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Keywords = bio-composite mortar

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17 pages, 6527 KB  
Article
Mechanical Properties of Bio-Printed Mortars with Bio-Additives for Green and Sustainable Construction
by Sotirios Pemas, Dimitrios Baliakas, Eleftheria Maria Pechlivani and Maria Stefanidou
Materials 2025, 18(14), 3375; https://doi.org/10.3390/ma18143375 - 18 Jul 2025
Cited by 1 | Viewed by 643
Abstract
Additive manufacturing (AM) has brought significant breakthroughs to the construction sector, such as the ability to fabricate complex geometries, enhance efficiency, and reduce both material usage and construction waste. However, several challenges must still be addressed to fully transition from conventional construction practices [...] Read more.
Additive manufacturing (AM) has brought significant breakthroughs to the construction sector, such as the ability to fabricate complex geometries, enhance efficiency, and reduce both material usage and construction waste. However, several challenges must still be addressed to fully transition from conventional construction practices to innovative and sustainable green alternatives. This study investigates the use of non-cementitious traditional mixtures for green construction applications through 3D printing using Liquid Deposition Modeling (LDM) technology. To explore the development of mixtures with enhanced physical and mechanical properties, natural pine and cypress wood shavings were added in varying proportions (1%, 3%, and 5%) as sustainable additives. The aim of this study is twofold: first, to demonstrate the printability of these eco-friendly mortars that can be used for conservation purposes and overcome the challenges of incorporating bio-products in 3D printing; and second, to develop sustainable composites that align with the objectives of the European Green Deal, offering low-emission construction solutions. The proposed mortars use hydrated lime and natural pozzolan as binders, river sand as an aggregate, and a polycarboxylate superplasticizer. While most studies with bio-products focus on traditional methods, this research provides proof of concept for their use in 3D printing. The study results indicate that, at low percentages, both additives had minimal effect on the physical and mechanical properties of the tested mortars, whereas higher percentages led to progressively more significant deterioration. Additionally, compared to molded specimens, the 3D-printed mortars exhibited slightly reduced mechanical strength and increased porosity, attributable to insufficient compaction during the printing process. Full article
(This article belongs to the Special Issue Eco-Friendly Materials for Sustainable Buildings)
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15 pages, 6274 KB  
Article
New Refined Experimental Analysis of Fungal Growth in Degraded Bio-Based Materials
by Dmytro Kosiachevskyi, Kamilia Abahri, Isabelle Trinsoutrot-Gattin, Lisa Castel, Anne Daubresse, Mohend Chaouche and Rachid Bennacer
Processes 2024, 12(10), 2188; https://doi.org/10.3390/pr12102188 - 9 Oct 2024
Viewed by 1196
Abstract
When exposed to different building environmental conditions, bio-composite materials, such as hemp mortars, represent a risk of mold proliferation. This later plays a critical role in the biodeterioration of the materials when their physical properties are locally modified by the natural aging process. [...] Read more.
When exposed to different building environmental conditions, bio-composite materials, such as hemp mortars, represent a risk of mold proliferation. This later plays a critical role in the biodeterioration of the materials when their physical properties are locally modified by the natural aging process. The primary objectives of the present work are first to assess the evolution of the surface of contaminated mortar; second, to investigate an accurate DNA extraction method that could be used for both bio-composite mortars and their fiber sources collected in situ; then, to understand the process of the proliferation of mold strains on both hemp shives and hemp mortar; and finally, to compare mold strains present in these phases to show their relationship to mold contamination and their impact on human health. In situ hemp mortar contamination behavior was investigated in the region of Pau (France) two months after hemp mortar application in extreme conditions (high humidity, low temperature, no aeration), which did not match the standard conditions under which hemp mortar must be used. The SEM observations and FTIR and pH analyses highlighted the decrease in pH level and the presence of organic matter on the mortar surface. DNA sequencing results showed that hemp shives were the main source of fungal contamination of hemp mortar. A mold population analysis showed that the most dominant phylum was Ophistokonta, which represented 83.6% in hemp shives and 99.97% in hemp mortar. The Acrostalagmus genus representatives were the most abundant, with 42% in hemp shives and 96% in hemp mortar. The interconnection between the mold strain characteristics (particularly the ability to grow in extreme environments) and the presence of hemp mortar was emphasized. Full article
(This article belongs to the Topic Advances in Sustainable Materials and Products)
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20 pages, 5830 KB  
Article
Influence of Accelerated Carbonation on the Physico-Mechanical Properties of Natural Fiber-Reinforced Lime Mortars
by Fotini Kesikidou, Ioanna Matamadiotou and Maria Stefanidou
Materials 2024, 17(18), 4461; https://doi.org/10.3390/ma17184461 - 11 Sep 2024
Cited by 2 | Viewed by 1695
Abstract
Lime mortars are considered the most compatible material for monuments and historic buildings, and they are widely used in restoration works. A key factor determining the mechanical and physical properties of lime mortars is carbonation, which provides strength and hardness. This paper indicates [...] Read more.
Lime mortars are considered the most compatible material for monuments and historic buildings, and they are widely used in restoration works. A key factor determining the mechanical and physical properties of lime mortars is carbonation, which provides strength and hardness. This paper indicates the properties gained in lime mortars produced by Ca(OH)2 and CaO reinforced with different bio-fibers (hemp and lavender) when exposed to the natural environment and in accelerated carbonation. At 90 and 180 days of manufacture, the mechanical and physical properties of the produced composites have been tested. The results show that the carbonation reaction works faster in the case of hot lime mortars, increasing their compressive strength by up to 3.5 times. Hemp-reinforced mortars led to an enhancement in strength by up to 30%, highlighting the significance of bio-fibers in facilitating CO2 diffusion. This was also verified by the thermogravimetric analysis and the determination of the carbon content of the samples. Optimal mechanical properties were observed in mixtures containing quicklime and hemp fibers when conditioned with 3% CO2 at the tested ages. Full article
(This article belongs to the Section Construction and Building Materials)
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16 pages, 2170 KB  
Article
Spent Coffee Grounds-Based Thermoplaster System to Improve Heritage Building Energy Efficiency: A Case Study in Madonie Park in Sicily
by Luisa Lombardo, Tiziana Campisi and Manfredi Saeli
Sustainability 2024, 16(15), 6625; https://doi.org/10.3390/su16156625 - 2 Aug 2024
Cited by 2 | Viewed by 1979
Abstract
This study reports on the application of an innovative plastering system that reuses organic waste, namely spent coffee grounds (SCG), to improve energy efficiency in historical buildings according to the European Green Deal. The case study was conducted in the village of Polizzi [...] Read more.
This study reports on the application of an innovative plastering system that reuses organic waste, namely spent coffee grounds (SCG), to improve energy efficiency in historical buildings according to the European Green Deal. The case study was conducted in the village of Polizzi Generosa, selected from 21 small villages located in the extensive UNESCO Geopark of Madonie Park in Sicily. Over time, traditional plasters used in Madonie buildings have shown durability issues due to thermal and hygrometric stresses caused by significant temperature fluctuations in the area. Moreover, much of the considered architectural heritage lacks energy efficiency. Given the global increase in coffee production and the need for more sustainable waste management systems, this investigation proposes an ecological method to reuse SCG in plaster formulation, thereby enhancing the circular economy. To achieve this, many thermoplaster formulations were developed, and the best-performing one, considering both material and aesthetic compatibility with historical buildings, was selected for a real-world application. Additionally, virtual modeling and energy simulations were conducted to test the energy performance of a traditional building in Polizzi Generosa using SCG-based thermoplaster in comparison to traditional lime mortar and commercial alternatives. The real-world application demonstrated the technical feasibility of the process, and the energy simulations showed an improved building masonry energy performance of 0.788 W/m2K and an 11% improvement compared to traditional plaster. Results clearly indicate that SCG can be successfully reused to produce eco-friendly bio composite plasters, providing a more sustainable housing option. This approach offers a durable and cost-effective alternative for housing solutions that meet regulatory requirements for energy efficiency, serving as a smart, highly sustainable, and long-lasting choice for the construction sector. Finally, this result supports the research goal of transforming the 21 municipalities of Madonie into smart and green villages, with the “Smart Coffee-House” exemplifying intelligent rehabilitation processes of existing heritage buildings. Full article
(This article belongs to the Special Issue Sustainability in Architecture and Engineering)
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14 pages, 3729 KB  
Article
Antifungal Susceptibility Assessment of Innovative and Non-Conventional Lime Mortars Incorporating Almond-Shell Powder Bio-Waste Subjected to Particle-Dispersion Technique
by Alexandre Jerónimo, Mafalda Loureiro, Mariana Fernandes, Verónica De Zea Bermudez and Ana Briga-Sá
Materials 2024, 17(6), 1426; https://doi.org/10.3390/ma17061426 - 20 Mar 2024
Cited by 1 | Viewed by 2391
Abstract
A favorable environment for fungi colonization in building materials’ surfaces can emerge when certain hygrothermal conditions occur. Thus, reducing fungal growth susceptibility is of major interest. Furthermore, if the integration of bio-wastes is performed in parallel with the development of innovative materials for [...] Read more.
A favorable environment for fungi colonization in building materials’ surfaces can emerge when certain hygrothermal conditions occur. Thus, reducing fungal growth susceptibility is of major interest. Furthermore, if the integration of bio-wastes is performed in parallel with the development of innovative materials for this purpose, a more sustainable and environmentally friendly material can be obtained. In this study, the fungal susceptibility of lime mortars incorporating almond-shell powder (ASP) microparticles (2 and 4%, wt.–wt. in relation to the binder content) was evaluated. The particle-dispersion technique was employed to prepare the bio-waste introduced in the mixtures. The fungal susceptibility of ASP samples was compared with nanotitania (n-TiO2) with recognized antifungal properties. Mechanical strength, water absorption, and wettability tests were also performed for a better characterization of the composites. Although the addition of 2% ASP led to mechanical properties reduction, an increase in the compressive and flexural strength resulted for 4% of the ASP content. Difficulties in fungal growth were observed for the samples incorporating ASP. No fungal development was detected in the mortar with 2% of ASP, which may be correlated with an increase in the surface hydrophobic behavior. Furthermore, mortars with ASP revealed a reduction in water absorption by capillarity ability, especially with 4% content, suggesting changes in the microstructure and pore characteristics. The results also demonstrated that an improvement in the physical and mechanical properties of the lime mortars can be achieved when ASP microparticles are previously subjected to dispersion techniques. Full article
(This article belongs to the Special Issue Trends in the Development of Building Materials with Recycled Waste)
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18 pages, 1973 KB  
Article
Granular Skeleton Optimisation and the Influence of the Cement Paste Content in Bio-Based Oyster Shell Mortar with 100% Aggregate Replacement
by Ana Cláudia Pinto Dabés Guimarães, Olivier Nouailletas, Céline Perlot and David Grégoire
Sustainability 2024, 16(6), 2297; https://doi.org/10.3390/su16062297 - 10 Mar 2024
Cited by 2 | Viewed by 2132
Abstract
The purpose of this paper is to propose a methodology to optimise the granular skeleton assembly of cementitious materials containing non-spherical aggregates. The method is general and can be applied to any granular skeleton whatever the aggregate shape, size, or composition because it [...] Read more.
The purpose of this paper is to propose a methodology to optimise the granular skeleton assembly of cementitious materials containing non-spherical aggregates. The method is general and can be applied to any granular skeleton whatever the aggregate shape, size, or composition because it is simply based on the direct minimisation of the intergranular porosity to consequently increase the skeleton’s compactness. Based on an experimental design approach, this method was applied to and validated for bio-based oyster shell (OS) mortar with 100% aggregate replacement. First, the best combination of seven crushed oyster shell particle classes was determined and compared with a standardised sand skeleton (0/4 mm) and three other non-optimised OS gradings in terms of intergranular porosity. In particular, it is shown that simply mimicking a reference grading curve initially designed for spherical particles with non-spherical particles led to poor performances. Then, different mortars were cast with the standardised sand skeleton, the optimised OS grading, and the three other non-optimised OS gradings by keeping the water-to-cement ratio (0.5), the aggregate bulk volume, and the cement paste content constant. Mechanical tests in compression confirmed the higher performance of the optimised OS mortar, validating the global optimisation approach. However, the high elongation of the oyster shell aggregates led to high skeleton intergranular porosities—even after optimisation—and the cement paste content needed to be adapted. For a given granular skeleton and for a constant aggregate bulk volume, the increase of the cement paste content led to an increase of both the filling ratio and the mechanical properties (compressive and flexural strengths). Finally, it is shown that the proposed skeleton optimisation and a cement paste content adjustment allowed recovering good mechanical properties for an oyster shell mortar with 100% aggregate replacement, especially in flexural tension. Full article
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18 pages, 3633 KB  
Article
Evaluation of Hydrothermally Treated Wood Fibre Performance in Cement Mortars
by Petrini Kampragkou, Vasiliki Kamperidou and Maria Stefanidou
Fibers 2024, 12(3), 21; https://doi.org/10.3390/fib12030021 - 26 Feb 2024
Cited by 10 | Viewed by 3165
Abstract
Biofibres’ wide application in mortar enhancement has thus far been restricted by factors related to their chemical composition and hygroscopic nature. Their hydrophilic behaviour increases the water demand of mortar mixtures and diminishes their affinity to the matrix, while further moisture-related fibre degradation [...] Read more.
Biofibres’ wide application in mortar enhancement has thus far been restricted by factors related to their chemical composition and hygroscopic nature. Their hydrophilic behaviour increases the water demand of mortar mixtures and diminishes their affinity to the matrix, while further moisture-related fibre degradation issues may arise. Additionally, natural fibres seem to be susceptible to degradation caused by exposure to alkaline environmental conditions such as those experienced by cement mortars, restricting their utilisation in the construction industry. Therefore, the current study investigates the potential of fibre modification through treatments that would permanently alter their structure and chemical composition to improve their performance. In this study, wood fibres of black pine and beech species were exposed to mild thermal treatment (140 °C 2 h, under a steam atmosphere), characterised in terms of the physical and chemical properties and incorporated in cement mortars, applying the proportion of 1.5% v/v in the mortar, in order to assess their performance as reinforcement material. The mortars’ workability (at a fresh state) was examined, as well as other physical, hygroscopic, thermal, and mechanical characteristics of the mortars at the ages of 28, 90 and 365 days and weathering performance, by subjecting them to different artificial ageing environments (freeze–thaw cycles or outdoor exposure). The results revealed the beneficial role of the treated fibres in dimensional stability, flexural strength, thermal insulation properties and capillary absorption of the mortar specimens, especially during the ageing process, with the black pine fibres showing the greatest improvement. The hydrothermally treated wood fibres seem to help maintain the integrity of cement mortars under all ageing conditions, proving that they could provide low-cost and eco-friendly mortar enhancement pathways. Full article
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23 pages, 4913 KB  
Review
A Review on Chemical and Autogenous Shrinkage of Cementitious Systems
by Hassan Ghanem, Rawan Ramadan, Jamal Khatib and Adel Elkordi
Materials 2024, 17(2), 283; https://doi.org/10.3390/ma17020283 - 5 Jan 2024
Cited by 34 | Viewed by 3597
Abstract
Chemical shrinkage (CS) is an intrinsic parameter that may affect the early age cracking of paste, mortar and concrete. It is well known as the driving force of self-desiccation, autogenous shrinkage (AGS) and drying shrinkage. During the first stage of cement hydration (at [...] Read more.
Chemical shrinkage (CS) is an intrinsic parameter that may affect the early age cracking of paste, mortar and concrete. It is well known as the driving force of self-desiccation, autogenous shrinkage (AGS) and drying shrinkage. During the first stage of cement hydration (at the initial setting time), the CS and AGS are equal. In the hardened stages, there is a difference in values between the two shrinkage parameters. This paper is a comprehensive review on CS and AGS, measurement techniques, modeling and prediction of different cementitious systems. Based on the various experimental studies, chemical shrinkage depends on the water to binder ratio (w/b) and is proportional to the degree of hydration. A low w/b ratio leads to high CS and AGS. The composition of cement has an effect on both CS and AGS. Also, incorporating supplementary cementitious materials (SCMs) affects both shrinkage parameters. It is concluded that adding fly ash (FA) to concrete contributes to CS and AGS reductions. However, this is not the case when concrete contains slag. More than 170 references were consulted including 35 which were published after 2020. According to the authors knowledge, there is no published work on the effect of fibers, especially bio-fibers, on the chemical shrinkage of cement-based composites. Therefore, in addition to traditional chemical shrinkage of cementitious systems, this review includes a section on recent papers conducted by the authors on the effect of bio-fibers on the chemical shrinkage of cement composites. Full article
(This article belongs to the Section Construction and Building Materials)
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21 pages, 9392 KB  
Article
Bio-Inspired Impregnations of Carbon Rovings for Tailored Bond Behavior in Carbon Fiber Reinforced Concrete
by Toni Utech, Tobias Neef, Viktor Mechtcherine and Christina Scheffler
Buildings 2023, 13(12), 3102; https://doi.org/10.3390/buildings13123102 - 14 Dec 2023
Cited by 3 | Viewed by 1888
Abstract
Nature provides various templates for integrating organic and inorganic materials to create high-performance composites. Biological structures such as nacre and the structural elements of the glass sponge are built up in layers, leading to remarkable fracture toughness. In this work, the brick-and-mortar and [...] Read more.
Nature provides various templates for integrating organic and inorganic materials to create high-performance composites. Biological structures such as nacre and the structural elements of the glass sponge are built up in layers, leading to remarkable fracture toughness. In this work, the brick-and-mortar and layer-by-layer structures found in these biological examples have been abstracted and implemented by using an aqueous polymer dispersion in combination with nanoclay particles and sodium water glass. These dispersions were used as impregnation of carbon rovings in order to form bio-inspired contact zones towards the concrete matrix. The bonding behavior was investigated using the Yarn Pull-Out (YPO) test, and a beneficial behavior of the layered polymer–nanoclay dispersions was observed. Thermogravimetric analysis (TGA) was used to determine the organic impregnation content of the roving. Further, light microscopy of the roving cross-sections prior to YPO and visual analyses of the fractured contact zone of split concrete specimens provided information on the quality of the impregnation and the interaction with the concrete matrix. Full article
(This article belongs to the Special Issue Research on the Performance of Non-metallic Reinforced Concrete)
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15 pages, 8663 KB  
Article
Innovative Thermal Renders Incorporating Oyster Shells for Sustainable Insulation
by Poliana Bellei, Fernanda Magalhães, Manuel Pereira, Isabel Torres, Runar Solstad and Inês Flores-Colen
Sustainability 2023, 15(22), 15952; https://doi.org/10.3390/su152215952 - 15 Nov 2023
Cited by 4 | Viewed by 3151
Abstract
In accordance with current sustainable development objectives, it is intended to implement innovative and sustainable solutions at economic, environmental, and functional levels, boosting the construction sector to increasingly contribute to society. Expanded cork is an alternative to sand aggregate in improving the thermal [...] Read more.
In accordance with current sustainable development objectives, it is intended to implement innovative and sustainable solutions at economic, environmental, and functional levels, boosting the construction sector to increasingly contribute to society. Expanded cork is an alternative to sand aggregate in improving the thermal insulating properties of renders. In addition, other materials can be incorporated as aggregates in an attempt to contribute to both the improvement of the physical characteristics that the render must fulfil as well as the improvement of thermal behaviour (if possible). In this sense, bio-based materials generated by the aquaculture sector, such as oyster shells, can contribute as a bio-based insulation material for thermal renders. In this study, thermal natural hydraulic lime mortars were produced from a mixture of expanded cork (EC) insulating aggregate and oyster shells (OSs). The percentages of replacing EC by OSs were 20, 30, 40, and 50%. The tests were carried out in fresh and hardened states. The studied mortars presented a thermal conductivity and compressive strength of 0.151 W/(m·K) and 0.63 MPa, respectively. The most interesting performance between thermal conductivity and compressive strength was for the composite with 50% of each bio-based material. The potential of incorporating oyster shells as a bio-based insulation material could contribute to a sustainable blue circular economy. Full article
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29 pages, 14324 KB  
Review
Research Progress in Preparation, Properties and Applications of Biomimetic Organic-Inorganic Composites with “Brick-and-Mortar” Structure
by Feng Liu, Hongyu Yang and Xiaming Feng
Materials 2023, 16(11), 4094; https://doi.org/10.3390/ma16114094 - 31 May 2023
Cited by 5 | Viewed by 2350
Abstract
Inspired by nature, materials scientists have been exploring and designing various biomimetic materials. Among them, composite materials with brick-and-mortar-like structure synthesized from organic and inorganic materials (BMOIs) have attracted increasing attention from scholars. These materials have the advantages of high strength, excellent flame [...] Read more.
Inspired by nature, materials scientists have been exploring and designing various biomimetic materials. Among them, composite materials with brick-and-mortar-like structure synthesized from organic and inorganic materials (BMOIs) have attracted increasing attention from scholars. These materials have the advantages of high strength, excellent flame retardancy, and good designability, which can meet the requirements of various fields for materials and have extremely high research value. Despite the increasing interest in and applications of this type of structural material, there is still a dearth of comprehensive reviews, leaving the scientific community with a limited understanding of its properties and applications. In this paper, we review the preparation, interface interaction, and research progress of BMOIs, and propose possible future development directions for this class of materials. Full article
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17 pages, 3427 KB  
Article
Recycling Mussel Shells as Secondary Sources in Green Construction Materials: A Preliminary Assessment
by Rosanna Leone, Adriana Calà, Marinélia N. Capela, Simona Colajanni, Tiziana Campisi and Manfredi Saeli
Sustainability 2023, 15(4), 3547; https://doi.org/10.3390/su15043547 - 15 Feb 2023
Cited by 16 | Viewed by 12767
Abstract
This paper reports the development of novel green bio-composite mortars obtained by reusing mussel shells, a waste from the fish canning industry, as recycled aggregate, used for the first time in total substitution to the traditional sand. It suggests that this is a [...] Read more.
This paper reports the development of novel green bio-composite mortars obtained by reusing mussel shells, a waste from the fish canning industry, as recycled aggregate, used for the first time in total substitution to the traditional sand. It suggests that this is a valid alternative to their usual disposal in landfills because the organic matter is potentially dangerous to humans and the environment. Different waste-based cementitious mixes were tested and compared to a traditional OPC mortar. The manufacturing process was performed at ambient conditions (20 °C, 65% RH) with highly sustainable results and consisted of simple operative steps reproducible in a real building site. The engineering performance was investigated to preliminarily assess the novel material potentials in construction. The main results showed that recycling mussel shells as aggregate while considerably decreasing the mechanical resistance (up to 60% in bending and 50% in compression), mixes could still find proper building applications (either structural, light partition, and plastering) according to the relevant standards. Moreover, the bulk density resulted up to 30% lower and the energy behavior was improved up to 40%, making the developed mortars highly suitable for promising energy-saving uses. Finally, the waste recycling about halves the materials cost and could also grant further financial saving for the fish industry. To conclude, the large amount of reused bio-waste not only represents a valid alternative to their usual disposal in landfills, but also makes the considered mortars suitable for building applications and promising candidates for the Minimum Environmental Criteria certification, in light of the EU Green Transition, and in line with the principles of the circular economy. Full article
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18 pages, 9821 KB  
Article
Biomineralisation to Increase Earth Infrastructure Resilience
by Ana Bras, Hazha Mohammed, Abbie Romano and Ismini Nakouti
Materials 2022, 15(7), 2490; https://doi.org/10.3390/ma15072490 - 28 Mar 2022
Cited by 8 | Viewed by 2581
Abstract
The vulnerability of buildings and structures to rain and flooding due to a lack of adaptive capacity is an issue all over the world. Exploring the bio-resources availability and engineering performance is crucial to increase infrastructure’s resilience. The current study analyses earth-based mortars [...] Read more.
The vulnerability of buildings and structures to rain and flooding due to a lack of adaptive capacity is an issue all over the world. Exploring the bio-resources availability and engineering performance is crucial to increase infrastructure’s resilience. The current study analyses earth-based mortars using mineral precipitation as a biostabiliser (bio) and compares their performance with cement-based mortars. Cultures of S. oneidensis with a concentration of 2.3 × 108 cfu/mL were used to prepare earth-based and cement-based mortars with a ratio of 6% of binder. Microstructure analyses through SEM/EDS, water absorption, moisture buffering, mechanical strength, and porosity are discussed. The biostabiliser decreases water absorption in tidal-splash and saturated environments for earth and cement mortars due to calcium carbonate precipitation. The biostabiliser can prevent water migration more effectively for the cement-based (60% reduction) than for the earth-based mortars (up to 10% reduction) in the first 1 h of contact with water. In an adsorption/desorption environment, the conditions favour desorption in cem+bio, and it seems that the biostabiliser precipitation facilitates the release of the chemicals into the mobile phase. The precipitation in the earth+bio mortar porous media conditions favours the adsorption of water molecules, making the molecule adhere to the stationary phase and be separated from the other sample chemicals. The SEM/EDS performed for the mortars confirms the calcium carbonate precipitation and shows that there is a decrease in the quantity of Si and K if the biostabiliser is used in cement and earth-mortars. This decrease, associated with the ability of S. oneidensis to leach silica, is more impressive for earth+bio, which might be associated with a dissolution of silicate structures due to the presence of more water. For the tested earth-based mortars, there was an increase of 10% for compressive and flexural strength if the biostabiliser was added. For the cement-based mortars, the strength increase was almost double that of the plain one due to the clay surface negative charge in the earth-based compositions. Full article
(This article belongs to the Special Issue Earth-Based Building Materials)
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12 pages, 5406 KB  
Article
Gypsum Mortars with Acacia dealbata Biomass Waste Additions: Effect of Different Fractions and Contents
by Alessandra Ranesi, Paulina Faria, Ricardo Correia, Maria Teresa Freire, Rosário Veiga and Margarida Gonçalves
Buildings 2022, 12(3), 339; https://doi.org/10.3390/buildings12030339 - 11 Mar 2022
Cited by 7 | Viewed by 2427
Abstract
In recent decades, interest in the eco-efficiency of building materials has led to numerous research projects focused on the replacement of raw materials with mineral and biomass wastes, and on the production of mortars with low-energy-consuming binders, such as gypsum. In this context, [...] Read more.
In recent decades, interest in the eco-efficiency of building materials has led to numerous research projects focused on the replacement of raw materials with mineral and biomass wastes, and on the production of mortars with low-energy-consuming binders, such as gypsum. In this context, five different fractions (bark, wood, branchlets, leaves, and flowers) of Acacia dealbata—an invasive species—were evaluated as fillers for premixed gypsum mortars, at 5% and 10% (vol.) addition levels and fixed water content. Although these biomass fractions had different bulk densities (>50% of variation), all the mortars were workable, although presenting different consistencies. As expected, dry density decreased with biomass addition, but, while mortars with addition at 5% presented a slight shrinkage, a slight expansion occurred with those with 10% addition. Generally, the mechanical properties decreased with the biomass additions even if this was not always proportional to the added content. The wood fraction showed the most positive mechanical results but flexural and compressive strengths of all the tested mortars were found to be higher than the lower standard limit, justifying further studies. Full article
(This article belongs to the Section Building Materials, and Repair & Renovation)
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14 pages, 41124 KB  
Article
Bamboo Sawdust as a Partial Replacement of Cement for the Production of Sustainable Cementitious Materials
by Yunyun Tong, Abdel-Okash Seibou, Mengya Li, Abdelhak Kaci and Jinjian Ye
Crystals 2021, 11(12), 1593; https://doi.org/10.3390/cryst11121593 - 20 Dec 2021
Cited by 11 | Viewed by 5931
Abstract
This paper reports on the utilization of recycled moso bamboo sawdust (BS) as a substitute in a new bio-based cementitious material. In order to improve the incompatibility between biomass and cement matrix, the study firstly investigated the effect of pretreatment methods on the [...] Read more.
This paper reports on the utilization of recycled moso bamboo sawdust (BS) as a substitute in a new bio-based cementitious material. In order to improve the incompatibility between biomass and cement matrix, the study firstly investigated the effect of pretreatment methods on the BS. Cold water, hot water, and alkaline solution were used. The SEM images and mechanical results showed that alkali-treated BS presented a more favorable bonding interface in the cementitious matrix, while both compressive and flexural strength were higher than for the other two treatments. Hence, the alkaline treatment method was adopted for additional studies on the effect of BS content on the microstructural, physical, rheological, and mechanical properties of composite mortar. Cement was replaced by alkali-treated BS at 1%, 3%, 5%, and 7% by mass in the mortar mixture. An increased proportion of BS led to a delayed cement setting and a reduction in workability, but a lighter and more porous structure compared to the conventional mortar. Meanwhile, the mechanical performance of composite decreased with BS content, while the compressive and flexural strength ranged between 14.1 and 37.8 MPa and 2.4 and 4.5 MPa, respectively, but still met the minimum strength requirements of masonry construction. The cement matrix incorporated 3% and 5% BS can be classified as load-bearing lightweight concrete. This result confirms that recycled BS can be a sustainable component to produce a lightweight and structural bio-based cementitious material. Full article
(This article belongs to the Special Issue Advances in Sustainable Concrete System)
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