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Theerawat Sinsiri - One of the best experts on this subject based on the ideXlab platform.
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Effect of palm oil fuel ash fineness on the microstructure of blended Cement Paste
Construction and Building Materials, 2011Co-Authors: Wunchock Kroehong, Chai Jaturapitakkul, Theerawat Sinsiri, Prinya ChindaprasirtAbstract:Abstract This paper presents the effect of palm oil fuel ash fineness on the microstructure of blended Cement Paste. Palm oil fuel ash (POFA) was ground to two different finenesses. Coarse and high fineness palm oil fuel ash, with median particle sizes of 15.6 and 2.1 μm, respectively, were used to replace ordinary Portland Cement (OPC) at 0%, 20% and 40% by binder weight. A water to binder ( W / B ) ratio of 0.35 was used for all blended Cement Pastes. The amorphous ground palm oil fuel ash was characterized by the Rietveld method. The compressive strength, thermogravimetric analysis and pore size distribution of the blended Cement Pastes were investigated. The test results indicate that the ground palm oil fuel ash was an amorphous silica material. The compressive strengths of the blended Cement Pastes containing coarse POFA were as high as that of OPC Cement Paste. Blended Cement Paste with high fineness POFA had a higher compressive strength than that with coarse POFA. The blended Cement Pastes containing 20% of POFA with high fineness had the lowest total porosity. The Ca(OH) 2 contents of blended Cement Paste containing POFA decreased with increasing replaCement of POFA and were lower than those of the OPC Cement Paste. In addition, the POFA fineness had an effect on the reduction rate of Ca(OH) 2 . Furthermore, the critical pore size and average pore size of blended Cement Paste containing POFA were lower than those of the OPC Cement Paste. The incorporation of high fineness POFA decreased the critical pore size and the average pore size of blended Cement Paste as compared to that with coarse POFA.
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effect of fly ash fineness on microstructure of blended Cement Paste
Construction and Building Materials, 2007Co-Authors: Chai Jaturapitakkul, Theerawat SinsiriAbstract:Abstract This research demonstrates the effect of fly ash fineness on pore size and microstructure of hardened blended Cement Pastes. Two sizes of fly ash, original fly ash and classified fly ash were used to replace Portland Cement type I Paste. Test results indicated that the pore sizes of hardened blended Cement Paste were significantly affected by the rate of replaCement and the fineness of fly ash. The replaCement of Cement by original fly ash decreased the pore sizes of blended Cement Paste and the incorporation of classified fly ash resulted in a further decrease in the pore sizes of blended Cement Paste. The X-ray diffraction (XRD) results showed that the blended Cement Paste with classified fly ash was more effective at reducing the intensity of Ca(OH)2 than that with the original fly ash. The scanning electron microscope (SEM) results revealed that the hardened blended Cement Paste containing finer fly ash produced a denser structure than the one containing coarser fly ash.
Surendra P Shah - One of the best experts on this subject based on the ideXlab platform.
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effects of graphene oxide on early age hydration and electrical resistivity of portland Cement Paste
Construction and Building Materials, 2017Co-Authors: Shu Jian Chen, Wenhui Duan, Yan Ming Liu, Surendra P ShahAbstract:The effects of graphene oxide (GO) on the early-age hydration process and mechanical properties of Portland Cement Paste were experimentally investigated in this study. Based on an isothermal calorimeter measurement, the hydration rate of Cement was observed to increase with the increase of GO content by nucleation effect. On the other hand, the electrical resistivity development of GO-Cement Paste was monitored using a non-contact electrical resistivity device. The result showed that electrical the resistivity of GO-Cement Paste was evidently higher than that of plain Cement Paste. However, Cement Paste with excessive amounts of GO exhibited a decreased electrical resistivity due to the massive ion diffusion caused by GO. Compared to plain Cement Paste, the GO-Cement Paste exhibited obviously higher compressive and flexural strengths, but the enhanCements in compressive strength began to decline when the GO amount was greater than 0.04%. The microstructure characterization indicated that GO can apparently densify the Cement Pastes with less porosity and hydrates networking, which is consistent with the results of hydration acceleration and strength enhanCement.
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observation of Cement Paste microstructure evolution
Transportation Research Record, 2010Co-Authors: Giri Venkiteela, Zhihui Sun, Surendra P ShahAbstract:During early hydration in fresh concrete, the Cement Paste hardens and bonds the aggregates together to make a solid concrete mass. During this process, along with chemical reactions, physical changes in the Cement Paste at the microlevel and the nanolevel also play major roles in the development of the properties of the concrete. An attempt was made to study the microstructure of Cement Paste and the evolution of its corresponding elastic modulus during setting. For this purpose, two different in situ testing methods, scanning electron microscopy (SEM) with a Quantomix capsuling system and a nondestructive one-sided ultrasonic technique, ultrasonic wave reflection method, were used. The features in the SEM images were quantified by the use of image analysis techniques, and quantitative analysis was used to examine the relationship between the microstructure of the Cement Paste and the corresponding dynamic shear modulus during the initial and final setting times. Cement particle growth, motions, and rota...
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identifying viscosity of Cement Paste from mini slump flow test
Aci Materials Journal, 2008Co-Authors: Nathan A Tregger, Liberato Ferrara, Surendra P ShahAbstract:For high-performance concretes, including self-consolidating concretes, to be successful, rheological property quality control is proving to be critical. No tests that are widely accepted for quick and accurate determination of these properties exist, however. Qualitative workability is current assessed through the slump-flow test. However, using a rheological description for a more complete view of workability can be provided through yield stress, viscosity, and other fundamental parameters. The correlations between yield stress and the final spread of the slump-flow tests, as well as between Cement Paste and mini-slump-flow tests, have been shown through previous studies. Demonstrating a relationship between time to final spread and Cement Paste viscosity is the intention of this study. Paving the way to an ultimate relationship for concrete can be assisted by this information, even though the study examines Cement Paste. Adequate quality control measures will be able to be provided for today's high-performance concrete by the slump-flow test with this relationship.
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modeling the linear elastic properties of portland Cement Paste
Cement and Concrete Research, 2005Co-Authors: Claus J Haecker, Zhihui Sun, Surendra P Shah, Edward J Garboczi, Jeffrey W Bullard, Robert B Bohn, Thomas VoigtAbstract:Abstract The linear elastic moduli of Cement Paste are key parameters, along with the Cement Paste compressive and tensile strengths, for characterizing the mechanical response of mortar and concrete. Predicting these moduli is difficult, as these materials are random, complex, multi-scale composites. This paper describes how finite element procedures combined with knowledge of individual phase moduli are used, in combination with a Cement Paste microstructure development model, to quantitatively predict elastic moduli as a function of degree of hydration, as measured by loss on ignition. Comparison between model predictions and experimental results are good for degrees of hydration of 50% or greater, for a range of water : Cement ratios. At early ages, the resolution of the typical 1003 digital microstructure is inadequate to give accurate results for the tenuous Cement Paste microstructure that exists at low degrees of hydration. Elastic computations were made on higher resolution microstructures, up to 4003, and compared to early age elastic moduli data. Increasing agreement with experiment was seen as the resolution increased, even when ignoring possible viscoelastic effects.
Zongjin Li - One of the best experts on this subject based on the ideXlab platform.
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micromechanical investigation of magnesium oxychloride Cement Paste
Construction and Building Materials, 2016Co-Authors: Chuanlin Hu, Binmeng Chen, Biwan Xu, Zongjin LiAbstract:Abstract In this study, nanoindentation coupled with scanning electron microscopy technique for the microstructural and micromechanical characterizations were applied on the magnesium oxychloride (MOC) Cement Paste. For the first time, micromechanical properties of the reaction product, phase 5 ( 5 Mg ( OH ) 2 · MgCl 2 · 8 H 2 O ) in MOC Cement system were investigated. It was determined that the average indentation modulus and hardness of phase 5 were 32.5 ± 4.2 GPa and 1.03 ± 0.19 GPa, respectively. Moreover, the elastic modulus of the MOC Cement Paste at micro- and macro-scales were further correlated, which built a framework for predicting its macroscopic elastic modulus.
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mechanism of Cement Paste reinforced by graphene oxide carbon nanotubes composites with enhanced mechanical properties
RSC Advances, 2015Co-Authors: Zeyu Lu, Lingshi Meng, Cong Lu, Zongjin LiAbstract:This study presents the enhanced mechanical properties of Cement Paste reinforced by graphene oxide (GO)/carbon nanotubes (CNTs) composites. The UV-vis spectroscopy and optical microscopy results show that the dispersion of CNTs in the GO solution is much better than in an aqueous solution due to the higher electrostatic repulsion, which allows a completely new approach of dispersing CNTs rather than by incorporating a dispersant. More importantly, the GO/CNTs composite plays an important role in improving the compressive and flexural strength of Cement Paste by 21.13% and 24.21%, which is much higher than Cement Paste reinforced by CNTs (6.40% and 10.14%) or GO (11.05% and 16.20%). The improved mechanical properties of Cement Paste are attributed to better dispersed CNTs and enhanced interactions among CNTs by the GO incorporation. Finally, the space interlocking mechanism of the GO/CNTs/Cement Paste composite with enhanced mechanical properties is proposed.
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two scale modeling of the capillary network in hydrated Cement Paste
Construction and Building Materials, 2014Co-Authors: Youyuan Lu, Zongjin LiAbstract:Abstract Objective Studies on pore structure are essential to better understand the transport properties and durability of Cement based materials. In this study, a two-scale modeling framework is proposed to simulate the capillary pore network in hydrated Cement Paste. Methods Capillary pores are divided into small capillary pores (SCPs) and large capillary pores (LCPs). It is assumed that all SCPs are embedded in the outer calcium silicate hydrates (C–S–H) layer, which is the mixture of low density (LD) C–S–H and SCPs at sub-micro-scale. The porosity of outer C–S–H layers is found to be a function of the water-to-Cement ratio ( w/c ) and the degree of hydration. Using this porosity to define the status, the outer C–S–H layer is simulated as a two-phase mixture based on a sub-micro-scale status-oriented model. Using the degree of hydration to define the status of a Cement Paste, Cement Paste is simulated as a mixture of unhydrated Cement cores, inner hydration products, outer C–S–H layers, micro-sized crystal hydrates particles and large capillary pores, based on a micro-scale status-oriented model. Results The two computer models developed for pore structure simulations of Cement Paste, at different scales, are verified by nitrogen adsorption and microscopic image processing, respectively.
Wenhui Duan - One of the best experts on this subject based on the ideXlab platform.
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effects of graphene oxide aggregates on hydration degree sorptivity and tensile splitting strength of Cement Paste
Composites Part A-applied Science and Manufacturing, 2017Co-Authors: Samuel Chuah, Yan Ming Liu, Wenhui DuanAbstract:Abstract It has recently been found the graphene oxide (GO) aggregates form in Cement Paste due to the chemical cross-linking of calcium cations. Therefore, the effects of GO addition on the properties of Cement based materials should be dependent on the properties of GO aggregates rather than GO nanosheets. In this study, GO aggregates were first characterized by particle size measurement. Then, the effects of GO aggregates on the degree of hydration, sorptivity, and tensile strength of Cement Paste were investigated. The aspect ratio of GO aggregates is much larger than that of the original GO nanosheets. Compared to plain Cement Paste, the increase of non-evaporable water content of the Cement Paste was found to be very limited, around 1.17% and 3.90% for Cement Pastes containing 0.02% and 0.04% by weight GO, respectively. The sorptivity of Cement Paste, especially the secondary sorptivity, was notably reduced for GO incorporated Cement Paste. The tensile strength was significantly improved by GO aggregates. Incorporation of 0.04% by weight GO increased the tensile strength by 67% compared to that of plain Cement Paste.
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effects of graphene oxide agglomerates on workability hydration microstructure and compressive strength of Cement Paste
Construction and Building Materials, 2017Co-Authors: Yan Ming Liu, Jay G Sanjayan, Wenhui DuanAbstract:Abstract In this study, the effects of graphene oxide (GO) agglomerates on the workability, hydration, microstructure, and compressive strength of Cement Paste were addressed. The workability of Cement Paste was reduced because of the presence of GO agglomerates, which entrap a large amount of water. The mini-slump diameter was reduced by 21% with the incorporation of 0.03% by weight GO in Cement Paste. Hydration of the Cement Paste was accelerated due to nucleation sites provided by GO agglomerates serving as seeding material in the Cement Paste. The incorporation of GO refined the pore structure of the Cement Paste. The incorporation of GO was found to have much greater impact on macropores than on large and small mesopores. At 28 days, the incorporation of 0.04% by weight GO produced a 14% improvement in the compressive strength of Cement Paste. Below 0.03%, the incorporation of GO had no positive effects on compressive strength.
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effects of graphene oxide on early age hydration and electrical resistivity of portland Cement Paste
Construction and Building Materials, 2017Co-Authors: Shu Jian Chen, Wenhui Duan, Yan Ming Liu, Surendra P ShahAbstract:The effects of graphene oxide (GO) on the early-age hydration process and mechanical properties of Portland Cement Paste were experimentally investigated in this study. Based on an isothermal calorimeter measurement, the hydration rate of Cement was observed to increase with the increase of GO content by nucleation effect. On the other hand, the electrical resistivity development of GO-Cement Paste was monitored using a non-contact electrical resistivity device. The result showed that electrical the resistivity of GO-Cement Paste was evidently higher than that of plain Cement Paste. However, Cement Paste with excessive amounts of GO exhibited a decreased electrical resistivity due to the massive ion diffusion caused by GO. Compared to plain Cement Paste, the GO-Cement Paste exhibited obviously higher compressive and flexural strengths, but the enhanCements in compressive strength began to decline when the GO amount was greater than 0.04%. The microstructure characterization indicated that GO can apparently densify the Cement Pastes with less porosity and hydrates networking, which is consistent with the results of hydration acceleration and strength enhanCement.
Chai Jaturapitakkul - One of the best experts on this subject based on the ideXlab platform.
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Effect of palm oil fuel ash fineness on the microstructure of blended Cement Paste
Construction and Building Materials, 2011Co-Authors: Wunchock Kroehong, Chai Jaturapitakkul, Theerawat Sinsiri, Prinya ChindaprasirtAbstract:Abstract This paper presents the effect of palm oil fuel ash fineness on the microstructure of blended Cement Paste. Palm oil fuel ash (POFA) was ground to two different finenesses. Coarse and high fineness palm oil fuel ash, with median particle sizes of 15.6 and 2.1 μm, respectively, were used to replace ordinary Portland Cement (OPC) at 0%, 20% and 40% by binder weight. A water to binder ( W / B ) ratio of 0.35 was used for all blended Cement Pastes. The amorphous ground palm oil fuel ash was characterized by the Rietveld method. The compressive strength, thermogravimetric analysis and pore size distribution of the blended Cement Pastes were investigated. The test results indicate that the ground palm oil fuel ash was an amorphous silica material. The compressive strengths of the blended Cement Pastes containing coarse POFA were as high as that of OPC Cement Paste. Blended Cement Paste with high fineness POFA had a higher compressive strength than that with coarse POFA. The blended Cement Pastes containing 20% of POFA with high fineness had the lowest total porosity. The Ca(OH) 2 contents of blended Cement Paste containing POFA decreased with increasing replaCement of POFA and were lower than those of the OPC Cement Paste. In addition, the POFA fineness had an effect on the reduction rate of Ca(OH) 2 . Furthermore, the critical pore size and average pore size of blended Cement Paste containing POFA were lower than those of the OPC Cement Paste. The incorporation of high fineness POFA decreased the critical pore size and the average pore size of blended Cement Paste as compared to that with coarse POFA.
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effect of fly ash fineness on microstructure of blended Cement Paste
Construction and Building Materials, 2007Co-Authors: Chai Jaturapitakkul, Theerawat SinsiriAbstract:Abstract This research demonstrates the effect of fly ash fineness on pore size and microstructure of hardened blended Cement Pastes. Two sizes of fly ash, original fly ash and classified fly ash were used to replace Portland Cement type I Paste. Test results indicated that the pore sizes of hardened blended Cement Paste were significantly affected by the rate of replaCement and the fineness of fly ash. The replaCement of Cement by original fly ash decreased the pore sizes of blended Cement Paste and the incorporation of classified fly ash resulted in a further decrease in the pore sizes of blended Cement Paste. The X-ray diffraction (XRD) results showed that the blended Cement Paste with classified fly ash was more effective at reducing the intensity of Ca(OH)2 than that with the original fly ash. The scanning electron microscope (SEM) results revealed that the hardened blended Cement Paste containing finer fly ash produced a denser structure than the one containing coarser fly ash.
