Factors affecting alkali-reactivity of quartz-rich metamorphic rocks: Qualitative vs. quantitative microscopy

Šťastná, Aneta; Šachlová, Šarka; Pertold, Zdeněk; Přikryl, Richard

doi:10.1016/j.enggeo.2014.12.012

Cited by 13 publications

(6 citation statements)

References 24 publications

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“…It is considered that the higher the silica dissolution, the higher the incidence of ASR. According to Figure 10 , the grains with Stage 2 (quartz deformed with stretched feature in bands) dissolve more intensely, which agrees with the Stastná et al [ 32 ]. These are the predominant grains in M2.…”

Section: Resultssupporting

confidence: 87%

Influence of the Quartz Deformation Structures for the Occurrence of the Alkali–Silica Reaction

et al. 2018

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Defects in the crystalline structure of quartz facilitate the connection with the alkali hydroxides, since under a high alkalinity condition (e.g., in concrete), the Si-O bonds of quartz are easily broken. This study set out to investigate the influence of the deformation structures of quartz on its susceptibility to the alkali–silica reaction. A granite, a protomylonite, and a mylonite were selected for this study. Using optical microscopy, the quartz grains contained in these rocks were quantified and their texture characterized. The quartz samples extracted from the rocks were analyzed by magnetic nuclear resonance, to evaluate their potential for dissolving silica as well as changes in their atomic scale before and after the reaction with alkali hydroxides. These analyses were compared with the results of the accelerated mortar bar test. The study showed that the quartz with intense undulatory extinction and deformation bands denotes the most favorable condition to the development of the alkali–silica reaction. However, on an atomic scale, the slightly deformed grains were highly prone to react. Thus, in a high alkalinity condition, over a long period of time, any quartz tends to develop the alkali–silica reaction, regardless of the deformation degree of the grain.

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Section: Resultssupporting

confidence: 87%

Influence of the Quartz Deformation Structures for the Occurrence of the Alkali–Silica Reaction

et al. 2018

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“…The authors verified the development of ASR in a Portuguese dam built in 1960, where the quartz in the granite was slightly deformed. Similar results were discussed by Št’astná et al [31]. …”

Section: Resultssupporting

confidence: 92%

Relationship between Degree of Deformation in Quartz and Silica Dissolution for the Development of Alkali-Silica Reaction in Concrete

et al. 2017

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This paper presents research on the influence of quartz deformation in aggregates for the development of the alkali-silica reaction in concrete and its relationship with silica dissolution. The study also compares these characteristics with the field behavior of such rocks in concrete. The paper proposes parameters to classify the different degrees of deformation of quartz. Transmission electron microscopy showed the presence of walls even in slightly deformed quartz, which indicate the presence of the internal paths available to react with the alkaline concrete pore solutions and point to the potential development of an alkali-silica reaction. The presence of the deformation bands in the quartz grains leads to the alkali aggregate reaction occurring more rapidly. The visible spectrophotometer test was performed to evaluate the dissolution potential of the different samples of deformed quartz, which confirmed that the reactivity of the quartz increases as the deformation of the crystalline structure increases. The parameters established in the present study could be verified by analyzing the behavior of reactive and innocuous aggregates from the buildings.

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“…Alkali-aggregate reaction (AAR) is an expansive reaction between alkali-active mineral components and the soluble alkaline solution from cement and admixtures in concrete pores [1][2][3][4]. Since AAR products have a strong water swelling capability, the expansion stress generated in the swelling process may exceed concrete strength, which, therefore, can further cause cracking damage to the concrete structures [5].…”

Section: Introductionmentioning

confidence: 99%

Experimental Application of Cement-Stabilized Pavement Base with Low-Grade Metamorphic Rock Aggregates

Yang

Liu²,

Zou³

et al. 2022

Buildings

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Low-grade metamorphic rock (LMR) is a kind of stone that is widely distributed in China. The alkali activity strictly prevents its application in conventional concrete. This paper evaluates the possibility of using LMR aggregate in cement-stabilized pavement base (CSPB). The compressive strength of CSPB prepared with LMR and limestone aggregates at various curing conditions was measured. Expansion rates were determined via accelerated simulation tests to assess the alkali reactivity of LMR, followed by microscopic analysis. Finally, the possibility of using LMR in CSPB was evaluated from the economic viewpoint. Results indicate that CSPB specimens prepared with LMR have similar compressive strength at each content of cement, regardless of curing conditions. The expansion rates of all CSPB specimens with LMR were lower than 0.1%, indicating the absence of an AAR, which was further validated by the absence of the AAR product in microscopic observations. It is inferred from the economic analysis that 70.9% lower cost can be achieved by the replacement of limestone aggregate with LMR aggregate. This demonstrates that technical, economic and environmental benefits endow LMR with wide market potential as the aggregate of CSPB.

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Factors affecting alkali-reactivity of quartz-rich metamorphic rocks: Qualitative vs. quantitative microscopy

Cited by 13 publications

References 24 publications

Influence of the Quartz Deformation Structures for the Occurrence of the Alkali–Silica Reaction

Influence of the Quartz Deformation Structures for the Occurrence of the Alkali–Silica Reaction

Relationship between Degree of Deformation in Quartz and Silica Dissolution for the Development of Alkali-Silica Reaction in Concrete

Experimental Application of Cement-Stabilized Pavement Base with Low-Grade Metamorphic Rock Aggregates

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