Alkali–silica reaction: Current understanding of the reaction mechanisms and the knowledge gaps

Rajabipour, Farshad; Giannini, Eric R.; Dunant, Cyrille F.; Ideker, Jason H.; Thomas, M D

doi:10.1016/j.cemconres.2015.05.024

Cited by 447 publications

(254 citation statements)

References 135 publications

(177 reference statements)

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“…Substitution of Na + by Ca 2+ in silica networks is considered a plausible mechanism for alkali exchange during ASR (Rajabipour et al, 2015), while substitution of calcium oxide (CaO) by sodium oxide in aluminates and silicates is reported by Jawed and Skalny (1978). The latter attribute this phenomenon to the similar ionic radii of Ca 2+ and Na + , which allows substitution in the crystal matrices without significant alteration of the free energy of the system.…”

Section: Advances In Cement Researchmentioning

confidence: 99%

“…However, the high pH of the cement pore fluid, as reported by a number of researchers, provides strong evidence that a significant number of alkalis remain in the aqueous medium (Buckley et al, 2007;Jawed and Skalny, 1978;Kim et al, 2015;Rajabipour et al, 2015;Taylor, 1987). This situation could increase the potential of alkali-silica reaction (ASR) occurrence in PC elements incorporating GPC RA because the pore fluid is the medium bringing alkalis into contact with the amorphous silica of the aggregates (Chatterji, 2005;Rajabipour et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

“…It has been suggested that alkali release from non-reactive aggregates can be sufficient to influence concrete prism test results (Ideker et al, 2010). In a particular study (Rajabipour et al, 2015), alkalis in pore fluid were measured by means of hot water extraction and were found to exceed the calculated amount (assuming concrete with typical cement content) by 0·25-0·30% sodium oxide equivalent (Na 2 Oeq) by mass of cement. The difference between the calculated and obtained value was attributed to the aggregates.…”

Section: Introductionmentioning

confidence: 99%

“…Hypotheses on the alkali contribution from natural aggregates (NA) into cement paste have been investigated by a number of researchers (Bérubé et al, 2002;Rajabipour et al, 2015). It has been suggested that alkali release from non-reactive aggregates can be sufficient to influence concrete prism test results (Ideker et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Chemical aspects related to using recycled geopolymers as aggregates

Chaliasou

Heath

Paine

et al. 2018

Advances in Cement Research

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Despite extensive research into sustainability of geopolymers, end-of-life aspects have been largely overlooked. A recycling scenario is examined in this study. This requires an investigation of alkali leaching potential from a geopolymeric matrix. To study the feasibility of geopolymer cement (GPC) recycling, the migration of alkalis was evaluated for the first time on a microstructural level through energy dispersive X-ray (EDX) scanning electron microscopy (SEM) elemental mapping and leaching tests. Macroscale impacts were assessed through an investigation of Portland cement (PC) mortar properties affected by alkali concentration. Leaching tests indicated that alkalis immediately become available in aqueous environments, but the majority remain chemically or physically bound in the matrix. This type of leaching accelerates the initial setting of PC paste. Elemental mapping and EDX/SEM analysis showed a complex paste-aggregate interfacial transition zone. Exchange of calcium and sodium, revealed by the maps, resulted in the migration of sodium into the PC paste and the formation of additional calcium-silicon-based phases in the geopolymeric matrix. Strength values of mortars with 25% and 50% recycled aggregates (RA) showed negligible differences compared with the reference sample. Screening tests indicated a low potential for GPC RA inducing alkali-silica reaction. Transport of GPC RA alkalis and the underlying mechanisms were observed. This transport phenomenon was found to have minor effects on the properties of the PC mortar, indicating that recycling of geopolymers is a viable reuse practice.

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Section: Advances In Cement Researchmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Chemical aspects related to using recycled geopolymers as aggregates

Chaliasou

Heath

Paine

et al. 2018

Advances in Cement Research

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“…For very extensive literature reviews of available ASR models, the reader may want to consult Refs. [1,14,58,59].…”

Section: Introductionmentioning

confidence: 99%

Modeling Time-Dependent Behavior of Concrete Affected by Alkali Silica Reaction in Variable Environmental Conditions

Alnaggar¹,

Luzio²,

Cusatis

2017

Preprint

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Alkali Silica Reaction (ASR) is known to be a serious problem for concrete worldwide, especially in high humidity and high temperature regions. ASR is a slow process that develops over years to decades and it is influenced by changes in environmental and loading conditions of the structure. The problem becomes even more complicated if one recognizes that other phenomena like creep and shrinkage are coupled with ASR. This results in synergistic mechanisms that can not be easily understood without a comprehensive computational model. In this paper, coupling between creep, shrinkage and ASR is modeled within the Lattice Discrete Particle Model (LDPM) framework. In order to achieve this, a multi-physics formulation is used to compute the evolution of temperature, humidity, cement hydration, and ASR in both space and time, which is then used within physics-based formulations of cracking, creep and shrinkage. The overall model is calibrated and validated on the basis of experimental data available in the literature. Results show that even during free expansions (zero macroscopic stress), a significant degree of coupling exists because ASR induced expansions are relaxed by meso-scale creep driven by self-equilibriated stresses at the meso-scale. This explains and highlights the importance of considering ASR and other time dependent aging and deterioration phenomena at an appropriate length scale in coupled modeling approaches.

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Evaluation of durability of hydraulic concrete with Colombian aggregates: an industrial byproduct and a mitigating addition of the reaction alkali‐silica

2019

Ceramic Transactions Series

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Alkali–silica reaction: Current understanding of the reaction mechanisms and the knowledge gaps

Cited by 447 publications

References 135 publications

Chemical aspects related to using recycled geopolymers as aggregates

Chemical aspects related to using recycled geopolymers as aggregates

Modeling Time-Dependent Behavior of Concrete Affected by Alkali Silica Reaction in Variable Environmental Conditions

Evaluation of durability of hydraulic concrete with Colombian aggregates: an industrial byproduct and a mitigating addition of the reaction alkali‐silica

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