ASR prevention — Effect of aluminum and lithium ions on the reaction products

Leemann, Andreas; Bernard, Laetitia; Alahraché, Salaheddine; Winnefeld, Frank

doi:10.1016/j.cemconres.2015.06.002

Cited by 63 publications

(21 citation statements)

References 33 publications

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“…This mechanism was first suggested by Lawrence and Vivian (1961), who reported that the lithium silicates formed had low solubility producing a coating effectively protecting the reactive aggregates from further participation in ASR. This observation has been supported by many later studies (Kawamura and Fuwa, 2003;Mitchell et al, 2004;Feng et al, 2010;Leemann et al, 2014;Leemann et al, 2015;Kim and Olek, 2016;Guo et al, 2019). Leemann et al (2015) observed that the mitigating efficiency of LiNO 3 lessens with increasing the specific surface area of the reactive aggregates, due to the increased area to be covered by the lithium products.…”

Section: Formation Of a Physical Barriersupporting

confidence: 57%

Role of Aluminum and Lithium in Mitigating Alkali-Silica Reaction—A Review

Shi

Lothenbach

2022

Front. Mater.

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Effective mitigation of alkali-silica reaction (ASR) is critical for producing durable concrete. The use of alumina-rich supplementary cementitious materials (SCMs) and chemical admixtures such as lithium salts to prevent expansion caused by ASR was first reported 70 years ago, shortly after the discovery of ASR in 1940s. Despite numerous investigations, the understanding of the mechanisms of Al and Li for mitigating ASR remain partially inexplicit in the case of Al, and hardly understood in the case of Li. This paper reviews the available information on the effect of Al and Li on ASR expansion, the influencing factors, possible mechanisms and limitations. The role of Al in mitigating ASR is likely related to the reduction of dissolution rate of reactive silica. Moreover, the presence of Al may alter the structure of crystalline ASR products to zeolite or its precursor, but such effect seems to be not that significant at ambient conditions due to the slow kinetics of zeolite formation. Several mechanisms for the lithium salts in mitigating ASR have been proposed, but most of them are not conclusive primarily due to the lack of knowledge about the formed reaction products. Combination of Al-rich SCMs and lithium salts may be used as an economic solution for ASR mitigation, although systematic studies are necessary prior to the applications.

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Section: Formation Of a Physical Barriersupporting

confidence: 57%

Role of Aluminum and Lithium in Mitigating Alkali-Silica Reaction—A Review

Shi

Lothenbach

2022

Front. Mater.

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“…In one study, Al contained in SCM was reported to reduce SiO2 dissolution rate, while not inducing alterations in the morphology, structure, and composition of reaction products. [130] Nonetheless, the role of Al in the precipitation and thermodynamics of ASR gels has remained unclear. [131] Here, synthetic Al-containing ASR gels with compositions in the SiO2-Na2O-CaO-Al2O3-H2O (S-N-C-A-H) system, were also studied.…”

Section: Examining the Effect Of Aluminum On The Solubility Of Asr Gelmentioning

confidence: 99%

The Influences of Neutron Irradiation on Aggregate Induced Degradation of Concrete

Sant

2018

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December 10, 2018 Characterization of mineral aggregatesNatural rocks may contain traces of other phases distinct from their main mineralogical components. Macroscopic observations of natural samples of albite, anorthite, almandine and dolomite suggest that they are impure. To characterize the purity of the samples, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), x-ray diffraction (XRD), and Raman spectroscopy were employed, as described below. Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDS)Energy dispersive X-ray spectroscopy (EDS) is an analytical technique that can be coupled with scanning electron microscopy (SEM). SEM-EDS can be used for elemental analysis and chemical characterization of different areas on a sample surface, with a resolution that is on the order of a few microns.[4] The working principle of EDS relies on the interaction between X-rays and the atoms on the sample surface. To stimulate characteristic X-rays from a specimen, highenergy electrons are focused on the sample, and the incident beam excites electrons in the inner shell of an atom, creating an electron hole that is then filled by electrons in the outer shell, releasing energy in the process. The amounts and energies of X-rays emitted from the sample are measured by a spectrometer to create a unique emission spectrum depending on the atomic structure.[5] Prior to SEM measurements, selected mineral samples were powdered to few micrometers in size using a ball mill, and then coated with Au for 1 minute using a Hummer® 6.6 Sputter Coater, producing a film with thickness of about 6-7 nanometers. SEM imaging was carried out using secondary electrons and backscattered electrons using a FEI Nova NanoSEM 230 (7 kV, 80 pA). X-ray Diffraction (XRD)Selected samples were analyzed using powder X-ray diffraction (XRD) to identify the crystalline phases that are present.[6] The pristine mineral samples were ball milled to produce particles that are a few micrometers in size. XRD patterns were recorded using a Bruker D8-Advance powder X-ray diffractometer in θ-θ Bragg-Brentano geometry, using Cu Kα radiation (λ = 1.5406 Å), 40 kV accelerating voltage, and 40 mA beam intensity. A 2θ range of 10° to 70°, a 2θ scan step size of 0.02°, and an exposure time of 0.5 seconds per step were employed. The peak locations and relative peak intensities in the X-ray diffractograms provide information on the particular crystalline compounds that are present in the sample. Raman SpectroscopyRaman spectroscopy is a technique for measuring the vibrational and rotational molecular bonding in a system. [7] Therefore, Raman spectroscopy was applied to observe structural changes in the mineral samples after ion-implantation. Similar to SEM-EDS and XRD, Raman spectroscopy also provides a fingerprint spectrum for the species present in a sample.[8] The working principle for Raman analysis relies on both elastic (Rayleigh) and inelastic (Raman) scattering of a laser beam. A monochromatic laser of wavelength near th...

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“…Besides excessive expansion, ASR reaction can result in cracking and microstructure degradation of cement composite, what was described among others in [28][29][30]. There are some methods preventing from ASR described in the literature that are based on applying appropriate additives, e.g., supplementary cementitious materials (SCM) like granulated blast furnace slag, fly ash, metakaolin [31], or metal ions [32]. Moreover, it is well known that microsilica is assumed as a very effective additive to mitigate ASR.…”

Section: Introductionmentioning

confidence: 99%

Cement Paste Mixture Proportioning with Particle Packing Theory: An Ambiguous Effect of Microsilica

et al. 2021

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Recently, the research of innovative building materials is focused on applying supplementary materials in the form of micro- and nanopowders in cementitious composites due to the growing insistence on sustainable development. Considering above, in paper, a research on the effect of microsilica and SiO2 nanoparticles addition to cement paste, designed with Andreasen and Andersen (AA) packing density model (PDM), in terms of its physical and mechanical properties was conducted. Density, porosity, compressive strength, hardness, and modulus of indentation were investigated and compared regarding different amount of additives used in cement paste mixes. Microstructure of the obtained pastes was analyzed. The possibility of negative influence of alkali-silica reaction (ASR) on the mechanical properties of the obtained composites was analyzed. The results of the conducted investigations were discussed, and conclusions, also practical, were presented. The obtained results confirmed that the applied PDM may be an effective tool in cement paste design, when low porosity of prepared composite is required. On the other hand, the application of AA model did not bring satisfactory results of mechanical performance as expected, what was related, as shown by SEM imaging, with inhomogeneous dispersion of microsilica, and creation of agglomerates acting as reactive aggregates, what as a consequence caused ASR reaction, crack occurrence and lowered mechanical properties. Finally, the study found that the use of about 7.5% wt. of microsilica is the optimum in regards to obtain low porosity, while, to achieve improved mechanical properties, the use of 4 wt. % of microsilica seems to be optimal, in the case of tested cement pastes.

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ASR prevention — Effect of aluminum and lithium ions on the reaction products

Cited by 63 publications

References 33 publications

Role of Aluminum and Lithium in Mitigating Alkali-Silica Reaction—A Review

Role of Aluminum and Lithium in Mitigating Alkali-Silica Reaction—A Review

The Influences of Neutron Irradiation on Aggregate Induced Degradation of Concrete

Cement Paste Mixture Proportioning with Particle Packing Theory: An Ambiguous Effect of Microsilica

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