Effects of a novel hydrophobic admixture on the sulfate attack resistance of the mortar in the wet-dry cycling environment

Yang, Lin; Pang, Y.; Li, Zhenqi; Tang, Qun

doi:10.1016/j.conbuildmat.2022.128148

Cited by 15 publications

(4 citation statements)

References 28 publications

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“…The study underscores the importance of proper CNF dispersion in UHPC to optimise mechanical performance, including hydrophobicity considerations for future research and development in advanced concrete materials. In the study by Gao et al [106] the novel hydrophobic admixture YREC showed varying effects on the compressive strength of mortars under wet-dry cycling conditions. Compressive strength initially increased with YREC content, peaking at 54% and 74% higher than control after 120 cycles at 3% and 5% YREC, respectively.…”

Section: Sulfate Expansion Reduced By 50% [55]mentioning

confidence: 99%

“…Reduced capillary water absorption contributed to almost complete ice cube removal from HSCRM surfaces, emphasising the enhanced durability of hydrophobic concrete formulations. Gao et al [106] study on a unique hydrophobic admixture for mortar's sulfate attack persistence showcased significant durability improvements. The corrosion resistance coefficient (Kf) for compressive strength surpassed 0.75 following 120 cycles, indicating successful performance.…”

Section: Impact On Durability Of Bmhcmentioning

confidence: 99%

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A comprehensive review of hydrophobic concrete: surface and bulk modifications for enhancing corrosion resistance

Gnanaraj S,

2024

Eng. Res. Express

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Corrosion in concrete structures constitutes significant challenges, threatening integrity and requiring high maintenance costs. Hydrophobic concrete presents an emerging solution for addressing corrosion in concrete structures, especially in marine environments. This review article investigates advanced techniques for surface and bulk modifications of hydrophobic concrete, focusing on their efficacy in enhancing corrosion resistance. Surface modifications using silane-siloxane coatings and polyurethane treatments significantly reduce water absorption by up to 30% and chloride ion permeability by up to 50%. Bulk modifications incorporating nano-silica and calcium stearate demonstrate marked improvements in mechanical properties and corrosion resistance, with calcium stearate reducing corrosion rates by 40%. These treatments also contribute to an average increase in compressive strength of 15% and a decrease in corrosion current densities, indicating practical utility in environments such as marine conditions. Additionally, innovative techniques like fluorosilane treatments and steel fibres further fortify impermeability and structural integrity, demonstrating the versatility of hydrophobic concrete in addressing corrosion challenges. Moreover, using eco-friendly ingredients underscores its potential for sustainable infrastructure development. In summary, hydrophobic concrete offers a comprehensive strategy for combating corrosion, providing surface and bulk modifications that enhance durability, reduce maintenance costs, and ensure the long-term sustainability of modern infrastructure.

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Section: Sulfate Expansion Reduced By 50% [55]mentioning

confidence: 99%

Section: Impact On Durability Of Bmhcmentioning

confidence: 99%

A comprehensive review of hydrophobic concrete: surface and bulk modifications for enhancing corrosion resistance

Gnanaraj S,

2024

Eng. Res. Express

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“…For instance, Lu et al [32] successfully formulated a high-performance polymer cement-based coating by innocuously introducing PDMS, which remarkably enhanced hydrophobicity, UV-aging resistance, and resistance to saltwater immersion while maintaining favorable physical properties. Similarly, Gao et al [33] employed PDMS as a surface functionalizer to prepare an innovative hydrophobic agent, resulting in significant improvements in surface cracking, strength loss, and structural stability of mortar subjected to dry and wet cyclic sulfate attack.…”

Section: Introductionmentioning

confidence: 99%

Nanoscale Insights into the Protection of Calcium Silicate Hydrate by Polydimethylsiloxane Coatings in Sulfate Environments: Different Degrees of Polymerization

Jiang,

Li,

Duan

et al. 2023

Coatings

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Calcium silicate hydrate (CSH) plays a crucial role in concrete by controlling its properties and durability. The degradation of CSH often signifies concrete damage. Polydimethylsiloxane (PDMS) is commonly used to protect concrete from sulfate corrosion; however, the comprehensive mechanistic understanding of its protective effects against CSH remains limited. Here, molecular dynamics (MD) simulations were employed to explore atomic-scale interactions between PDMS coatings and CSH in a sulfate-rich environment. Our results reveal that PDMS mitigates sulfate-induced CSH decalcification by forming a positively charged layer, ultimately reducing sulfate bonding by 83.3% compared to the blank group. Molecular structure analysis highlights key hydrogen bonding and calcium–oxygen bonding interactions that are critical for this protection. Higher polymerization stabilizes substrate adsorption, reducing surface diffusion to 33.3% of low-polymerization PDMS, thereby enhancing protection. Additionally, water molecule interactions with the CSH matrix are negatively correlated with the amount of adsorbed sulfate. Simulation results offer valuable insights into the molecular-level dynamic response of the material, contributing to a deeper understanding of the protective mechanisms of PDMS against sulfate-induced CSH degradation in concrete. These findings can guide experimenters and engineers in designing more effective protective coatings for concrete exposed to sulfate-rich environments, thereby laying a foundation for further experimental research and the development of concrete materials with enhanced durability under challenging environmental conditions.

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“…SCMs, such as slag, fly ash, metakaolin, and silica fume could mitigate sulfate corrosion by densifying the pore structure of cement-based materials and improving the hydrated paste properties [ 18 , 22 , 23 , 24 ]. Chemical admixtures improve the sulfate resistance by increasing the sulfate threshold value and decreasing the corrosion rate [ 25 , 26 , 27 , 28 , 29 ]. In addition, changing the curing method, adjusting the ambient temperature, and adding agricultural waste ashes can also significantly improve the sulfate resistance of cement-based materials [ 15 , 30 ].…”

Section: Introductionmentioning

confidence: 99%

Effect of Layered Double Hydroxides on the Deterioration Process of Cement Paste under Sulfate Attack

et al. 2022

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This study investigated the effect of layered double hydroxides (LDHs) on the deterioration process of cement paste in the sulfate environment. Cement pastes with the addition of original and calcined LDHs at 2.5 wt.% and 5.0 wt.% of cement were exposed to Na2SO4 solution for 360 days. The macroscopic performance of the cement paste was assessed based on mass variation, porosity, compressive strength, and content of sulfate ions. Furthermore, the microhardness, microstructures, and composition of the degraded pastes were examined using Vickers hardness (HV), mercury intrusion porosimetry (MIP), scanning electron microscope (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The results indicate that cement paste incorporated with LDHs can mitigate the corrosion caused by sulfate effectively, especially in the case of calcined LDHs (C-LDHs), which primarily increase the adsorption of sulfate. Compared with the control specimen, the 180 d compressive strength loss ratio of specimens with 2.5 wt.% and 5.0 wt.% of C-LDHs decreased by 63.66% and 80.51%, respectively. Moreover, LDHs can reduce the amount of ettringite crystals, densify the microstructure, and refine the pore structure to mitigate the cement paste’s sulfate corrosion significantly. Compared with the control specimen, the 180 d harmful pore volume fraction of specimens laced with 2.5 wt.% and 5.0 wt.% C-LDHs decreased by 43.77% and 54.51%, respectively. In terms of the content of C-LDHs, an optimal content of C-LDHs could ensure the dominant effect of adsorption, while excessive C-LDHs could refine pores. In addition, Vickers hardness has an excellent correlation with compressive strength, which could precisely predict the compressive strength. Moreover, by combining the Vickers hardness distribution and content distribution of sulfate ions, the cross-section of the paste could be classified into four regions to evaluate the deterioration process accurately: the degraded zone, the strengthened zone, the invaded zone, and the intact zone.

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Effects of a novel hydrophobic admixture on the sulfate attack resistance of the mortar in the wet-dry cycling environment

Cited by 15 publications

References 28 publications

A comprehensive review of hydrophobic concrete: surface and bulk modifications for enhancing corrosion resistance

A comprehensive review of hydrophobic concrete: surface and bulk modifications for enhancing corrosion resistance

Nanoscale Insights into the Protection of Calcium Silicate Hydrate by Polydimethylsiloxane Coatings in Sulfate Environments: Different Degrees of Polymerization

Effect of Layered Double Hydroxides on the Deterioration Process of Cement Paste under Sulfate Attack

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