scholarly journals Long-term sulfuric and hydrochloric acid resistance of silica fume and colemanite waste reinforced metakaolin-based geopolymers

2021 ◽  
Vol 20 (2) ◽  
pp. 291-307
Author(s):  
Yurdakul Aygörmez ◽  
◽  
Orhan Canpolat ◽  
Keyword(s):  
Sulfuric Acid ◽  
Hydrochloric Acid ◽  
Silica Fume ◽  
Acid Resistance ◽  
Micro Computed Tomography ◽  
Geopolymer Matrix ◽  
Before And After ◽  
The Matrix ◽  
Compressive And Flexural Strengths ◽  
Geopolymer Composites

For this paper, silica fume (SF), slag (S), and colemanite waste (C) were added to metakaolin (MK)-based geopolymer composites and exposed to 10% (by volume) hydrochloric acid (HCl) and sulfuric acid (H2SO4) solutions for up to 12 months. Geopolymer composites were examined in terms of weight loss, compressive strength, and flexural strength at 3, 6, and 12 months in solutions. Furthermore, Scanning Electron Microscopy (SEM), Micro-computed Tomography (micro-CT), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Diffraction (XRD) analyses were carried out to examine the microstructure before and after acid attacks. An important decrease in flexural and compressive strengths was seen when geopolymer mortars were subjected to sulfuric and hydrochloric acid attacks. The main cause of this situation is the deterioration of the oxy-aluminum bridge (-Al-Si-O) when exposed to sulfuric and hydrochloric acid. The oxy-aluminum bridge (-Al-Si-O), the primary factor in the geopolymer matrix, plays a significant role in consolidating the gel and enhancing the bond formed between the matrix components. Despite this, geopolymer mortar samples maintain the aluminosilicate structure. Compared to hydrochloric acid, sulfuric acid is a stronger solution, resulting in a greater loss of compressive and flexural strengths.

scholarly journals Effect of Silica Fume on Metakaolin Geopolymers’ Sulfuric Acid Resistance

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5396
Author(s):  
Oliver Vogt ◽  
Neven Ukrainczyk ◽  
Eddie Koenders
Keyword(s):  
Sulfuric Acid ◽  
Silica Fume ◽  
Acid Resistance ◽  
Sample Surface ◽  
Acid Attack ◽  
Solution Ph ◽  
X Ray ◽  
Dependent Change ◽  
Before And After ◽  
Time Dependent Change

To demonstrate the importance of the Si/Al ratio in terms of geopolymer mix designs for acid resistance, a metakaolin-based geopolymer was modified by replacing the aforementioned precursor with different percentages of silica fume. Durability tests were performed by exposing geopolymers with varying amounts of silica fume (up to 9%) to sulfuric acid solution (pH 1) over a period of 84 days. Geopolymer samples were analyzed by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) before and after 7, 14, 28, 56 and 84 days of exposure. To show the time-dependent change of the elemental composition in the corroded layer after sulfuric acid attack, SEM-EDX elemental mappings were conducted and divided into 100 µm segments to generate element-specific depth profiles. The results show that above a critical silica fume content, the erosion of the sample surface by complete dissolution can be prevented and higher amounts of silica fume lead to a significant densification of large (protective) areas of the corroded layer, which delays the progress of corrosion.

Cropped Steel Fiber Reinforced Chemically Bonded Ceramic (CBC) Composites

1987 ◽  
Vol 114 ◽  
Author(s):  
Sean Wise ◽  
Kevan Jones ◽  
Claudio Herzfeld ◽  
David D. Double
Keyword(s):  
Silica Fume ◽  
Steel Fiber ◽  
High Strength ◽  
Cement Matrix ◽  
Metal Fiber ◽  
Morphological Form ◽  
The Matrix ◽  
Compressive And Flexural Strengths ◽  
Equivalent Properties ◽  
Very High

ABSTRACTVery high strength castable chemically bonded ceramic (CBC) materials have been prepared which consist of finely chopped steel fibers and steel aggregate in a silica modified portland cement matrix. This paper examines the effect of metal fiber addition on compressive and flexural strengths. The overall chemistry of the matrix is held constant but the morphological form of silica used and the cure conditions are altered to examine their effect. Compressive strengths in excess of 500 MPa and flexural strengths in excess of 80 MPa can be obtained.It is found that flexural strength increases proportionally with fiber content over the range of 0 to 10% by volume. Compressive strengths are not affected. Use of silica fume in the mixes produces higher strengths at low temperatures than mixes which contain only crystalline silica. High temperature curing/drying (400°C), which produces the highest strengths, produces equivalent properties for formulations with and without silica fume. Higher water/cement ratios are found to reduce compressive strengths but have relatively little effect on the flexural properties.

Strength and Sulfuric Acid Resistance of Three Component Geopolymer

2015 ◽  
Vol 1129 ◽  
pp. 607-613
Author(s):  
Hiroki Goda ◽  
Koji Harada ◽  
Shunji Tsugo ◽  
Makoto Hibino
Keyword(s):  
Compressive Strength ◽  
Sulfuric Acid ◽  
Silica Fume ◽  
Blast Furnace Slag ◽  
Acid Resistance ◽  
Mineral Admixtures ◽  
Chemical Attack ◽  
Granulated Blast Furnace Slag ◽  
Sulfate Solutions ◽  
Furnace Slag

The compressive strength and resistance to chemical attack of a fly-ash-based geopolymer, to which ground granulated blast furnace slag (B.F.S) and silica fume were added as mineral admixtures, were evaluated. The B.F.S. constituted 10% of the total powder amount in this geopolymer, which exhibited a high compressive strength. In addition, the compressive strength remained unchanged with proportional additions of silica fume to the mixture. The geopolymer exhibited, however, different resistance to sulfuric acid and sodium sulfate solutions during diffusion testing. In fact, the resistance of the B.F.S-containing mix to sulfuric acid was enhanced by the addition of silica fume and by autoclaving.

Study on Performance of Alkali-Activated Flyash-Based Geopolymer Reinforced by Silica Fume and Styrene-Acrylic Emulsion

2011 ◽  
Vol 374-377 ◽  
pp. 1632-1636
Author(s):  
Ya Chao Wang ◽  
Yao Jun Zhang ◽  
Yong Xu ◽  
De Long Xu
Keyword(s):  
Fly Ash ◽  
Silica Fume ◽  
Doping Content ◽  
X Ray Diffraction ◽  
Acrylic Emulsion ◽  
X Ray ◽  
Structure Morphology ◽  
The Matrix ◽  
Compressive And Flexural Strengths ◽  
Alkali Activated

In order to improve the inherent fragility of alkali-activated fly ash-based geopolymer, the silica fume and styrene-acrylic emulsion were used to reinforce and toughen the geopolymer. The phase structure, morphology and chemical composition were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and X-ray fluorescence (XRF). The results showed that the mechanical properties of alkali-activated fly ash-based geopolymer were dramaticlly improved and the specimen with doping content of 10 wt% silica fume, 1wt% styrene-acrylic emulsion and 15wt% the alkaline excitation agent Na2SiO39H2O showed the highest compressive and flexural strengths of 42.11MPa and 5.30MPa in the ambient temperature curing 28d, respectively. SEM results indicated that doped silica fume and styrene-acrylic emulsion were embedded within the matrix of fly ash-based geopolymer. XRD results demonstrated that the mineral structures did not change obviously when silica fume and styrene-acrylic emulsion were added to the geopolymer

Effect of Acid Treated Hydroxyapatite on Osteoblast Maturation

2007 ◽  
Vol 361-363 ◽  
pp. 1029-1032
Author(s):  
Taro Takemura ◽  
Toshiyuki Ikoma ◽  
Nobutaka Hanagata
Keyword(s):  
Hydrogen Peroxide ◽  
Alkaline Phosphatase ◽  
Sulfuric Acid ◽  
Nitric Acid ◽  
Hydrochloric Acid ◽  
Gene Expressions ◽  
Matrix Mineralization ◽  
Mature Osteoblast ◽  
The Matrix ◽  
Osteoblast Maturation

Surfaces of sintered hydroxyapatite (HAp) were treated with four kinds of acids, hydrochloric acid (HCl), nitric acid (HNO3), sulfuric acid (H2SO4) and hydrogen peroxide (H2O2). On these acid-treated HAp surfaces, osteoblast-like MC3T3-E1 cells were cultured for 20 days. The matrix mineralization was observed in HCl-treated HAp and HNO3-treated HAp, but not in non-treated HAp, H2SO4-treated HAp and H2O2-treated HAp. Gene expressions of Bglap2 encoding osteocalcin and Akp2 encoding alkaline phosphatase were higher in HCl-treated HAp and HNO3-treated HAp than those in the others. These results indicate that not only hydrochloric acid but also nitric acid improves performance of HAp to mature osteoblast.

scholarly journals Effect of Nanosilica on Mechanical Properties and Microstructure of PVA Fiber-Reinforced Geopolymer Composite (PVA-FRGC)

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3624 ◽  
Author(s):  
Hasan Assaedi ◽  
Thamer Alomayri ◽  
Ayesha Siddika ◽  
Faiz Shaikh ◽  
Hatem Alamri ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Microstructure Analysis ◽  
Flexural Behavior ◽  
Optimum Level ◽  
Fiber Reinforced ◽  
X Ray Diffraction ◽  
Geopolymer Matrix ◽  
The Matrix ◽  
Pva Fiber ◽  
Geopolymer Composites

This paper presents the effects of various nanosilica (NS) contents on the mechanical properties of polyvinyl alcohol (PVA) fiber-reinforced geopolymer composites (PVA-FRGC). Microstructure analysis with X-ray diffraction (XRD) and scanning electron microscopy (SEM) was used to characterize the geopolymer composites. The results showed that the mechanical properties in terms of compressive strength, impact strength, and flexural behavior were improved due to the addition of NS to the PVA-FRGC. The optimum NS content was 1.0 to 2.0 wt%, which exhibited highest improvement in the above mechanical properties. Microstructure analysis showed that the addition of NS up to an optimum level densified the microstructure of the matrix as well as the PVA fiber–geopolymer matrix interface.

scholarly journals Composites Base on Geopolymer Matrices: Preliminary Fabrication, Mechanical Properties and Future Applications

2008 ◽  
Vol 55-57 ◽  
pp. 477-480 ◽  
Author(s):  
T.D. Hung ◽  
D. Pernica ◽  
Dora Kroisová ◽  
Oleg Bortnovsky ◽  
Petr Louda ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Structure Characterization ◽  
Alkali Resistance ◽  
Matrix Composites ◽  
Japanese Industrial Standard ◽  
Geopolymer Matrix ◽  
The Matrix ◽  
Fiber Reinforcements ◽  
Geopolymer Composites

Geopolymer matrice Composites are fabricated at room temperature or thermoset in a simple autoclave. After approximately four hours of curing, composite materials exhibit excellent properties. Finding applications of geopolymeric composites in all fields of industry are the hot topics. This paper covers: (i) mechanical properties of fibers: carbon, Saint-Gobain Cemfil/CFV alkali resistance glass (various types), ARG-NEC (Nippon electric Columbia) alkali resistance glass, E-glass for pultrusion, AR glass for pultrusion were evaluated in accordance with Japanese Industrial Standard (JIS R 7601). (ii) properties of geopolymeric matrices: geopolymeric matrices are fabricated from various types of geopolymeric resins that were made at Research Institute of Inorganic Chemistry, Inc., Czech Republic and testing for mechanical properties, and by SEM for structure characterization. (iii) fabrication procedures of geopolymer matrix composites with carbon and other fiber reinforcements. (iv) results of mechanical testing of geopolymer composites, SEM for adhesion between the matrix and reinforcement, and (v) Results and discussion.

Tem analysis of multiple-energy arsenic implanted and Rta'd silicon

1987 ◽  
Vol 45 ◽  
pp. 246-247
Author(s):  
R.A. Herring
Keyword(s):  
Device Fabrication ◽  
High Concentration ◽  
Tem Analysis ◽  
Defect Clusters ◽  
High Fluences ◽  
Small Defect ◽  
Before And After ◽  
The Matrix ◽  
The Difference ◽  
Factor Type

Rapid thermal annealing (RTA) of ion-implanted Si is important for device fabrication. The defect structures of 2.5, 4.0, and 6.0 MeV As-implanted silicon irradiated to fluences of 2E14, 4E14, and 6E14, respectively, have been analyzed by electron diffraction both before and after RTA at 1100°C for 10 seconds. At such high fluences and energies the implanted As ions change the Si from crystalline to amorphous. Three distinct amorphous regions emerge due to the three implantation energies used (Fig. 1). The amorphous regions are separated from each other by crystalline Si (marked L1, L2, and L3 in Fig. 1) which contains a high concentration of small defect clusters. The small defect clusters were similar to what had been determined earlier as being amorphous zones since their contrast was principally of the structure-factor type that arises due to the difference in extinction distance between the matrix and damage regions.

Radiolabeled r-Hirudin as a Measure of Thrombin Activity at, or within, the Rabbit Aorta Wall In Vitro and In Vivo

1994 ◽  
Vol 71 (04) ◽  
pp. 499-506 ◽  
Author(s):  
Mark W C Hatton ◽  
Bonnie Ross-Ouellet
Keyword(s):  
Rabbit Aorta ◽  
Balloon Injury ◽  
Recombinant Hirudin ◽  
Aorta Wall ◽  
Thrombin Activity ◽  
Before And After ◽  
The Matrix

SummaryThe behavior of 125I-labeled recombinant hirudin towards the uninjured and de-endothelialized rabbit aorta wall has been studied in vitro and in vivo to determine its usefulness as an indicator of thrombin activity associated with the aorta wall. Thrombin adsorbed to either sulfopropyl-Sephadex or heparin-Sepharose bound >95% of 125I-r-hirudin and the complex remained bound to the matrix. Binding of 125I-r-hirudin to the exposed aorta subendothelium (intima-media) in vitro was increased substantially if the tissue was pre-treated with thrombin; the quantity of l25I-r-hirudin bound to the de-endothelialized intima-media (i.e. balloon-injured in vitro) correlated positively with the quantity of bound 131I-thrombin (p <0.01). Aortas balloon-injured in vivo were measured for thrombin release from, and binding of 125I-r-hirudin to, the de-endothelialized intimal surface in vitro; 125I-r-hirudin binding correlated with the amount of active thrombin released (p <0.001). Uptake of 125I-r-hirudin by the aorta wall in vivo was proportional to the uptake of 131I-fibrinogen (as an indicator of thrombin activity) before and after balloon injury. After 30 min in the circulation, specific 125I-r-hirudin binding to the uninjured and de-endo- thelialized (at 1.5 h after injury) aorta wall was equivalent to 3.4 (± 2.5) and 25.6 (±18.1) fmol of thrombin/cm2 of intima-media, respectively. Possibly, only hirudin-accessible, glycosaminoglycan-bound thrombin is measured in this way.

scholarly journals A Repeatable and Reproducible Digital Method to Quantify the Cement Excess and Enamel Loss after Debonding Lingual Multibracket Appliance Therapy

2021 ◽  
Vol 11 (3) ◽  
pp. 1295
Author(s):  
Alba Belanche Monterde ◽  
Alberto Albaladejo Martínez ◽  
Alfonso Alvarado Lorenzo ◽  
Adrián Curto ◽  
Jorge Alonso Pérez-Barquero ◽  
...  
Keyword(s):  
Measurement Technique ◽  
Measurement Method ◽  
Dental Arch ◽  
Micro Computed Tomography ◽  
Morphometric Measurement ◽  
Before And After ◽  
Repeatability And Reproducibility ◽  
Lingual Brackets ◽  
Multibracket Appliance ◽  
Area And Volume

The aim of the present study is to present a repeatable, reproductible, and accurate morphometric measurement method for measuring and quantifying the area and volume of cement that remains after fixed lingual multibracket appliance debonding, enamel loss after fixed lingual multibracket appliance debonding, and the volume of cement used to adhere fixed lingual multibracket appliances. Ten conventional lingual brackets were cemented in 10 extracted teeth embedded into an epoxy resin model simulating a dental arch. This model was scanned before and after bonding the lingual brackets, after debonding, and after polishing the surfaces. We also performed a Micro-Computed Tomography scan of the lingual brackets used. Afterward, the standard tessellation language (STL) digital file was aligned, each tooth was segmented individually, and the file was re-aligned using engineer morphometry software. Inter-operator and intra-operator comparative analyses were performed using the ANOVA test, and the repeatability and reproducibility of the morphometric measurement technique were analyzed using Gage R&R statistical analysis. Repeatability showed 0.07% and 0.16% variability associated with the area and volume measures, respectively, while reproducibility showed 0.00% variability associated with the area and volume measures, respectively. In conclusion, the morphometric measurement technique is a repeatable, reproductible, and accurate morphometric measurement method for quantifying the area and volume of cement that remains after fixed lingual multibracket appliance debonding, enamel loss after fixed lingual multibracket appliance debonding, and the volume of cement used to adhere fixed lingual multibracket appliances.

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