Scaling of strength in hardened cement pastes - Unveiling the role of microstructural defects and the susceptibility of C-S-H gel to physical/chemical degradation by multiscale modeling

Hlobil, Michal; Sotiriadis, Konstantinos; Hlobilová, Adéla

doi:10.1016/j.cemconres.2022.106714

Cited by 20 publications

(11 citation statements)

References 71 publications

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“…Concrete is the most used construction material, and there is a high potential to improve existing products and recycle waste material into new and useful products (Hlobil et al, 2022). Waste materials such as bottom ash, waste marble, waste crushed tile, and fly ash (Wang et al, 2022) have been evaluated for use as fine aggregate in cement mortar and concrete (Abebaw and Vadivu, 2021;Al-Lebban et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Investigation of the performance of cement mortar incorporating lithium slag as a super-fine aggregate

Dong

Chen

et al. 2023

Front. Mater.

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As a by-product of lithium salt mining, the emission of lithium slag increases yearly due to increased demand. Therefore, the utilization of lithium slag faces a huge challenge. In this study, a new approach to using lithium slag as a super-fine aggregate in cement systems was proposed. The use of lithium slag as a super-fine aggregate replacing 0%, 30%, 50%, 70%, and 100% of the standard sand was tested. The main hydration products of cement–lithium slag paste were calcium silicate hydrate gel, calcium hydroxide, unhydrated particles, and a small amount of ettringite. Lithium slag as a super-fine aggregate could significantly reduce the dead load of structures, enhance flexural and compressive strength and the peak stress of mortar, and no more than 50% lithium slag could significantly enhance the permeability of mortar. The study revealed that the replacement rate of lithium slag as a super-fine aggregate could reach 50%, which is five times more than the amount used as supplementary cementitious material. Therefore, the study brings an innovation in the use of lithium slag in cement systems and improves the performance of cement mortar.

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Section: Introductionmentioning

confidence: 99%

Investigation of the performance of cement mortar incorporating lithium slag as a super-fine aggregate

Dong

Chen

et al. 2023

Front. Mater.

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“…products of PC cement, and C−S−H gel has a large specific surface area and accounts for 50−70% of cement hydration products, which has become an important contributor to the performance of cement products. 12,13 In addition, the micromorphology of C−S−H gel is also one of the important factors affecting the performance of cement paste. The chemical formula and micromorphology of C−S−H gel are not fixed and are affected by various factors, such as alkalinity, temperature, and calcium−silicon ratio.…”

Section: Introductionmentioning

confidence: 99%

“…The structure and composition of the hydration products determine the properties of the cementitious materials, and the contribution of the gel phase cannot be ignored. Ettringite, C–S–H gel, and calcium hydroxide are the main hydration products of PC cement, and C–S–H gel has a large specific surface area and accounts for 50–70% of cement hydration products, which has become an important contributor to the performance of cement products. , In addition, the micromorphology of C–S–H gel is also one of the important factors affecting the performance of cement paste. The chemical formula and micromorphology of C–S–H gel are not fixed and are affected by various factors, such as alkalinity, temperature, and calcium–silicon ratio. , For CSA cement, ettringite (AFt)/monosulfoaluminate (AFm) and aluminum hydroxide (AH 3 ) gel phases are the main hydration products.…”

Section: Introductionmentioning

confidence: 99%

Temperature Effects on Fe(OH)₃ Gel Phase Nanostructures: Implications for the Performance Regulation and Application of Calcium Sulfoaluminate Cement

Li,

Chang,

Zeng

2023

ACS Appl. Nano Mater.

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Temperature is one of the most important factors affecting the hydration process and the crystallinity of cement pastes, and its effect on the gel phase cannot be ignored. The Fe(OH) 3 phase is an indispensable gel phase in calcium sulfoaluminate cement, which significantly contributes to the desirable properties of CSA cement (especially ferric-rich calcium sulfoaluminate (FR-CSA) cement). In order to thoroughly study the influence of temperature on the nanostructure of the Fe(OH) 3 gel phase, XRD, TGA, FTIR, SEM, TEM and Mossbauer spectroscopy were used to investigate the nanostructure of the Fe(OH) 3 phase synthesized by the sol−gel method and Fe(OH) 3 phase in ferric phase hydration products prepared by solid-phase sintering at different temperatures. The results show that the chemically synthesized Fe(OH) 3 phase has a crystal structure, goethite/hematite is the main product of the Fe(OH) 3 phase, and temperature has a significant effect on the crystallinity and microstructure of Fe(OH) 3 . The increase of temperature leads to the gradual increase of the crystallinity of the Fe(OH) 3 phase, changes the crystallization path of the Fe(OH) 3 phase, and is conducive to the formation of a hematite crystal. At the same time, the microstructure changes from a needle-like structure of goethite to a flaky structure of hematite. In addition, Fe(OH) 3 has a significant crystal structure during hydration at different temperatures. As the temperature increases, the crystallinity of Fe(OH) 3 generated by hydration increases and the particle size gradually increases. The microscopic morphology of the Fe(OH) 3 phase formed by hydration is predominantly scaly with significantly smaller particle sizes and weaker crystallization compared to the chemically synthesized Fe(OH) 3 phase.

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“…The investigation of calcium silicate hydrate gel, which is the main binder phase in Portland cement, at the micro- and nanoscales allows us to identify and quantify the strength scaling “mechanisms arising from various types of defects, and critically assesses the susceptibility of CSH gel to physical and/or chemical wear, quantifies determining their influence on the structural integrity of the gel, which is subsequently projected as a decrease in the bearing capacity of the material” [ 36 ]. The mechanisms of “the effect of nanofillers on the C-S-H gel are explained by the nucleation effect and the pozzolanic effect (for nano silica) of nanofillers that promote cement hydration; high water absorption capacity of nanofillers, which reduces the proton water inside the C-S-H gel and reduces the distance between the structural groups of Ca, O, and Si atoms” [ 24 ].…”

Section: Introductionmentioning

confidence: 99%

A Study on the Cement Gel Formation Process during the Creation of Nanomodified High-Performance Concrete Based on Nanosilica

Beskopylny

Stel’makh

Shcherban’

et al. 2022

Gels

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One of the most science-intensive and developing areas is nano-modified concrete. Its characteristics of high-strength, high density, and improved structure, which is not only important at the stage of monitoring their performance, but also at the manufacturing stage, characterize high-performance concrete. The aim of this study is to obtain new theoretical knowledge and experimental-applied dependencies arising from the “composition–microstructure–properties” ratio of high-strength concretes with a nano-modifying additive of the most effective type. The methods of laser granulometry and electron microscopy are applied. The existing concepts from the point of view of theory and practice about the processes of cement gel formation during the creation of nano-modified high-strength concretes with nano-modifying additives are developed. The most rational mode of the nano-modification of high-strength concretes is substantiated as follows: microsilica ground to nanosilica within 12 h. A complex nano-modifier containing nanosilica, superplasticizer, hyperplasticizer, and sodium sulfate was developed. The most effective combination of the four considered factors are: the content of nanosilica is 4% by weight of cement; the content of the superplasticizer additive is 1.4% by weight of cement; the content of the hyperplasticizer additive is 3% by weight of cement; and the water–cement ratio—0.33. The maximum difference of the strength characteristics in comparison with other combinations ranged from 45% to 57%.

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Scaling of strength in hardened cement pastes - Unveiling the role of microstructural defects and the susceptibility of C-S-H gel to physical/chemical degradation by multiscale modeling

Cited by 20 publications

References 71 publications

Investigation of the performance of cement mortar incorporating lithium slag as a super-fine aggregate

Investigation of the performance of cement mortar incorporating lithium slag as a super-fine aggregate

Temperature Effects on Fe(OH)₃ Gel Phase Nanostructures: Implications for the Performance Regulation and Application of Calcium Sulfoaluminate Cement

A Study on the Cement Gel Formation Process during the Creation of Nanomodified High-Performance Concrete Based on Nanosilica

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Scaling of strength in hardened cement pastes - Unveiling the role of microstructural defects and the susceptibility of C-S-H gel to physical/chemical degradation by multiscale modeling

Cited by 20 publications

References 71 publications

Investigation of the performance of cement mortar incorporating lithium slag as a super-fine aggregate

Investigation of the performance of cement mortar incorporating lithium slag as a super-fine aggregate

Temperature Effects on Fe(OH)3 Gel Phase Nanostructures: Implications for the Performance Regulation and Application of Calcium Sulfoaluminate Cement

A Study on the Cement Gel Formation Process during the Creation of Nanomodified High-Performance Concrete Based on Nanosilica

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Temperature Effects on Fe(OH)₃ Gel Phase Nanostructures: Implications for the Performance Regulation and Application of Calcium Sulfoaluminate Cement