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19 pages, 5882 KiB

Open AccessArticle

Analysis and Comparison of Three Bending Tests on Phosphogypsum-Based Material According to Peridynamic Theory

by Haoyu Ma, Kai Zhang, Sheng Liang, Jiatian Dong, Xiangyang Fan and Xuemei Zhang

Buildings 2024, 14(7), 2181; https://doi.org/10.3390/buildings14072181 - 15 Jul 2024

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Phosphogypsum-based materials have gained much attention in the field of road infrastructure from the economic and sustainable perspectives. The Three-point bending test, the Four-point bending test and the Semi-circular bending test are three typical test methods applied for fracture energy measurement. However, the [...] Read more.

Phosphogypsum-based materials have gained much attention in the field of road infrastructure from the economic and sustainable perspectives. The Three-point bending test, the Four-point bending test and the Semi-circular bending test are three typical test methods applied for fracture energy measurement. However, the optimal test method for fracture energy evaluation has not been determined for phosphogypsum-based materials. To contribute to the gap, this study aims to analyze and compare the three test methods for fracture energy evaluation of phosphogypsum materials based on the peridynamic theory. For this purpose, the load–displacement, vertical displacement–Crack Mouth Opening Displacement (CMOD) and fracture energy of the phosphogypsum-based materials were measured and calculated from the three test methods. The simulated load–displacement and vertical displacement–CMOD by PD numerical models, with different fracture energy as inputs, were compared to the corresponding tested values according to simulation error results. The results showed that the Four-point bending test led to minimized errors lower than 0.189 and indicators lower than 0.124, demonstrating the most optimal test method for the fracture energy measurement of phosphogypsum-based material. The results of this study can provide new methodological references for the selection of material fracture energy measurement tests. Full article

(This article belongs to the Special Issue Carbon-Neutral Infrastructure)

17 pages, 1651 KiB

Open AccessArticle

Environment Assessment of Modified Red Mud Utilized in Roadbed

by Yu Cheng, Na Jiang, Wentong Wang, Lu Jin and Shiying Yan

Buildings 2024, 14(7), 2135; https://doi.org/10.3390/buildings14072135 - 11 Jul 2024

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Abstract

Utilization of red mud in road projects is an effective way to consume large amounts of red mud on a large scale. In order to meet the requirements for road performance, a modified material, Heinchem, has been developed on the basis of extensive [...] Read more.

Utilization of red mud in road projects is an effective way to consume large amounts of red mud on a large scale. In order to meet the requirements for road performance, a modified material, Heinchem, has been developed on the basis of extensive experiments, and the long-term environmental risks of red mud modified by this material have been investigated. By collecting and modifying original red mud samples, a series of continuous leaching tank experiments are carried out based on the exposure scenario analysis. According to the leaching content of pollution in the original and modified red mud, the characteristic pollutants are identified. The release mechanism of these characteristic pollutants in the modified red mud is revealed, and the long-term release amount is predicted. Furthermore, in light of the actual road use scenario of the modified red mud, a risk assessment model is established and used to simulate the release, migration, and transformation of characteristic pollutants during the use of modified red mud as roadbed material. The groundwater environmental risk is then assessed. Finally, an acute toxicity test of earthworms and a seed germination test are conducted to investigate the impact of the modified red mud on the farmlands. The results showed that the proposed red mud modified materials have obvious curing effects on V, As, Se, Mo, and F. When the leaching contents of V, Cr⁶⁺, C^r3+, As³⁺, Se⁴⁺, Se⁶⁺, Mo, and F in the modified red mud were lower than 0.15 mg/L, 0.1 mg/L, 0.2 mg/L, 0.012 mg/L, 0.012 mg/L, 0.012 mg/L, 0.075 mg/L, and 1.2 mg/L, respectively, the environmental risk of modified red mud during long-term road use is acceptable. This study provides a new way for the resource utilization of red mud. Full article

(This article belongs to the Special Issue Carbon-Neutral Infrastructure)

21 pages, 14216 KiB

Open AccessArticle

Gypsum-Enhanced Red Mud Composites: A Study on Strength, Durability, and Leaching Characteristics

by Shiying Yan, Yu Cheng, Wentong Wang, Lu Jin and Ziyi Ding

Buildings 2024, 14(7), 1979; https://doi.org/10.3390/buildings14071979 - 1 Jul 2024

Viewed by 406

Abstract

The strong alkalinity of red mud and the heavy metals it contains pose a serious threat to the environment. This study investigated the possibility of applying red mud as a solid waste material in road construction to mitigate the problem of red mud [...] Read more.

The strong alkalinity of red mud and the heavy metals it contains pose a serious threat to the environment. This study investigated the possibility of applying red mud as a solid waste material in road construction to mitigate the problem of red mud accumulation. Red mud was modified using titanium gypsum and phosphogypsum as curing agents. The effects of varying gypsum types and mixing ratios on the mechanical properties and heavy metal leaching of the resulting red mud-based materials were assessed using percussion tests, unconfined compressive strength measurements, scanning electron microscopy (SEM), and continuous heavy metal leaching tests. The results showed that the optimal moisture content for titanium gypsum–cement-stabilized red mud (RTC) exceeds that of phosphogypsum–cement-stabilized red mud (RPC), with RTC exhibiting a lower maximum dry density compared to RPC. When the gypsum admixture was within 10%, the strength of the RPC was higher than that of the RTC at the same and curing time. The reticulation in RPC-10 was denser. The cumulative heavy metal releases from both RTC and RPC were within the permissible limits for Class III groundwater discharge standards. Based on the comprehensive test results, RPC is identified as the superior modified red mud material, with an optimal mix ratio of red mud/phosphogypsum/cement of 87:5:8. Full article

(This article belongs to the Special Issue Carbon-Neutral Infrastructure)

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17 pages, 4965 KiB

Open AccessArticle

Investigation into the Characteristics of Expansion and Compression Deformation of Interbedded Weak Expansive Rocks in Water Immersion

by Yaning Wang, Yuchen Li, Haoyu Qin, Yangui Zhu, Yibo Yao, Jin Jin, Tao Zheng, Qingting Qian and De Chen

Buildings 2024, 14(7), 1901; https://doi.org/10.3390/buildings14071901 - 21 Jun 2024

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Abstract

In order to investigate the deformation characteristics of interbedded weak expansive rocks in water immersion, the sandstone–mudstone interbedded structures were taken as the object of this study. A total of 27 sets of indoor immersion tests were designed with three influencing factors, namely, [...] Read more.

In order to investigate the deformation characteristics of interbedded weak expansive rocks in water immersion, the sandstone–mudstone interbedded structures were taken as the object of this study. A total of 27 sets of indoor immersion tests were designed with three influencing factors, namely, the layer thickness ratios of sandstone and mudstone (1:1, 2:1, 3:1), the occurrence of the rock layers (flat, oblique, and vertical), and the overburden loadings (0 kPa, 12.5 kPa, and 25 kPa). Tests were conducted to obtain the deformation time series data of the samples during the immersion loading process. Based on this, the influence pattern of each influencing factor on the sample deformation was analyzed individually. The results show that with the increase in overburden loading and rock inclination angle, the sample develops from expansion deformation to compression deformation. Changes in the layer thickness ratio will not change the deformation trend of the sample, and the decrease in the relative mudstone content will only reduce the absolute value of the sample’s expansion and compression deformation. The deformation stability rate of the sample under load is 5~7 times that under no load. The increase in layer thickness ratio and rock inclination angle will lead to different degrees of attenuation of sample expansion force in the range of 8.91~38.68% and 51.00~58.83%, respectively. The research results of this paper can provide a meaningful reference for the design and maintenance of a high-speed railway subgrade in a weak expansive rock area with an interbedded structure. Full article

(This article belongs to the Special Issue Carbon-Neutral Infrastructure)

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14 pages, 4053 KiB

Open AccessArticle

Interface Interaction of Waste Rubber–Asphalt System

by Jinfei Su, Peilong Li, Guangxin Zhu, Xiaoxu Wang and Shihao Dong

Buildings 2024, 14(6), 1868; https://doi.org/10.3390/buildings14061868 - 20 Jun 2024

Viewed by 371

Abstract

Asphalt pavement construction is a large-volume project, with the ability to recycle the industrial waste and reduce carbon emissions. Rubber-modified asphalt is a carbon-neutralized asphalt-based material, facilitating the recycling of waste rubber materials and improving the road performance of the asphalt mixture. To [...] Read more.

Asphalt pavement construction is a large-volume project, with the ability to recycle the industrial waste and reduce carbon emissions. Rubber-modified asphalt is a carbon-neutralized asphalt-based material, facilitating the recycling of waste rubber materials and improving the road performance of the asphalt mixture. To evaluate the interface interaction of the rubber–asphalt system and its effect on the viscosity characteristics of rubber-modified asphalt, the contact properties of rubber particles in asphalt were analyzed on a microscopic level. Rubber swelling tests and solvent elution tests were conducted on the rubber–asphalt system under different preparation conditions. The swelling ratio, degradation ratio, and swelling–degradation ratio were proposed to evaluate the interface interaction. The results show that the interface interaction of the rubber–asphalt system can be divided into the following three stages: swelling, effective degradation, and over-degradation. The degree of swelling is mainly affected by the content and size of the rubber particles and it is physically condensed, while the degradation is mainly affected by the preparation temperature and preparation time. The effective interface interaction greatly affects the viscosity with the building of the stable three-dimensional network structure. The stronger the interface interaction, the greater the viscosity of the rubber-modified asphalt, except for the 25% content of rubber particles. The gel film will be generated on the surface of the rubber particles throughout the swelling and effective degradation, increasing the viscosity of the rubber-modified asphalt. Full article

(This article belongs to the Special Issue Carbon-Neutral Infrastructure)

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17 pages, 4158 KiB

Open AccessArticle

Implementing All-Weather Photocatalysis of Exhaust Fumes Based on the g-C₃N₄/TiO₂/SrAl₂O₄: Eu²⁺, Dy³⁺ Ternary Composite Coating

by Bochao Zhou, Hailong Li, Ao Cui, Di Wang, Fucheng Guo and Chao Wang

Buildings 2024, 14(6), 1743; https://doi.org/10.3390/buildings14061743 - 10 Jun 2024

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Abstract

This study examines the use of SrAl₂O₄: Eu²⁺, Dy³⁺ long-afterglow materials doped into g-C₃N₄/TiO₂ coatings for photodegradation. The prepared sample was tested for the purification of automotive exhaust fumes, with the [...] Read more.

This study examines the use of SrAl₂O₄: Eu²⁺, Dy³⁺ long-afterglow materials doped into g-C₃N₄/TiO₂ coatings for photodegradation. The prepared sample was tested for the purification of automotive exhaust fumes, with the optimal mass ratio of g-C₃N₄/TiO₂ and SrAl₂O₄: Eu²⁺, Dy³⁺ determined to be 1:1. Characterization tests, including XRD, FT-IR, XPS, and TG-DSC, were conducted to evaluate the microstructure and properties of the samples. Under poor lighting conditions, g-C₃N₄/TiO₂ reduced CH and NO_x by 59 ppm and 13 ppm within 4 h, respectively, while g-C₃N₄/TiO₂/SrAl₂O₄: Eu²⁺, Dy³⁺ decreased CH and NO_x by 98ppm and 34ppm, respectively, resulting in a significant improvement in degradation efficiency. The addition of long-afterglow materials significantly improves the efficiency of photocatalysts in purifying exhaust fumes in low-light environments, providing potential value for all-weather exhaust treatment in the future. Full article

(This article belongs to the Special Issue Carbon-Neutral Infrastructure)

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17 pages, 5731 KiB

Open AccessArticle

Research on Laboratory Testing Method of Fatigue Performance of Semi-Rigid Base Considering Spatial Stress State

by Longfei Wang, Zhizhong Zhao, Hao Liang, Yilong He, Xianzhang Kang and Meng Xu

Buildings 2024, 14(2), 365; https://doi.org/10.3390/buildings14020365 - 29 Jan 2024

Viewed by 627

Abstract

In order to accurately assess the fatigue performance of semi-rigid base layers, this paper proposes a novel fatigue testing method for semi-rigid base layers that takes into account the spatial stress state. Based on this method, the fatigue performance of three types of [...] Read more.

In order to accurately assess the fatigue performance of semi-rigid base layers, this paper proposes a novel fatigue testing method for semi-rigid base layers that takes into account the spatial stress state. Based on this method, the fatigue performance of three types of reinforced semi-rigid base-layer materials (steel wire mesh, plastic geogrid, and fiberglass) was tested and compared with unreinforced materials. The fatigue strain evolution patterns of these materials were analyzed, and a fatigue strain characteristic value at the limit state was proposed as an evaluation index for the fatigue failure of base layer materials. The results showed that in terms of fatigue performance, plastic geogrid > steel wire mesh > fiberglass > unreinforced specimens. The development of tensile strain can be approximately classified into a three-stage growth pattern, consisting of “curve + straight line + curve”. For the unreinforced specimens, the three stages of bending strain accounted for 10%, 70%, and 20% of the total fatigue life, respectively. The fatigue failure stages of the three types of reinforced materials had similar proportional ranges, representing 5%, 75%, and 20% of the total fatigue life, respectively. The fatigue strain characteristic values for plastic geogrid, steel wire mesh, fiberglass, and unreinforced specimens were 371 με, 280 με, 280 με, and 195 με, respectively. In summary, the use of reinforced materials within semi-rigid base layers enhances their fatigue performance, providing new insights and methods for extending the service life of road surfaces and offering scientific guidance for the practical application of reinforced materials in semi-rigid base layer road surfaces’ fatigue performance. Full article

(This article belongs to the Special Issue Carbon-Neutral Infrastructure)

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20 pages, 4926 KiB

Open AccessArticle

An Explainable Evaluation Model for Building Thermal Comfort in China

by Haiyang Liu and Enlin Ma

Buildings 2023, 13(12), 3107; https://doi.org/10.3390/buildings13123107 - 14 Dec 2023

Cited by 1 | Viewed by 922

Abstract

The concentration of atmospheric greenhouse gases is being amplified by human activity. Building energy consumption, particularly for heating and cooling purposes, constitutes a significant proportion of overall energy demand. This research aims to establish a smart evaluation model to understand the thermal requirements [...] Read more.

The concentration of atmospheric greenhouse gases is being amplified by human activity. Building energy consumption, particularly for heating and cooling purposes, constitutes a significant proportion of overall energy demand. This research aims to establish a smart evaluation model to understand the thermal requirements of building occupants based on an open-access dataset. This model is beneficial for making reasonable adjustments to building thermal management, based on factors such as different regions and building user characteristics. Employing Bayesian-optimized LightGBM and SHAP (SHapley Additive exPlanations) methods, an explainable machine learning model was developed to evaluate the thermal comfort design of buildings in different areas and with different purpose. Our developed LightGBM model exhibited superior evaluation performance on the test set, outperforming other machine learning models, such as XGBoost and SVR (Support Vector Regression). The SHAP method further helps us to understand the interior evaluation mechanism of the model and the interactive effect among input features. An accurate thermal comfort design for buildings based on the evaluation model can benefit the carbon-neutral strategy. Full article

(This article belongs to the Special Issue Carbon-Neutral Infrastructure)

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