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L P Singh - One of the best experts on this subject based on the ideXlab platform.
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performance and durability of high volume fly ash Cementitious System incorporating silica nanoparticles
2020Co-Authors: L P Singh, U SharmaAbstract:This paper presents the beneficial role of silica nanoparticles (SNPs) in high volume fly ash (HVFA) Cementitious System. The dosages of fly ash (FA) replaced with cement in the present study were 40% (40 FA) and 50% (50 FA). The dosages of SNPs were first optimized in mortar, and the optimized dosages were used in the concrete study. The fresh stage properties of mortar show that delay in setting time in HVFA System can address using SNPs as the initial final setting time gets shorten in the presence of SNPs. In addition to this, mechanical strength improves significantly especially at an early age of hydration. Compressive strength of the concrete containing 3% SNPs resulted in the speedy construction because we can achieve maximum compressive strength in 7 days in spite of 28 days, which is around four times faster. Long-term carbonation results revealed that SNPs incorporated mixes show a reduction of carbonation depth up to 45% with respect to control specimens containing 40 FA, while with 50 FA mix, the reduction was ~38%. Similarly, SNPs incorporated specimens show significant resistance towards the sulphate attack of about 41% with 40 FA and 34% with 50 FA samples and as compared to control specimens. Therefore, the incorporation of SNPs in concrete leads to the improvement of its durability and service life.
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Quantification and characterization of C-S-H in silica nanoparticles incorporated Cementitious System
Cement and Concrete Composites, 2017Co-Authors: L P Singh, W. Zhu, Torsten Howind, U SharmaAbstract:This paper presents the quantification and nanomechanical properties of calcium silicate hydrate (C-S-H), formed at early stage hydration of tricalcium silicate (major cement phase) in presence of silica nanoparticles (SNPs). SNPs showed dominant nucleation effect at 8 h and pozzolanic effect at 24 h and accelerate the hydration rate (∼83% at 8 h and ∼51% at 24 h) due to the formation of additional C-S-H nuclei. Further, 29Si-NMR and FTIR techniques showed the acceleration in polymerization of silicate chain leading to the formation of tobermorite like structure. Formation of polymerized and crystalline C-S-H gel in presence of SNPs increases the percentage of high density C-S-H (∼40%) and lowers the low density C-S-H (∼52%) at 24 h of hydration, as observed in nanoindentation results.
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Studies on optimization of silica nanoparticles dosage in Cementitious System
Cement and Concrete Composites, 2016Co-Authors: L P Singh, D. Ali, U SharmaAbstract:Optimization of silica nanoparticles (SNPs) dosage in Cementitious System was carried out analytically as well as experimentally by understanding the early stage hydration reaction of tricalcium silicate (C3S). XRD and TGA results show the maximum nucleation effect of SNPs at 8 h, when the rate of product formation was higher than the control (∼66% additional C-S-H and ∼61% more CH with 10% SNPs addition). While at 24 h of hydration, ∼25% additional C-S-H was formed and CH content reduced by ∼32% with 10% addition showing the pozzolanic effect of SNPs. Further, FTIR results reveal that SNPs accelerate the polymerization in silicate chain and with 10% SNPs addition more crystalline (probably tobermorite like) structure is formed. This is responsible for the formation of highly compact and dense microstructure at 24 h as observed in electron micrographs, which may be responsible for the slow hydration rate at later age. XRD, FTIR and TGA studies on C3S revealed that up to 5% addition of SNPs is beneficial, whereas higher dosages do not contribute significantly. Based on these investigations, studies were performed on cement paste, mortar and concrete samples, which revealed that 2-3% addition of SNPs is the optimum quantity for significant contribution in strength properties.
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Beneficial role of nanosilica in cement based materials - A review
Construction and Building Materials, 2013Co-Authors: L P Singh, S. R. Karade, M. M. Yousuf, S. K. Bhattacharyya, Saurabh AhalawatAbstract:Nanomaterials are gaining widespread attention to be used in construction sector so as to exhibit enhanced performance of materials in terms of smart functions and sustainable features. During the last one decade a number of nanomaterials such as nanosilica, nanotitania, carbon nanotubes and nanoalumina have been explored and among them nanosilica has been used most extensively. A number of publications appeared towards the use of nanosilica in Cementitious System is mainly due to the fact that concrete remains the most complex material and its hydration mechanism is still not completely understood. Consequently, researchers are focusing on the basic science of this material at nano/atomic level. Further, researchers are continuing to improve the durability and sustainability of concrete, and they have realized significant increment in mechanical properties of Cementitious materials by incorporating nanosilica. This review paper summarizes the effects of nanosilica addition on hydration kinetics, microstructure refinement, fresh/hardened properties and durability characteristics of concrete. © 2013 Elsevier Ltd. All rights reserved.
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granulometric synthesis and characterisation of dispersed nanosilica powder and its application in Cementitious System
Advances in Applied Ceramics, 2012Co-Authors: L P Singh, S. K. Bhattacharyya, P Singh, Saurabh AhalawatAbstract:AbstractDispersed, spherical particles of nanosilica with controllable size have been synthesised using a metal alkoxide, i.e. tetraethoxysilane, as starting material, ammonia as base catalyst and non-ionic surfactant as template by sol–gel method. Size of particles and dispersivity were controlled by varying the surfactant chain length and temperature conditions of the reaction mixture. Silica nanoparticles were synthesised using a series of non-ionic surfactants, namely Polyoxyethylene (20) sorbitan monolaurate (Tween 20) and Polyoxyethylene (80) sorbitan monooleate (Tween 80), at different reaction temperatures of 25, 50, 70 and 90°C. The particle size of silica nanoparticles gradually decreased with increasing carbon chain length of the surfactant and at higher temperature particle size became larger. Furthermore, these silica nanoparticles are incorporated into the Cementitious System to improve the mechanical properties and reduce calcium leaching in the hydration process. Addition of silica nanopar...
U Sharma - One of the best experts on this subject based on the ideXlab platform.
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performance and durability of high volume fly ash Cementitious System incorporating silica nanoparticles
2020Co-Authors: L P Singh, U SharmaAbstract:This paper presents the beneficial role of silica nanoparticles (SNPs) in high volume fly ash (HVFA) Cementitious System. The dosages of fly ash (FA) replaced with cement in the present study were 40% (40 FA) and 50% (50 FA). The dosages of SNPs were first optimized in mortar, and the optimized dosages were used in the concrete study. The fresh stage properties of mortar show that delay in setting time in HVFA System can address using SNPs as the initial final setting time gets shorten in the presence of SNPs. In addition to this, mechanical strength improves significantly especially at an early age of hydration. Compressive strength of the concrete containing 3% SNPs resulted in the speedy construction because we can achieve maximum compressive strength in 7 days in spite of 28 days, which is around four times faster. Long-term carbonation results revealed that SNPs incorporated mixes show a reduction of carbonation depth up to 45% with respect to control specimens containing 40 FA, while with 50 FA mix, the reduction was ~38%. Similarly, SNPs incorporated specimens show significant resistance towards the sulphate attack of about 41% with 40 FA and 34% with 50 FA samples and as compared to control specimens. Therefore, the incorporation of SNPs in concrete leads to the improvement of its durability and service life.
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Quantification and characterization of C-S-H in silica nanoparticles incorporated Cementitious System
Cement and Concrete Composites, 2017Co-Authors: L P Singh, W. Zhu, Torsten Howind, U SharmaAbstract:This paper presents the quantification and nanomechanical properties of calcium silicate hydrate (C-S-H), formed at early stage hydration of tricalcium silicate (major cement phase) in presence of silica nanoparticles (SNPs). SNPs showed dominant nucleation effect at 8 h and pozzolanic effect at 24 h and accelerate the hydration rate (∼83% at 8 h and ∼51% at 24 h) due to the formation of additional C-S-H nuclei. Further, 29Si-NMR and FTIR techniques showed the acceleration in polymerization of silicate chain leading to the formation of tobermorite like structure. Formation of polymerized and crystalline C-S-H gel in presence of SNPs increases the percentage of high density C-S-H (∼40%) and lowers the low density C-S-H (∼52%) at 24 h of hydration, as observed in nanoindentation results.
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Studies on optimization of silica nanoparticles dosage in Cementitious System
Cement and Concrete Composites, 2016Co-Authors: L P Singh, D. Ali, U SharmaAbstract:Optimization of silica nanoparticles (SNPs) dosage in Cementitious System was carried out analytically as well as experimentally by understanding the early stage hydration reaction of tricalcium silicate (C3S). XRD and TGA results show the maximum nucleation effect of SNPs at 8 h, when the rate of product formation was higher than the control (∼66% additional C-S-H and ∼61% more CH with 10% SNPs addition). While at 24 h of hydration, ∼25% additional C-S-H was formed and CH content reduced by ∼32% with 10% addition showing the pozzolanic effect of SNPs. Further, FTIR results reveal that SNPs accelerate the polymerization in silicate chain and with 10% SNPs addition more crystalline (probably tobermorite like) structure is formed. This is responsible for the formation of highly compact and dense microstructure at 24 h as observed in electron micrographs, which may be responsible for the slow hydration rate at later age. XRD, FTIR and TGA studies on C3S revealed that up to 5% addition of SNPs is beneficial, whereas higher dosages do not contribute significantly. Based on these investigations, studies were performed on cement paste, mortar and concrete samples, which revealed that 2-3% addition of SNPs is the optimum quantity for significant contribution in strength properties.
Haibin Zhang - One of the best experts on this subject based on the ideXlab platform.
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preparation of lignin based superplasticizer by graft sulfonation and investigation of the dispersive performance and mechanism in a Cementitious System
Industrial & Engineering Chemistry Research, 2013Co-Authors: Mengxia Wang, Dongjie Yang, Yuxia Pang, Bin Wang, Haibin ZhangAbstract:A practical graft sulfonation process was developed to synthesize a lignin-based superplasticizer using acid-precipitated lignin from wheat straw black liquor as raw material. The graft-sulfonated lignin, prepared in optimal reaction conditions, was named GSL. The properties of GSL in a Cementitious System were investigated. The adsorption isotherms of GSL fractions separated by ultrafiltration and the thickness of their absorbed films on cement particles were measured to reveal the dispersion mechanism. Also, it was found that the molecular weight of graft-sulfonated lignin increased with the dosage of acetone and formaldehyde, but having too high a molecular weight reduced its dispersive performance. High sulfonic group content in graft-sulfonated lignin severely inhibited the increase of molecular weight, resulting in a decrease of dispersive performance. GSL has stronger compressive strength enhancement in concrete and lower hydration heat temperature than the commercial naphthalene-sulfonated formald...
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effect of molecular weight of sulphonated acetone formaldehyde condensate on its adsorption and dispersion properties in Cementitious System
Cement and Concrete Research, 2012Co-Authors: Kaibin Ji, Yuxia Pang, Yonghong Deng, Haibin ZhangAbstract:Abstract This article studied the effect of molecular weight of sulphonated acetone-formaldehyde condensate (SAF) on the adsorption and dispersion properties in Cementitious System. SAF was separated into four different molecular weight fractions using ultrafiltration membranes. The adsorption behaviors were investigated by measuring the adsorption amount, zeta potential, and thickness of the adsorbed films obtained from various SAF fractions. Results show that the SAF fraction with a higher molecular weight has larger adsorption amount, higher absolute value of zeta potential, and thicker adsorbed film, which induces better dispersibility of the corresponding cement paste. An adsorption model of SAF on cement surface is presented. The SAF fraction with a higher molecular weight is more likely to twist and be adsorbed on cement particles through “loop and tail” adsorption. On the contrary, SAF fraction with a lower molecular weight tends to be adsorbed on cement particles through “flat train” adsorption.
Saurabh Ahalawat - One of the best experts on this subject based on the ideXlab platform.
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Beneficial role of nanosilica in cement based materials - A review
Construction and Building Materials, 2013Co-Authors: L P Singh, S. R. Karade, M. M. Yousuf, S. K. Bhattacharyya, Saurabh AhalawatAbstract:Nanomaterials are gaining widespread attention to be used in construction sector so as to exhibit enhanced performance of materials in terms of smart functions and sustainable features. During the last one decade a number of nanomaterials such as nanosilica, nanotitania, carbon nanotubes and nanoalumina have been explored and among them nanosilica has been used most extensively. A number of publications appeared towards the use of nanosilica in Cementitious System is mainly due to the fact that concrete remains the most complex material and its hydration mechanism is still not completely understood. Consequently, researchers are focusing on the basic science of this material at nano/atomic level. Further, researchers are continuing to improve the durability and sustainability of concrete, and they have realized significant increment in mechanical properties of Cementitious materials by incorporating nanosilica. This review paper summarizes the effects of nanosilica addition on hydration kinetics, microstructure refinement, fresh/hardened properties and durability characteristics of concrete. © 2013 Elsevier Ltd. All rights reserved.
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granulometric synthesis and characterisation of dispersed nanosilica powder and its application in Cementitious System
Advances in Applied Ceramics, 2012Co-Authors: L P Singh, S. K. Bhattacharyya, P Singh, Saurabh AhalawatAbstract:AbstractDispersed, spherical particles of nanosilica with controllable size have been synthesised using a metal alkoxide, i.e. tetraethoxysilane, as starting material, ammonia as base catalyst and non-ionic surfactant as template by sol–gel method. Size of particles and dispersivity were controlled by varying the surfactant chain length and temperature conditions of the reaction mixture. Silica nanoparticles were synthesised using a series of non-ionic surfactants, namely Polyoxyethylene (20) sorbitan monolaurate (Tween 20) and Polyoxyethylene (80) sorbitan monooleate (Tween 80), at different reaction temperatures of 25, 50, 70 and 90°C. The particle size of silica nanoparticles gradually decreased with increasing carbon chain length of the surfactant and at higher temperature particle size became larger. Furthermore, these silica nanoparticles are incorporated into the Cementitious System to improve the mechanical properties and reduce calcium leaching in the hydration process. Addition of silica nanopar...
B B Sabir - One of the best experts on this subject based on the ideXlab platform.
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sorptivity and strength of air cured and water cured pc pfa mk concrete and the influence of binder composition on carbonation depth
Cement and Concrete Research, 2002Co-Authors: J Bai, S Wild, B B SabirAbstract:Abstract The paper reports the influence of the composition of Portland cement–pulverised fuel ash–metakaolin (PC–PFA–MK) binders on sorptivity and strength development of PC–PFA–MK concrete cured both in air and in water and on carbonation depth, and relates this to measured changes in sorptivity of the concrete. Concrete mixtures covering four different total cement replacement levels (10%, 20%, 30% and 40%) for PC–PFA–MK concrete with various MK/PFA proportions, water and air cured for up to 18 months, were investigated. The change in compressive strength and sorptivity with age at all cement replacement levels under both water and air curing are compared with those of the control PC concrete. The results presented in this paper form part of an investigation into the optimisation of a ternary blended Cementitious System based on ordinary PC, PFA and MK for the development of high-performance concrete.
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Sorptivity and strength of air-cured and water-cured PC–PFA–MK concrete and the influence of binder composition on carbonation depth
Cement and Concrete Research, 2002Co-Authors: J Bai, S Wild, B B SabirAbstract:Abstract The paper reports the influence of the composition of Portland cement–pulverised fuel ash–metakaolin (PC–PFA–MK) binders on sorptivity and strength development of PC–PFA–MK concrete cured both in air and in water and on carbonation depth, and relates this to measured changes in sorptivity of the concrete. Concrete mixtures covering four different total cement replacement levels (10%, 20%, 30% and 40%) for PC–PFA–MK concrete with various MK/PFA proportions, water and air cured for up to 18 months, were investigated. The change in compressive strength and sorptivity with age at all cement replacement levels under both water and air curing are compared with those of the control PC concrete. The results presented in this paper form part of an investigation into the optimisation of a ternary blended Cementitious System based on ordinary PC, PFA and MK for the development of high-performance concrete.