw materials, such as bio-aggregates, in concrete production could address to this environmental challenge. While the physical and mechanical properties of various bio-based concretes have been explored, research on their microstructure and resistance to extreme conditions is limited. Cork is a light, renewable and biodegradable material. Cork industries produce a considerable number of solid wastes, among them is granulated cork with bark (GCB) that is not adequate to produce agglomerated cork. To reduce this waste volume, it is possible to use GCB as a bio-based aggregate in the production of concrete for applications in non-structural precast elements that are lighter and/or have thermal properties. The influence of GCB on the microstructure and resistance to extreme conditions of concrete for non-structural use is presented here. Concrete mixes with GCB are compared with a concrete mix made with natural aggregates (RC). Replacements of 20% and 30% of natural aggregate (2–5 mm) by GCB were considered. The microstructure shows the good integration of the GCB in the cement matrix. Freeze–thaw and wet–dry cycle tests do not affect the variation in mass and compressive strength of concrete mixes with GCB in comparison to RC mixes, although they do affect its visual appearance and microstructure somewhat. Concrete mixes with GCB present a greater variation in mass and compressive strength, 30% for RC mix and 43–49% for concrete mixes with GCB, under high temperatures. Concrete mixes with GCB did not show spontaneous combustion. Full article

(This article belongs to the Special Issue Advance in Sustainable Construction Materials, Second Volume)

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18 pages, 4092 KiB

Open AccessArticle

Research on the Main Properties of Cementitious Mortars Prepared with High-Fe₂O₃-Content Raw Drinking Water Treatment Sludge

by Giedrius Girskas and Modestas Kligys

Materials 2025, 18(4), 759; https://doi.org/10.3390/ma18040759 - 8 Feb 2025

Viewed by 866

Abstract

Drinking water treatment sludge (DWTS) is a typical by-product of drinking water treatment plants. Concerns are growing about how to deal with big amounts of this sludge generated globally. One of the ways is to reuse DWTS as a supplementary material in cementitious [...] Read more.

Drinking water treatment sludge (DWTS) is a typical by-product of drinking water treatment plants. Concerns are growing about how to deal with big amounts of this sludge generated globally. One of the ways is to reuse DWTS as a supplementary material in cementitious systems and thus reduce landfill disposals. For our studies, we used DWTS containing more than 52% Fe₂O₃. The DWTS was taken from a water treatment plant in Vilnius, Lithuania. This work aimed to find potential applications of unprocessed DWTS in cementitious systems as a supplementary material that changes the physical and mechanical properties of the final product. Tests were performed with cementitious mortars where the binder was replaced with DWTS (from 0% to 12.5%). Local raw materials such as Portland cement CEM I 42.5R and sand 0/4 were used in the tests. Water absorption, absorption kinetics, and mechanical strength tests were conducted, and predictive freeze–thaw resistance was estimated. The heat release rate and open–closed porosity were also measured. The results showed that DWTS impacts the hydration of cementitious mortars, lowers their density (from 2122 kg/m³ to 1954 kg/m³), as well as compressive strength (from 41.78 MPa to 24.76 MPa) and flexural strength (from 6.24 MPa to 4.07 MPa), and increases total porosity (from 28.1% to 34.6%) and closed porosity (from 9.1% to 14.9%). The lowest toughness value of 6.08 was recorded in the 12.5% DWTS sample. From our conducted research, it could be observed that raw DWTS potentially changed the porosity parameters of cementitious mortars. This resulted in an incremental improvement in durability and an improvement in the hardness of cementitious mortars. A higher content of raw DWTS changed the colour (to reddish) of cementitious mortars, due to its higher Fe₂O₃ content (up to 53%). All of the above-mentioned properties allowed the designing of cementitious landscape products with a wider range of colours. Full article

(This article belongs to the Special Issue Advance in Sustainable Construction Materials, Second Volume)

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15 pages, 5314 KiB

Open AccessArticle

Optimisation of Using Low-Grade Kaolinitic Clays in Limestone Calcined Clay Cement Production (LC3)

by Paola Vargas, María Victoria Borrachero, Jordi Payá, Ana Macián, Jorge Iván Tobón, Fernando Martirena and Lourdes Soriano

Materials 2025, 18(2), 285; https://doi.org/10.3390/ma18020285 - 10 Jan 2025

Viewed by 1182

Abstract

LC3 (limestone calcined clay cement) is poised to become the construction industry’s future as a so-called low-carbon-footprint cement. Research into this subject has determined the minimum kaolinite content in calcined clays to guarantee good mechanical performance. This study examines the use of clay [...] Read more.

LC3 (limestone calcined clay cement) is poised to become the construction industry’s future as a so-called low-carbon-footprint cement. Research into this subject has determined the minimum kaolinite content in calcined clays to guarantee good mechanical performance. This study examines the use of clay from the Valencian Community (Spain), which has a lower kaolinite content than the recommended amount (around 30%) for use in LC3 and how its performance can be enhanced by replacing part of that clay with metakaolin. This study begins with a physico-chemical characterisation of the starting materials. This is followed by a microstructural analysis of cement pastes, which includes isothermal calorimetry, thermogravimetry, and X-ray diffraction tests at different curing ages. Finally, this study analyses the mechanical performance of standard mortars under compression to observe the evolution of the control mortars and the mortars with calcined clay and metakaolin over time. The results show that the LC3 mortars exhibited higher compressive strength in the mixtures with higher calcined kaolinite contents, achieved by adding metakaolin. Adding 6% metakaolin increased the compressive strength after 90 days, while 10% additions surpassed the control mortar’s compressive strength after 28 days. Mortars with 15% metakaolin exceeded the control mortar’s compressive strength after just 7 curing days. The hydration kinetics showed an acceleration of LC3 hydration with metakaolin additions due to the nucleation effect and the formation of monocarboaluminate and hemicarboaluminate (both AFm phases). The results suggest the potential for combining less reactive materials blended with highly reactive materials. Full article

(This article belongs to the Special Issue Advance in Sustainable Construction Materials, Second Volume)

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21 pages, 5045 KiB

Open AccessArticle

Recycling of Agricultural Film Wastes for Use as a Binder in Building Composites

by Bartosz Zegardło, Chrysanthos Maraveas, Kacper Rastawicki, Paweł Woliński and Antoni Bombik

Materials 2025, 18(2), 251; https://doi.org/10.3390/ma18020251 - 8 Jan 2025

Viewed by 1071

Abstract

Plastic film, also known as low-density polyethylene (LDPE), poses serious environmental challenges due to mass production, short life cycle, and poor waste management. The main aim of this paper was to examine the suitability of using agricultural waste film as a binder in [...] Read more.

Plastic film, also known as low-density polyethylene (LDPE), poses serious environmental challenges due to mass production, short life cycle, and poor waste management. The main aim of this paper was to examine the suitability of using agricultural waste film as a binder in construction composites instead of the traditional cement slurry. Molten at temperatures of around 120–150 °C wastes was mixed with fine sand and gravel aggregate as filler. Twelve samples consisting of different mixtures were produced—F20, F25, F30, F35, F40, F45, F50, F60, F70, F80, F90, and F100—where a given number indicates the weight ratio of film waste to aggregate used. The composites were subjected to various tests, including volumetric density, compressive strength, and flexural strength. The volumetric density (

ρ

) of the composites decreased with increasing amounts of waste. Composites containing 100% recyclate (F100) depicted density,

ρ

= 0.74 g/cm³, was 50.7% lower than for a composite that contained 20% recyclate (F20). The highest soakability was recorded in F20 (2.19%). Subsequently, the absorbency tested in composites decreased with increasing recyclate content. Compression strength (σ_comp) was highest for F40 (σ_comp = 39.46 MPa). In contrast, F20 had the lowest recorded compressive strength value (σ_comp = 11.13 MPa) and was 71.8% lower than F40. F70 had the highest recorded flexural strength value (σ_flex = 27.77 MPa). The other composites showed lower strength for higher amounts of recyclate and the amount of sand. SEM imaging proved that the contact zone between the aggregate grains and the bonding phase of the recycled film was consistent, with no anomalies, cracks, or voids. The results prove that LDPE film waste is suitable for use as a binder in building composites. However, appropriately selecting proportions of the recyclate, sand, and gravel aggregate is crucial to obtain a composite with technical parameters similar to those of cementitious composites. Full article

(This article belongs to the Special Issue Advance in Sustainable Construction Materials, Second Volume)

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20 pages, 9206 KiB

Open AccessArticle

Experimental, Numerical and Analytical Evaluation of Load-Bearing Capacity of Cold-Formed S-Beam with Sectional Transverse Strengthening

by Robert Studziński, Volodymyr Semko, Katarzyna Ciesielczyk and Mateusz Fabisiak

Materials 2024, 17(24), 6198; https://doi.org/10.3390/ma17246198 - 18 Dec 2024

Viewed by 1036

Abstract

The article provides information about strengthening cold-formed thin-walled steel beams made of the sigma profile. An innovative concept for sectional transverse strengthening of thin-walled beams subjected to concentrated forces was investigated. The proposed solution’s novelty lies in attaching the sectional transverse strengthening to [...] Read more.

The article provides information about strengthening cold-formed thin-walled steel beams made of the sigma profile. An innovative concept for sectional transverse strengthening of thin-walled beams subjected to concentrated forces was investigated. The proposed solution’s novelty lies in attaching the sectional transverse strengthening to the beam’s cross-section, employing a point crimping technique. This technique requires a specific modification of the cross-section edges, necessitating double-lipped flanges. This strengthening method is innovative, as it has not been previously applied to cold-formed structures. Typically, strengthening is achieved using other cold-formed elements or materials, such as timber, lightweight concrete, or CFRP tapes. The laboratory experimentally validated the proposed method using short- and medium-length beams. The experimental results were then compared with the results of the numerical analyses and the conventional design approach described in EC3. The results demonstrated the feasibility of implementing this type of strengthening, its reliability under load, and the confirmation of an increase in the load-bearing capacity of the experimental samples by 11–24%. Full article

(This article belongs to the Special Issue Advance in Sustainable Construction Materials, Second Volume)

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18 pages, 8653 KiB

Open AccessArticle

Effect of Sand Addition on Laterite Soil Stabilization

by Bárbara Drumond Almeida, Lisley Madeira Coelho, Antônio Carlos Rodrigues Guimarães and Sergio Neves Monteiro

Materials 2024, 17(24), 6033; https://doi.org/10.3390/ma17246033 - 10 Dec 2024

Cited by 2 | Viewed by 827

Abstract

Lateritic soils, particularly abundant in tropical regions, have been successfully used in the construction of unbound layers of flexible pavements in Brazil since the 1970s. Despite their potential, these soils are often discarded or only recommended after stabilization processes, based on traditional parameters [...] Read more.

Lateritic soils, particularly abundant in tropical regions, have been successfully used in the construction of unbound layers of flexible pavements in Brazil since the 1970s. Despite their potential, these soils are often discarded or only recommended after stabilization processes, based on traditional parameters such as gradation requirements and Atterberg limits. This study investigates the mechanical characteristics of a lateritic soil from Roraima, focusing on its resilient modulus and permanent deformation properties, assessed through repeated load triaxial tests. Specifically, this research examines the effect of adding 20% sand on the mechanical behavior of the material. The results indicate that sand addition did not significantly improve the mechanical performance. The laterite–sand mixture exhibited an average resilient modulus (RM) of 744 MPa, lower than the 790 MPa of pure lateritic soil, suggesting that pure laterite remains suitable for pavement applications. Furthermore, the permanent deformation analysis revealed that the mixture with sand experienced nearly twice the plastic strain compared to pure laterite, which demonstrated superior accommodation under repeated loading. In the shakedown analysis, pure laterite exhibited a more stable performance, indicating greater durability in pavement applications. These findings highlight the importance of understanding the mechanical behavior of lateritic soils beyond conventional testing methods, emphasizing the potential of pure laterite as a viable alternative to enhance the strength and durability of pavement structures. Full article

(This article belongs to the Special Issue Advance in Sustainable Construction Materials, Second Volume)

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15 pages, 11048 KiB

Open AccessArticle

Granite Dust and Silica Fume as a Combined Filler of Reactive Powder Concrete

by Andriy Huts, Janusz Konkol and Vitalii Marchuk

Materials 2024, 17(24), 6025; https://doi.org/10.3390/ma17246025 - 10 Dec 2024

Viewed by 738

Abstract

By volume, cement concrete is one of the most widely used construction materials in the world. This requires a significant amount of Portland cement, and the cement industry, in turn, causes a significant amount of CO₂ emissions. Therefore, the development of concrete [...] Read more.

By volume, cement concrete is one of the most widely used construction materials in the world. This requires a significant amount of Portland cement, and the cement industry, in turn, causes a significant amount of CO₂ emissions. Therefore, the development of concrete with a reduced cement content is becoming an urgent problem for countries with a significant level of production and consumption of concrete. Therefore, the purpose of this article is to critically investigate the possibility of using inert granite dust in combination with highly active silica fume in reactive powder concrete. The main physical and mechanical properties, such as the compressive strength at different curing ages and the water absorption, were studied using mathematical planning of experiments. The consistency and microstructure of the reactive powder concrete modified with granite dust in combination with silica fume were also analyzed. Mathematical models of the main properties of this concrete are presented and analyzed, and the graphical dependencies of the influence of composition factors are constructed. A more significant factor that affects the compressive strength at all curing ages is the silica fume content, increases in which to 50 kg/m³ lead to a 25–40% increase in strength at 1 day of age, depending on the granite dust content. In turn, an increase in the amount of granite dust from 0 kg/m³ to 100 kg/m³ in the absence of silica is followed by an increase in strength of 8–10%. After 3 days of curing, the effect of granite dust becomes more significant. Increases in the 28-day strength of 25%, 46% and 56% were obtained at a content of 50 kg/m³ of silica fume and 0 kg/m³, 100 kg/m³ and 200 kg/m³ of granite dust in concrete, respectively. It is shown that the effect of inert granite dust is more significant in combination with silica fume at its maximum content in the range of variation. The pozzolanic reaction between highly active silica and Ca(OH)₂ stimulates the formation of hydrate phases in the space between the grains and causes the microstructure of the cement matrix to compact. In this case, the granite dust particles act as crystallization centers. Full article

(This article belongs to the Special Issue Advance in Sustainable Construction Materials, Second Volume)

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25 pages, 6812 KiB

Open AccessArticle

Lavender and Black Pine Waste as Additives Enhancing Selected Mechanical and Hygrothermal Properties of Cement Mortars

by Jarosław Strzałkowski, Petrini Kampragkou, Maria Stefanidou, Agata Markowska-Szczupak, Elżbieta Horszczaruk and Anna Głowacka

Materials 2024, 17(22), 5475; https://doi.org/10.3390/ma17225475 - 9 Nov 2024

Cited by 2 | Viewed by 812

Abstract

The paper presents the mechanical and hygrothermal properties of cement mortars containing bio-powders made from lavender waste and black pine wood. The wastes were mechanically ground with a hammer mill to a fraction not exceeding 0.5 mm and then dried in air-dry conditions. [...] Read more.

The paper presents the mechanical and hygrothermal properties of cement mortars containing bio-powders made from lavender waste and black pine wood. The wastes were mechanically ground with a hammer mill to a fraction not exceeding 0.5 mm and then dried in air-dry conditions. The influence of bio-additives in amounts of 1.5% and 2.5% of the overall mortar volume was tested. The aim of the paper was to determine the impact of bio-additives on the mechanical and hygrothermal properties of the tested cement mortars. This publication included tests of compressive and flexural strength, elastic modulus, water absorption, absorption due to capillary rise, sorption and desorption properties, thermal properties, microstructural tests using mercury intrusion porosimetry and SEM, and EDS. The main conclusions of the research indicate that mortars with both 1.5% and 2.5% bio-powders are characterized by strong bactericidal properties, lower sorption properties at high air humidity, lower thermal conductivity, reduced compressive strength by 22–27%, no significant effect on the flexural strength, and significant reduction in capillary action of mortars both with short-term and long-term water exposure. Full article

(This article belongs to the Special Issue Advance in Sustainable Construction Materials, Second Volume)

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20 pages, 5793 KiB

Open AccessArticle

Development of Biodegradable and Recyclable FRLM Composites Incorporating Cork Aggregates for Sustainable Construction Practices

by Dora Pugliese, Valerio Alecci, Mohammad Sadegh Tale Masoule, Ali Ghahremaninezhad, Mario De Stefano and Antonio Nanni

Materials 2024, 17(21), 5232; https://doi.org/10.3390/ma17215232 - 27 Oct 2024

Viewed by 960

Abstract

Reducing energy consumption in the building sector has driven the search for more sustainable construction methods. This study explores the potential of cork-modified mortars reinforced with basalt fabric, focusing on optimizing both mechanical and hygroscopic properties. Six mortar mixtures were produced using a [...] Read more.

Reducing energy consumption in the building sector has driven the search for more sustainable construction methods. This study explores the potential of cork-modified mortars reinforced with basalt fabric, focusing on optimizing both mechanical and hygroscopic properties. Six mortar mixtures were produced using a breathable structural mortar made from pure natural hydraulic lime, incorporating varying percentages (0–3%) of cork granules (Quercus suber) as lightweight aggregates. Micro-computed tomography was first used to assess the homogeneity of the mixtures, followed by flow tests to evaluate workability. The mixtures were then tested for water absorption, compressive strength, and adhesion to tuff and clay brick surfaces. Adhesion was measured through pull-off tests, to evaluate internal bonding strength. Additionally, this study examined the relationship between surface roughness and bond strength in FRLM composites, revealing that rougher surfaces significantly improved adhesion to clay and tuff bricks. These findings suggest that cork-reinforced mortars offer promising potential for sustainable construction, achieving improved hygroscopic performance, sufficient mechanical strength, internal bonding, and optimized surface adhesion. Full article

(This article belongs to the Special Issue Advance in Sustainable Construction Materials, Second Volume)

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20 pages, 6974 KiB

Open AccessArticle

Valorisation of Aggregate-Washing Sludges in Innovative Applications in Construction

by Yury Villagran-Zaccardi, Francisca Carreño, Line Granheim, Antonio Espín de Gea, Ulf Smith Minke, Stefania Butera, Elena López-Martínez and Arne Peys

Materials 2024, 17(19), 4892; https://doi.org/10.3390/ma17194892 - 5 Oct 2024

Viewed by 1278

Abstract

The valorisation of sludges from aggregate production into construction materials is required for full circularity in mining waste management. This study explores valorisation pathways, relevant regulatory frameworks, and End-of-Waste (EoW) criteria for specific settings in Spain and Norway. The explored valorisation routes involved [...] Read more.

The valorisation of sludges from aggregate production into construction materials is required for full circularity in mining waste management. This study explores valorisation pathways, relevant regulatory frameworks, and End-of-Waste (EoW) criteria for specific settings in Spain and Norway. The explored valorisation routes involved the production of filler, supplementary cementitious materials (SCMs), and lightweight aggregates (LWAs) for the production of cement-based products, and precursors for 3D printed construction material. The sludge from Norway revealed a non-polluted stream and a stream contaminated with organic phases and clays. Sludge-based filler proved suitable in concrete production with contents of up to 40% of total binder, providing adequate consistency and cohesion. However, clays in the sludge increased the demand for water and superplasticizer. Clay contents were still insufficient for the applications as SCMs, as the calcined sludge demonstrated limited reactivity. The application to produce LWAs was promising, but further microstructure optimization is still required. The clay content was also relevant for the sludge from the site in Spain, as it provided 3D printing mixes with good plasticity. The dosage optimization still required the addition of enzymes, limestone, and natural fibres to improve cohesion, workability, and resistance to the cracking of the 3D printing mix. Full article

(This article belongs to the Special Issue Advance in Sustainable Construction Materials, Second Volume)

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17 pages, 6928 KiB

Open AccessArticle

Hydration and Mechanical Properties of Cement Kiln Dust-Blended Cement Composite

by Woo-Seok Lee and Young-Cheol Choi

Materials 2024, 17(19), 4841; https://doi.org/10.3390/ma17194841 - 30 Sep 2024

Cited by 1 | Viewed by 1322

Abstract

This study aims to investigate the effects of cement kiln dust (CKD) on the hydration reactions and mechanical properties of cement, and to evaluate its potential for use as a supplementary cementitious material (SCM). The key variables are the CKD type and the [...] Read more.

This study aims to investigate the effects of cement kiln dust (CKD) on the hydration reactions and mechanical properties of cement, and to evaluate its potential for use as a supplementary cementitious material (SCM). The key variables are the CKD type and the replacement ratio. Cement paste and mortar specimens containing CKD were prepared to examine their effects on the cement hydration and mechanical properties. The effect on hydration was assessed using setting time measurements, heat of hydration tests, and thermogravimetric analyses (TG). In addition, compressive strength tests were conducted to evaluate the effect of CKD on the mechanical properties of the cement. The results indicated that CKD promoted early-age cement hydration and enhanced the early-age mechanical properties. However, owing to its lack of pozzolanic reactivity, it did not significantly affect long-term hydration. Given that the effects of CKD vary slightly depending on its chemical composition, careful consideration of CKD’s properties suggests that its potential use as an SCM is promising. Full article

(This article belongs to the Special Issue Advance in Sustainable Construction Materials, Second Volume)

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13 pages, 4908 KiB

Open AccessArticle

Effect of Phosphoric Acid and Soluble Phosphate on the Properties of Magnesium Oxychloride Cement

by Qing Huang, Su Wang, Yongsheng Du, Zhigang Yin, Bing Chen, Jie Zhang and Weixin Zheng

Materials 2024, 17(19), 4828; https://doi.org/10.3390/ma17194828 - 30 Sep 2024

Viewed by 902

Abstract

This study investigates the effects of phosphoric acid (H₃PO₄), potassium dihydrogen phosphate (KH₂PO₄) and sodium dihydrogen phosphate (NaH₂PO₄) admixtures on the setting time, compressive strength and water resistance of magnesium oxychloride [...] Read more.

This study investigates the effects of phosphoric acid (H₃PO₄), potassium dihydrogen phosphate (KH₂PO₄) and sodium dihydrogen phosphate (NaH₂PO₄) admixtures on the setting time, compressive strength and water resistance of magnesium oxychloride cement (MOC). MOC samples incorporating different admixtures are prepared, and their hydration products and microstructures are studied via X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicate that the addition of H₃PO₄, KH₂PO₄ and NaH₂PO₄ reduces the initial and final setting times and decreases the compressive strength. However, the compressive strength of MOC is higher than 30.00 MPa with the addition of 2.0 wt.% phosphoric acid and its phosphate after 14 days of air curing. The water resistance of modified MOC slurries is significantly improved. The softening coefficient of MOC with 2.0 wt.% H₃PO₄ is 1.2 after 14 days of water immersion, which is 3.44 times higher than that of the neat MOC. The enhancement in water resistance is attributed to the formation of amorphous gel facilitated by H₃PO₄, KH₂PO₄ and NaH₂PO₄. Furthermore, the improvement in water resistance is manifested as H₃PO₄ > KH₂PO₄ > NaH₂PO₄. Full article

(This article belongs to the Special Issue Advance in Sustainable Construction Materials, Second Volume)

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23 pages, 15414 KiB

Open AccessArticle

Research on Vault Settlement during Three-Step Tunnel Construction Process Based on Sandstone Rheological Experiment

by Chang Peng, Yong Qu, Helin Fu, Chengda Xie and Guiqian Cao

Materials 2024, 17(18), 4619; https://doi.org/10.3390/ma17184619 - 20 Sep 2024

Viewed by 716

Abstract

Tunnel stability is influenced by the rheological properties of the surrounding rock. This study, based on the Ganshen high-speed railway tunnel project, examines the rheological characteristics of siltstone and sandstone through laboratory tests and theoretical analysis. Rheological curves and parameters are derived, revealing [...] Read more.

Tunnel stability is influenced by the rheological properties of the surrounding rock. This study, based on the Ganshen high-speed railway tunnel project, examines the rheological characteristics of siltstone and sandstone through laboratory tests and theoretical analysis. Rheological curves and parameters are derived, revealing the time-dependent deformation mechanisms of the surrounding rocks. A numerical simulation model is created using these parameters to analyze deformation and stress characteristics based on different rock levels and inverted arch closure distances. Results indicate that sandstone follows the Cvisc model, with the Maxwell elastic modulus increasing under higher loads while the viscous coefficient decreases. The vault displacement is mainly affected by the surrounding rock strength; lower strength leads to greater displacement, which also increases with the closure distance of the inverted arch. These findings are crucial for determining the optimal closure distance of inverted arches in sandstone conditions. Full article

(This article belongs to the Special Issue Advance in Sustainable Construction Materials, Second Volume)

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22 pages, 4167 KiB

Open AccessArticle

Evaluating the Role of Mortar Composition on the Cyclic Behavior of Unreinforced Masonry Shear Walls

by Meera Ramesh, Rafael Ramirez, Miguel Azenha and Paulo B. Lourenço

Materials 2024, 17(18), 4443; https://doi.org/10.3390/ma17184443 - 10 Sep 2024

Viewed by 1051

Abstract

The mechanical behavior of unreinforced masonry (URM) shear walls under in-plane cyclic loading is crucial for assessing their seismic performance. Although masonry structures have been extensively studied, the specific influence of varying lime content in cement-lime mortars on the cyclic behavior of URM [...] Read more.

The mechanical behavior of unreinforced masonry (URM) shear walls under in-plane cyclic loading is crucial for assessing their seismic performance. Although masonry structures have been extensively studied, the specific influence of varying lime content in cement-lime mortars on the cyclic behavior of URM walls has not been adequately explored. This study addresses this gap by experimentally evaluating the effects of three mortar mixes with increasing lime content, 1:0:5, 1:1:6, and 1:2:9 (cement:lime:sand, by volume), on the cyclic performance of brick URM walls. Nine single-leaf wall specimens 900 mm × 900 mm were constructed and subjected to combined vertical compression and horizontal cyclic loading. Key parameters such as drift capacity, stiffness degradation, and energy dissipation were measured. The results indicated that the inclusion of lime leads to a moderate improvement in drift capacity and ductility of the walls, with the 1:1:6 mix showing the highest lateral capacity (0.55 MPa), drift at cracking (0.08%), and drift at peak capacity (0.31%). Stiffness degradation and energy dissipation were found to be comparable across all mortar types. These findings suggest that partial substitution of cement with lime can enhance certain aspects of masonry performance. Further research is recommended to optimize mortar compositions for unreinforced masonry applications. Full article

(This article belongs to the Special Issue Advance in Sustainable Construction Materials, Second Volume)

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14 pages, 7057 KiB

Open AccessArticle

Auto-Combustion of Corn Straw: Production and Characterization of Corn Straw Ash (CSA) for Its Use in Portland Cement Mortars

by Jordi Payá, Alejandro Escalera, María Victoria Borrachero, Josefa Roselló, José Monzó and Lourdes Soriano

Materials 2024, 17(17), 4374; https://doi.org/10.3390/ma17174374 - 4 Sep 2024

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Abstract

Agricultural waste availability implies the possibility of recovering energy as biomass. The collateral effect is the production of ashes that, in some cases, have the potential to be reused in the manufacture of cement, mortar, and concrete. This article presents the study of [...] Read more.

Agricultural waste availability implies the possibility of recovering energy as biomass. The collateral effect is the production of ashes that, in some cases, have the potential to be reused in the manufacture of cement, mortar, and concrete. This article presents the study of the auto-combustion (unlike all previous studies) of corn (maize) straw (stems and leaves). The auto-combustion temperature was monitored, and the obtained corn straw ash (CSA) was characterized by means of X-ray fluorescence, X-ray diffraction, thermogravimetry, and scanning electron microscopy. Finally, the behavior of ground CSA was analyzed in both the fresh state by measurement of workability on the spreading table and the hardened state by compressive strength measurement on mortars in which 10% of ordinary Portland cement (OPC) was replaced with CSA. These values were compared to both a control mortar (OPC) and a mortar in which OPC was partially replaced with 10% limestone filler. Ashes showed adequate pozzolanic reactivity because, at 90 curing days, the compressive strength of the mortars with 10% replacement of OPC with CSA was practically equal (98% of the strength) to the control mortar without pozzolan replacement. The auto-combustion of biomass is a process that can be easily available, and the results on pozzolanic reactivity of CSA are satisfactory. The auto-combustion could be used by low-income communities to reduce Portland cement clinker use and to recover waste. Full article

(This article belongs to the Special Issue Advance in Sustainable Construction Materials, Second Volume)

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18 pages, 6122 KiB

Open AccessArticle

Durability of Magnesium Potassium Phosphate Cements (MKPCs) under Chemical Attack

by Salma Chhaiba, Sergio Martinez-Sanchez, Nuria Husillos-Rodriguez, Ángel Palomo, Hajime Kinoshita and Inés Garcia-Lodeiro

Materials 2024, 17(17), 4252; https://doi.org/10.3390/ma17174252 - 28 Aug 2024

Cited by 3 | Viewed by 1539

Abstract

Magnesium phosphate cements (MPCs), also known as chemically bonded ceramics, represent a class of inorganic cements that have garnered considerable interest in recent years for their exceptional properties and diverse applications in the construction and engineering sectors. However, the development of these cements [...] Read more.

Magnesium phosphate cements (MPCs), also known as chemically bonded ceramics, represent a class of inorganic cements that have garnered considerable interest in recent years for their exceptional properties and diverse applications in the construction and engineering sectors. However, the development of these cements is relatively recent (they emerged at the beginning of the 20th century), so there are still certain aspects relating to their durability that need to be evaluated. The present work analyses the chemical durability of magnesium potassium phosphate cements (MKPCs) during 1 year of immersion in three leaching media: seawater, a Na₂SO₄ solution (4% by mass) and deionized water. For this, pastes of prismatic specimens of MKPC, prepared with different M/P ratio (2 and 3), were submitted to the different chemical attacks. At different ages, the changes on the mechanical strengths, microstructure (BSEM, MIP) and mineralogy (XRD, FTIR, TG/DTG) were evaluated. The results obtained indicate that, in general terms, MKPC systems show good behavior in the three media, with the more resistant system being the one prepared with a M/P molar ratio of 3. Full article

(This article belongs to the Special Issue Advance in Sustainable Construction Materials, Second Volume)

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12 pages, 4989 KiB

Open AccessArticle

Experimental Study on Influence of Lime on Cross-Scale Characteristics of Cemented Backfill with Multiple Solid Wastes

by Xiaosheng Liu, Weijun Wang and Zhengwei Han

Materials 2024, 17(16), 4090; https://doi.org/10.3390/ma17164090 - 17 Aug 2024

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Abstract

The utilization of industrial solid waste in mines is an important approach to resource utilization. The backfill material in mines is mainly composed of solid waste, which plays a supporting role. The excitation effect of lime on phosphogypsum and fly ash in backfill [...] Read more.

The utilization of industrial solid waste in mines is an important approach to resource utilization. The backfill material in mines is mainly composed of solid waste, which plays a supporting role. The excitation effect of lime on phosphogypsum and fly ash in backfill was studied in this paper. The macroscopic and microscopic characteristics of the backfill material were tested using uniaxial compression, nuclear magnetic resonance, scanning electron microscopy, and electrochemical techniques, and a relationship model was established between them. Furthermore, the influence of industrial solid waste on the properties of the backfill material under the action of lime and the hydration mechanism between different industrial solid wastes were studied. The results show that (1) under the action of lime, fly ash reacts with lime to produce C-S-H and C-A-H, and then C-A-H reacts with phosphogypsum to produce AFt. (2) The excess phosphogypsum also fills the pores. Therefore, 1.8% lime reduces the porosity of the backfill by 17.88% and increases the strength by 21.57%. (3) The cross-scale relationship shows that strength is inversely proportional to each type of pore content and fractal dimension, and it logarithmically increases with impedance at different frequencies. The lower the frequency, the stronger the relationship is. (4) This study indicates that industrial solid waste is a suitable cement replacement. Full article

(This article belongs to the Special Issue Advance in Sustainable Construction Materials, Second Volume)

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19 pages, 8375 KiB

Open AccessArticle

Enhancing Hydraulic Lime Mortar with Metakaolin: A Study on Improving Restoration Materials for Historic Buildings

by Xiaolong Wang, Huaishuai Shang, Junhao Zhou, Lilong Gu, Zhenhao Xiao, Xiaoqin Wang and Ruiping Wang

Materials 2024, 17(14), 3548; https://doi.org/10.3390/ma17143548 - 18 Jul 2024

Cited by 6 | Viewed by 1458

Abstract

This study investigates the enhancement of hydraulic lime mortar (HLM) using varying contents of metakaolin (MK) to improve its application in the restoration of historic buildings. Samples from historic structures were analyzed, and the effects of different MK contents on the physical and [...] Read more.

This study investigates the enhancement of hydraulic lime mortar (HLM) using varying contents of metakaolin (MK) to improve its application in the restoration of historic buildings. Samples from historic structures were analyzed, and the effects of different MK contents on the physical and mechanical properties of HLM were examined. The reaction mechanism and microstructural changes were evaluated using XRD and SEM analysis. The results indicated that increasing MK levels in HLM led to a decrease in fluidity, with fluidity reducing by 4.8% at 12% MK. The addition of MK increased water consumption for standard consistency by 5.4% and shortened the final setting time by 10.2%. MK consumption promoted secondary hydration, enhancing compressive strength by up to 98.1% and flexural strength by up to 55.1%, and increasing bonding strength by 26.9%. The density of HLM improved with MK addition, slightly reducing moisture content by 4.5% and water absorption by 4.6%, while the water vapor transmission properties decreased by 50.9%, indicating reduced porosity. The elastic modulus of the mortar increased significantly from 2.19 GPa to 7.88 GPa with the addition of MK, enhancing rigidity and crack resistance. The optimal blend for restoration materials was found to be 9.0% MK and 25.0% heavy calcium carbonate and was characterized by moderate mechanical strength, enhanced early strength, commendable permeability, minimal risk of cracking, and ease of application. This blend is highly suitable for the rehabilitation of historic structures. Full article

(This article belongs to the Special Issue Advance in Sustainable Construction Materials, Second Volume)

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22 pages, 3067 KiB

Open AccessArticle

Preparation and Performance Study of Rapid Repair Epoxy Concrete for Bridge Deck Pavement

by Linhao Sun, Xinling Hao, Jilei He, Yingchun Cai, Pan Guo and Qingwen Ma

Materials 2024, 17(11), 2674; https://doi.org/10.3390/ma17112674 - 1 Jun 2024

Cited by 5 | Viewed by 1037

Abstract

With the rapid development of bridge construction, the service life of bridges and traffic volume continue to increase, leading to the gradual appearance of diseases such as potholes and cracks in bridge deck pavements under repeated external loads. These issues severely impact the [...] Read more.

With the rapid development of bridge construction, the service life of bridges and traffic volume continue to increase, leading to the gradual appearance of diseases such as potholes and cracks in bridge deck pavements under repeated external loads. These issues severely impact the safety and service life of bridges. The repair of bridge deck potholes and cracks is crucial for ensuring the integrity and safety of bridge structures. Rapid repair materials designed for this purpose play a critical role in effectively and efficiently addressing these issues. In order to address the issues of pavement diseases, this study focuses on the rapid repair of epoxy concrete for bridge deck pavements and its performance is studied using experimental methods. Firstly, carbon black, rubber powder, and other materials were used to improve the elastic modulus and aging resistance of the epoxy concrete. Secondly, the addition of solid asphalt particles provided thermal sensitivity to the repair material. Finally, various properties of the rapid repair epoxy concrete for bridge deck pavements were tested through experiments including compressive strength testing, elastic modulus measurement, thermal sensitivity testing, and anti-UV aging testing. The experimental results show that adding carbon black and rubber powder reduces the elastic modulus of epoxy concrete by 25% compared to normal epoxy concrete, while increasing its aging resistance by 1.8%. The inclusion of solid asphalt particles provided thermal sensitivity to the repair material, contributing to better stress coordination between the repair material and the original pavement material under different temperature conditions. The epoxy concrete has early strength, toughness, and anti-aging properties, making it suitable for rapid repair of bridge deck pavement. Full article

(This article belongs to the Special Issue Advance in Sustainable Construction Materials, Second Volume)

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Review

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19 pages, 4950 KiB

Open AccessReview

Use of Biomass Bottom Ash as an Alternative Solution to Natural Aggregates in Concrete Applications: A Review

by Florian Schlupp, Jonathan Page, Chafika Djelal and Laurent Libessart

Materials 2024, 17(18), 4504; https://doi.org/10.3390/ma17184504 - 13 Sep 2024

Cited by 1 | Viewed by 1542

Abstract

Biomass bottom ash (BBA) is a by-product of the energy industry and is produced from biomass-fired thermal power plants. They represent the coarsest fraction of the recovered ash and are mostly landfilled. Several researchers have investigated the feasibility of the use of BBA [...] Read more.

Biomass bottom ash (BBA) is a by-product of the energy industry and is produced from biomass-fired thermal power plants. They represent the coarsest fraction of the recovered ash and are mostly landfilled. Several researchers have investigated the feasibility of the use of BBA as a replacement for natural aggregates in cementitious material. The utilisation of BBA in the manufacturing of concrete provides an economic and ecological way to upcycle it. At the same time, its use conserves natural resources and promotes sustainability. This review article first presents the chemical, mineralogical and physical properties of BBA, to highlight the possible effects on cementitious materials and the interest in valorising them as a building material. Secondly, the focus is on the utilisation of BBA incorporated in place of natural aggregates used in the manufacturing of concrete. This review investigates the multi-physical properties of concrete manufactured with the partial incorporation of BBA. This substitution leads to decreased workability, which can be limited by the use of admixtures. In the hardened state, a reduction in the mechanical properties is shown with BBA replacement. However, many experimental works show that BBA can be used in appropriate proportions to maintain the specified properties of the concrete. Full article

(This article belongs to the Special Issue Advance in Sustainable Construction Materials, Second Volume)

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