The potential of ground clay brick to mitigate Alkali–Silica Reaction in mortar prepared with highly reactive aggregate

Afshinnia, Kaveh; Poursaee, Amir

doi:10.1016/j.conbuildmat.2015.07.155

Cited by 50 publications

(16 citation statements)

References 32 publications

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“…It can also be observed that the linear trend of FCW expansion, over time, is significantly lower than the reference sample. These results are similar to those presented by Afshinnia and Poursaee (2015), who verified a 67% reduction in sample expansions containing 25% FCW. Differently than the RHA samples, samples tested with FCW did not show any changes in their surfaces, such as microcracks or gel bleeding.…”

Section: Efficiency Of Pozzolans In Mitigating Alkali-silica Reactionsupporting

confidence: 91%

Synergistic effect of RHA and FCW in alkali-aggregate reaction mitigation

et al. 2019

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Pozzolans rich in silica, such as Rice Husk Ash (RHA), contribute to compressive strength gain but at the same time might increase alkali-aggregate reaction (AAR) in mortar mixtures. Pozzolans that have aluminates, such as Fired Clay Brick Waste (FCW), can be efficient to mitigate AAR but tend to lead to a slower compressive strength development. The association of different types of pozzolans, however, may result in a synergistic effect, compensating individual deficiencies. This paper presents a study of mixtures containing RHA, FCW and these two materials combined, aiming to obtain benefits in the mechanical behavior and in the durability regarding AAR. A substitution rate of 20% Portland cement by pozzolanic material was used. Through accelerated AAR tests and compressive strength measurements, it was found that while RHA is considered harmful to AAR - even when using an innocuous aggregate - FCW presents benefits, also avoiding this deleterious effect when combined with RHA. The same occurs in the compressive strength development, where RHA compensates a small loss of compressive strength associated with the use of FWC alone.

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Section: Efficiency Of Pozzolans In Mitigating Alkali-silica Reactionsupporting

confidence: 91%

Synergistic effect of RHA and FCW in alkali-aggregate reaction mitigation

et al. 2019

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“…White exudations of alkali silicate gels on the surface of mortars were more abundant in the lithium nitrate mortar, where increased formation of reactive aggregate corrosion products occurred. Observation of the gels in the air voids and on mortar surfaces indicates their lower viscosity, as also observed by Afshinnia in mortars with ground clay bricks used as a potential inhibitor of corrosion processes [32]. Indeed, it is possible that a large quantity of gels, even with a lower swelling capacity, causes a significant expansion of mortars [33].…”

Section: Discussionsupporting

confidence: 51%

Effect of lithium nitrate on the reaction between opal aggregate and sodium and potassium hydroxides in concrete over a long period of time

Zapała-Sławeta

Owsiak

2017

Bulletin of the Polish Academy of Sciences Technical Sciences

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Abstract. Alkali-silica reaction (ASR) is a reaction between amorphous or poorly crystallized siliceous phase, present in aggregates, and sodium and potassium hydroxides in the pore solution of concrete. Chemical admixtures such as lithium compounds are known to have high potential of inhibiting ASR. The aim of this study was to determine the effect of lithium nitrate on ASR in mortars containing high reactive opal aggregate over a long period of time. Mortar bar expansion tests were performed and microstructures of mortar bars were observed by scanning electron microscopy coupled with an energy dispersive X-ray microanalyser. Results from this study showed that effectiveness of lithium nitrate in mitigating ASR was limited over a long period of time. A larger amount of ASR gel which was formed in the presence of lithium nitrate indicated that the deterioration processes intensify within longer periods of time, which so far has not been observed in literature. Microscopic observation confirmed the presence of alkali-silica gel and delayed ettringite in mortars with lithium nitrate.Key words: alkali-silica reaction, lithium nitrate, ettringite formation, expansion, SEM/EDS. Effect of lithium nitrate on the reaction between opal aggregateand sodium and potassium hydroxides in concrete over a long period of time J. ZAPAŁA-SŁAWETA * and Z. OWSIAK Kielce University of Technology eses have been put forward to explain the role of lithium ions in the reaction. These include, but are not limited to, a hypothesis of reduced silica reactivity caused by the formation of a layer of lithium silicate crystallites or lithium ion-rich amorphous products on the silica surface. This layer on the surface of the aggregate prevents the reaction of silica with sodium and potassium hydroxides [12,13]. Recent years have brought more reports on the modified composition and properties of sodium-potassium-calcium silicate gels with lithium ions. Sodium and potassium ions in gels are exchanged for lithium ions, which makes them less swellable [14,15]. Gels with lithium ions are more compact, which limits the diffusion of hydroxyl, sodium and potassium ions into reactive grains [16]. Studies of the alkali-aggregate reaction have often indicated the presence of delayed ettringite [17,18]. The coexistence of aggregate reaction products with ettringite has been widely observed, especially in concrete railway sleepers in Finland, Sweden, Australia, Germany, South Africa, United States and China [19][20][21][22][23]. According to the current state of knowledge, the delayed ettringite crystallizes in the microcracks generated by the aggregate reaction with sodium and potassium hydroxides, but is not the primary source of the cracks [24,25]. Ettringite is not produced in strongly alkaline environments. However, when the concentration of sodium and potassium hydroxides decreases as a result of reacting with reactive aggregates, the conditions for its crystallization become favourable [26,27].Data on the simultaneous effects of lithium ions on alkali...

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“…Figure 12 illustrates a schematic simulation of the bridging effect of rubber aggregate and hookedended steel fiber. Where the crumb rubber aggregate particles are responsible for the arresting of the micro -cracks generated in the cement matrix and affect as energy absorbers, due to their elastic property (Afshinnia, Poursaee 2015). While for the higher level of crack propagation, the hook end steel fiber provided the sufficient bridging of the cracks and this effect continue until failure.…”

Section: Rubberized Concretementioning

confidence: 99%

Investigation on the Mechanical Properties of Rubberized Steel Fiber Concrete

Noaman

Bakar

Akil

2017

Engineering Structures and Technologies

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Researchers investigated the utilization of crumb rubber aggregate recycled from waste tire in concrete to solve the problem of discarded tire and to produce a green sustainable concrete. However, a reduction in the mechanical properties due to crumb rubber inclusion occurs. Steel fiber rubberized concrete used in this study to provide a balance between the strength loss and sustainable issue. An investigation on the mechanical properties of rubberized concrete combined with hooked – end steel fiber is presented. Rubberized concrete with different replacement ratios of crumb rubber was incorporated in plain and steel fiber concrete mixes via partial replacement of fine aggregate. Four replacement ratios (17.5%, 20%, 22.5%, and 25%) were used to investigate the effect of the partial replacement of fine aggregate by crumb rubber on the mechanical properties of plain and steel fiber concrete. In both mixes, reduction in mechanical properties was observed to be proportionate with the increment of crumb rubber. Finally, a successful combination of steel fiber and crumb rubber was obtained due to improvement of strain capacity under flexural loading.

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The potential of ground clay brick to mitigate Alkali–Silica Reaction in mortar prepared with highly reactive aggregate

Cited by 50 publications

References 32 publications

Synergistic effect of RHA and FCW in alkali-aggregate reaction mitigation

Synergistic effect of RHA and FCW in alkali-aggregate reaction mitigation

Effect of lithium nitrate on the reaction between opal aggregate and sodium and potassium hydroxides in concrete over a long period of time

Investigation on the Mechanical Properties of Rubberized Steel Fiber Concrete

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