Assessment of pozzolanic activity of thermally activated clay and its impact on strength development in cement mortar

RSC Advances ◽  
2015 ◽  
Vol 5 (8) ◽  
pp. 6079-6084 ◽  
Author(s):  
Noor-ul- Amin ◽  
Sultan Alam ◽  
Saeed gul
Keyword(s):  
Cement Mortar ◽  
Pozzolanic Activity ◽  
Strength Development ◽  
Thermally Activated ◽  
Different Temperatures ◽  
Kaolinitic Clay

Natural kaolinitic clay from Khyber Pakhtoonkhwa, Pakistan was thermally activated at different temperatures and its pozzolanic behavior was studied.

scholarly journals Correction: Assessment of pozzolanic activity of thermally activated clay and its impact on strength development in cement mortar

RSC Advances ◽  
2015 ◽  
Vol 5 (14) ◽  
pp. 10680-10680 ◽  
Author(s):  
Noor-ul- Amin ◽  
Sultan Alam ◽  
Saeed Gul
Keyword(s):  
Cement Mortar ◽  
Pozzolanic Activity ◽  
Strength Development ◽  
Thermally Activated

Correction for ‘Assessment of pozzolanic activity of thermally activated clay and its impact on strength development in cement mortar’ by Noor-ul- Amin et al., RSC Adv., 2015, 5, 6079–6084.

scholarly journals Surface Modification of Fly Ash for Active Catalysis

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Deepti Jain ◽  
Renu Hada ◽  
Ashu Rani
Keyword(s):  
Fly Ash ◽  
Heterogeneous Catalysts ◽  
Chemical Activation ◽  
Alumina Content ◽  
Precipitation Method ◽  
Solid Base ◽  
Thermally Activated ◽  
Flame Atomic Absorption ◽  
Flame Atomic Absorption Spectrophotometer ◽  
Different Temperatures

Fly ash based effective solid base catalyst (KF/Al2O3/fly ash473, KF/Al2O3/fly ash673, and KF/Al2O3/fly ash873) was synthesized by loading KF over chemically and thermally activated fly ash. The chemical activation was done by treating fly ash with aluminum nitrate via precipitation method followed by thermal activation at 650°C to increase the alumina content in fly ash. The increased alumina content was confirmed by SEM-EDX analysis. The alumina enriched fly ash was then loaded with KF (10 wt%) and calcined at three different temperatures 473 K, 673 K and 873 K. The amount of loaded KF was monitored by XRD, FTIR spectroscopy, SEM-EDX, TEM and Flame Atomic Absorption Spectrophotometer. The catalytic activities of the catalysts were tested in the Claisen-Schmidt condensation of benzaldehyde and 4-methoxybenzaldehyde with 2′-hydroxyacetophenone to produce 2′-hydroxychalcone and 4-methoxy-2′-hydroxychalcone respectively. Higher conversion (83%) of benzaldehyde and (89%) of 4-methoxybenzaldehyde reveals that among these heterogeneous catalysts KF/Al2O3/fly ash673 is very active.

The Effect on Cement Mortar and Concrete by Admixture of Spray Drying Absorption Products

1989 ◽  
Vol 178 ◽  
Author(s):  
Kirsten G. Jeppesen
Keyword(s):  
Grain Size ◽  
Fly Ash ◽  
Cement Mortar ◽  
Setting Time ◽  
Mineralogical Composition ◽  
Cement Clinker ◽  
Strength Development ◽  
Fall Meeting ◽  
Freeze Thaw ◽  
Spray Dried

AbstractSpray dried absorption products (SDA) having special characteristics are used as substitutes for cement in the preparation of mortars; the qualities of the resulting mixed mortars are described. Conditions are described for mortar mixes, data for which were presented at the MRS Fall Meeting 1987.The influence of the composition of the SDA on water requirement and setting time has been studied. A full scale project involving 3 precast, reinforced concrete front-elements containing 20 and 30 wt.% SDA is described. Strength development, mineralogical composition and corrosion were monitored for two years.A non-standard freeze-thaw experiment was performed which compares mortars containing SDA and fly ash (FA) and also shows the effect of superplasticizer.The possibility of improving the SDA by grinding has been tested and a limited improvement has been found. The strength of the mixed mortars seems slightly influenced by the grain size of SDAGypsum (CaSO4·2H2O), synthetic calcium-sulphite (CaSO3·½H2O) and 2 SDAs have been used as retarders for cement clinker. Mortar test prisms have been cast and comparative strengths after curing for 3 years are reported

scholarly journals Calcined Oyster Shell Powder as an Expansive Additive in Cement Mortar

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1322 ◽  
Author(s):  
Joon Ho Seo ◽  
Sol Moi Park ◽  
Beom Joo Yang ◽  
Jeong Gook Jang
Keyword(s):  
Compressive Strength ◽  
Cement Mortar ◽  
Autogenous Shrinkage ◽  
Oyster Shell ◽  
Heat Of Hydration ◽  
Strength Development ◽  
Flow Loss ◽  
Hardened Properties ◽  
Oyster Shell Powder ◽  
Shell Powder

The present study prepared calcined oyster shell powder having chemical composition and crystal structure of calcium oxide and lime, respectively, and investigated the fresh and hardened properties of cement mortar incorporating calcined oyster shell powder as an additive. The test results indicated that the hydration of calcined oyster shell powder promoted the additional formation of Ca(OH)2 at the initial reaction stage, thereby increasing the heat of hydration. In particular, the volumetric increase of calcined oyster shell powder during hydration compensated the autogenous shrinkage of mortar at early ages, ultimately leading to a clear difference in the shrinkage values at final readings. However, an excessive incorporation of calcined oyster shell powder affected the rate of C–S–H formation in the acceleratory period of hydration, resulting in a decrease in the compressive strength development. Meanwhile, the degree of flow loss was inconsequential and rapid flow loss was not observed in the specimens with calcined oyster shell powder. Therefore, considering the fresh and hardened properties of cement mortar, the incorporation of calcined oyster shell powder of approximately 3% by weight of cement is recommended to enhance the properties of cement mortar in terms of compressive strength and autogenous shrinkage.

Electrical and piezoresistive properties of carbon nanofiber cement mortar under different temperatures and water contents

2020 ◽  
Vol 265 ◽  
pp. 120740 ◽  
Author(s):  
Hui Wang ◽  
Ailian Zhang ◽  
Linchun Zhang ◽  
Qian Wang ◽  
Xiao-hong Yang ◽  
...  
Keyword(s):  
Carbon Nanofiber ◽  
Cement Mortar ◽  
Different Temperatures ◽  
Water Contents

scholarly journals Long-term hydrophilization of polydimethylsiloxane (PDMS) for capillary filling microfluidic chips

2019 ◽  
Vol 24 (1) ◽  
Author(s):  
Farzin Jahangiri ◽  
Tuuli Hakala ◽  
Ville Jokinen
Keyword(s):  
Cold Storage ◽  
Storage Temperature ◽  
Microfluidic Channel ◽  
Vibration Band ◽  
Microfluidic Chips ◽  
Thermally Activated ◽  
Capillary Filling ◽  
Different Temperatures ◽  
Long Term Preservation

AbstractWe present a simple and facile method for long-term preservation of hydrophilicity of oxygen plasma-hydrophilized poly (dimethylsiloxane) (PDMS) by cold storage. We show that storage under temperature of − 80 °C can maintain superhydrophilicity of plasma-exposed PDMS for at least 100 days. Storage at − 15 °C and at 22 °C room temperature (RT) is shown to exhibit, respectively, about half and full recovery of the original hydrophobicity after 100 days in storage. Furthermore, we investigated the implications of the cold storage for microfluidic applications, the capillary filling rate and the ability of the flow to bypass geometrical obstacles in a microfluidic channel. It is shown that the preservation of capillary filling properties of microchannels is in close agreement with the contact angle (CA) measurements and that the colder the storage temperature, the better the capillary filling capability of the channels is preserved. We ascribe the significantly reduced recovery rate to reduced thermally activated relaxation phenomena such as diminished diffusion of low molecular weight species (LMW) in the polymer matrix at colder temperatures. This is supported by ATR-FTIR measurements of the OH vibration band over time for samples stored at different temperatures.

Formation Mechanism and its Pozzolanic Activity of Metakaolin

2014 ◽  
Vol 602-603 ◽  
pp. 620-623 ◽  
Author(s):  
Mei Rong Wang ◽  
Ning Guo ◽  
Pei Gang He ◽  
Jing Bo Yu ◽  
De Chang Jia
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Fourier Transform ◽  
Solid State ◽  
Magnetic Resonance ◽  
Formation Mechanism ◽  
Infrared Spectra ◽  
Fourier Transform Infrared ◽  
Pozzolanic Activity ◽  
Different Temperatures ◽  
Increasing Temperature

In this paper, the process of the transformation from kaolin to metakaolin was investigated. The kaolin was calcined at different temperatures and analyzed by Xray diffraction (XRD), Fourier transform infrared spectra (FTIR) and solid state nuclear magnetic resonance (NMR). The formation of metakaolin structure was based on the stacking polyhedrons changes, which originated from dehydroxylation of kaolinite. With increasing temperature, kaolin kept structure of kaolinite unchanged in the course of dehydroxylation and then structure of kaolinite transformed to metakaolin when the dehydroxylation was over. It was demonstrated that the essence of pozzolanic activity of metakaolin. The result revealed that the pozzolanic activity of metakaolin increased with increasing temperature at the range of 600~900 °C.

The Meyer–Neldel Rule in Conduction Mechanism of the Electrospun ZnO Nanofibers

NANO ◽  
2016 ◽  
Vol 11 (03) ◽  
pp. 1650025 ◽  
Author(s):  
Andrzej Stafiniak ◽  
Marek Tłaczała
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Conduction Mechanism ◽  
Deep Level ◽  
Electrical Measurements ◽  
Thermally Activated ◽  
Theoretical Assumptions ◽  
Different Temperatures ◽  
Zno Nanofibers ◽  
Improved Model

An analytical model describing the conductivity of ZnO nanofibers depending on the grains size is proposed. The research is based on the thermal dc electrical measurements of a single electrospun ZnO nanofiber calcined at different temperatures. In the our previous research, we showed that electrical conduction of ZnO nanofibers is mainly thermally activated. The activation energy of conductivity was strongly dependent on the grain size, which in turn depended on the calcination temperature. This could be due to migration of a point defect in the grain of ZnO and could change the carrier concentration. Our recent studies have shown that ZnO nanofibers behavior is consistent with the Meyer–Neldel rule. This indicates an exponential energy distribution of deep level traps in the material. Based on the theoretical assumptions and experimental data, the improved model of conductivity in a single ZnO nanofiber calcined at different temperatures was proposed.

Experimental Evidence of Temperature Path Independence in the Polycrystalline Alloy Ni3AI

1995 ◽  
Vol 117 (4) ◽  
pp. 478-482 ◽  
Author(s):  
G. Webb ◽  
S. D. Antolovich
Keyword(s):  
Dislocation Substructure ◽  
Deformation Characteristic ◽  
Thermally Activated ◽  
Path Independence ◽  
History Independence ◽  
Polycrystalline Alloy ◽  
Different Temperatures ◽  
Deformation Processes ◽  
Thermal Reversibility ◽  
Temperature Path

The results from a series of elevated temperature prestrain experiments on a hypostoichiometric polycrstalline Ni3Al are presented. Experiments were conducted to examine the deformation characteristic of “thermal reversibility” or temperature path history independence (TPHI). Temperature path history independence was experimentally observed from prestraining experiments (also known as Cottrell-Stokes experiments) in which the specimen was deformed at different temperatures; the results were compared to those obtained from tests conducted at constant temperature. The purpose of such experiments was to macroscopically evaluate the effects of intrinsic dislocation mobility and dislocation substructure on deformation. These experiments provide a framework in which to evaluate fundamental characteristics of thermally activated deformation processes. The results for polycrystalline Ni3Al alloys indicate that the mechanisms responsible for thermal strengthening is independent of prior deformation history. This observation implies that the mechanism of anomalous strengthening in such alloys is fully reversible and independent of the development of a dislocation “substructure”.

scholarly journals Effect of Different Surface-charged Lamellar Materials on Swelling Properties of Nanocomposite Hydrogels

2021 ◽  
Author(s):  
Marcela Pfeifer ◽  
Flávio A. C. Andrade ◽  
Ricardo Bortoletto-Santos ◽  
Fauze A. Aouada ◽  
Caue Ribeiro
Keyword(s):  
Water Absorption ◽  
Anomalous Behavior ◽  
Absorption Capacity ◽  
Water Absorption Capacity ◽  
Swelling Properties ◽  
Ph Variation ◽  
Nanocomposite Hydrogels ◽  
Thermally Activated ◽  
Different Temperatures ◽  
Lamellar Materials

Abstract This study investigated the effect of different surface-charged lamellar materials on the swelling and diffusion properties of synthesized polyacrylamide-methylcellulose hydrogels (HG). Montmorillonite and hydrotalcite thermally activated at two different temperatures (300 and 550 ºC) were incorporated in the preparation of nanocomposite (NC) hydrogels. A series of NC hydrogels were prepared by varying the lamellar material content (1:1, 2:1 and 4:1). The results showed that the HG with hydrotalcite (550 ºC) was strongly dependent on the ionic intensity, and that the swelling degree increased by 50%, 65% and 78% with reducing the hydrotalcite content at (1:1), (2:1) and (4:1), respectively. The water absorption capacity of HG containing montmorillonite or hydrotalcite (300 ºC) was slightly affected when the pH decreased from 7 to 3. However, the pH variation from 7 to 10 increased the water absorption capacity of most HG, except those containing hydrotalcite (550 ºC) at (2:1) and (4:1). The presence of lamellar nanoparticles in hydrogels made the polymer matrix more rigid, and less likely to absorb water. In contrast, HG with hydrotalcite (550 ºC) at (2:1) and (4:1) showed anomalous behavior with an increase in their water absorption capacity. The results support that the developed NC-HG can be suitable candidates for applications as controlled released materials.

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