scholarly journals Influence of Coarse Aggregates and Silica Fume on the Mechanical Properties, Durability, and Microstructure of Concrete

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3324 ◽  
Author(s):  
Seong Soo Kim ◽  
Abdul Qudoos ◽  
Sadam Hussain Jakhrani ◽  
Jeong Bae Lee ◽  
Hong Gi Kim
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Silica Fume ◽  
Mercury Intrusion Porosimetry ◽  
Construction Material ◽  
Chloride Penetration ◽  
Mercury Intrusion ◽  
Coarse Aggregates ◽  
Overall Performance ◽  
Scanning Electron

Globally, concrete is the most widely used construction material. The composition of concrete plays an important role in controlling its overall performance. Concrete is composed of approximately 70%–80% aggregates, by volume. Therefore, it is mandatory to investigate the effect of aggregates on the performance of concrete. For this purpose, this study investigated the effect of three different coarse aggregates on the mechanical properties, durability, and microstructure of concrete. Concrete specimens were made using aggregates obtained from three regions with different mineralogies. The specimens were also made by replacing cement with silica fume. The specimens were analyzed in terms of compressive, flexural, and splitting tensile strengths, chloride penetration, carbonation, mercury intrusion porosimetry, and scanning electron microscopy. The results demonstrate that the specimens made with rougher coarse aggregates and silica fume had enhanced performance in comparison to those made with smoother aggregates.

Enhanced Electrical Properties of Fly Ash Geopolymer Composites with Carbon Nanotubes

2019 ◽  
Vol 296 ◽  
pp. 137-142 ◽  
Author(s):  
Cecílie Mizerová ◽  
Ivo Kusák ◽  
Pavel Rovnaník ◽  
Patrik Bayer
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Scanning Electron Microscopy ◽  
Fly Ash ◽  
Electrical Properties ◽  
Mercury Intrusion Porosimetry ◽  
Mercury Intrusion ◽  
Geopolymer Composites ◽  
Scanning Electron

Carbon nanotubes (CNTs) are used for the application in concrete especially due to their excellent physical properties. In this study, CNTs were used as a conductive admixture to prepare composites with enhanced electrical properties that might be potentially used in smart concretes or structures. We assessed the changes in selected electrical properties of fly ash geopolymer mortars (conductivity, resistance, capacitance) depending on the concentration of CNTs that ranged from 0.05 to 0.20%. The most convenient CNTs concentration was discussed considering both the electrical and mechanical properties (compressive and flexural strength). Mercury intrusion porosimetry and scanning electron microscopy were used to observe the distribution of CNTs and porosity of the mortars.

Microstructure and Pore Systems Development of Ternary Gypsum-Based Mortars

2018 ◽  
Vol 760 ◽  
pp. 67-72
Author(s):  
Magdaléna Doleželová ◽  
Jitka Krejsová ◽  
Lenka Scheinherrová ◽  
Petr Svora ◽  
Alena Vimmrová
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Pore Structure ◽  
Silica Fume ◽  
Mercury Intrusion Porosimetry ◽  
Hydrated Lime ◽  
Systems Development ◽  
Elementary Composition ◽  
Mercury Intrusion ◽  
Scanning Electron

Paper deals with ternary gypsum-based mortars with higher resistance against water, prepared from gypsum, hydrated lime, several pozzolans (crushed ceramic, silica fume, granulated blast slag) and sand. The samples were stored in the water and the pore systems development in time was studied by mercury intrusion porosimetry. The change of pore structure in samples with pozzolans were observed, the size of pores shifted to the smaller pores during tested period. The elementary composition and microstructure of all materials were also studied by scanning electron microscopy (SEM).

scholarly journals Nanoscale Pore Structure Characterization and Permeability of Mudrocks and Fine-Grained Sandstones in Coal Reservoirs by Scanning Electron Microscopy, Mercury Intrusion Porosimetry, and Low-Field Nuclear Magnetic Resonance

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-20 ◽  
Author(s):  
Na Zhang ◽  
Fangfang Zhao ◽  
Pingye Guo ◽  
Jiabin Li ◽  
Weili Gong ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Pore Size ◽  
Mercury Intrusion Porosimetry ◽  
Mercury Intrusion ◽  
Rock Samples ◽  
Fine Grained ◽  
Low Field ◽  
Water Saturated ◽  
Pore Types ◽  
Scanning Electron

Porosity and permeability of two typical sedimentary rocks in coal bearing strata of underground coal mines in China, i.e., mudrocks and fine-grained sandstones, were comprehensively investigated by multiple experimental methods. Measured porosity averages of the helium gas porosity (φg), MIP porosity (φMIP), water porosity (φw), and NMR porosity (φNMR) of the twelve investigated rock samples range from 1.78 to 16.50% and the measured gas permeabilities (Kg) range from 0.0003 to 2.4133 mD. Meanwhile, pore types, pore morphologies, and pore size distributions (PSD) were determined by focused ion beam scanning electron microscopy (FIB-SEM), mercury intrusion porosimetry (MIP), and low-field nuclear magnetic resonance (NMR). FIB-SEM image analyses showed that the mineral matrix pores including interparticle (interP) and intraparticle (intraP) pores with varied morphologies are the dominant pore types of the investigated rock samples while very few organic matter (OM) pores were observed. Results of the MIP and the full water-saturated NMR measurements showed that the PSD curves of the mudrock samples mostly present a unimodal pattern and nanopores with pore diameter less than 0.1 μm are their predominant pore type, while the PSD curves of the fine-grained sandstone samples are featured by a bimodal distribution. Furthermore, comparison of the full water-saturated and irreducible-water-saturated NMR measurements indicated that pores in the mudrocks are solely adsorption pores (normally pore size < 0.1 μm) whereas apart from a fraction of adsorption pores, a large part of the pores in the sandstone sample with relatively high porosity are seepage pores (normally pore size > 0.1 μm). Moreover, the PSD curves of NMR quantitatively converted from the NMR T2 spectra by T2Pc and weighted arithmetic mean (WAM) methods are in good agreement with the PSD curves of MIP. Finally, the applicability of three classic permeability estimation models based on MIP and NMR data to the investigated rock samples was evaluated.

scholarly journals Enhanced Anti-Mold Property and Mechanism Description of Ag/TiO2 Wood-Based Nanocomposites Formation by Ultrasound- and Vacuum-Impregnation

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 682
Author(s):  
Lin Lin ◽  
Jiaming Cao ◽  
Jian Zhang ◽  
Qiliang Cui ◽  
Yi Liu
Keyword(s):  
Electron Microscopy ◽  
Cell Walls ◽  
Mercury Intrusion Porosimetry ◽  
Water Source ◽  
Contact Angles ◽  
Vacuum Impregnation ◽  
Water Contact ◽  
Mercury Intrusion ◽  
Wood Surfaces ◽  
Scanning Electron

Ag/TiO2 wood-based nanocomposites were prepared by the methods of ultrasound impregnation and vacuum impregnation. The as-prepared samples were characterized by field emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), mercury intrusion porosimetry (MIP), and water contact angles (WCAs). The anti-mold properties of the Ag/TiO2 wood-based nanocomposites were improved by 14 times compared to those of the original wood. The nano-Ag/TiO2, which was impregnated in the tracheid and attached to the cell walls, was able to form a two-stage rough structure and reduce the number of hydroxyl functional groups on the wood surfaces. The resulting decline of wood hydrophobic and equilibrium moisture content (EMC) destroyed the moisture environment necessary for mold survival. Ag/TiO2 was deposited in the wood pores, which reduced the number and volume of pores and blocked the path of mold infection. Thus, the anti-mold properties of the Ag/TiO2 wood-based nanocomposite were improved by cutting off the water source and blocking the mold infection path. This study reveals the anti-mold mechanism of Ag/TiO2 wood-based nanocomposites and provides a feasible pathway for wood-based nanocomposites with anti-mold functions.

Microstructural characterization of biobased carbon foam by means of X-ray microtomography and compared to conventional techniques

RSC Advances ◽  
2016 ◽  
Vol 6 (98) ◽  
pp. 96057-96064 ◽  
Author(s):  
Juliette Merle ◽  
Pascale Sénéchal ◽  
Fabrice Guerton ◽  
Peter Moonen ◽  
Pierre Trinsoutrot ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Mercury Intrusion Porosimetry ◽  
Microstructural Characterization ◽  
Carbon Foam ◽  
X Ray ◽  
Mercury Intrusion ◽  
Scanning Electron

The objective of this work is to compare three techniques for characterizing the morphology of porous bio-based carbon foam, namely mercury intrusion porosimetry, scanning electron microscopy and X-ray microtomography.

scholarly journals Experimental Study on the Permeability of SAP Modified Concrete

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3368 ◽  
Author(s):  
Yaohua Guo ◽  
Puyang Zhang ◽  
Hongyan Ding ◽  
Conghuan Le
Keyword(s):  
Electron Microscopy ◽  
Mercury Intrusion Porosimetry ◽  
Threshold Effect ◽  
Superabsorbent Polymer ◽  
Water Penetration ◽  
Pore Characteristics ◽  
Mercury Intrusion ◽  
Pressure Test ◽  
Internal Pore ◽  
Scanning Electron

To study the permeability of superabsorbent polymer (SAP) modified concrete and the effect of internal pore characteristics on the permeability of concrete specimens, the results of the water penetration under pressure test, the mercury intrusion porosimetry (MIP) test, and scanning electron microscopy (SEM) of SAP concrete were obtained and analyzed. The research shows that the addition of an appropriate amount of SAP can effectively improve the anti-permeability performance of concrete. After adding 0.2~0.6% SAP of cement quality to concrete, the penetration height value was reduced by 35~45%, the porosity was increased by 21–95%, and the tortuosity is increased by 14–15%, and all indicators show regular changes with the increase in SAP usage. Adding SAP to concrete changes the internal connection state of concrete, thereby further improving its impermeability by reducing the capillary pressure and changing the shape of the pores. The liquid permeation resistance is increased by the “threshold effect” inside concrete; this “threshold effect” is caused by the addition of SAP.

Research on microstructure properties of clay-sand mixtures studied by ipp and mip methods

2020 ◽  
pp. 16-23
Author(s):  
QI DAOZHENG ◽  
GU CONG ◽  
FU JIAJIA ◽  
WANG YAO
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Scanning Electron Microscopy ◽  
Mercury Intrusion Porosimetry ◽  
Fractal Theory ◽  
Sand Content ◽  
Sem Images ◽  
Mercury Intrusion ◽  
Sem Image ◽  
Scanning Electron

The clay-sand mixtures with diferent partcle sizes were prepared to investgate partcle and pore characteristcs. The microstructure characteristcs of the sand-clay mixtures were studied by the Mercury Intrusion Porosimetry (MIP) test and Scanning Electron Microscopy (SEM). Image-Pro Plus (IPP) image processing sofware was used to quantfy SEM images which investgated the micro-mechanism of structural evoluton of mixtures under diferent gradatons. The research results indicate that the units of mixtures develop from platelets and honeycomb to agglomerated and granular with the increase of sand content. The contact between partcles transits from face-face contacts to edge-face and pointface contacts. This artcle evaluated the fractal characteristc of partcle and pore structure based on the fractal theory. With the increase Circularity of the partcles, the ordered arrangement of the partcles in the mixed soil is further reduced. In general, the distributon of pores changes from intergranular pores to pores in aggregate, which provides a theoretcal basis for further study on the micro-macro correlaton of mixtures.

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