Surface fractal analysis of pore structure of high-volume fly-ash cement pastes

Zeng, Qiang; Li, Kefei; Fen‐Chong, Teddy; Dangla, Patrick

doi:10.1016/j.apsusc.2010.07.061

Cited by 162 publications

(47 citation statements)

References 31 publications

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“…The repeating 3 nm globules give a self-similar property to calcium-silicate-hydrate structure for the size range 3-30 nm (Jennings, 2008). This statement has been confirmed by Zeng et al (2010), and the corresponding fractal dimension was determined for HCP with different binder types (Zeng et al, 2013a).…”

Section: Introductionmentioning

confidence: 65%

Pore structure of cement pastes through NAD and MIP analysis

Zeng

Fen‐Chong

et al. 2016

Advances in Cement Research

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Two cement pastes (water to cement ratio, w/c = 0·5, 0·3) were investigated through mercury intrusion porosimetry (MIP) and nitrogen adsorption/desorption (NAD) methods at different hardening ages. The pore structure is characterised by specific surface area, pore volume and pore size distribution. The results show that: (a) the pore structure has strong scale dependence and NAD-MIP joint measurement helps to identify the different pore structure patterns; (b) MIP total pore volume captures the global process of the hydrates filling process with curing age, the mesopore (2-70 nm) volume is dominated by hydrates filling for w/c = 0·5 but countered by high-density calcium-silicate-hydrate growth for w/c = 0·3; (c) specific surface area is sensitive to calcium-silicate-hydrate growth and specific surface area values are likely to confirm that high w/c (0·5) favours low-density calcium-silicate-hydrate growth whereas low w/c (0·3) facilitates high-density calcium-silicate-hydrate formation.

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Section: Introductionmentioning

confidence: 65%

Pore structure of cement pastes through NAD and MIP analysis

Zeng

Fen‐Chong

et al. 2016

Advances in Cement Research

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“…where C is a constant; P i and V i stand for the mercury pressure and intruded pore volume at step i; and D stands for the fractal dimension of the pore surface [45][46][47][48]. erefore, equation 9is expressed as equation (12).…”

Section: Nmrmentioning

confidence: 99%

“…It was observed that two fractal areas were separated by a transition area. It was reported that Ds-a of the macrofractal region represented the packing patterns of the hydrated binder particles, while the Ds-i of the differential region mainly showed the microstructure of the C-S-H gel [45,46]. 2% and 4% NS increased the Ds-a of the samples from 2.006 in reference to 2.066 and 2.329 and increased Ds-i from 2.685 in reference ese phenomena indicated that the addition of NS disordered the transport tunnel and made the pore structure more tortuous at the age of 28 d, which could reduce the transport properties of the hardened paste.…”

Section: Mipmentioning

confidence: 99%

Effect of Nanosilica on Impermeability of Cement-Fly Ash System

Liu

Zhang

Tong

et al. 2020

Advances in Civil Engineering

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Surface protection has been accepted as an effective way to improve the durability of concrete. In this study, nanosilica (NS) was used to improve the impermeability of cement-fly ash system and this kind of material was expected to be applied as surface protection material (SPM) for concrete. Binders composed of 70% cement and 30% fly ash (FA) were designed and nanosilica (NS, 0–4% of the binder) was added. Pore structure of the paste samples was evaluated by MIP and the fractal dimension of the pore structure was also discussed. Hydrates were investigated by XRD, SEM, and TG; the microstructure of hydrates was analyzed with SEM-EDS. The results showed that in the C-FA-NS system, NS accelerated the whole hydration of the cement-FA system. Cement hydration was accelerated by adding NS, and probably, the pozzolanic reaction of FA was slightly hastened because NS not only consumed calcium hydroxide by the pozzolanic reaction to induce the cement hydration but also acted as nucleation seed to induce the formation of C-S-H gel. NS obviously refined the pore structure, increased the complexity of the pore structure, and improved the microstructure, thereby significantly improving the impermeability of the cement-FA system. This kind of materials would be expected to be used as SPM; the interface performance between SPM and matrix, such as shrinkage and bond strength, and how to cast it onto the surface of matrix should be carefully considered.

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“…For instance, Xu and Li (2016) and Du et al (2015) employed a simply spherical core-shell structure (or two-phase ring structure for two-dimensional case) to represent the pore-solid system of cement paste, and Xu and Li (2017) and Jin et al (2015) extended this simple geometry to a multilayer structure for concrete modelling. The microstructure of CBPMs, however, would be much more complex than the simple core-shell structure (Zeng et al 2010(Zeng et al , 2012a(Zeng et al , 2012b(Zeng et al , 2013(Zeng et al , 2014a(Zeng et al , 2016. Furthermore, classic elastic theory does not consider the possible effects of pore fluid on the deformation of porous media and the pore phase itself.…”

Section: Introductionmentioning

confidence: 99%

Poroelastic Insights into Stress Dependence of Chloride Penetration into Saturated Cement-Based Porous Materials

Zeng

Wang

2019

ACT

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Most concrete structures service under external loads and the studies of the external-loading effects on chloride diffusivity in these porous media remain insufficient. This paper reports a relationship between porosity variation and external load inspired by poroelastic theory. This porosity-load relationship, together with an empirical equation for chloride diffusivity versus porosity, provides an explicit diffusivity-load model for saturated porous media. Without the specific assumptions of geometries of the pores and the matrix phases, the present model shows flexible expressions. Comprehensive analyses are performed to demonstrate the effects of external load and initial porosity on the porosity variation, chloride diffusion coefficient, penetration depth and durable time of specific cement-based samples. Two models reported in the literature are employed for the purpose of comparison. Overall, initial porosity is a primarily dominative factor affecting the chloride diffusivity, penetration profile and durability of cement-based porous materials. Within the elastic regime, external loads only influence the outcomes in limited degrees.

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Surface fractal analysis of pore structure of high-volume fly-ash cement pastes

Cited by 162 publications

References 31 publications

Pore structure of cement pastes through NAD and MIP analysis

Pore structure of cement pastes through NAD and MIP analysis

Effect of Nanosilica on Impermeability of Cement-Fly Ash System

Poroelastic Insights into Stress Dependence of Chloride Penetration into Saturated Cement-Based Porous Materials

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