Interfacial Degradation of Calcium Silicate Hydrate and Epoxy under a Hygrothermal Environment: An Experimental and Molecular Model Study

Luo, Qi; Zhang, Xinyu; Li, Yuyang; Zhang, Zhe; Geng, Guoqing

doi:10.1021/acs.jpcc.2c06797

Cited by 20 publications

(2 citation statements)

References 64 publications

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“…Hydrogen bonding is a type of intermolecular interaction force formed between a hydrogen atom and an atom with a higher electronegativity, such as F, O, or N [57,58]. In this study, hydrogen bonding indirectly characterizes the interaction between the C-S-H surface and water molecules.…”

Section: Hydrogen Bondmentioning

confidence: 98%

Study on the Properties and Mechanism of Recycled Aggregate/Asphalt Interface Modified by Silane Coupling Agent

Zhou,

Hu,

Gao

et al. 2023

Applied Sciences

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The use of recycled concrete aggregates (RCA) instead of natural aggregates in hot-mix asphalt mixtures is one of the ways to achieve energy savings and reduce carbon emissions in road engineering. However, the cement mortar on the surface of RCA adversely affects the adhesion properties between asphalt and aggregates, leading to a reduction in the performance characteristics of asphalt mixtures. In this study, a silane coupling agent (SCA) was employed to improve the adhesion properties of the RCA/asphalt interface. The enhancement mechanism of SCA on the RCA/asphalt interface was investigated from multiple perspectives, including macroscopic properties, interfacial microstructure, and nanoscale interfacial interactions. Firstly, the adhesion behavior and tensile strength of the interface between RCA and asphalt were determined through a boiling water test and direct tensile test, both before and after SCA modification. Secondly, scanning electron microscopy (SEM) was employed to observe the surface microstructure of RCA and the microstructure of the RCA/asphalt interface. Finally, the main component of mortar, calcium silicate hydrate (C-S-H), was taken as the research subject of investigation to examine the hydrogen bonding, interaction energy, and interface transition zone of the C-S-H/asphalt interface system using the molecular dynamics methodology. The results demonstrate a two-level enhancement in the adhesion performance of the interface at the macroscopic scale following SCA modification. The interface tensile strength increased by 72.2% and 119.7% under dry and wet conditions, respectively. At the microscopic scale, it was observed that the surface pores of RCA were repaired after SCA modification, resulting in a more tightly bonded interface between the RCA and asphalt. At the nanoscale, SCA modification reduces the hydrophilicity of the C-S-H surface, increases the interaction energy and water resistance of the C-S-H/asphalt interface, and enhances the weak interface transition zone between C-S-H and asphalt. This study provides a theoretical basis for using SCA to enhance the bond strength of the RCA/asphalt interface and lays the foundation for the application of RCA asphalt mixtures on highways.

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Section: Hydrogen Bondmentioning

confidence: 98%

Study on the Properties and Mechanism of Recycled Aggregate/Asphalt Interface Modified by Silane Coupling Agent

Zhou,

Hu,

Gao

et al. 2023

Applied Sciences

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“…In addition, the water molecules may react with the polar functional groups, leading to the recombination of polymer chains and changing the chemical structure of the coating, resulting in swelling phenomenon (Bouvet et al, 2016, Yang et al, 2002. On the other hand, the water molecules in the pores of the mortar substrate were heated at a higher ambient temperature and generated thermal motion, which may result in an upward expansion act on the coating (Luo et al, 2023). Therefore, these two actions of water may lead to the debonding at the coating-mortar interface.…”

Section: Surface Appearance Changesmentioning

confidence: 99%

Accelerated Degradation of Coating-mortar Interface under UV Radiation in Presence of Water

Dai,

Zeng

2023

16th International Conference on Durability of Building Materials and Components

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The application of organic coatings is one of the most effective and economic methods to protect concrete structures from deterioration. However, organic coatings are prone to degradation under aggressive environmental actions, so the protective function may loss. While ultraviolet (UV) aging is often blamed for the degradation of organic coatings, water may play a more important role on the interfacial adhesion between the coatings and the substrate. To uncover the effect of water on the degradation performance of coating-substrate system, mortar samples coated with water-borne epoxy resin (WER) were exposed to three assigned environments, i.e., UV radiation, UV/water immersion, and UV/dry-wet cycle, up to 60 days. The surface appearance, chemical structure, wettability, and surface micro-morphology of the aged WER coatings were characterized via image process analysis, attenuated total reflectance flourier transform infrared spectroscopy (ATR-FTIR), static water contact angle, and scanning electronic microscopy (SEM). Results show that the UV/water immersion resulted in severest blistering on the WER-mortar interface, while the UV/wet-dry cycle caused the formation of micropinholes on the WER surface. In contrast, the UV radiation did not induce such severe aging. The data implied that water can accelerate the aging of WER-mortar system.

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Atomistic insights into the effect of temperature on capillary transport of water molecules in epoxy-modified calcium silicate hydrate nanopore: diffusion, kinetics, and mechanism

Xie,

Luo

2023

J Mater Sci

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The movement of water molecules at the atomic scale within the calcium silicate hydrate (C–S–H) gel pores serves a dual role: it creates an environment for harmful chemical reactions within the pores and functions as a carrier for the transport of detrimental ions, thereby affects the mechanical properties and durability of cementitious materials. However, direct experimental observation poses substantial challenges. This study offers new insights into how temperature (253 K, 273 K, 293 K, and 313 K) affects the capillary transport of water molecules in epoxy-modified C–S–H. The findings demonstrate that the pore size undergoes continuous changes during immersion due to epoxy clustering or detachment, resulting in three scenarios: narrowing of epoxy/C–S–H channels (253 K, 273 K), channel blockage (293 K), and complete detachment (313 K). Moreover, the interactions between water molecules and epoxy lead to epoxy detachment or cluster formation on the C–S–H surface. As the temperature increases, the interaction between C–S–H and cross-linked epoxy resin weakens. The coordination between C–S–H and epoxy resin decreases, while the coordination with water increases. This paper provides valuable insights into the transport behavior of liquids within the epoxy-modified C–S–H pores of cement-based materials. It contributes to a better understanding of how liquids move and interact within the modified pore structure, which is beneficial for enhancing the performance and properties of cement-based materials.

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Interfacial Degradation of Calcium Silicate Hydrate and Epoxy under a Hygrothermal Environment: An Experimental and Molecular Model Study

Cited by 20 publications

References 64 publications

Study on the Properties and Mechanism of Recycled Aggregate/Asphalt Interface Modified by Silane Coupling Agent

Study on the Properties and Mechanism of Recycled Aggregate/Asphalt Interface Modified by Silane Coupling Agent

Accelerated Degradation of Coating-mortar Interface under UV Radiation in Presence of Water

Atomistic insights into the effect of temperature on capillary transport of water molecules in epoxy-modified calcium silicate hydrate nanopore: diffusion, kinetics, and mechanism

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