Geetika Mishra - Academia.edu (original) (raw)
Papers by Geetika Mishra
Applied Nanoscience, 2011
Journal of Building Engineering
Cement and Concrete Composites
Journal of emerging technologies and innovative research, 2020
India’s Power sector is expanding but due to increasing population energy demands are increasing ... more India’s Power sector is expanding but due to increasing population energy demands are increasing day by day. Solar energy is infinite energy resources to meet up long term energy crunch. India is a tropical country, where sunshine is available for longer hours per day and in great intensity. India has great potential in solar energy. The government also runs various schemes on solar power to increase the energy production and supply. This study is focusing on current status of energy generation, solar energy, its potential, government schemes and importance of solar energy to meet the energy crisis This paper also discusses upon the various challenges faced in the efficient and effective utilization of solar power and gives recommendations.
Diamond and Related Materials
Construction and Building Materials, 2022
Construction and Building Materials, 2015
ABSTRACT Hydration of tricalcium silicate (C3S) in presence of nano silica at early stage has bee... more ABSTRACT Hydration of tricalcium silicate (C3S) in presence of nano silica at early stage has been investigated and formation of addition calcium silicate hydrate (C–S–H) has been quantitatively estimated. Prepared C3S was hydrated in the presence of powder nanosilica (30–70 nm) using w/b ratio 0.4 for paste study and 5.0 for aqueous phase study. Results of ICP and XRD showed that the stage of supersaturation of Ca2+ is delayed by 30 min and formation of secondary/additional C–S–H starts at the early stages of C3S hydration in the presence of nano silica. This additional C–S–H is responsible for higher dissolution of C3S as observed by FTIR. SEM/EDX results show the formation of denser C–S–H with low C/S ratio in the presence of nano silica, whereas TG analysis revealed the formation of additional C–S–H (∼50%) in nano silica incorporated C3S system which is accountable for the higher specific surface area as obtained by N2-adsorption.
Applied Nanoscience, 2011
Mechanics and Physics of Creep, Shrinkage, and Durability of Concrete, 2013
Advances in Cement Research, 2014
An accelerated electro-migration experiment is carried out to examine the chloride penetration of... more An accelerated electro-migration experiment is carried out to examine the chloride penetration of cement mortar admixed with two types of nanosilica and compared with the natural diffusion measurement. The chloride ion concentration in the destination solution is measured by ultra violet–visible spectrophotometer at different time intervals. In the natural condition, the penetration of chloride ions through a 7-mm thick mortar disc takes approximately 24 h, whereas nanosilica incorporated mortar resists the ingress of chloride ions up to around 72 h. Furthermore, in the accelerated condition, the diffusion coefficient is reduced from 6·8 × 10−11 m2/s to 4·7 × 10−11 m2/s with 3% addition of nanosilica (type I) by weight of cement. The microstructure studies through scanning electron microscopy reveal that the nanosilica refines the pore structure of the mortar and leads to a denser microstructure owing to the formation of additional calcium-silicate-hydrate gel. The pozzolanic reacti...
Advances in colloid and interface science, Dec 6, 2014
Recently, silica nanoparticles (SNPs) have drawn widespread attention due to their applications i... more Recently, silica nanoparticles (SNPs) have drawn widespread attention due to their applications in many emerging areas because of their tailorable morphology. During the last decade, remarkable efforts have been made on the investigations for novel processing methodologies to prepare SNPs, resulting in better control of the size, shape, porosity and significant improvements in the physio-chemical properties. A number of techniques available for preparing SNPs namely, flame spray pyrolysis, chemical vapour deposition, micro-emulsion, ball milling, sol-gel etc. have resulted, a number of publications. Among these, preparation by sol-gel has been the focus of research as the synthesis is straightforward, scalable and controllable. Therefore, this review focuses on the recent progress in the field of synthesis of SNPs exhibiting ordered mesoporous structure, their distribution pattern, morphological attributes and applications. The mesoporous silica nanoparticles (MSNPs) with good dispe...
Materials Technology: Advanced Performance Materials, 2012
Applied Nanoscience, 2011
An experimental work was conducted for studying the influence of early age curing temperature on ... more An experimental work was conducted for studying the influence of early age curing temperature on the performance of low clinker blends. Three low clinker blends, limestone calcined clay cement (LC3), Portland pozzolanic cement (PPC) using fly ash, and Portland slag cement (PSC) were used in this study. The clinker replacement level was kept at 50% by weight for all the blends. In addition to the isothermal curing conditions at 27 and 50 °C till 28 days, samples were also exposed to two different temperature regimes by changing the specimens from 27 to 50 °C at the age of 1 day and 3 days. Mortar compressive strength and X-ray diffraction were carried out at the age of 28 days. Strength and degree of hydration of clinker phases were compared. The later age performance of low clinker blends observed to be detrimental at a higher temperature (50 °C). It is observed that reduction in performance is relatively higher in LC3 as compared to PSC and PPC. However, when the time of temperatur...
Supplementary cementitious materials (SCMs) are added to improve various mechanical and durabilit... more Supplementary cementitious materials (SCMs) are added to improve various mechanical and durability properties of cement and concrete. One of the indirect benefits of binary and ternary blended cements is to reduce CO2 emissions. As per Indian standards (IS), reactivity of pozzolanic material is observed in the presence of calcium hydroxide (CH) using lime reactivity test. A pozzolana should qualify lime reactivity test before adding it to the cement. In this study, reactivity of SCMs was observed using lime reactivity strength test and isothermal calorimeter. For this purpose, different calcined clays, fly ashes (FA), and slags were selected. Lime reactivity test was used to study the mechanical strength potential of SCMs and calorimeter was performed to measure total energy evolved during the reaction of SCMs with CH in the presence of water at 27 °C. Strength data from lime reactivity test was then finally correlated with the calorimeter heat evolved data in different conditions.
Carbonation of concrete is a complex physicochemical process. The overall volume of the system ch... more Carbonation of concrete is a complex physicochemical process. The overall volume of the system changes due to carbonation of different hydration products. During carbonation, t products formed on conversion of calcium hydroxide have a higher volume as compared to the initial products, thus the surplus volume fills up the empty space in the capillary system, resulting in a reduced porosity. Supplementary cementitious materials (SCMs) consume calcium hydroxide by pozzolanic reaction, which is the majorly responsible for high alkalinity. Volume change due to CSH transformation is most uncertain, and the type of polymorph formed depends on the calcium-to-silica ratio and water content of the silica gel. Therefore, the change in the microstructure of concrete due to carbonation depends upon the type of cement. In this study, the effect of accelerated carbonation on the microstructure of concrete, made from different cements, was analysed. Change in properties of concrete such as porosity...
The conventional use of binary cement is changing towards a composite cementitious system which a... more The conventional use of binary cement is changing towards a composite cementitious system which allows two or more supplementary materials in combination. In this way, present study focuses on the preparation of limestone-calcined clay blend and introduction into cement system at variable replacement level to study their influence on the properties of resulting concrete. The hydration behaviour of the ternary blended cement was carried out using heat of hydration and XRD analysis. Similarly, compressive strength was performed on mortar cubes at different hydration ages (1, 3, 7 and 28 days). From this study, it was observed that, the limestone in the presence of calcined clay results in the formation of additional hydrates. Furthermore, it is found that this ternary combination can significantly improve the substitution level of clinker with good mechanical characteristics.
Portand pozzolanic cement using fly ash (FA30), which replaces 30% of clinker, is the most produc... more Portand pozzolanic cement using fly ash (FA30), which replaces 30% of clinker, is the most produced cement in India. But, rules due to the fast depletion of natural resources and stricter on emissions, the industry is keen to reduce the clinker factor further. New ternary blended cement, limestone calcined clay cement (LC3) can be a good option due to its high clinker replacement and use of low grade raw materials. The cement is aimed for general purpose. India, having wide range of climatic conditions, producing general purpose cement for the entire country is always a hard task for cement companies. For a new cement, it is worthy to check the performance under different climatic conditions. In this regard, concrete columns were cast in both FA30 and LC3, and placed at 8 locations. NDT test was performed on columns to understand the performance concrete.
Applied Nanoscience, 2011
Journal of Building Engineering
Cement and Concrete Composites
Journal of emerging technologies and innovative research, 2020
India’s Power sector is expanding but due to increasing population energy demands are increasing ... more India’s Power sector is expanding but due to increasing population energy demands are increasing day by day. Solar energy is infinite energy resources to meet up long term energy crunch. India is a tropical country, where sunshine is available for longer hours per day and in great intensity. India has great potential in solar energy. The government also runs various schemes on solar power to increase the energy production and supply. This study is focusing on current status of energy generation, solar energy, its potential, government schemes and importance of solar energy to meet the energy crisis This paper also discusses upon the various challenges faced in the efficient and effective utilization of solar power and gives recommendations.
Diamond and Related Materials
Construction and Building Materials, 2022
Construction and Building Materials, 2015
ABSTRACT Hydration of tricalcium silicate (C3S) in presence of nano silica at early stage has bee... more ABSTRACT Hydration of tricalcium silicate (C3S) in presence of nano silica at early stage has been investigated and formation of addition calcium silicate hydrate (C–S–H) has been quantitatively estimated. Prepared C3S was hydrated in the presence of powder nanosilica (30–70 nm) using w/b ratio 0.4 for paste study and 5.0 for aqueous phase study. Results of ICP and XRD showed that the stage of supersaturation of Ca2+ is delayed by 30 min and formation of secondary/additional C–S–H starts at the early stages of C3S hydration in the presence of nano silica. This additional C–S–H is responsible for higher dissolution of C3S as observed by FTIR. SEM/EDX results show the formation of denser C–S–H with low C/S ratio in the presence of nano silica, whereas TG analysis revealed the formation of additional C–S–H (∼50%) in nano silica incorporated C3S system which is accountable for the higher specific surface area as obtained by N2-adsorption.
Applied Nanoscience, 2011
Mechanics and Physics of Creep, Shrinkage, and Durability of Concrete, 2013
Advances in Cement Research, 2014
An accelerated electro-migration experiment is carried out to examine the chloride penetration of... more An accelerated electro-migration experiment is carried out to examine the chloride penetration of cement mortar admixed with two types of nanosilica and compared with the natural diffusion measurement. The chloride ion concentration in the destination solution is measured by ultra violet–visible spectrophotometer at different time intervals. In the natural condition, the penetration of chloride ions through a 7-mm thick mortar disc takes approximately 24 h, whereas nanosilica incorporated mortar resists the ingress of chloride ions up to around 72 h. Furthermore, in the accelerated condition, the diffusion coefficient is reduced from 6·8 × 10−11 m2/s to 4·7 × 10−11 m2/s with 3% addition of nanosilica (type I) by weight of cement. The microstructure studies through scanning electron microscopy reveal that the nanosilica refines the pore structure of the mortar and leads to a denser microstructure owing to the formation of additional calcium-silicate-hydrate gel. The pozzolanic reacti...
Advances in colloid and interface science, Dec 6, 2014
Recently, silica nanoparticles (SNPs) have drawn widespread attention due to their applications i... more Recently, silica nanoparticles (SNPs) have drawn widespread attention due to their applications in many emerging areas because of their tailorable morphology. During the last decade, remarkable efforts have been made on the investigations for novel processing methodologies to prepare SNPs, resulting in better control of the size, shape, porosity and significant improvements in the physio-chemical properties. A number of techniques available for preparing SNPs namely, flame spray pyrolysis, chemical vapour deposition, micro-emulsion, ball milling, sol-gel etc. have resulted, a number of publications. Among these, preparation by sol-gel has been the focus of research as the synthesis is straightforward, scalable and controllable. Therefore, this review focuses on the recent progress in the field of synthesis of SNPs exhibiting ordered mesoporous structure, their distribution pattern, morphological attributes and applications. The mesoporous silica nanoparticles (MSNPs) with good dispe...
Materials Technology: Advanced Performance Materials, 2012
Applied Nanoscience, 2011
An experimental work was conducted for studying the influence of early age curing temperature on ... more An experimental work was conducted for studying the influence of early age curing temperature on the performance of low clinker blends. Three low clinker blends, limestone calcined clay cement (LC3), Portland pozzolanic cement (PPC) using fly ash, and Portland slag cement (PSC) were used in this study. The clinker replacement level was kept at 50% by weight for all the blends. In addition to the isothermal curing conditions at 27 and 50 °C till 28 days, samples were also exposed to two different temperature regimes by changing the specimens from 27 to 50 °C at the age of 1 day and 3 days. Mortar compressive strength and X-ray diffraction were carried out at the age of 28 days. Strength and degree of hydration of clinker phases were compared. The later age performance of low clinker blends observed to be detrimental at a higher temperature (50 °C). It is observed that reduction in performance is relatively higher in LC3 as compared to PSC and PPC. However, when the time of temperatur...
Supplementary cementitious materials (SCMs) are added to improve various mechanical and durabilit... more Supplementary cementitious materials (SCMs) are added to improve various mechanical and durability properties of cement and concrete. One of the indirect benefits of binary and ternary blended cements is to reduce CO2 emissions. As per Indian standards (IS), reactivity of pozzolanic material is observed in the presence of calcium hydroxide (CH) using lime reactivity test. A pozzolana should qualify lime reactivity test before adding it to the cement. In this study, reactivity of SCMs was observed using lime reactivity strength test and isothermal calorimeter. For this purpose, different calcined clays, fly ashes (FA), and slags were selected. Lime reactivity test was used to study the mechanical strength potential of SCMs and calorimeter was performed to measure total energy evolved during the reaction of SCMs with CH in the presence of water at 27 °C. Strength data from lime reactivity test was then finally correlated with the calorimeter heat evolved data in different conditions.
Carbonation of concrete is a complex physicochemical process. The overall volume of the system ch... more Carbonation of concrete is a complex physicochemical process. The overall volume of the system changes due to carbonation of different hydration products. During carbonation, t products formed on conversion of calcium hydroxide have a higher volume as compared to the initial products, thus the surplus volume fills up the empty space in the capillary system, resulting in a reduced porosity. Supplementary cementitious materials (SCMs) consume calcium hydroxide by pozzolanic reaction, which is the majorly responsible for high alkalinity. Volume change due to CSH transformation is most uncertain, and the type of polymorph formed depends on the calcium-to-silica ratio and water content of the silica gel. Therefore, the change in the microstructure of concrete due to carbonation depends upon the type of cement. In this study, the effect of accelerated carbonation on the microstructure of concrete, made from different cements, was analysed. Change in properties of concrete such as porosity...
The conventional use of binary cement is changing towards a composite cementitious system which a... more The conventional use of binary cement is changing towards a composite cementitious system which allows two or more supplementary materials in combination. In this way, present study focuses on the preparation of limestone-calcined clay blend and introduction into cement system at variable replacement level to study their influence on the properties of resulting concrete. The hydration behaviour of the ternary blended cement was carried out using heat of hydration and XRD analysis. Similarly, compressive strength was performed on mortar cubes at different hydration ages (1, 3, 7 and 28 days). From this study, it was observed that, the limestone in the presence of calcined clay results in the formation of additional hydrates. Furthermore, it is found that this ternary combination can significantly improve the substitution level of clinker with good mechanical characteristics.
Portand pozzolanic cement using fly ash (FA30), which replaces 30% of clinker, is the most produc... more Portand pozzolanic cement using fly ash (FA30), which replaces 30% of clinker, is the most produced cement in India. But, rules due to the fast depletion of natural resources and stricter on emissions, the industry is keen to reduce the clinker factor further. New ternary blended cement, limestone calcined clay cement (LC3) can be a good option due to its high clinker replacement and use of low grade raw materials. The cement is aimed for general purpose. India, having wide range of climatic conditions, producing general purpose cement for the entire country is always a hard task for cement companies. For a new cement, it is worthy to check the performance under different climatic conditions. In this regard, concrete columns were cast in both FA30 and LC3, and placed at 8 locations. NDT test was performed on columns to understand the performance concrete.