Experimental study on geopolymer concrete prepared using high-silica RHA incorporating alccofine

Parveen, Parveen,Singhal, Dhirendra,Jindal, Bharat Bhushan Techno-Press 2017 Advances in concrete construction Vol.5 No.4

This paper describes the experimental investigation carried out to develop geopolymer concrete using rice husk ash (RHA) along with alccofine. The study reports the fresh and hardened properties of the geopolymer concrete (GPC) activated using alkaline solution. GPC were prepared using different RHA content (350, 375 and $400kg/m^3$), the molarity of the NaOH (8, 12 and 16M). The specimens were cured at $27^{\circ}C$ and $90^{\circ}C$. GPC was activated using NaOH, $Na_2SiO_3$, and alccofine. Prepared GPC samples were tested for compressive and splitting tensile strengths after 3, 7 and 28 days. RHA was suitable to produce geopolymer concrete. Results indicate that behavior of GPC prepared with RHA is similar to fly ash based GPC. Workability and strength can be improved by incorporating the alccofine. Further, alccofine and heat curing improve the early age properties of the GPC. Heat curing is responsible for the initial polymerization of GPC which leads to high workability and improved mechanical properties of the GPC. High strength can be achieved by using the high concentration alkaline solution in terms of molarity and at elevated heat curing. Further, RHA based geopolymer concrete has tremendous potential as a substitute for ordinary concrete.

Mechanical and microstructural study of rice husk ash geopolymer paste with ultrafine slag

Parveen, Parveen,Jindal, Bharat Bhushan,Junaid, M. Talha,Saloni, Saloni Techno-Press 2019 Advances in concrete construction Vol.8 No.3

This paper presents the mechanical and microstructural properties of the geopolymer paste which was developed by utilizing the industrial by-products, rice husk ash (RHA) and ultra-fine slag. Ultra-fine slag particles with average particle size in the range of 4 to 5 microns. RHA is partially replaced with ultra-fine slag at different levels of 0 to 50%. Sodium silicate to sodium hydroxide ratio of 1.0 and alkaline liquid to binder (AL/B) ratio of 0.60 is taken. Setting time, compressive, flexural strengths were studied up to the age of 90 days with different concentrations of NaOH. The microstructure of the hybrid geopolymer paste was studied by performing the SEM, EDS, and XRD on the broken samples. RHA based geopolymer paste blended with ultrafine slag resulted in high compressive and flexural strengths and increased setting times of the paste. Strength increased with the increase in NaOH concentration at all ages. The ultra-small particles of the slag acted as a micro-filler into the paste and enhanced the properties by improving the CASH, NASH, and CSH. The maximum compressive strength of 70MPa was achieved at 30% slag content with 16M NaOH. The results of XRD, SEM, and EDS at 30% replacement of RHA with ultra-fine slag densified the paste microstructure.

Development of mix design method for geopolymer concrete

Parveen, Parveen,Singhal, Dhirendra Techno-Press 2017 Advances in concrete construction Vol.5 No.4

This study proposes a mix design method for geopolymer concrete (GPC) using low calcium fly ash and alccofine, with the focus on achieving the required compressive strength and workability at heat and ambient curing. Key factors identified and nine mixes with varied fly ash content (350, 375 and $400kg/m^3$) and different molarity (8, 12 and 16M) of NaOH solutions were prepared. The cubes prepared were cured at different temperatures ($27^{\circ}C$, $60^{\circ}C$ and $90^{\circ}C$) and tested for its compressive strength after 3, 7 and 28 days of curing. Fly ash content has been considered as the direct measure of workability and strength. The suggested mix design approach has been verified with the help of the example and targets well the requirements of fresh and hardened concrete.

Effect of ultra-fine slag on mechanical and permeability properties of Metakaolin-based sustainable geopolymer concrete

Parveen, Parveen,Mehta, Ankur,Saloni, Saloni Techno-Press 2019 Advances in concrete construction Vol.7 No.4

The present study deals with the development of metakaolin-based geopolymer concrete (GPC) and thereafter studying the effects of adding ultra-fine slag on its mechanical and permeability characteristics. The mechanical characteristics including compressive, split tensile, flexural strengths and elastic modulus were studied. In addition, permeability characteristics including water absorption, porosity, sorptivity and chloride permeability were studied up to 90 days. The results showed the effective utilization of metakaolin for the development of elevated temperature cured geopolymer concrete having high 3-day compressive strength of 42.6 MPa. The addition of ultra-fine slag up to 15%, as partial replacement of metakaolin resulted in an increase in strength characteristics. Similar improvement in durability properties was also observed with the inclusion of ultra-fine slag up to 15%. Beyond this optimum content of 15%, further increase in ultra-fine slag content affected the mechanical as well as permeability parameters in a negative way. In addition, the relationship between various properties of GPC was also derived.

Time harmonic interactions in non local thermoelastic solid with two temperatures

Parveen Lata,Sukhveer Singh 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.74 No.3

The present investigation is concerned with two dimensional deformation in a non local thermoelastic solid with two temperatures due to time harmonic sources. The nonlocal thermoelastic solid is homogeneous with the effect of two temperature parameters. Fourier transforms are used to solve the problem. The bounding surface is subjected to concentrated and distributed sources. The analytical expressions of displacement, stress components and conductive temperature are obtained in the transformed domain. Numerical inversion technique has been applied to obtain the results in the physical domain. Numerical simulated results are depicted graphically to show the effect of nonlocal parameter and frequency on the components of displacements, stresses and conductive temperature. Some special cases are also deduced from the present investigation.

Thermomechanical interactions in transversely isotropic thick circular plate with axisymmetric heat supply

Parveen Lata,Iqbal Kaur 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.69 No.6

The present investigation has focus on the study of deformation due to thermomechanical sources in a thick circular plate. The thick circular plate is homogeneous, transversely isotropic with two temperatures and without energy dissipation. The upper and lower surfaces of the thick circular plate are traction free. The Laplace and Hankel transform has been used for finding the general solution to the field equations. The analytical expressions of stresses, conductive temperature and displacement components are computed in the transformed domain. However, the resulting quantities are obtained in the physical domain by using numerical inversion technique. Numerically simulated results are illustrated graphically. The effects of two temperatures by considering different values of temperature parameters are shown on the various components. Some particular cases are also figured out from the present investigation.

Truth of Quality

Parveen S. Goel 대한산업공학회 2000 ie 매거진 Vol.7 No.1

Time harmonic interactions in an orthotropic media in the context of fractional order theory of thermoelasticity

Parveen Lata,Himanshi Zakhmi 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.73 No.6

The present investigation deals with the thermomechanical interactions in an orthotropic thermoelastic homogeneous body in the context of fractional order theory of thermoelasticity due to time harmonic sources. The application of a time harmonic concentrated and distributed sources has been considered to show the utility of the solution obtained. Assuming the disturbances to be harmonically time dependent, the expressions for displacement components, stress components and temperature change are derived in frequency domain. Numerical inversion technique has been used to determine the results in physical domain. The effect of frequency on various components has been depicted through graphs.

Intercalated reduced graphene oxide and its content effect on the supercapacitance performance of the three dimensional flower-like β-Ni(OH)₂ architecture

Parveen, Nazish,Ansari, Sajid Ali,Ansari, S. G.,Fouad, H.,Cho, Moo Hwan The Royal Society of Chemistry 2017 NEW JOURNAL OF CHEMISTRY Vol.41 No.18

<▼1><▼1><P>Anchoring of three dimensional (3D) metal oxides with a controlled morphology on a reduced graphene sheet (rGO) is a promising and challenging route towards the development of highly efficient electrode materials for supercapacitor applications.</P></▼1><▼2><P>Anchoring of three dimensional (3D) metal oxides with a controlled morphology on a reduced graphene sheet (rGO) is a promising and challenging route towards the development of highly efficient electrode materials for supercapacitor applications. Herein, we have designed an interconnected 3D flower-like β-Ni(OH)2@rGO (3D-FL-NiH@rGO) architecture and studied the effect of rGO on the morphology as well as supercapacitive performance of 3D-FL-NiH in detail. By varying the experimental parameters, the optimized 3D-FL-NiH@rGO composite achieved the highest capacitance of ∼1710 F g<SUP>−1</SUP> at a current load of 2 A g<SUP>−1</SUP> and also exhibited outstanding cycling performance as compared to the bare 3D-FL-NiH. Further investigation revealed that the improved capacitance of 3D-FL-NiH@rGO is due to the unique 3D and flower like architecture of 3D-FL-NiH which provides a high surface area (124.21 m<SUP>2</SUP> g<SUP>−1</SUP>) and more optimal mesoporous size (∼8–15 nm) as compared to the corresponding value of 72.9 m<SUP>2</SUP> g<SUP>−1</SUP> and microporous size of the bare 3D-FL-NiH. The presence of rGO and 3D-FL of the β-NiH provided strain relaxation during the charge–discharge procedures, which enhanced the electrical conductivity of the electrode and hence improved the cycling performance of 3D-FL-NiH@rGO.</P></▼2></▼1>

Manganese dioxide nanorods intercalated reduced graphene oxide nanocomposite toward high performance electrochemical supercapacitive electrode materials

Parveen, Nazish,Ansari, Sajid Ali,Ansari, Mohammad Omaish,Cho, Moo Hwan Elsevier 2017 JOURNAL OF COLLOID AND INTERFACE SCIENCE - Vol.506 No.-

<P><B>Abstract</B></P> <P>The development of manganese dioxide-based nanocomposites as materials for energy storage applications is advantageous because of its polymorphism behavior and structural flexibility. In this study, manganese dioxide (MnO<SUB>2</SUB>) nanorod-intercalated reduced graphene oxide (rGO) nanocomposite was obtained through a simple hydrothermal method and their electrochemical supercapacitance was studied in a three electrode half-assembly electrochemical cell. The basic spectroscopic and diffraction data including Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy were employed to characterize the resulting nanocomposite. Cyclic voltammetry and galvanostatic charge-discharge measurements were conducted to evaluate the electrochemical supercapacitance of the rGO-MnO<SUB>2</SUB> nanocomposite electrode. The rGO-MnO<SUB>2</SUB> nanocomposite delivered significantly higher capacitance than the P-MnO<SUB>2</SUB> under similar measurement conditions. This enhanced supercapacitive performance of the rGO-MnO<SUB>2</SUB> nanocomposite was attributed to chemical interactions and the synergistic effect between rGO and MnO<SUB>2</SUB>, which was helpful in enhancing the electrical conductivity and providing sufficient space for electrode/electrolyte contact during the electrochemical reaction.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>