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Nanoengineered Clay-Based Internal Conditioning: Cement Hydration and Alkali-Silica Reaction Mitigation /

Record Type:	Electronic resources : Monograph/item
Title/Author:	Nanoengineered Clay-Based Internal Conditioning: Cement Hydration and Alkali-Silica Reaction Mitigation // Dayou Luo.
Author:	Luo, Dayou,
Description:	1 electronic resource (470 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 85-11, Section: B.
Contained By:	Dissertations Abstracts International85-11B.
Subject:	Materials science. -
Online resource:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=31141867
ISBN:	9798382734538

Nanoengineered Clay-Based Internal Conditioning: Cement Hydration and Alkali-Silica Reaction Mitigation /
Luo, Dayou,

Nanoengineered Clay-Based Internal Conditioning: Cement Hydration and Alkali-Silica Reaction Mitigation /Dayou Luo. - 1 electronic resource (470 pages)

Source: Dissertations Abstracts International, Volume: 85-11, Section: B.

Alkali-silica reaction (ASR), a reaction between the alkali from cement and the metastable silica from aggregates, is one of major deterioration mechanisms of concrete that can cause volume expansion, cracking, and premature failure of structures. Concerns over durable concrete design and the high maintenance costs for ASR-impacted concrete structures have driven investigations into new strategies for ASR mitigation. However, how to develop a practical, robust, and cost-effective approach without deleterious effect on cement hydration and concrete performance is still a long-standing challenge. Towards this end, a nanoengineered internal conditioning (NIC) technology based on clay minerals is investigated in this work with an objective to achieve targeted ASR suppression without sacrificing the performance of concrete. In pursuit of this goal, the following tasks have been performed:(i) Functionalization of sodium montmorillonites (sMTs). In this study, two non-ionic surfactants, t-octyl phenoxy poly ethoxyethanol (TX100) and polyethylene glycol ether (PONPE9), were employed to upgrade sMT into an effective agent for internal conditioning. With effective intercalation of the surfactants into the interlayer space, the overall properties of sMT including pozzolanic reactivity, hygroscopic swelling, water uptake, and dispersion in both water and a cement pore solution were improved, which paves a solid pathway for the cement modification and ASR mitigation.(ii) Development of NIC based on the functionalized sMTs and its influence on the hydration of cement. The positive role of NIC on the hydration kinetics and phase evolutions of Portland cement was explored and it was found that both the silicate and secondary aluminate reactions can be enhanced, the apparent activation energy of cement hydration was decreased, the calcium hydroxide content was reduced, and the degree of hydration was improved in the presence of NIC. In addition, increased chemical shrinkage, and enhanced formation of calcium silicate hydrate (C-S-H) and aluminum-containing phases were obtained.(iii) Development of metakaolin-based internal conditioning (MIC) and its role in cement hydration. In addition to sMT, metakaolin (MK, a calcined clay) was investigated as an alternative NIC agent. The influences of MIC and its integration with lithium nitrate (an ASR retarding chemical admixture) on the hydration kinetics, phase evolution, and developments of microstructure and molecular structures of hydration products of cement was investigated through a combined experiment-modeling approach. A synergistic effect was found to exist between the saturated MK and lithium in enhancing the hydration of cement, interaction between metakaolin and cement, incorporation of Al in the silicate chains, and precipitations of Al-rich phases.(iv) Investigation of the efficacy of functionalized sMT in mitigating ASR. To understand the role of NIC in ASR mitigation, the expansion and cracking behavior of mortars containing reactive aggregates were investigated. Superior to raw sMT, substantial mitigations of ASR-induced expansion and cracking were obtained in the presence of the functionalized sMT, which is supported by the improved consumption of portlandite, reduced formations of both crystalline and amorphous ASR gels, suppressed Q3 polymerization sites, and decreased [K + Na]/Si atomic ratio in ASR products.(v) Examination of the role of MIC in mitigating ASR. The developments of volume expansion, cracking, permeability, strength, and microstructure in mortars containing reactive aggregates with and without MIC were investigated to elucidate the role of MIC in ASR suppression, as well as the underlying mechanisms. Substantial decreases in ASR expansion and cracking density revealed the robust role of MIC in ASR suppression outperforming single uses of metakaolin or lithium. Multiple prerequisites of ASR from silica dissolution to water uptake and swelling of ASR gels were arrested.(vi) Exploration of magnesium-based ASR mitigating admixture. With an objective to tailor a new chemical admixture for ASR mitigation that can overcome the challenges of lithium salts, such as low abundance, high cost, and negative impacts on the hydration and shrinkage of cement, magnesium nitrate was investigated. The effects of magnesium nitrate in volume expansion, cracking behavior, and strength loss are investigated at varying Mg/alkali ratios from 0 to 3.0. The underlying mechanisms were analyzed by elucidating the modifications of cement hydration kinetics, silica dissolution behavior, as well as the evolutions in phase, microstructure and composition of ASR products.(vii) The interaction between carbonation and ASR. A direct concrete deterioration induced by ASR is cracking, which provides channels for the ingress of external salts, moisture, and CO2. In this study the interaction between ASR and carbonation was investigated by monitoring the development of mass change, CO2 uptake, carbon profile, volume expansion, cracking behavior, and the development of compressive strength in mortars containing reactive aggregates conditioned under different concentrations of CO2. The effective suppression of ASR with a 97.9% decrease in volume expansion, fully suppressed cracking, and 61.0% improvement in strength extends our knowledge of leveraging early-age carbonation as a potential ASR mitigation strategy.

English

ISBN: 9798382734538Subjects--Topical Terms:

543314
Materials science.
Subjects--Index Terms:

Alkali-silica reaction

Nanoengineered Clay-Based Internal Conditioning: Cement Hydration and Alkali-Silica Reaction Mitigation /
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520 $a Alkali-silica reaction (ASR), a reaction between the alkali from cement and the metastable silica from aggregates, is one of major deterioration mechanisms of concrete that can cause volume expansion, cracking, and premature failure of structures. Concerns over durable concrete design and the high maintenance costs for ASR-impacted concrete structures have driven investigations into new strategies for ASR mitigation. However, how to develop a practical, robust, and cost-effective approach without deleterious effect on cement hydration and concrete performance is still a long-standing challenge. Towards this end, a nanoengineered internal conditioning (NIC) technology based on clay minerals is investigated in this work with an objective to achieve targeted ASR suppression without sacrificing the performance of concrete. In pursuit of this goal, the following tasks have been performed:(i) Functionalization of sodium montmorillonites (sMTs). In this study, two non-ionic surfactants, t-octyl phenoxy poly ethoxyethanol (TX100) and polyethylene glycol ether (PONPE9), were employed to upgrade sMT into an effective agent for internal conditioning. With effective intercalation of the surfactants into the interlayer space, the overall properties of sMT including pozzolanic reactivity, hygroscopic swelling, water uptake, and dispersion in both water and a cement pore solution were improved, which paves a solid pathway for the cement modification and ASR mitigation.(ii) Development of NIC based on the functionalized sMTs and its influence on the hydration of cement. The positive role of NIC on the hydration kinetics and phase evolutions of Portland cement was explored and it was found that both the silicate and secondary aluminate reactions can be enhanced, the apparent activation energy of cement hydration was decreased, the calcium hydroxide content was reduced, and the degree of hydration was improved in the presence of NIC. In addition, increased chemical shrinkage, and enhanced formation of calcium silicate hydrate (C-S-H) and aluminum-containing phases were obtained.(iii) Development of metakaolin-based internal conditioning (MIC) and its role in cement hydration. In addition to sMT, metakaolin (MK, a calcined clay) was investigated as an alternative NIC agent. The influences of MIC and its integration with lithium nitrate (an ASR retarding chemical admixture) on the hydration kinetics, phase evolution, and developments of microstructure and molecular structures of hydration products of cement was investigated through a combined experiment-modeling approach. A synergistic effect was found to exist between the saturated MK and lithium in enhancing the hydration of cement, interaction between metakaolin and cement, incorporation of Al in the silicate chains, and precipitations of Al-rich phases.(iv) Investigation of the efficacy of functionalized sMT in mitigating ASR. To understand the role of NIC in ASR mitigation, the expansion and cracking behavior of mortars containing reactive aggregates were investigated. Superior to raw sMT, substantial mitigations of ASR-induced expansion and cracking were obtained in the presence of the functionalized sMT, which is supported by the improved consumption of portlandite, reduced formations of both crystalline and amorphous ASR gels, suppressed Q3 polymerization sites, and decreased [K + Na]/Si atomic ratio in ASR products.(v) Examination of the role of MIC in mitigating ASR. The developments of volume expansion, cracking, permeability, strength, and microstructure in mortars containing reactive aggregates with and without MIC were investigated to elucidate the role of MIC in ASR suppression, as well as the underlying mechanisms. Substantial decreases in ASR expansion and cracking density revealed the robust role of MIC in ASR suppression outperforming single uses of metakaolin or lithium. Multiple prerequisites of ASR from silica dissolution to water uptake and swelling of ASR gels were arrested.(vi) Exploration of magnesium-based ASR mitigating admixture. With an objective to tailor a new chemical admixture for ASR mitigation that can overcome the challenges of lithium salts, such as low abundance, high cost, and negative impacts on the hydration and shrinkage of cement, magnesium nitrate was investigated. The effects of magnesium nitrate in volume expansion, cracking behavior, and strength loss are investigated at varying Mg/alkali ratios from 0 to 3.0. The underlying mechanisms were analyzed by elucidating the modifications of cement hydration kinetics, silica dissolution behavior, as well as the evolutions in phase, microstructure and composition of ASR products.(vii) The interaction between carbonation and ASR. A direct concrete deterioration induced by ASR is cracking, which provides channels for the ingress of external salts, moisture, and CO2. In this study the interaction between ASR and carbonation was investigated by monitoring the development of mass change, CO2 uptake, carbon profile, volume expansion, cracking behavior, and the development of compressive strength in mortars containing reactive aggregates conditioned under different concentrations of CO2. The effective suppression of ASR with a 97.9% decrease in volume expansion, fully suppressed cracking, and 61.0% improvement in strength extends our knowledge of leveraging early-age carbonation as a potential ASR mitigation strategy.
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650 4 $a Nanotechnology. $3 526235
650 4 $a Organic chemistry. $3 523952
653 $a Alkali-silica reaction
653 $a Sodium montmorillonites
653 $a Nanoengineered internal conditioning
653 $a Polyethylene glycol ether
653 $a Metakaolin-based internal conditioning
690 $a 0543
690 $a 0794
690 $a 0652
690 $a 0490
710 2 $a University of Massachusetts Lowell. $b Civil Engineering. $e degree granting institution. $3 3817081
720 1 $a Wei, Jianqiang $e degree supervisor.
773 0 $t Dissertations Abstracts International $g 85-11B.
790 $a 0111
791 $a Ph.D.
792 $a 2024
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