Investigation on the change of shear strength of concrete with cold joint under the action of sulfate dry–wet cycles

Men, Bo; Qin, Yuan; Zhang, Xianwei; Wu, Jiangjiang; Da, Liu; Li, Ming; Zhou, Heng

doi:10.1016/j.jobe.2023.106770

Cited by 3 publications

(2 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In Figure a, we utilized aqueous solutions having various ratios of nitrate to sulfate (ratios of 10:0, 8:2, 6:4, 4:6, 2:8, and 0:10, respectively) to evaluate the adsorption behavior of the C–S–H interface using coated/uncoated silane. Specifically, we selected sulfate concentrations similar to those used by Men et al and nitrate concentrations similar to those used by Bibi et al to ensure relevance and comparability with the existing literature. To evaluate the protective properties of silane on the substrate, we utilized the atomic structure created by Pellenq et al to simulate the structure of C–S–H This structure was generated by treating Tobermorite crystals, − as can be seen in Figure c.…”

Section: Methodsmentioning

confidence: 99%

Acid Radical Tolerance of Silane Coatings on Calcium Silicate Hydrate Surfaces in Aggressive Environments: The Role of Nitrate/Sulfate Ratio

Jiang

Wang

et al. 2023

Langmuir

View full text Add to dashboard Cite

Silane is known as an effective coating for enhancing the resistance of concrete to harmful acids and radicals that are usually produced by the metabolism of microorganisms. However, the mechanism of silane protection is still unclear due to its nanoscale attributes. Here, the protective behavior of silane on the calcium silicate hydrate (C–S–H) surface is examined under the attack environment of nitrate/sulfate ions using molecular dynamics simulations. The findings revealed that silane coating improved the resistance of C–S–H to nitrate/sulfate ions. This resistance is considered the origin of silane protection against harmful ion attacks. Further research on the details of molecular structures suggests that the interaction between the oxygen in the silane molecule and the calcium in C–S–H, which can prevent the coordination of sulfate and nitrate to calcium on the C–S–H surface, is the cause of the silane molecules’ strong adsorption. These results are also proved in terms of free energy, which found that the adsorption free energy on the C–S–H surface followed the order silane > sulfate > nitrate. This research confirms the excellent protection performance of silane on the nanoscale. The revealed mechanism can be further used to help the development of high-performance composite coatings.

show abstract

Section: Methodsmentioning

confidence: 99%

Acid Radical Tolerance of Silane Coatings on Calcium Silicate Hydrate Surfaces in Aggressive Environments: The Role of Nitrate/Sulfate Ratio

Jiang

Wang

et al. 2023

Langmuir

View full text Add to dashboard Cite

show abstract

“…Sulfate attack initiates gradually and subsequently reacts with hydrates and other cement phases, leading to the formation of expansive corrosion products such as gypsum. This expansion applies pressure on the surrounding matrix, causing extensive concrete fragmentation and posing a prevalent and severe chemical erosion issue in modern times [3][4][5][6].…”

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

View full text Add to dashboard Cite

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.

show abstract

Under Sulfate Dry–Wet Cycling: Exploring the Symmetry of the Mechanical Performance Trend and Grey Prediction of Lightweight Aggregate Concrete with Silica Powder Content

Wang,

Chen,

Wang

2024

Symmetry

View full text Add to dashboard Cite

In order to improve the mechanical properties and durability of lightweight aggregate concrete in extreme environments, this study utilized Inner Mongolia pumice as the coarse aggregate to formulate pumice lightweight aggregate concrete (P-LWAC) with a silica powder content of 0%, 2%, 4%, 6%, 8%, and 10%. Under sulfate dry–wet cycling conditions, this study mainly conducted a mass loss rate test, compressive strength test, NMR test, and SEM test to investigate the improvement effect of silica powder content on the corrosion resistance performance of P-LWAC. In addition, using grey prediction theory, the relationship between pore characteristic parameters and compressive strength was elucidated, and a grey prediction model GM (1,3) was established to predict the compressive strength of P-LWAC after cycling. Research indicates that under sulfate corrosion conditions, as the cycle times and silica powder content increased, the corrosion resistance of P-LWAC showed a trend of first increasing and then decreasing. At 60 cycles, P-LWAC with a content of 6% exhibited the lowest mass loss rate and the highest relative dynamic elastic modulus, compressive strength, and corrosion resistance coefficient. From the perspective of data distribution, various durability indicators showed a clear mirror symmetry towards both sides with a silica powder content of 6% as the symmetrical center. The addition of silica fume reduced the porosity and permeability of P-LWAC, enhanced the saturation degree of bound fluid, and facilitated internal structural development from harmful pores towards less harmful and harmless pores, a feature most prominent at the 6% silica fume mixing ratio. In addition, a bound fluid saturation and pore size of 0.02~0.05 μm/% exerted the most significant influence on the compressive strength of P-LWAC subjected to 90 dry–wet cycles. Based on these two factors, grey prediction model GM (1,3) was established. This model can accurately evaluate the durability of P-LWAC, improving the efficiency of curing decision-making and construction of concrete materials.

show abstract

Investigation on the change of shear strength of concrete with cold joint under the action of sulfate dry–wet cycles

Cited by 3 publications

References 39 publications

Acid Radical Tolerance of Silane Coatings on Calcium Silicate Hydrate Surfaces in Aggressive Environments: The Role of Nitrate/Sulfate Ratio

Acid Radical Tolerance of Silane Coatings on Calcium Silicate Hydrate Surfaces in Aggressive Environments: The Role of Nitrate/Sulfate Ratio

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

Under Sulfate Dry–Wet Cycling: Exploring the Symmetry of the Mechanical Performance Trend and Grey Prediction of Lightweight Aggregate Concrete with Silica Powder Content

Contact Info

Product

Resources

About