Study on Crack Development and Micro-Pore Mechanism of Expansive Soil Improved by Coal Gangue under Drying–Wetting Cycles

Zhu, Hua; Zhang, Yan; Li, Zhuhan; Xue, Xiaoyu

doi:10.3390/ma14216546

Cited by 17 publications

(5 citation statements)

References 40 publications

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“…Classical research about crack patterns of RC beams [ 19 , 23 , 35 , 73 , 74 , 75 , 76 ] supports the following two further assumptions ( Figure 1 ).…”

Section: Assumptions Of the Analytical Model And Further Nomenclaturementioning

confidence: 67%

Strengthening of Reinforced Concrete Beams Subjected to Concentrated Loads Using Externally Bonded Fiber Composite Materials

Foraboschi

2022

Materials

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Renovation, restoration, remodeling, refurbishment, and the retrofitting of buildings often imply applying forces (i.e., concentrated loads) to beams that before were subjected to distributed loads only. In the case of reinforced concrete structures, the new condition causes a beam to bear a concentrated load with the crack pattern that resulted from the distributed loads which had acted before. If the concentrated load is applied at or near the beam’s midspan, the new shear demand reaches the maximum where cracks are vertical or quasi-vertical, and where inclined bars are not common according to any standards. So, the actual shear capacity can be substantially lower than new shear demand due to the concentrated load. This paper focuses on reinforced concrete beams whose load distribution has to be changed from distributed to concentrated and presents a design method to bring the beam’s shear capacity up to the new demand. The method consists of applying fiber composites (fiber-reinforced polymers or fiber-reinforced cementitious material) with fibers at an angle of 45° bonded to the beam’s web. This kind of external reinforcement arrangement has to comply with some practical measures, which are presented as well. The paper also provides the analytical model that predicts the concentrated load-carrying capacity of a beam in the strengthened state. The model accounts for the crack’s verticality, which nullifies the contributions of steel stirrups, aggregate interlock, and dowel action, and for the effective bond length of each fiber, which depends on the distance between the ends of the fiber and the crack it crosses.

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“…Classical research about crack patterns of RC beams [ 19 , 23 , 35 , 73 , 74 , 75 , 76 ] supports the following two further assumptions ( Figure 1 ).…”

Section: Assumptions Of the Analytical Model And Further Nomenclaturementioning

confidence: 67%

Strengthening of Reinforced Concrete Beams Subjected to Concentrated Loads Using Externally Bonded Fiber Composite Materials

Foraboschi

2022

Materials

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“…As for the changes of expansive soil properties under the alternations of seasons, many scholars have simulated the alternating environment of dry and wet through dry-wet cycle experiments, and have combined different improved methods to treat expansive soil (Mao et al, 2018;Shahsavani et al, 2020;Zhu et al, 2021;Wu et al, 2021). Currently, the improved methods of expansive soil mainly include physical, chemical, and biotechnology methods.…”

Section: Introductionmentioning

confidence: 99%

Study on the effect of microwave irradiation improvement on the long-term stability of expansive soil

Zhang,

Hu,

et al. 2024

Preprint

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In dry-wet cycles, the clay minerals of expansive soil repeatedly hydrate and dehydrate, causing its expansion and contraction, resulting in many cracks, which will bring harm to human engineering construction. Microwave, as an efficient material improvement method, has been used in clay mineral synthesis and material manufacturing. Our previous studies have proved that microwave technology can improve the performance of soil, but the long-term stability of expansive soil by microwave has not been studied. In this paper, microwave technology is used to improve the performance of expansive soil, and the effect of microwave on the damage law and long-term stability of expansive soil under dry-wet cycles is studied. The soil was heated to 200°C, 300°C, 400°C and 500°C respectively by microwave irradiation, and dry-wet cycle tests were carried out. According to the data of SEM, unconfined compressive strength and free expansion rate, the damage law and long-term stability of expansive soil were analyzed. The results show that, compared with original samples, the compressive strength can be increased by 27 times and the expansion rate can be reduced to 0 by microwave heating to 500°C. In addition, microwave irradiation changes the way of fracture development. The change of fracture development pattern leads to the improvement of water resistance and strength of expansive soil, and thus the long-term stability of expansive soil is improved. The researches result of this paper can provide a reference for stability evaluation and design of expansive soil slope engineering.

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“…These deformations occurred during the wet and dry cycling process. Furthermore, some scholars have examined the formation of cracking patterns in expansive soils subjected to wet and dry cycling conditions (Li et al, 2012;Tang et al, 2019;Zhu et al, 2021;Ribeiro Filho et al, 2022). Nevertheless, traditional experimental methods and observations frequently fail to provide comprehensive information due to the complexity of the cracking process in expansive soils and the micro-scale variations.…”

Section: Introductionmentioning

confidence: 99%

Microscopic Mechanism and Evolution Model of Cracks Development in Expansive Soil under Rainfall-Evaporation Cycle

Han,

Chen,

et al. 2023

Preprint

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This study investigated the cracking development of expansive soils under cycling conditions of rainfall evaporation using Nuclear Magnetic Resonance(NMR) testing and image analysis methods. The study examined both internal and surface perspectives and analyzed the impact of small and medium rainfall cycles on the fine-scale mechanism of expansive soils. The experimental results showed that micropores and small-medium pores transformed into macropores during the cycling process, and this transformation was directly related to the intensity of rainfall. Furthermore, the porosity of the expansive soil increased during moisture absorption and decreased during dehumidification. Additionally, as the number of cycles increased, irreversible pores formed, resulting in the dispersion and damage of soil samples. The surface cracking development was divided into four stages, with primary cracking development occurring more rapidly during cycles of moderate rainfall evaporation. The average width of cracks was used to quantify the degradation of soil samples, and a model was developed to predict the evolution of crack width with an approximate relative error of 20% between predicted and measured values. This study has significant theoretical and practical implications for understanding the mechanisms of deformation and damage in expansive soils.

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Study on Crack Development and Micro-Pore Mechanism of Expansive Soil Improved by Coal Gangue under Drying–Wetting Cycles

Cited by 17 publications

References 40 publications

Strengthening of Reinforced Concrete Beams Subjected to Concentrated Loads Using Externally Bonded Fiber Composite Materials

Strengthening of Reinforced Concrete Beams Subjected to Concentrated Loads Using Externally Bonded Fiber Composite Materials

Study on the effect of microwave irradiation improvement on the long-term stability of expansive soil

Microscopic Mechanism and Evolution Model of Cracks Development in Expansive Soil under Rainfall-Evaporation Cycle

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