scholarly journals Micro-Mechanical and 3D Fractal Analysis, Durability, and Thermal Behaviour of Nano-Modified Cementitious Lightweight Composites for Building Facades

Buildings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 85
Author(s):  
Marva Angela Blankson ◽  
Savaş Erdem ◽  
Ezgi Gürbüz
Keyword(s):  
Fractal Analysis ◽  
Water Permeability ◽  
Fractal Dimensions ◽  
Hardness Measurement ◽  
Silica Content ◽  
Silica Particles ◽  
Strength Increase ◽  
Nano Silica ◽  
Flexural Response ◽  
Lightweight Composites

There are increasing research endeavours on the application of nanotechnology in the construction industry and lightweight composites. In this study, the influence of different percentage (1%, 2%, and 3% by weight of cement) colloidal nano-silica particles on the mechanical, thermal, and durability properties of lightweight cementitious composites was studied through measurement of compressive strength, flexural response, micro-hardness measurement, pore structure analysis, thermal conductivity, water permeability, and chloride penetration. Moreover, 3D X-ray Compute Tomography together with digital image analysis and 3D fractal analysis was used to characterize the nano-silica, micro-structures, and the fracture surfaces. The experimental results show that incorporating nano-silica particles resulted in a mechanical strength increase up to 45.4 % and a water permeability and chloride migration decrease up to 51.2% and 48.2%, respectively. The micro-structural and 3D fractal analysis also indicated that dense, flaw-free, and thus more resistant, interfaces to micro-cracks were formed and greater fractal dimensions were obtained with the increase of the nano-silica content. Finally, the 3D views confirmed that the nano-silica clusters were well interconnected which further increase the carrying capacity and reducing the heat flow.

Influence of Nano-Silica on Microstructure and Mechanical Properties of SiO2/BN Ceramics

2007 ◽  
Vol 353-358 ◽  
pp. 1529-1532 ◽  
Author(s):  
Li Zhong Zhou ◽  
De Chang Jia
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Silica Content ◽  
Silica Particles ◽  
Fused Silica ◽  
Sintering Behavior ◽  
Dual Phase ◽  
Spatial Network ◽  
Nano Silica

In this paper, nano-silica particles were incorporated to a fused silica-boron nitride dual phase ceramics originally using micrometer sized particles as starting powders. Effects of nano-silica content on density, sintering behavior, mechanical properties and microstructure of the dual phase ceramics were investigated. It was found that with the addition of nano-silica particles, the density and mechanical properties of the dual phase ceramics increased. Flexural strength and fracture toughness of them attained to 51.4MPa and 0.8MPa·m1/2, respectively. The increased density and spatial network structure of fused silica attribute to the improvement of the mechanical properties of the dual phase ceramics.

Structure characterization of ground calcium carbonate flocs by fractal analysis and their effects on handsheet properties

TAPPI Journal ◽  
2013 ◽  
Vol 12 (3) ◽  
pp. 17-23 ◽  
Author(s):  
WANHEE IM ◽  
HAK LAE LEE ◽  
HYE JUNG YOUN ◽  
DONGIL SEO
Keyword(s):  
Fractal Analysis ◽  
Structural Characteristics ◽  
Fractal Dimensions ◽  
Strength Loss ◽  
Structure Characterization ◽  
Uniform Size ◽  
Cross Sectional ◽  
Floc Size ◽  
Mass Fractal ◽  
Handsheet Properties

Preflocculation of filler particles before their addition to pulp stock provides the most viable and practical solution to increase filler content while minimizing strength loss. The characteristics of filler flocs, such as floc size and structure, have a strong influence on preflocculation efficiency. The influence of flocculant systems on the structural characteristics of filler flocs was examined using a mass fractal analysis method. Mass fractal dimensions of filler flocs under high shear conditions were obtained using light diffraction spectroscopy for three different flocculants. A single polymer (C-PAM), a dual cationic polymer (p-DADMAC/C-PAM) and a C-PAM/micropolymer system were used as flocculants, and their effects on handsheet properties were investigated. The C-PAM/micropolymer system gave the greatest improvement in tensile index. The mass fractal analysis showed that this can be attributed to the formation of highly dense and spherical flocs by this flocculant. A cross-sectional analysis of the handsheets showed that filler flocs with more uniform size were formed when a C-PAM/micropolymer was used. The results suggest that a better understanding of the characteristics of preflocculated fillers and their influence on the properties of paper can be gained based on a fractal analysis.

Preparation of Raspberry-Like Polymer/Silica Composite Particles through Cationic Soap-Free Emulsion Polymerization

2012 ◽  
Vol 476-478 ◽  
pp. 1408-1411
Author(s):  
Xin Fan ◽  
Qiu Ju Qin ◽  
Xiu Fang Wen ◽  
Jiang Cheng ◽  
Zhuo Ru Yang
Keyword(s):  
Emulsion Polymerization ◽  
Silica Content ◽  
Silica Particles ◽  
Vital Role ◽  
Silica Sol ◽  
Electrostatic Attraction ◽  
Composite Particles ◽  
Silica Composite ◽  
Soap Free Emulsion Polymerization

In this paper raspberry-like composite particles were prepared via cationic soap-free emulsion polymerization with silica sol as stabilizer and 2-(methacryloyl) ethyltrimethylammonium chloride (MTC) as cationic auxiliary monomer. According to the TGA and TEM results we could find that the electrostatic attraction supplied by MTC played a vital role in the adsorption of silica particles as well as the generation of raspberry-like morphology. The silica content and appearance of composite particles were found to be improved with the increasing amount of silica sol and MTC while varied little with changes of AIBA amount.

Preparation of high purity nano silica particles from blast-furnace slag

2010 ◽  
Vol 27 (6) ◽  
pp. 1901-1905 ◽  
Author(s):  
Sun-Jae Kim ◽  
Seong-Gyu Seo ◽  
Sang-Chul Jung
Keyword(s):  
Blast Furnace ◽  
High Purity ◽  
Blast Furnace Slag ◽  
Silica Particles ◽  
Nano Silica ◽  
Furnace Slag

Architectural Bias in Recurrent Neural Networks: Fractal Analysis

2003 ◽  
Vol 15 (8) ◽  
pp. 1931-1957 ◽  
Author(s):  
Peter Tiňo ◽  
Barbara Hammer
Keyword(s):  
Neural Networks ◽  
Fractal Analysis ◽  
Recurrent Neural Networks ◽  
Markov Models ◽  
Fractal Dimensions ◽  
Transition Diagram ◽  
Activation Patterns ◽  
Box Counting ◽  
Fractal Clusters ◽  
Finite State

We have recently shown that when initialized with “small” weights, recurrent neural networks (RNNs) with standard sigmoid-type activation functions are inherently biased toward Markov models; even prior to any training, RNN dynamics can be readily used to extract finite memory machines (Hammer & Tiňo, 2002; Tiňo, Čerňanský, &Beňušková, 2002a, 2002b). Following Christiansen and Chater (1999), we refer to this phenomenon as the architectural bias of RNNs. In this article, we extend our work on the architectural bias in RNNs by performing a rigorous fractal analysis of recurrent activation patterns. We assume the network is driven by sequences obtained by traversing an underlying finite-state transition diagram&a scenario that has been frequently considered in the past, for example, when studying RNN-based learning and implementation of regular grammars and finite-state transducers. We obtain lower and upper bounds on various types of fractal dimensions, such as box counting and Hausdorff dimensions. It turns out that not only can the recurrent activations inside RNNs with small initial weights be explored to build Markovian predictive models, but also the activations form fractal clusters, the dimension of which can be bounded by the scaled entropy of the underlying driving source. The scaling factors are fixed and are given by the RNN parameters.

Influence of sulfuric and hydrochloric acid on the resistance of geopolymer cement with nano-silica additive for oil well cement application

2018 ◽  
Vol 9 (5) ◽  
pp. 616-624 ◽  
Author(s):  
Syahrir Ridha ◽  
Afif Izwan Abd Hamid ◽  
Riau Andriana Setiawan ◽  
Ahmad Radzi Shahari
Keyword(s):  
Fly Ash ◽  
Hydrochloric Acid ◽  
Strength Increase ◽  
Oil Well ◽  
Nano Silica ◽  
Content Type ◽  
Oil Well Cement ◽  
Geopolymer Cement ◽  
Well Cement ◽  
Silica Additive

PurposeThe purpose of this paper is to investigate the resistivity of geopolymer cement with nano-silica additive toward acid exposure for oil well cement application.Design/methodology/approachAn experimental study was conducted to assess the acid resistance of fly ash-based geopolymer cement with nano-silica additive at a concentration of 0 and 1 wt.% to understand its effect on the strength and microstructural development. Geopolymer cement of Class C fly ash and API Class G cement were used. The alkaline activator was prepared by mixing the proportion of sodium hydroxide (NaOH) solutions of 8 M and sodium silicate (Na2SiO3) using ratio of 1:2.5 by weight. After casting, the specimens were subjected to elevated curing condition at 3,500 psi and 130°C for 24 h. Durability of cement samples was assessed by immersing them in 15 wt.% of hydrochloric acid and 15 wt.% sulfuric acid for a period of 14 days. Evaluation of its resistance in terms of compressive strength and microstructural behavior were carried out by using ELE ADR 3000 and SEM, respectively.FindingsThe paper shows that geopolymer cement with 1 wt.% addition of nano-silica were highly resistant to sulfuric and hydrochloric acid. The strength increase was contributed by the densification of the microstructure with the addition of nano-silica.Originality/valueThis paper investigates the mechanical property and microstructure behavior of emerging geopolymer cement due to hydrochloric and sulfuric acids exposure. The results provide potential application of fly ash-based geopolymer cement as oil well cementing.

scholarly journals Novel β-galactosidase nanobiocatalyst systems for application in the synthesis of bioactive galactosides

RSC Advances ◽  
2016 ◽  
Vol 6 (99) ◽  
pp. 97216-97225 ◽  
Author(s):  
Katarina Banjanac ◽  
Milica Carević ◽  
Marija Ćorović ◽  
Ana Milivojević ◽  
Nevena Prlainović ◽  
...  
Keyword(s):  
Silica Particles ◽  
Nano Silica

Amino modified nonporous fumed nano-silica particles was used for the development of efficient nanobiocatalysts for application in the biosynthesis of bioactive galactosides, galacto-oligosaccharides (GOS).

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