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13 pages, 4273 KiB

Open AccessArticle

Production of a Wood–Plastic Composite with Wastes from Disposable Masks and Corrugated Cardboard: A Sustainable Post-Pandemic Approach

by Anderson Ravik dos Santos, Rivelino Neri Silva, Nayara Mendes dos Santos, Mariana Fernandes Costa Vieira, Patrícia Santiago de Oliveira Patrício and Wanna Carvalho Fontes

Sustainability 2024, 16(22), 9726; https://doi.org/10.3390/su16229726 - 8 Nov 2024

Viewed by 1084

Abstract

The increasing demand for disposable textile products, personal care items, and electronic commerce has led to a substantial rise in waste generation, particularly from nonwoven fabric masks (wNWFs) and corrugated cardboard (wCC). This study assessed the feasibility of utilizing these waste materials, which were produced in significant amounts during the COVID-19 pandemic, as both a matrix and reinforcement filler in wood–plastic composites (WPCs). The WPC was fabricated using either two extrusion cycles or thermokinetic homogenization, with both processes being followed by hot pressing. The formulations consisted of virgin polypropylene (vPP), wNWF, and wCC in proportions of 45, 45, and 10 wt %, respectively. The results demonstrated that the composites produced via two extrusion cycles exhibited a tensile strength that was 85% higher and three-point flexural strength three times greater than those produced through thermokinetic homogenization. These findings contribute to advancements in scientific and technological knowledge and offer an efficient solution for managing these types of waste, which continue to be generated post-pandemic. Full article

(This article belongs to the Topic Sustainable Building Materials)

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16 pages, 20185 KiB

Open AccessArticle

Study on the Improvement Performance of Different Clay Components with Desulfurization Gypsum-Containing Cementitious Material

by Tingzhu Chen, Xin Dong, Hongxu Chen, Feng Zhou, Gang Liu, Wei Chang and Rui Zhu

Buildings 2024, 14(10), 3274; https://doi.org/10.3390/buildings14103274 - 16 Oct 2024

Viewed by 647

Abstract

The use of cementitious materials to improve clay is a common technique in engineering. However, the effectiveness of these materials, particularly desulfurized gypsum, on clays with different mineral compositions remains unclear, resulting in a lack of theoretical basis for their application in engineering. This study investigated the synergistic effects of clinker–metakaolin–desulfurized gypsum on clays with various mineral compositions through a series of macroscopic and microscopic laboratory tests. The results revealed that the stress–strain relationships of all clay samples exhibited softening characteristics. The softening was most pronounced in kaolinite samples, followed by illite and bentonite samples. For single-phase clays, the unconfined compressive strength followed the order of kaolinite > illite > bentonite. For multiphase clays, the order was illite + kaolinite > bentonite + illite + kaolinite > bentonite + kaolinite > bentonite + illite. The strength enhancement in the improved soils was primarily due to kaolinite and illite. As the content of desulfurized gypsum increased, the ettringite crystals in the improved soils transformed from cluster-like to framework-like structures. When the gypsum content exceeded 10%, the macroscopic performance of the improved soils decreased. These findings provide valuable insights for related engineering applications. Full article

(This article belongs to the Topic Sustainable Building Materials)

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13 pages, 5331 KiB

Open AccessArticle

Alkali Activation of Metakaolin and Wollastonite: Reducing Sodium Hydroxide Use and Enhancing Gel Formation through Carbonation

by Veronica Viola, Prince Allah, Priyadharshini Perumal and Michelina Catauro

Materials 2024, 17(19), 4910; https://doi.org/10.3390/ma17194910 - 8 Oct 2024

Viewed by 687

Abstract

Alkali activated materials (AAMs) offer significant advantages over traditional materials like Portland cement, but require the use of strong alkaline solutions, which can have negative environmental impacts. This study investigates the synthesis of AAMs using metakaolin and wollastonite, aiming to reduce environmental impact by eliminating sodium silicate and using only sodium hydroxide as an activator. The hypothesis is that wollastonite can provide the necessary silicon for the reaction, with calcium from wollastonite potentially balancing the negative charges usually countered by sodium in the alkaline solution. This study compares raw and carbonated wollastonite (AAM-W and AAM-CW) systems, with raw materials carefully characterized and binding networks analyzed using TGA, FT-IR, and XRD. The results show that while wollastonite can reduce the amount of sodium hydroxide needed, this reduction cannot exceed 50%, as higher substitution levels lead to an insufficiently alkaline environment for the reactions. The carbonation of wollastonite enhances the availability of silicon and calcium, promoting the formation of both N-A-S-H and C-A-S-H gels. Full article

(This article belongs to the Topic Sustainable Building Materials)

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13 pages, 7221 KiB

Open AccessArticle

Investigation of the Temperature and Horizontal Freezing Force of Loess in Three-Dimensional Freezing

by Yidan Yin, Fei Liu, Dongqi Tang, Longze Chen and Binbin Yang

Materials 2024, 17(18), 4614; https://doi.org/10.3390/ma17184614 - 20 Sep 2024

Viewed by 566

Abstract

Seasonal frozen soil has significant impacts on changes in soil mechanical properties, settlement, and damage to foundations. In order to study variations in the temperature and horizontal freezing force of loess during three-dimensional freezing, a three-dimensional freezing model test of loess was carried out. This experiment analyzed and studied the soil temperature change distribution characteristics, horizontal freezing force distribution rules, and water migration phenomena caused by temperature. The research results show that the temperature change in soil samples exhibits a “ring-like” decrease from the outside to the inside. When the soil temperature reaches the supercooling point, the cooling curve jumps and rises, and this is accompanied by a stable section with constant temperature. In the late freezing period, the temperature rate drops slowly. Under the action of freezing, the horizontal freezing forces at different positions have similar change characteristics and can be divided into four change stages: stable stage, rapid freezing stage, “secondary” freezing stage, and freezing–shrinkage–rebound stable stage. At lower moisture contents, loess samples undergo freeze–thaw shrinkage during the freezing process. During the rapid freezing stage of soil samples, the water in the soil sample migrates and causes secondary freezing. After the rapid freezing stage, the soil temperature continues to decrease, and the horizontal freezing force no longer decreases. Full article

(This article belongs to the Topic Sustainable Building Materials)

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18 pages, 12388 KiB

Open AccessArticle

Factors Affecting the Physical Properties of Microbial Induced Calcium Carbonate Precipitation (MICP) Enhanced Recycled Aggregates

by Jin Zhang, Cong Wang and Zhipeng Wang

Buildings 2024, 14(9), 2851; https://doi.org/10.3390/buildings14092851 - 10 Sep 2024

Viewed by 951

Abstract

Microbial-induced calcium carbonate precipitation (MICP) can enhance the physical properties of recycled aggregates. Compared to traditional technologies, MICP offers environmental benefits and produces no pollution. However, its mineralization efficacy is significantly influenced by the process parameters. To investigate this, an MICP mineralization test was conducted by manipulating various process parameters throughout the mineralization process. The water absorption rate, apparent density, and calcium carbonate content of the mineralized recycled aggregates were assessed to discern the impact of these parameters on the mineralization outcome. Further analysis using techniques such as thermogravimetric analysis (TG), X-ray diffraction (XRD), nuclear magnetic resonance (NMR), and scanning electron microscopy (SEM) were employed to elucidate the mineralization mechanism of the recycled aggregates at a micro-level. The findings indicated that the MICP treatment induced bacteria to precipitate CaCO₃, forming calcite crystalline CaCO₃ within the pores and microcracks. This led to a denser interfacial transition zone and, consequently, improved the physical properties of the recycled aggregates. Optimal mineralization was achieved when the bacterial solution concentration was 1.4, the temperature and pH were 35 °C and 9, respectively, and the urea concentration, Ca⁺ concentration, and mineralization time were 0.5 mol/L, 0.5 mol/L, and 7 days, respectively. Under these conditions, the mineralized recycled aggregate exhibited a 16.07% reduction in water absorption, a 1.07% increase in apparent density, and a 2.28% change in mass. Full article

(This article belongs to the Topic Sustainable Building Materials)

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13 pages, 9941 KiB

Open AccessArticle

Non-Destructive Monitoring of Hydration Characteristics in Alternative Materials and Seawater-Based Cementitious Pastes Using Electrochemical Impedance Spectroscopy

by Fangsheng Gao, Lei Cheng, Jun Liu and Jihua Zhu

Sustainability 2024, 16(17), 7368; https://doi.org/10.3390/su16177368 - 27 Aug 2024

Viewed by 658

Abstract

This study investigates the hydration behavior of cementitious materials incorporating fly ash, limestone and calcined clay (LC2), and seawater, aiming to understand the individual and synergistic effects of these components on hydration kinetics. The motivation behind this research lies in the growing interest in enhancing the performance and sustainability of cement-based materials by incorporating supplementary materials and utilizing seawater. To achieve this, the hydration process was meticulously examined using electrochemical impedance spectroscopy (EIS). An innovative equivalent circuit model was developed to analyze the results. The experimental data indicated that, with ongoing hydration, the diameter of the impedance arc in the high-frequency range gradually increases. A noteworthy observation is that increasing the proportion of fly ash and LC2 in the cement paste leads to a corresponding enlargement of the high-frequency arc, indicating a significant influence of these supplementary materials on the hydration process. Additionally, LC2 was found to be more effective in accelerating the hydration process compared to fly ash. Full article

(This article belongs to the Topic Sustainable Building Materials)

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17 pages, 13539 KiB

Open AccessArticle

Investigation of the Impact of Geotextile Incorporation on the Mechanical Properties of Geopolymer

by Wei Zhou, Xiujie Zhang, Hongzhong Li, Rongtao Yan, Xianlun Huang, Jianjun Gan, Jinping Zhang, Xiaoyong Cheng, Junhong Yuan and Bingxiang Yuan

Buildings 2024, 14(9), 2595; https://doi.org/10.3390/buildings14092595 - 23 Aug 2024

Viewed by 654

Abstract

Geopolymers assume an irreplaceable position in the engineering field on account of their numerous merits, such as durability and high temperature resistance. Nevertheless, geopolymers also demonstrate brittleness. In this study, geotextiles with different layers were added to geopolymer to study its compressive strength and stability. Laboratory materials such as alkali activators, geotextiles and granite residual soil (GRS) were utilized. The samples were characterized via XRD, TG-DTG, SEM-EDS and FT-IR. The results indicate that the toughness of geopolymer is significantly enhanced by adding geotextiles, and the strength increase is most obvious when adding one layer of geotextile: the strength increased from 2.57 Mpa to 3.26 Mpa on the 14th day, an increase of 27%. Additionally, the D-W cycle has a great influence on geotextile polymers. On the 14th day, the average strength of the D-W cyclic sample (1.935 Mpa) was 1.305 Mpa smaller than that of the naturally cured sample (3.24 Mpa), and the strength decreased by 40%. These discoveries offer a novel approach for further promoting the application of geopolymers, especially in the field of foundation reinforcement. Full article

(This article belongs to the Topic Sustainable Building Materials)

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16 pages, 8344 KiB

Open AccessArticle

Deformation Effects of Deep Foundation Pit Excavation on Retaining Structures and Adjacent Subway Stations

by Zhijian Jiang, Shu Zhu, Xiangcheng Que and Xinliang Ge

Buildings 2024, 14(8), 2521; https://doi.org/10.3390/buildings14082521 - 15 Aug 2024

Cited by 2 | Viewed by 920

Abstract

In complex underground conditions, the excavation of deep foundation pits has a significant impact on the deformation of retaining structures and nearby subway stations. To investigate the influence of deep excavation on the deformation of adjacent structures, a three-dimensional numerical model of the foundation pit, existing subway station, and tunnel structure was established using FLAC 3D software, based on the Shenzhen Bay Super Headquarters C Tower foundation pit project. The study analyzed the deformation characteristics of retaining structures, adjacent subway stations, and tunnels during different stages of deep excavation, and the accuracy of the numerical simulation results was validated through field monitoring data. The results indicate that during the excavation process of the foundation pit, the lateral horizontal displacement of the retaining structure is generally small, with a typical “concave inward” lateral deformation curve; the horizontal displacement value of the contiguous wall section is less than that of the interlocking pile section. The bending moments of the retaining structure show a distribution pattern with larger values in the middle and smaller values at the top and bottom of the pit, with a relatively uniform distribution of internal support forces. The maximum displacement of the nearby subway station is 8.75 mm, and the maximum displacement of the subway tunnel is 2.29 mm. The research findings can provide references for evaluating the impact of newly built foundation pits near subway stations and contribute to the rational design and safe construction of new projects. Full article

(This article belongs to the Topic Sustainable Building Materials)

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Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Buildings buildings	3.1	3.4	2011	17.2 Days	CHF 2600	Submit
Materials materials	3.1	5.8	2008	15.5 Days	CHF 2600	Submit
Recycling recycling	4.6	6.8	2016	22.7 Days	CHF 1800	Submit
Sustainability sustainability	3.3	6.8	2009	20 Days	CHF 2400	Submit

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