Effects of calcium bicarbonate on the properties of ordinary Portland cement paste

Wang, Yuli; He, Fengxia; Wang, Junjie; Wang, Cheng; Xiong, Zuqiang

doi:10.1016/j.conbuildmat.2019.07.262

Cited by 56 publications

(17 citation statements)

References 48 publications

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“…Hence, the presence of excessive Al will force out from Ca-rich area into the AAFA network. Past research also found that C-S-H gel contribute to the strength development at later age such as at 28th days [57,58].…”

Section: Microstructure and Elemental Composition Of Reaction Productsmentioning

confidence: 84%

“…Through EDS analysis, the existence of Fe was noticeable from all specimens and was reconfirmed by the XRF result. The high percentage of Fe in AAFA network due to involvement as substitution for Al, which leads to formation ferro-sialate-siloxo and ferro-sialate-disiloxo poly binders where Ca 2+ and Na + act as charge-balancing cations [57].…”

Section: Discussionmentioning

confidence: 99%

“…Referring to the FESEM images, spectrum 15 showed the particle shapes of fly ash. It can therefore be surmised that the unreacted fly ash contributed to the strength increment with respect to the aging period due to the complex reaction between the surfaces of the particles via bonding strength [53][54][55][56][57]. Meanwhile, the elemental composition in spectrum 16 majorly consists of Si, but for spectrum 17 is dominated by Si, Ca, Na, and Al as in Figure 6b.…”

Section: Microstructure and Elemental Composition Of Reaction Productsmentioning

confidence: 99%

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Behavior of Alkali-Activated Fly Ash through Underwater Placement

Yahya

Abdullah

et al. 2021

Materials

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Underwater concrete is a cohesive self-consolidated concrete used for concreting underwater structures such as bridge piers. Conventional concrete used anti-washout admixture (AWA) to form a high-viscosity underwater concrete to minimise the dispersion of concrete material into the surrounding water. The reduction of quality for conventional concrete is mainly due to the washing out of cement and fine particles upon casting in the water. This research focused on the detailed investigations into the setting time, washout effect, compressive strength, and chemical composition analysis of alkali-activated fly ash (AAFA) paste through underwater placement in seawater and freshwater. Class C fly ash as source materials, sodium silicate, and sodium hydroxide solution as alkaline activator were used for this study. Specimens produced through underwater placement in seawater showed impressive performance with strength 71.10 MPa on 28 days. According to the Standard of the Japan Society of Civil Engineers (JSCE), the strength of specimens for underwater placement must not be lower than 80% of the specimen’s strength prepared in dry conditions. As result, the AAFA specimens only showed 12.11% reduction in strength compared to the specimen prepared in dry conditions, thus proving that AAFA paste has high potential to be applied in seawater and freshwater applications.

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Section: Microstructure and Elemental Composition Of Reaction Productsmentioning

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Section: Microstructure and Elemental Composition Of Reaction Productsmentioning

confidence: 99%

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Behavior of Alkali-Activated Fly Ash through Underwater Placement

Yahya

Abdullah

et al. 2021

Materials

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“…Changes in the ratio of open to closed pores affect the properties of the concrete. According to research publications, carbonate salts can increase the porosity of concrete specimens, however higher amounts of these salts can increase the amount of damage-causing pores [34]. Another test, reporting the results of addition of sodium aluminate admixture to concrete showed, that the addition of sodium aluminate at 2 %, 4 %, 6 %, and 8 % by weight percent of cement increase the porosity of concrete specimens.…”

Section: Resultsmentioning

confidence: 99%

The Effect of Crystallizing Admixture on the Properties and Shrinkage of Concrete

Nagrockienė¹

2021

Ceramics - Silikaty

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This study investigates the effect of the amount (from 0.6 % to 1.4 %) of crystallizing admixture (CA) on the shrinkage, density, porosity and mechanical properties of concrete specimens. A higher content of CA increased the total porosity of concrete from 10.6 % to 11.15 %. In contrast to the specimens containing 0.8-1.0 % of CA, the lowest amount of closed pores and highest total porosity was observed in the specimens containing 1.2-1.4 % of the CA. Compared to the control specimen, concrete specimens containing 1.4 % of CA showed a 5.4 % decrease in flexural strength and a 13.6 % decrease in compressive strength after 28 days of curing. The specimens containing 0.9 -1.0 % of CA demonstrated the lowest shrinkage in the period of 190 days. The shrinkage of these specimens reduced 4.8 -4.9 % compared to the control specimen. Higher content of CA had an opposite effect on the shrinkage, a short-term expansion of specimens was observed after 28-56 days. Taking into account all the properties of the concrete specimen, the optimum amount of CA, which could prevent cracks in the structures is 1.0 % of the cement mass.

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“…It was found that when the content of CaCO 3 whisker was in the range of 1.5-2.0%, its flexural strength and compressive strength increased by 27.59% and 12.60%, respectively. is is because CaCO 3 can not only improve the compactness of the cement matrix but also enhance the early hydration of cement [13][14][15]. However, when the amount of calcium carbonate whisker is more than 2%, its fluidity will decrease, and its initial consistency value is higher than 30B C , which is not conducive to cementing operation.…”

Section: Introductionmentioning

confidence: 99%

Effect of Acid Activation-Hydrophilic-Modified Sepiolite on Comprehensive Properties of Oil-Well Cement

Zhang

et al. 2019

Journal of Chemistry

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In this paper, sepiolite was treated by acid activation, coupling agent treatment, and sulfonation modification. The purpose of this study was to explore the changes in the fluidity and mechanical properties of sepiolite cement slurry before and after modification. Therefore, the comprehensive properties of unmodified sepiolite fiber (HPS) and acid activation-coupling agent treatment-sulfonated sepiolite fiber (S-O-H-HPS) in oil-well cement slurry were evaluated. FT-IR and microscopic mechanism of cement paste fracture surface before and after sepiolite modification were analyzed. The results showed that HPS can effectively improve the toughness of cement paste, but when the content of HPS was more than 1%, the fluidity of cement paste deteriorated sharply and the compressive strength decreased gradually. The addition of S-O-H-HPS can significantly improve the fluidity and stability of HPS slurry. Without affecting the compressive strength, it can effectively improve the flexural strength and impact strength and reduce the elastic modulus of cement paste. The mechanism analysis showed that S-O-H-HPS can not only form network structure in cement paste but also improve the toughness of cement paste by forming a bridge. This also explains why the strength of S-O-H-HPS cement paste does not decrease significantly with the increase of S-O-H-HPS.

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Effects of calcium bicarbonate on the properties of ordinary Portland cement paste

Cited by 56 publications

References 48 publications

Behavior of Alkali-Activated Fly Ash through Underwater Placement

Behavior of Alkali-Activated Fly Ash through Underwater Placement

The Effect of Crystallizing Admixture on the Properties and Shrinkage of Concrete

Effect of Acid Activation-Hydrophilic-Modified Sepiolite on Comprehensive Properties of Oil-Well Cement

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