Early hydration of cementitious systems accelerated by aluminium sulphate: Effect of fine limestone

Briendl, Lukas; Mittermayr, Florian; Baldermann, Andre; Steindl, Florian Roman; Sakoparnig, Marlene; Letofsky-Papst, Ilse; Galán, Isabel Moratilla

doi:10.1016/j.cemconres.2020.106069

Cited by 63 publications

(13 citation statements)

References 58 publications

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“…According to the literatures [ 40 , 60 , 61 ], the decomposition temperatures of hydration products (AFt, AFm, and C–(A)–S–H) and portlandite are 50–550 °C and 400–550 °C, respectively, while the decomposition of carbonate mainly appears between 550–1000 °C. The amount of hydrate water and portlandite obtained is shown in Figure 12 .…”

Section: Resultsmentioning

confidence: 99%

Quicklime and Calcium Sulfoaluminate Cement Used as Mineral Accelerators to Improve the Properties of Cemented Paste Backfill with a High Volume of Fly Ash

Ding

Zhang

2020

Materials

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In order to reduce the CO2 emission and cost of binders used in cemented paste backfill (CPB) technology, new blended binders with a large amount of fly ash (FA) were fabricated. Different doses of quicklime and calcium sulfoaluminate cement (CṠA) were used as mineral accelerators to improve the early workability of CPB. The effects of CṠA and quicklime on flowability, compressive strength, pore structure, hydration heat, and hydration evolution were investigated experimentally. The results showed that the addition of quicklime and CṠA reduced the spread diameter of the fresh backfill and improved the mechanical performance of the hardened CPB. With increasing quicklime and CṠA, the cumulative hydration heat of the blended binder distinctly increased in the first 6 h. CṠA improved the initial hydration by increasing the reactivity, and quicklime increased the hydration rate by activating FA. The blended binder (15% quicklime + 10% CṠA) with the lowest CO2 emission and cost had potential application in filling technology.

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Section: Resultsmentioning

confidence: 99%

Quicklime and Calcium Sulfoaluminate Cement Used as Mineral Accelerators to Improve the Properties of Cemented Paste Backfill with a High Volume of Fly Ash

Ding

Zhang

2020

Materials

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“…4, where mixture W9, with a much lower clinker content compared to W3 and W4 (W9 = 66%, W3 = 90%; W4 = 95%), shows a much lower Clpenetration depth. The effect of SCMs on the formation of Friedel's salt is mainly due to the influence on the formation of AFm phases which can also be affected by the use of aluminium sulphate accelerators [9]. Both, SCMs and the accelerator in the concrete mixture change the total Al 2 O 3 contents, which correlate with the amount of CO 3 -AFm formed for the mixtures W1-W8 (R 2 = 0.72; Supplement .…”

Section: Influence Of Binder Compositionmentioning

confidence: 98%

“…In the case of shotcrete the use of setting accelerators may induce an earlier activation of the GGBFS [73]. Another commonly used supplementary material is powdered limestone, which forms CO 3 -AFm phases, stabilises ettringite and contributes to the formation of C-(A)-S-H [9,[74][75][76].…”

Section: Clinker Reduced Shotcrete: Influence Of Scmsmentioning

confidence: 99%

“…This difference is hypothesized to be related to the higher calcium availability during the hydration process of dry-mix shotcrete. In the case of wet-mix shotcrete accelerated by means of aluminium sulphate, considerably high amounts of calcium are needed to form ettringite at the very early stages of hydration [9,76]. In the case of dry-mix shotcretes produced with spray binder with low sulphate, lower quantities of calcium are expected to be needed for the formation of the AFm phases, responsible for the fast setting.…”

Section: Wet-vs Dry-mixmentioning

confidence: 99%

“…The durability of all concretes is influenced by physical (porosity) and chemical (phase assemblage, pore solution) parameters. In the case of shotcrete, those parameters differ from conventional concrete due to several reasons: (1) the use of setting accelerators and special fast-setting binders leads to different hydrated phase assemblages and pore solution chemistry [8,9], and (2) the application method influences the porosity [10,11], the matrix homogeneity [12][13][14][15], and the binder to aggregate ratio [16][17][18]. The type of durability issue affecting shotcrete depends on the environmental surroundings [19].…”

Section: Introductionmentioning

confidence: 99%

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Durability of clinker reduced shotcrete: Ca2+ leaching, sintering, carbonation and chloride penetration

et al. 2021

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The reduction of clinker use is mandatory to lower the negative environmental impact of concrete. In shotcrete mixes, similarly to the case of conventional concrete, the use of supplementary cementitious materials (SCMs) and proper mix design allow for the substitution of clinker without compromising the mechanical properties. However, the impact of the substitution on the durability of shotcrete needs to be further assessed and understood. The results from the present study, obtained from real-scale sprayed concrete applications, show a reduction of the Ca2+ leaching and sintering potential of clinker-reduced shotcrete mixes due to the presence of SCMs. This positive effect, crucial for low maintenance costs of tunnels, is mainly related to a reduced portlandite content, which on the other hand negatively affects the carbonation resistance of shotcrete. Additionally, the hydration of SCMs positively influences the chloride penetration resistance presumably due to a combination of microstructural changes and changes in the chloride binding capacity. Differences found in the pore size distribution of the various mixes have low impact on the determined durability parameters, in particular compared to the effect of inhomogeneities produced during shotcrete application.

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Ökologisierung von Normalbeton

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Krüger²,

Briendl³

et al. 2022

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Early hydration of cementitious systems accelerated by aluminium sulphate: Effect of fine limestone

Cited by 63 publications

References 58 publications

Quicklime and Calcium Sulfoaluminate Cement Used as Mineral Accelerators to Improve the Properties of Cemented Paste Backfill with a High Volume of Fly Ash

Quicklime and Calcium Sulfoaluminate Cement Used as Mineral Accelerators to Improve the Properties of Cemented Paste Backfill with a High Volume of Fly Ash

Durability of clinker reduced shotcrete: Ca2+ leaching, sintering, carbonation and chloride penetration

Ökologisierung von Normalbeton

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