Effect of chloride attack on the bonded concrete system repaired by UHPC

Chen, Qing; Ma, Rui; Li, Haoxin; Jiang, Zhengwu; Zhu, Hehua; Yan, Zhiguo

doi:10.1016/j.conbuildmat.2020.121971

Cited by 55 publications

(19 citation statements)

References 45 publications

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“…文献 [11,12]采用质量增加率、表面覆盖率、裂缝愈合率、裂缝填充深度和渗透系数等评价其修复效果. 此外, 学者们采用超声波速度 [13] 和抗碳化性能及孔分布变化等评价修复效果 [10,14] . 为探究电沉积的微观机理, Otsuki等人 [11] 分析了修复过程正负两极的化学反应机理, 采用XRD (X-…”

Section: 引言unclassified

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Debye layer effect of ion migration in repairing cracks byelectrodeposition

Liu¹,

Zhou²,

Chen³

et al. 2021

Sci. Sin.-Tech.

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Section: 引言unclassified

“…In particular, the ion concentration satisfies the neutral relations, and the electric potential is linearly distributed. When the Debye number increases, the numerical solution of the classic PNP equation results in a very high non-physical ion concentration (10 ).…”

Section: 值得注意的是本文的浓度非物理累积是双电层重叠mentioning

confidence: 99%

Debye layer effect of ion migration in repairing cracks byelectrodeposition

Liu¹,

Zhou²,

Chen³

et al. 2021

Sci. Sin.-Tech.

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“…Engineering structures can be seriously damaged when fire accidents occur (Guo et al, 2021). The calcium silicate hydrate (CÀSÀH) gels are the main binding phase of cement-based materials, which are widely used in high-rise buildings, bridges, and tunnels, and hence its fire-induced degradation governs the damage evolution of engineering structures (Alabdullah and Ghoniem, 2020;Chen et al, 2016Chen et al, , 2017Chen et al, , 2020aChen et al, , 2020bChen et al, , 2021Luo et al, 2020;Zhang et al, 2020aZhang et al, 2020bZhao et al, 2014). Therefore, effects of temperature on Young's modulus (Odelson et al, 2007), compressive strength (Karim et al, 2018;Suh et al, 2020), thermal cracking (Fic and Szeląg, 2015;Szeląg, 2018), and pore structure (Kim et al, 2013) of cement paste have been widely investigated.…”

Section: Introductionmentioning

confidence: 99%

Effects of high temperature on the mechanical behavior of calcium silicate hydrate under uniaxial tension and compression

Zhang

Chen

et al. 2021

International Journal of Damage Mechanics

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When subjected to high temperatures, cement-based materials can dehydrate, which, in turn, affects the mechanical property of the main binding phase (calcium silicate hydrate) at the atomic scale. However, the effects of high temperature on the tensile and compressive behavior of calcium silicate hydrate (C−S−H) grains under uniaxial loading remains poorly understood. In this work, based on reactive molecular simulations, the tensile strength, compressive strength, and stress-strain relations of C−S−H grains with four calcium/silicon (C/S) ratios (1.10, 1.33, 164, and 1.80) both under and after (residual properties) high temperatures are investigated. It is shown that C−S−H grains can shrink due to the water loss induced by high temperature, and a low C/S ratio can lead to a thermo-stable molecular structure. Meanwhile, the residual tensile strength can be enhanced, particularly the tensile strength in the z-direction. Upon the residual compressive strength, in the x and y directions, high temperature can decrease the residual compressive strength for C/S = 1.10 or 1.33 but has no apparent effect for C/S = 1.64 or 1.80. While in the z-direction, the residual compressive strength can be enhanced due to the reduction in the interlayer space. In addition, high temperature can improve the residual tensile ductility but has no obvious effect on the residual compressive stress-strain relations. As for the mechanical properties under high temperature, both the tensile and compressive strengths can be weakened except that the tensile strength in the z-direction can undergo an increasing trend when the temperature is below 800 K due to significant shrinkage in the z-direction. Moreover, high temperature can make stress-strain curves exhibit good plasticity. Discussion indicates that the strength degradation of C−S−H gels or cement paste exposure to high temperatures is likely caused by the increasing porosity and coarsening of the void or defect size.

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“…Moreover, the moisture content also controls the electrical resistivity and oxygen diffusivity, which, in turn, can both influence the long-term durability of cementitious materials exposed to the complex environment (acid and damp). 11,12 As a result, the origin, mechanism, and manifestations of water sorption in cementitious materials has attracted some significant attention. [13][14][15] The cement paste presents a complex, heterogeneous, and multiscale structure, wherein calcium-silicate-hydrate (C-S-H) acts as the binding phase.…”

Section: Introductionmentioning

confidence: 99%

Deconstructing water sorption isotherms in cement pastes by lattice density functional theory simulations

et al. 2021

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The moisture content in cement pastes influences their mechanical properties and durability. However, the complex, multiscale nature of cement pastes makes it challenging to isolate the contributions of each scale to their macroscopic water sorption isotherms. In particular, the contribution of the calcium-silicate-hydrate gel (the binding phase of cement pastes) remains only partially understood. Here, we introduce a density functional theory lattice model describing water sorption in calciumsilicate-hydrate, which properly reproduces experimental water sorption isotherms in cement pastes. Based on this model, we deconstruct the contribution of each pore scale (interlayer spacing, gel pores, and capillary pores) to the total sorption isotherm.We show that, when the relative humidity is below 80%, the calcium-silicate-hydrate gel accounts for more than 90% of the moisture content adsorbed in cement pastes. In turn, we find that the contribution of the interlayer space within the calcium-silicatehydrate grains is governed by the competition between the rate of interlayer space opening and the increasing propensity for water to fill larger pores upon increasing relative humidity. Overall, our results highlight the key role played by the calciumsilicate-hydrate in governing the sorption isotherms of cement pastes.

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Effect of chloride attack on the bonded concrete system repaired by UHPC

Cited by 55 publications

References 45 publications

Debye layer effect of ion migration in repairing cracks byelectrodeposition

Debye layer effect of ion migration in repairing cracks byelectrodeposition

Effects of high temperature on the mechanical behavior of calcium silicate hydrate under uniaxial tension and compression

Deconstructing water sorption isotherms in cement pastes by lattice density functional theory simulations

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