Influence of slag content and water-binder ratio on leaching behavior of cement pastes

Tang, Yu-Juan; Zuo, Xiao-Bao; He, Shao-Li; Ayinde, Olawale Olatunde; Yin, Guang-Ji

doi:10.1016/j.conbuildmat.2016.11.003

Cited by 57 publications

(22 citation statements)

References 37 publications

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“…The initial porosity of cement paste has a large impact on its calcium leaching process. Tang has [59] reported that the reduction of water-binder ratio improved the compactness and initial porosity of slag cement pastes, and decreased the diffusion rate of calcium ions in pore solution, leading to an enhanced calcium leaching resistance. On the contrary, large initial porosity leads to a decreased leaching resistance.…”

Section: Self-degradationmentioning

confidence: 99%

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A Study on the Effects of Starches on the Properties of Alkali-Activated Cement and the Potential of Starch as a Self-Degradable Additive

Tan¹,

Zheng²,

Ma³

et al. 2017

Energies

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An urgent problem of geothermal energy source development is how to cut down the production costs. The use of temporary sealing materials can reduce the costs associated with the circulation lost by plugging, and increase the production by self-degradation. Based on the utilization of starches as self-degradable additives in the medical field, this paper investigated the effects of three kinds of starches, namely corn starch (CS), hydroxypropyl starch (HPS) and carboxymethyl starch (CMS) on the properties of alkali-activated cement (AAC). In addition, the thermal properties of starch, the compressive strength and microstructures of the cement with starch were tested, to evaluate the potentiality of starch as self-degradable additive for geothermal cement. The analysis showed that: (1) all the starches have the effect of increasing the apparent viscosity, prolonging the setting time and reducing the static fluid loss of alkali-activated cement; (2) the addition of starch increased the number of pores in 200 • C-heated cement, facilitated the leaching process, and thus promoted the self-degradation; and (3) among the three starches, CMS has the most potential as a self-degradable additive.

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Section: Self-degradationmentioning

confidence: 99%

“…Besides that, contact with pure water creates concentration gradients between the interstitial solution and the aggressive environment of these cementitious materials, as a result of which some ions in the pore solution diffuse outwards into the aggressive solution. The leaching process has been investigated previously [57][58][59].…”

Section: Self-degradationmentioning

confidence: 99%

A Study on the Effects of Starches on the Properties of Alkali-Activated Cement and the Potential of Starch as a Self-Degradable Additive

Tan¹,

Zheng²,

Ma³

et al. 2017

Energies

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“…The reduction in concentration of calcium ions in the pore solution forces the dissolution of calcium hydroxide and calcium-silicate-hydrate gel and decrease the alkalinity of the pore solution [12,13]. Calcium leaching also causes the increased porosity, and permeability of material and the reduction of concrete strength [2,11].…”

Section: Introductionmentioning

confidence: 99%

“…These aggressive agents can easily deteriorate the structures, causing the reduction in material durability and performance [2,3]. This is thus a challenging problem mainly because of significant maintenance costs [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

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Calcium Extraction from Blast-Furnace-Slag-Based Mortars in Sulphate Bacterial Medium

2018

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Abstract:Wastewater structures, such as treatment plants or sewers can be easily affected by bio-corrosion influenced by microorganisms living in waste water. The activity of these microbes results in deterioration and can cause the reduction in structural performance of such structures. In order to improve the durability of mortar and concrete, different admixtures are being used and the best impact is observed in cement based materials combined with blast furnace slag. In this study, mortar samples with blast furnace slag were exposed to bacterial sulphate attack for 90 and 180 days. The leaching of calcium ions from the cement matrix and equivalent damaged depths of studied mortar samples were evaluated. The results showed more significant leaching of samples placed in bacterial environment, compared to the samples placed in non-bacterial environment. Similarly, the equivalent damaged depths of mortars were much higher for the bacteria-influenced samples. The slag-based cement mortars did not clearly show improved resistance in bacterial medium in terms of calcium leaching.

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Influence of microenvironment evolution induced by calcium leaching in concrete under pressurized water conditions on chloride transport

Chen,

Lyu,

Jin

et al. 2024

Structural Concrete

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The investigation into the influence of microenvironmental evolution, induced by calcium leaching on chloride transport in concrete in pressurized water environments, encompassed analysis of aspects such as the solid phase composition, microstructure characteristics, pH value distribution, free and total chloride concentrations using X‐ray diffraction (XRD), Thermogravimetric (TG), Mercury intrusion porosimetry (MIP), Scanning electron microscopy/Energy dispersive spectrometer (SEM/EDS), and titration tests. The results exhibit a weakening of the diffraction peaks of Ca(OH)2 (CH) in the XRD spectra over time under hydraulic pressure. Throughout the calcium leaching procedure, there was an increase in the proportion of pores with diameters exceeding 100 nm. The pH distribution notably followed a pattern where it initially increased, then decreased, ultimately stabilizing at a distinct level. As exposure progressed from the surface to the interior of the concrete, hydroxide ions accumulated predominantly at 10–20 mm. According to the calcium leaching characteristics under pressurized water conditions, concrete can be sectioned into four zones. Specifically, there is a decrease in calcium ions and pH value in concrete Zone 1 near the exposure surface, indicative of a corresponding decrease in the chloride binding capacity. Concrete Zone 2 shows enrichment of hydroxide ions enhances Friedel's salt stability, while leached calcium amplifies the chloride adsorption of ≡SiOH. These effects collectively trigger an increase in both pH and chloride binding capacity.

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Influence of slag content and water-binder ratio on leaching behavior of cement pastes

Cited by 57 publications

References 37 publications

A Study on the Effects of Starches on the Properties of Alkali-Activated Cement and the Potential of Starch as a Self-Degradable Additive

A Study on the Effects of Starches on the Properties of Alkali-Activated Cement and the Potential of Starch as a Self-Degradable Additive

Calcium Extraction from Blast-Furnace-Slag-Based Mortars in Sulphate Bacterial Medium

Influence of microenvironment evolution induced by calcium leaching in concrete under pressurized water conditions on chloride transport

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