Reaction of Ca(OH)2 and of Ca(OH)2 + CaSO4.2H2O at various temperatures with feldspars in aggregates used for concrete making

Aardt, J.H.P. van; Visser, Susan A.

doi:10.1016/0008-8846(78)90076-5

Cited by 23 publications

(7 citation statements)

References 2 publications

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“…This might also explain the comparably low Na release of the co-calcined materials mixed with Ca(OH)2 solution in this study. Other feldspar minerals were also reported to react in alkaline solutions and even show signs of pozzolanic reactivity [32]. Samples 4, 5 and 6 separated after mixing in cement pastes and had free water on the top after curing for 40 days due to the much lesser water demand.…”

Section: Co-calcination Of Bauxite Residue With Other Constituentsmentioning

confidence: 99%

Bauxite Residue as Supplementary Cementitious Material – Efforts to Reduce the Amount of Soluble Sodium

Danner

Justnes

2020

Nordic Concrete Research

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This study investigates the feasibility of using bauxite residue (BR) as supplementary cementitious material (SCM) for the cement and concrete industry. It is shown from pastes of BR and calcium hydroxide, that BR is highly pozzolanic in nature. The early hydration of cement pastes with BR is accelerated while long-term strength is reduced probably due to the alkaline nature of BR. To be used as cement replacement material in concrete, attempts have been made to reduce the alkali content of BR, in particular to reduce the chance of alkali-aggregate reactions. Co-calcination of BR with kaolin or washing and cooking of BR with calcium hydroxide or calcium hydroxide and gypsum resulted in considerable reduction of alkali content; up to 75%. At the same time the reactivity of the BR was reduced but still being higher compared to fly ash already used in the cement industry.

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Section: Co-calcination Of Bauxite Residue With Other Constituentsmentioning

confidence: 99%

Bauxite Residue as Supplementary Cementitious Material – Efforts to Reduce the Amount of Soluble Sodium

Danner

Justnes

2020

Nordic Concrete Research

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“…micas, clay minerals, alkali feldspars, zeolites and volcanic glass may gradually release significant quantities of alkalis, i.e. sodium (Na + ) and potassium (K+), to the concrete pore water ( [78], [79], [80], [81]) [82]). Temperature has an influence on the extraction of alkalis, as concluded by Lu et al [83], which varies with the type of rocks as well as with the fineness of the rock particles and the type of solution.…”

Section: 4mentioning

confidence: 99%

Alkali–silica reactions (ASR): Literature review on parameters influencing laboratory performance testing

Lindgård

Andiç‐Çakır

Fernandes

et al. 2012

Cement and Concrete Research

275

154

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Utilization of potentially alkali-silica reactive aggregates requires reliable performance tests to evaluate the alkali-silica reactivity of various aggregate combinations, including their alkali threshold dependence on binder type. Several such performance tests have been used worldwide for more than 15 years, but none of the methods have proven to be reliable for use with all aggregate types and all binders. One of the objectives of RILEM TC 219-ACS (2007-2012) is to develop and validate one or more of such performance tests. Several parameters may influence the results obtained in an accelerated performance test compared to the field behavior. Based on a state of the art literature review, this paper discusses which parameters must be considered to be able to develop reliable ASR performance testing methods and provides some tentative recommendations. The internal humidity in the test specimens, the extent of alkali leaching and the storage temperature are of particular importance.

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“…In the literature, feldspars are mentioned as sources for alkali ions repeatedly (e.g. [10,11]). The release of alkali ions from feldspar bearing aggregate has been demonstrated indirectly by hot water extractions [12].…”

Section: Dissolution Phenomenamentioning

confidence: 99%

Alkali-aggregate reaction—identifying reactive silicates in complex aggregates by ESEM observation of dissolution features

Leemann

Holzer

2005

Cement and Concrete Composites

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Reaction of Ca(OH)2 and of Ca(OH)2 + CaSO4.2H2O at various temperatures with feldspars in aggregates used for concrete making

Cited by 23 publications

References 2 publications

Bauxite Residue as Supplementary Cementitious Material – Efforts to Reduce the Amount of Soluble Sodium

Bauxite Residue as Supplementary Cementitious Material – Efforts to Reduce the Amount of Soluble Sodium

Alkali–silica reactions (ASR): Literature review on parameters influencing laboratory performance testing

Alkali-aggregate reaction—identifying reactive silicates in complex aggregates by ESEM observation of dissolution features

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