Inhibitory mechanism of fly ash on alkali-silica reactivity of siliceous rock fine aggregate: A case study of Yangxi concrete dam

Chen, Jianguo; Huang, ZhuoJie; Du, Weilian; Zhu, Yinian; Shi, Mingsheng; Xue, Binghan

doi:10.1016/j.cscm.2023.e02093

Cited by 3 publications

(1 citation statement)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Recommendations covering the use of fly ash for this purpose are provided in several standards [2][3][4] yet this application continues to be a popular topic for current research. 5,6 This study is no exception and, while adding to the long list of examples of the implementation of fly ash in concrete, provides a detailed examination of the mechanism behind one of the physical manifestations of AAR, namely darkened reaction rims on reacted aggregates. 7…”

Section: Introductionmentioning

confidence: 99%

The dam that fly ash built

Montgomery,

Kasaniya,

Zhao

et al. 2023

Journal of Microscopy

View full text Add to dashboard Cite

When the first concrete was poured in 1949 for the Hungry Horse Dam (Montana, USA), pozzolan cements had already been used in several major North American dams, including Grand Coulee on the Columbia River (diatomaceous earth explored but ultimately not used), Friant on the San Joaquin River and Altus on the North Fork Red River (pumicite) and Bonneville on the Columbia River and Davis on the Colorado River (calcined clay). But Hungry Horse Dam stands out as the first dam constructed using coal combustion fly ash. Utilising 2.4 million cubic metres of concrete, the dam is located on the South Fork Flathead River, one of the tributaries feeding one of the nation's major waterways, the Columbia River, and closely related to the adjacent Glacier National Park. In this respect, Hungry Horse is directly connected to two momentous periods in modern history – the massive adoption in the 1950s of coal as fuel for power plants, and the ongoing threats to fresh water supply and the rapid retreat of alpine glaciers due to global warming. Two concrete cores from this dam, one with fly ash and one without fly ash, are examined microscopically to explore the long‐term suppression of alkali‐aggregate reaction by fly ash. The core without fly ash exhibits clear evidence of alkali‐aggregate reaction, manifested by sandstone coarse aggregate particles with darkened reaction rims. Sandstone coarse aggregate particles of the same lithology in the core with fly ash are without signs of alkali‐aggregate reaction. A detailed examination of the darkened rims indicates that alkali‐silica reaction products fill the narrow gaps between adjacent sand grains in the sandstone. This alkali‐silica gel infilling allows for optical continuity between adjacent sand grains and is responsible for the classic darkened rim associated with the alkali‐aggregate reaction.

show abstract

Section: Introductionmentioning

confidence: 99%

The dam that fly ash built

Montgomery,

Kasaniya,

Zhao

et al. 2023

Journal of Microscopy

View full text Add to dashboard Cite

show abstract

Effects of different roughness on Brazilian splitting characteristics of rock-concrete interface

Chen,

Wang,

Zhou

et al. 2024

PLoS ONE

View full text Add to dashboard Cite

In order to study the tensile properties of rock-concrete composite disc specimens with different roughness, the surface of the gray-white sand specimen was artificially grooved, and six different roughness were configured. The test results show that the roughness size and roughness mode jointly control the tensile strength of the rock-concrete interface. With the increase of roughness, the tensile strength of the sample changes from the initial decrease to the increase and then decrease, and the tensile strength reaches the highest when the roughness is f3. The variation trend of pre-peak energy accumulation and post-peak energy accumulation of the sample is opposite, and the dissipation energy is closely related to the crack propagation strain. The roughness and crack closure strain, crack peak strain, crack propagation strain and crack closure stress show a sinusoidal periodic variation. The crack propagation strain is closely related to the change of dissipation energy. The change trend of crack closure stress is basically consistent with the change trend of tensile strength. Therefore, in the actual project, grasping the period of roughness variation and selecting the construction position can make the rock-concrete interface stable and get twice the result with half the effort.

show abstract

Modelling alkali–silica reaction from micro-computed tomography images: role of particle size and water/cement ratio

Dyer

2024

Magazine of Concrete Research

View full text Add to dashboard Cite

An experimental programme has been conducted to non-destructively observe the influence of aggregate particle size and low water/cement (w/c) ratios on alkali-silica reaction (ASR) in concrete using μ-CT scanning. The results are further analysed using a model developed as part of a previous study. ASR expansion and cracking is observed to increase to strain levels of around 0.010 with a decrease in particle diameter up to a ‘pessimum’ diameter of between 1 and 2 mm. Below the pessimum, expansion is low: around 0.001 strain. Analysis with the model clearly illustrates a transition from above the pessimum diameter, where ASR is the main process occurring, to below this size, where a pozzolanic reaction dominates. ASR expansion increases with decreasing w/c ratio, reaching strains of around 0.015. The model indicates that this is fundamentally a result of extended periods of restraint of ASR gel around aggregates ultimately ending in much greater expansion when fracture eventually occurs. Additionally, cracking of aggregate coincides with an accelerated rate of expansion in mixes with w/c ratios below 0.6.

show abstract

Inhibitory mechanism of fly ash on alkali-silica reactivity of siliceous rock fine aggregate: A case study of Yangxi concrete dam

Cited by 3 publications

References 21 publications

The dam that fly ash built

The dam that fly ash built

Effects of different roughness on Brazilian splitting characteristics of rock-concrete interface

Modelling alkali–silica reaction from micro-computed tomography images: role of particle size and water/cement ratio

Contact Info

Product

Resources

About