Risk of early age cracking in geopolymer concrete due to restrained shrinkage

Khan, Inamullah; Xu, Tong; Castel, Arnaud; Gilbert, Raymond Ian; Babaee, Mahdi

doi:10.1016/j.conbuildmat.2019.116840

Cited by 88 publications

(28 citation statements)

References 27 publications

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“…The addition of GGBFS increases the calcium content in the material structure, increases early strength, shortens the setting time at ambient temperature and increases the density and mechanical parameters of the binder [ 21 ]. In the case of certain geopolymer composites with a mixed FA-GGBFS binder, high tensile stress caused by shrinkage was observed, which increases the risk of cracks in the material at the early stage of curing [ 22 ]. In the case of geopolymer materials, the microstructure and mechanisms of the formation of a contact zone between the geopolymer binder and aggregate are still not fully understood.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Changes in the Microstructure of Geopolymer Mortar after Exposure to High Temperatures

Dudek

Sitarz

2020

Materials

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The inorganic structure formed at the stage of setting of the geopolymer binder ensures high durability of the material under high-temperature conditions. However, changes in the microstructure of the material are observed. The purpose of the study was to analyze changes in the structure of geopolymer mortar after exposure to high temperatures T = 200, 400, 600, 800, and 1000 °C. Mortars with a binder based solely on fly ash (FA) and mixed in the 1:1 ratio with a binder containing fly ash and ground granulated blast-furnace slag (GGBFS) were tested. The descriptions of their microstructures were prepared based on digital microscope observations, scanning electron microscope (SEM) observations, EDS (energy dispersive spectroscopy) analysis, and mercury intrusion porosimetry (MIP) porosity test results. Changes in the material due to high temperature were observed. The differences in the microstructure of the samples are also visible in the materials that were not exposed to temperature, which was influenced by the composition of the materials. Porosity increases with increasing annealing temperature. The distribution of individual pores also changes. In both materials, the proportion of pores larger than 1000 nm increases with the temperature increase. Moreover, the number of cracks and their width also increases, reaching 20 µm in the case of GGBFS. Furthermore, the color of geopolymers has changed. The obtained results extend the current state of knowledge in the field of changes in the microstructure of geopolymers subjected to high temperature.

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Section: Introductionmentioning

confidence: 99%

Analysis of Changes in the Microstructure of Geopolymer Mortar after Exposure to High Temperatures

Dudek

Sitarz

2020

Materials

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“…Inamullah Khan found that the creep coefficient has a significant impact on the cracking risk of concrete. The higher the creep coefficient, the lower the cracking risk of concrete (Khan et al, 2019). Bendimerad et al (2020) have observed the same phenomenon.…”

Section: Introductionmentioning

confidence: 55%

Optimum Design of High-Strength Concrete Mix Proportion for Crack Resistance Using Artificial Neural Networks and Genetic Algorithm

et al. 2020

Front. Mater.

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The fact that high-strength concrete is easily to crack has a significant negative impact on its durability and strength. This paper gives an optimum design method of high-strength concrete for improving crack resistance based on orthogonal test artificial neural networks (ANN) and genetic algorithm. First, orthogonal test is operated to determine the influence of the concrete mix proportion to the slump, compressive strength, tensile strength, and elastic modulus, followed by calculating and predicting the concrete performance using ANN. Based on results from orthogonal test and ANN, a functional relationship among slump, compressive strength, tensile strength, elastic modulus, and mix proportion has been built. On this basis, using the widely used shrinkage and creep models, the functional relationship between the concrete cracking risk coefficient and the mix proportion is derived, and finally genetic algorithm is used to optimize the concrete mix proportion to improve its crack resistance. The research results showed that, compared with the control concrete, the cracking risk coefficient of the optimized concrete was reduced by 25%, and its crack resistance was significantly improved.

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“…Zhao et al (2019e) researched the frost resistance of geopolymer concrete and found that the frost resistance of fly ash-based geopolymer concrete is weak, which, however, can be improved by adding slag. Khan et al (2019) investigated the early-age constrained shrinkage and tensile creep characteristics of geopolymer concrete to explore the cracking risk of constrained shrinkage.…”

Section: High-performance Concrete Materialsmentioning

confidence: 99%

Review of annual progress of bridge engineering in 2019

Zhao

Yuan

Wei

et al. 2020

ABEN

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Bridge construction is one of the cores of traffic infrastructure construction. To better develop relevant bridge science, this paper introduces the main research progress in China and abroad in 2019 from 13 aspects, including concrete bridges and the high-performance materials, the latest research on steel-concrete composite girders, advances in box girder and cable-supported bridge analysis theories, advance in steel bridges, the theory of bridge evaluation and reinforcement, bridge model tests and new testing techniques, steel bridge fatigue, wind resistance of bridges, vehicle-bridge interactions, progress in seismic design of bridges, bridge hydrodynamics, bridge informatization and intelligent bridge and prefabricated concrete bridge structures.

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Risk of early age cracking in geopolymer concrete due to restrained shrinkage

Cited by 88 publications

References 27 publications

Analysis of Changes in the Microstructure of Geopolymer Mortar after Exposure to High Temperatures

Analysis of Changes in the Microstructure of Geopolymer Mortar after Exposure to High Temperatures

Optimum Design of High-Strength Concrete Mix Proportion for Crack Resistance Using Artificial Neural Networks and Genetic Algorithm

Review of annual progress of bridge engineering in 2019

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