A comparative study of high- and low-Al 2 O 3 fly ash based-geopolymers: The role of mix proportion factors and curing temperature

Zhou, Wei; Yan, Chunjie; Duan, Ping; Liu, Yi; Zhang, Zuhua; Qiu, Xiumei; Li, Dan

doi:10.1016/j.matdes.2016.01.084

Cited by 115 publications

(42 citation statements)

References 45 publications

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“…Comparing the TGA profiles of the five AAFA samples in Figure 1B, the major difference still occurs before 150°C, which again confirms that choosing the four drying procedures mainly affects the removal of free water and partial loosely bound water, but with some minor differences in other water environments. In the TGA curves there is still some mass loss (about 1%) above 600°C, which was also shown in a previous study [28]; the DTG curves show a weak peak at 600-800°C…”

Section: Tgasupporting

confidence: 87%

Effect of drying procedures on pore structure and phase evolution of alkali-activated cements

Zhang

Zhu

et al. 2019

Cement and Concrete Composites

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119

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This study reports the effects of different drying procedures on the pore determination and phase evolution of alkali-activated cements based on metakaolin (AAMK), fly ash (AAFA) and slag (AAS), as characterized by N2 adsorption and XRD and FTIR analysis, in comparison with ordinary Portland cement (OPC) paste. The selected drying methods are: (1) 65°C/24 h vacuum drying, (2) 105°C/24 h oven drying, (3) solvent-exchange with ethanol for 3 days then 50°C/24 h oven drying, and (4) freeze-drying with liquid nitrogen. The pore structures of AAMK and AAFA, with zeolite-like sodium aluminosilicate gel phases and little bound water, are less sensitive to drying conditions than are AAS and OPC, which consist of calcium (alumino)silicate hydrates. The drying procedures have less impact on the phase compositions of alkali-activated cements than OPC in general. Nonetheless, caution must be applied in selection of appropriate drying procedures to obtain reproducible and meaningful information regarding the pore and phase structure of alkali-activated cements.

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Section: Tgasupporting

confidence: 87%

Effect of drying procedures on pore structure and phase evolution of alkali-activated cements

Zhang

Zhu

et al. 2019

Cement and Concrete Composites

Self Cite

119

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“…The samples were cured for 20 h in an oven at 85 • C and a relative humidity of ≥90%. These conditions usually guarantee a proper FA reactivity (Fernández-Jiménez and Zhou et al, 2016). The compressive strength of the specimens was found on an Ibertest Autotest 200/10-SW frame 24 h after mixing.…”

Section: Methodsmentioning

confidence: 99%

Mechanical-Chemical Activation of Coal Fly Ashes: An Effective Way for Recycling and Make Cementitious Materials

et al. 2019

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This paper is wholly committed to resource efficiency through the valorization of waste from other industries, and more specifically fly ash as a raw material to produce concrete-like geopolymers. In particular, this study aimed to determine the effect of the physical and chemical characteristics of recycled coal fly ash used to manufacture alkaline cement on reaction kinetics and product microstructure and performance. The ash was mixed with 8 M NaOH and cured for 20 h at 85 • C and RH > 90% to form a compact paste, after which mechanical strength was determined and the reaction rate was calculated using isothermal conduction calorimetry. The findings showed that vitreous content (SiO 2 /Al 2 O 3 ), reactive and (especially) fineness play a very important role in both the development of cement mechanical strength and the composition and structure of the reaction products formed.

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“…It can be stated that FBCFA could be suitable for an alkali-activated material precursor, but often co-binders or pre-treatment of fly ash is needed. The studies acknowledged the low reactivity of FBCFAs in alkali-activation due to their crystalline nature, but compressive strengths of 10-30 MPa were often achieved [130][131][132][133][134][135][136][137][138][139], which is enough for most mortar-and paste-type applications. Even up to 50 MPa was reached [140] when most of the binder was slag-based and fly ash amount was 10-20 wt %.…”

Section: Alkali-activated Fbcfamentioning

confidence: 99%

Utilization of Fly Ashes from Fluidized Bed Combustion: A Review

et al. 2020

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Traditionally fly ash is thought to be glassy, spherical particle originating from pulverized coal combustion (PCC) at temperature up to 1700 °C. However, nowadays fluidized bed combustion (FBC) technology is spreading quickly around the world as it is an efficient and environmentally friendly method. FBC is also able to utilize mixtures of low-grade solid fuels (e.g., coal, lignite, biomass, and waste) that have fluctuating quality, composition, and moisture contents. However, this leads to a high variation in the produced fly ash quality, unlike PCC fly ash, and hence challenges when attempting to utilize this fly ash. In this study, the utilization of fluidized bed combustion fly ash (FBCFA) was reviewed using the Scopus database. The most promising utilization target for FBCFA from biomass combustion is as a fertilizer and soil amendment. In construction, the FBCFA from various fuels is utilized as cement replacement material, in non-cement binders, as lightweight aggregates and cast-concrete products. Other types of construction applications include mine backfilling material, soil stabilizer, and road construction material. There are also other promising applications for FBCFA utilization, such as catalysts support material and utilization in waste stabilization.

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A comparative study of high- and low-Al 2 O 3 fly ash based-geopolymers: The role of mix proportion factors and curing temperature

Cited by 115 publications

References 45 publications

Effect of drying procedures on pore structure and phase evolution of alkali-activated cements

Effect of drying procedures on pore structure and phase evolution of alkali-activated cements

Mechanical-Chemical Activation of Coal Fly Ashes: An Effective Way for Recycling and Make Cementitious Materials

Utilization of Fly Ashes from Fluidized Bed Combustion: A Review

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