scholarly journals Resistance of Soda Residue–Fly Ash Based Geopolymer Mortar to Acid and Sulfate Environments

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 785
Author(s):  
Xianhui Zhao ◽  
Haoyu Wang ◽  
Boyu Zhou ◽  
Han Gao ◽  
Yonghui Lin
Keyword(s):  
Fly Ash ◽  
Cement Mortar ◽  
Experimental Basis ◽  
Chemical Attack ◽  
Before And After ◽  
Infrared Spectrometer ◽  
Mechanical Performances ◽  
Mechanical Strengths ◽  
Scanning Electron

The early mechanical performances of low-calcium fly ash (FFA)-based geopolymer (FFA–GEO) mortar can be enhanced by soda residue (SR). However, the resistance of SR–FFA–GEO mortar to acid or sulfate environments is unclear, owing to the various inorganic calcium salts in SR. The aim of this study was to investigate the long-term mechanical strengths of up to 360 d and evaluate the resistance of SR–FFA–GEO mortar to 5% HCl and 5% Na2SO4 environments through the losses in compressive strength and mass. Scanning Electron Microscopy (SEM), Energy-Dispersive Spectroscopy (EDS) and Fourier Transform Infrared Spectrometer (FTIR) experiments were conducted for the SR–FFA–GEO mortars, both before and after chemical attack, to clarify the attack mechanism. The results show that the resistances of the SR–FFA–GEO mortar with 20% SR (namely M10) to 5% HCl and 5% Na2SO4 environments are superior to those of cement mortar. The environmental HCl reacts with the calcites in SR to produce CaCl2, CO2 and H2O to form more pores under HCl attack, and the environmental Na+ cations from Na2SO4 go into Si-O-Al network structure, to further enhance the strength of mortar under Na2SO4 attack. These results provide the experimental basis for the durability optimization of SR–FFA–GEO mortars.

scholarly journals Microstructure, Durability and Mechanical Properties of Mortars Prepared Using Ternary Binders with Addition of Slag, Fly Ash and Limestone

2021 ◽  
Vol 11 (14) ◽  
pp. 6388
Author(s):  
Javier Ibáñez-Gosálvez ◽  
Teresa Real-Herraiz ◽  
José Marcos Ortega
Keyword(s):  
Fly Ash ◽  
Mercury Intrusion Porosimetry ◽  
Mechanical Performance ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Cement Production ◽  
Mechanical Strengths ◽  
Furnace Slag

In order to improve the contribution to sustainability of cement production, several strategies have been developed, such as the incorporation of additions as clinker replacement. Regarding the production of commercial cements with additions, those made with binary binders are mostly produced. However, the use of ternary binders for manufacturing commercial cements is still very low, at least in Spain, and they could also be an adequate solution for producing eco-friendly cements. The objective of this research is to study the effects in the long term produced by ternary binders which combine the additions of blast furnace slag, fly ash and limestone in the microstructure, durability and mechanical performance of mortars, compared to mortars without additions and mortars made with binary binders. The ternary and binary binders accomplished the prescriptions for a cement type CEM II/B. The microstructure was characterized using mercury intrusion porosimetry, electrical resistivity and differential thermal analysis. Absorption after immersion, diffusion coefficient, mechanical strengths and ultrasonic pulse velocity were studied. The best performance was noted for ternary binder with both slag and fly ash, probably produced by the synergetic effects of slag hydration and fly ash pozzolanic reactions. These effects were more noticeable regarding the compressive strength.

Electrospun CuO Nanofibre Assemblies for H2S Sensing

2018 ◽  
Vol 233 (1) ◽  
pp. 105-116
Author(s):  
Christoph Seitz ◽  
Sebastian Werner ◽  
Roland Marschall ◽  
Bernd M. Smarsly
Keyword(s):  
Electron Microscopy ◽  
Linear Sweep Voltammetry ◽  
X Ray Diffraction ◽  
Linear Sweep ◽  
X Ray ◽  
Transmission Electron ◽  
Before And After ◽  
Volumetric Stress ◽  
Scanning Electron

Abstract Copper oxide (CuO) nanofibres are utilised to sense the toxic and abrasive gas hydrogen sulfide (H2S) in the ppm (parts per million) range. The detection by CuO is based on a significant increase in the conductance upon the formation of CuS, and is thereby selective and sensitive towards H2S. Nanofibres outperform thin films of CuO by compensating the volumetric stress which occurs during sensing. Here, sensors are presented exhibiting up to 600 cycles of sensing and regeneration. To get further insights into the degradation of the fibres upon the reaction with H2S the sensors were analysed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), resistance and linear sweep voltammetry (LSV) measurements before and after cycling. SEM and TEM revealed a drastic change in morphology of the CuO fibres resulting in an undefined aggregate of nanoparticles after 600 cycles. Resistance and LSV measurements showed that the contacting and the measurement process itself are crucial factors for optimising long-term use of CuO-based H2S sensors.

Test Research on Preparation of New Wall Material with Iron Tailings in Tangshan Area

2011 ◽  
Vol 295-297 ◽  
pp. 535-538
Author(s):  
De Qing Gan ◽  
Chao Chen ◽  
Jin Xia Zhang
Keyword(s):  
Compressive Strength ◽  
Electron Microscope ◽  
Fly Ash ◽  
Wall Material ◽  
X Ray Diffraction ◽  
Steam Curing ◽  
X Ray ◽  
A New Technique ◽  
Scanning Electron

This paper discussed the experimental resuhs of exploiting brick materials with iron tailing materials in Tanshang area. Through preparation of iron tailing bricks, the technical flow and production proportion was obtained. The results show that a burning-and steam curing-free brick product with a compressive strength of 28.30 MPa and Flexural strength of 5.63 MPa as the following: iron tailing; fly ash; sand; CaO; gypsum; cement. And long-term properties of a burning-and steam curing-flee brick is also studied by experiments in this paper. Put forward a new technique of making materials with iron tailing. At the same time, the micro mechanism of iron tailing brick was also studied with X-Ray Diffraction (XRD) and Scanning Electron Microscope(SEM).

The Preparation and Micro Mechanism of Brick Materials with Iron Tailings in Tanshang Area

2013 ◽  
Vol 753-755 ◽  
pp. 572-575
Author(s):  
Shu Xian Liu ◽  
Shao Bo Wei
Keyword(s):  
Compressive Strength ◽  
Electron Microscope ◽  
Fly Ash ◽  
Flexural Strength ◽  
Scanning Electron Microscope ◽  
Steam Curing ◽  
X Ray ◽  
A New Technique ◽  
Scanning Electron

This paper discussed the experimental results of exploiting brick materials with iron tailing materials in Tanshang area. Through preparation of iron tailing bricks, the technical flow and production proportion was obtained. The results show that a burning-and steam curing-free brick product with a compressive strength of 28.30 MPa and Flexural strength of 5.63 MPa as the following: iron tailing; fly ash; sand; CaO; gypsum; cement. And long-term properties of a burning-and steam curing-free brick is also studied by experiments in this paper. Put forward a new technique of making materials with iron tailing. At the same time, the micro mechanism of iron tailing brick was also studied with X-Ray Diffractometer (XRD) and Scanning Electron Microscope (SEM).

Experimental Study on Superficial Modification of Recycled Aggregate with Fly Ash

2014 ◽  
Vol 541-542 ◽  
pp. 384-387
Author(s):  
Fu Xing Wang ◽  
Guo Zhong Li ◽  
Juan Chen
Keyword(s):  
Fly Ash ◽  
Mechanical Performance ◽  
Cement Mortar ◽  
Recycled Aggregate ◽  
Enhancement Effect ◽  
Fine Aggregate ◽  
Recycled Fine Aggregate ◽  
Before And After ◽  
Reference Samples ◽  
Different Levels

A modification of using fly ash grout of different levels was adapted to treat the surface of recycled fine aggregate (RFA).The physical properties of RFA before and after modification and the effect on the mechanical performance of cement mortar was studied.The result indicated that the modification of RFA could strengthen the enhancement effect on mechanical performance when modified by 15wt% fly ash grout. After modification, water absorption of RFA was 6.12% and decreased by 47.5%. The 28d flexural strength was increased by 17.4% and compressive strength was increased by 24.2% of RFA cement mortar compared with the reference samples. The superficial microstructure and sectional morphology of RFA was observed by scanning electron microscopy (SEM). The modification mechanism was carried out.

scholarly journals Tc and Re Behavior in Borosilicate Waste Glass Vapor Hydration Tests

2006 ◽  
Vol 985 ◽  
Author(s):  
David A. McKeown ◽  
Andrew C. Buechele ◽  
Wayne W. Lukens ◽  
David K. Shuh ◽  
Ian L. Pegg
Keyword(s):  
High Mobility ◽  
Sample Surface ◽  
Hydrothermal Conditions ◽  
X Ray ◽  
Long Term Storage ◽  
Before And After ◽  
X Ray Absorption ◽  
Term Storage ◽  
Scanning Electron

AbstractTechnetium (Tc), found in some nuclear wastes, is of particular concern with regard to long-term storage, because of its long-lived radioactivity and high mobility in the environment. Tc and rhenium (Re), commonly used as a non-radioactive surrogate for Tc, were studied to assess their behavior in borosilicate glass under hydrothermal conditions in the Vapor Hydration Test (VHT). X-ray absorption spectroscopy (XAS) and scanning electron microscopy (SEM) measurements were made on the original Tc- and Re-containing glasses and their corresponding VHT samples, and show different behavior for Tc and Re under VHT conditions. XAS indicates that, despite starting with different Tc(IV) and Tc(VII) distributions in each glass, the VHT samples have 100% Tc(IV)O6 environments. SEM shows complete alteration of the original glass, Tc enrichment near the sample surface, and Tc depletion in the center. Perrhenate (Re(VII)O4−) is dominant in both Re-containing samples before and after the VHT, where Re is depleted near the VHT sample surface and more concentrated toward the center.

FIB Enhancement of Mechanically Polished Cross-sections

2019 ◽  
Author(s):  
Becky Holdford
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Scanning Electron Microscope ◽  
Cross Sections ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
High Resolution Imaging ◽  
Chemical Attack ◽  
Resolution Imaging ◽  
Scanning Electron

Abstract On mechanically polished cross-sections, getting a surface adequate for high-resolution imaging is sometimes beyond the analyst’s ability, due to material smearing, chipping, polishing media chemical attack, etc.. A method has been developed to enable the focused ion beam (FIB) to re-face the section block and achieve a surface that can be imaged at high resolution in the scanning electron microscope (SEM).

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