Alkali fusion of bentonite to synthesize one-part geopolymeric cements cured at elevated temperature by comparison with two-part ones

Peng, Mei Xun; Wang, Zheng Hong; Shen, Shao Hua; Xiao, Qiang; Li, Long Jiang; Tang, Yu; Hu, Lin

doi:10.1016/j.conbuildmat.2016.11.010

Cited by 67 publications

(10 citation statements)

References 28 publications

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“…However, the trend showed that dissolution of alkali activator for both samples Mix 4 and Mix 5 reached its peak at 7 days, whereby the lack of alkali activator did not make sufficient to react with the excessive amount of calcium resulting in incomplete reaction and inadequate binding between precursor and aggregate, creating more pores and crack propagation prevent the compressive strength growth at a later stage. Also, declined compressive strength over time was found in the fact that one-part AAMs were not water-resistant compared to the two-part AAMs system and subsequently encountered a slow hydration rate 8 , associated with a higher water/binder ratio of 0.4 to 0.5, in addition to the low dosage of alkali activator used to compose these mortar samples.…”

Section: Resultsmentioning

confidence: 99%

“…It is worth mentioning that the alkali activator reported in this experiment was between 8 and 14% weightage from the precursor's total weight and demonstrated the influence of the alkali activator where bonding strength will increase when the amount of Si and Na is boosted 6 . Too much alkali content, however, will cost more and affect the mechanical strength with efflorescent, especially metakaolin-based cementitious 8 . Nunes et al 9 explained that the precursors composed with GGBFS/ metakaolin under high alkalinity conditions tend to reduce adhesive strength due to the unreactive slag caused by high reactivity calcium precipitation that caused Ca(OH) 2 drops in the loss of C–S–H type of gels, risking the bond.…”

Section: Introductionmentioning

confidence: 99%

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The potential of one-part alkali-activated materials (AAMs) as a concrete patch mortar

Yusslee

Beskhyroun

2022

Sci Rep

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One-part alkali-activated materials (AAMs) are developed to improve conventional two-part systems. One-part AAMs technology has been used in cement binders to produce concrete, mortar, and paste. Current research mainly focuses on synthesizing raw materials obtained from industrial and agricultural waste as the main aluminosilicate precursors of the cement binder for a concrete application. The one-part AAMs were reported to have higher early compressive strength at 7 days of age, contributed by its fast-setting time, mainly when the binder activates by a higher dosage of alkaline activator and containing OPC-rich. Due to bonding issues, single or combination, FA/GGBFS/MK precursors were reported as unsuitable for use as a concrete repair material. They were the reason for the lack of one-part AAMs application of mortar compared to concrete usage. This study was conducted to determine the potential of one-part AAMs used as concrete patch mortar by investigating its rheology and mechanical properties. The compressive strength of the mortar was tested under lab ambient temperature in the tropical climate country of Malaysia. The setting time of fresh mortar and bonding strength were set under controlled lab temperature. The one-part alkali-activated mortar was composed of hybrid aluminosilicate precursors between fly ash (FA), Ground Granulated Blast Furnace Slag (GGBFS) and ordinary Portland cement (OPC). A low alkaline activator of solid potassium carbonate was used for the geopolymerization process. Three types of solid admixtures were added to complete the composition of the new mix design. The experiment's outcome showed that the mortar composed with the combination of conventional Portland cement and industrial waste products has compressive and pull-off adherence strength that meets with Class R3—EN1504-3 standard for structural concrete repair materials requirement.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The potential of one-part alkali-activated materials (AAMs) as a concrete patch mortar

Yusslee

Beskhyroun

2022

Sci Rep

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“…At the beginning of the twenty-first century, Duxson and Provis 4 outlined various potential methods for tuning the precursor chemistry and particle behavior of geopolymers and proposed a one-part geopolymer that exceeded the potential of conventional two-part (solid plus alkaline-activator solution) hybrid designs. Peng et al 5 prepared a one-part geopolymer with excellent compressive strength by a process of calcined bentonite and the addition of solid alkali, which exceeded the compressive strength of a two-part geopolymer with the same ratio and achieved a higher softening factor of 0.93. Additionally, in terms of environmental protection and economy, the raw material sources of alkali-inspired cementitious materials are mostly fly ash, slag, and other industrial waste.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Sulfate Resistance of One-Part Alkali- Activated Materials Prepared by Mechanochemistry

2023

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In this paper, the resistance of mechanically prepared one-part alkali-activated materials to external sulfuric acid attack was investigated by simulating realistic erosion environments in terms of sulfate type, concentration, and erosion mode. The macroscopic properties of the specimens were measured at different ages. Microscopic analyses were performed by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), mercury intrusion porosimetry (MIP), and other techniques to obtain the effect of different erosion environments on the mechanical-force chemically prepared one-part alkali-activated materials against sulfate erosion. The study shows that the mechanical properties of the specimens showed a trend of increasing and then decreasing with the extension of erosion time. Compared with Na 2 SO 4 erosion, the erosion damage was greatest when the sulfate containing Mg 2+ was eroded in a wetting-and-drying cycle; the erosion products of Na 2 SO 4 solution coexist in the form of calcite and gypsum, while the erosion products of MgSO 4 solution mainly consist of gypsum.

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“…The experimental idea is shown in Figure 1. Specifically, granulated blast-furnace slag/fly ash were regarded as the supplements of precursors in the geopolymer, and powdered sodium carbonate was chosen as the primary activator because its buffer capacity can moderate the corrosive of the CSW-composite and improve the handling safety for the researchers (Peng et al, 2017;Ishwarya et al, 2019). Besides, sodium metasilicate pentahydrate, as an auxiliary activator, was adopted to enhance the properties of geopolymer, and the silica fume was expected to substitute it to expand the environmental benefits (Sturm et al, 2016;Ye et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Basic Properties of fly Ash/Slag -Concrete Slurry Waste Geopolymer Activated by Sodium Carbonate and Different Silicon Sources

et al. 2021

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As a kind of granular waste with complex composition and alkali corrosiveness, concrete slurry waste (CSW) has severe recycling limitations in the ordinary Portland cement (OPC). Considering this, a new type of geopolymer, prepared by granulated blast furnace slag/fly ash, concrete slurry waste, and powdered activators (sodium carbonate and different silicon sources including sodium metasilicate pentahydrate and silica fume), was adopted to conduct a comparative study with the OPC counterpart. In this study, the homogenized CSW was mixed in the OPC and geopolymer with a constant ratio of 50 wt%, respectively. Then the properties were studied in terms of the flowability, setting times, mechanical strengths, and microstructures. The results showed that better flowability (200 mm) could be achieved in the obtained geopolymer than in the OPC reference group (95 mm) by increasing the powdered activators. The setting time of the OPC was significantly shortened due to the addition of CSW. The strengths of geopolymer were supported by the produced C-A-S-H and carbonates, with less chemically bonded water than the hydration products in the reference group. The dominant size of pores in the hardened geopolymer was much smaller than that in the OPC group which was 80 nm. Silica fume could be the alternate of the sodium metasilicate pentahydrate and had an insignificant negative impact on the fresh and hardened properties and microstructures of the geopolymer when the incorporation rate was within 5%.

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Alkali fusion of bentonite to synthesize one-part geopolymeric cements cured at elevated temperature by comparison with two-part ones

Cited by 67 publications

References 28 publications

The potential of one-part alkali-activated materials (AAMs) as a concrete patch mortar

The potential of one-part alkali-activated materials (AAMs) as a concrete patch mortar

Evaluation of Sulfate Resistance of One-Part Alkali- Activated Materials Prepared by Mechanochemistry

Basic Properties of fly Ash/Slag -Concrete Slurry Waste Geopolymer Activated by Sodium Carbonate and Different Silicon Sources

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