scholarly journals Mechanical Properties of Cement-Treated Soil Mixed with Cellulose Nanofibre

2021 ◽  
Vol 11 (14) ◽  
pp. 6425
Author(s):  
Hidenori Takahashi ◽  
Shinya Omori ◽  
Hideyuki Asada ◽  
Hirofumi Fukawa ◽  
Yusuke Gotoh ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Geotechnical Engineering ◽  
Strength Development ◽  
Soft Ground ◽  
Wood Cellulose ◽  
Treated Soil ◽  
Made In ◽  
Cement Treatment

Cellulose nanofibre (CNF), a material composed of ultrafine fibres of wood cellulose fibrillated to nano-order level, is expected to be widely used because of its excellent properties. However, in the field of geotechnical engineering, almost no progress has been made in the development of techniques for using CNFs. The authors have focused on the use of CNF as an additive in cement treatment for soft ground, where cement is added to solidify the ground, because CNF can reduce the problems associated with cement-treated soil. This paper presents the results of a study on the method of mixing CNF, the strength and its variation obtained by adding CNF, and the change in permeability. CNF had the effect of mixing the cement evenly and reducing the variation in the strength of the treated soil. The CNF mixture increased the strength at the initial age but reduced the strength development in the long term. The addition of CNF also increased the flexural strength, although it hardly changed the permeability.

scholarly journals Long-term mechanical and shrinkage properties of cementitious grouts for structural repair

2019 ◽  
Vol 4 ◽  
pp. 9-15
Author(s):  
Md Shamsuddoha ◽  
Götz Hüsken ◽  
Wolfram Schmidt ◽  
Hans-Carsten Kühne ◽  
Matthias Baeßler
Keyword(s):  
Fly Ash ◽  
Flexural Strength ◽  
Cementitious Materials ◽  
Response Surfaces ◽  
Supplementary Cementitious Materials ◽  
Strength Development ◽  
Structural Repair ◽  
Positive Effects ◽  
Micro Silica

Grouts have numerous applications in construction industry such as joint sealing, structural repair, and connections in precast elements. They are particularly favoured in rehabilitation of structures due to penetrability and convenience of application. Grouts for repair applications typically require high-performance properties such as rapid strength development and superior shrinkage characteristics. Sometimes industrial by-products referred as supplementary cementitious materials (SCM) are used with neat cement due to their capabilities to provide binding properties at delayed stage. Micro silica, fly ash and metakaolin are such SCMs, those can modify and improve properties of cement products. This study aims at investigating long-term mass loss and linear shrinkage along with long-term compressive and flexural strength for grouts produced from ultrafine cement and SCMs. A series of mixtures were formulated to observe the effect of SCMs on these grout properties. Properties were determined after 365 days of curing at 23oC and 55% relative humidity. The effect of SCMs on the properties are characterised by statistical models. Response surfaces were constructed to quantify these properties in relation to SCMs replacement. The results suggested that shrinkage was reduced by metakaolin, while micro silica and fly ash had positive effects on compressive and flexural strength, respectively.

scholarly journals Effect of Disinfectants on Mechanical Properties of Orthodontic Acrylics

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Tobias Bensel ◽  
Jens J. Bock ◽  
Anne Kebernik ◽  
Christin Arnold ◽  
Sonia Mansour ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Significant Influence ◽  
Colour Change ◽  
Water Disinfection ◽  
Distilled Water ◽  
Micro Hardness ◽  
Average Roughness ◽  
The Impact

Objective. Infection control protocols in dentistry dictate that orthodontic acrylics have to be disinfected. No specific products for orthodontic acrylics are available. The objective of this study was to investigate the influence of chemical disinfectants on mechanical properties of orthodontic acrylics.Materials and Methods. 260 test specimens of two cold-curing orthodontic acrylics were manufactured. Three chemical disinfecting agents were tested: Impresept, D050 Instru-Gen, and Stammopur DR. Test specimens were stored in distilled water and divided into test groups. E-Modulus, flexural strength, macro hardness, micro hardness, average roughness, and colour change were measured.Results. Disinfection agents showed no significant influence on E-modulus. Values ranged from 1783.80 ± 163.80 MPa (Forestacryl colourless) to 2474.00 ± 135.00 MPa (Orthocryl green) after storage in distilled water. Disinfection agents performed no significant influence on flexural strength. Values ranged from 18.64±1.59 N/mm2(Forestacryl colourless) to 25.64 ± 1.43 N/mm2(Orthocryl green) after storage in distilled water. Orthocryl colourless showed a reduction of the macro hardness after disinfection (Stammopur DR (p≤0.001), D050 Instru-Gen (p≤0.037)). Disinfection of Orthocryl green with D050 Instru-Gen (p<0.001) and Forestacryl colourless with Impresept (p≤0.001) led to a reduction of macro hardness. Micro hardness of Orthocryl colourless altered significantly after disinfection with D050 Instru-Gen (p≤0.001). Micro hardness of Forestacryl colourless increased (Impresept (p≤0.039)) and decreased (Stammopur DR (p≤0.006) Instru-Gen (p≤0.001)) after disinfection. Average roughness did not change significantly (Orthocryl colourless). Forestacryl colourless performed a significant change after disinfection with Stammopur DR (p≤0.05). This is also true for the disinfection of Orthocryl green and Forestacryl pink with Instru-Gen (p≤0.05). Disinfection performed no significant influence on colour change. ΔE-values were in a range of 1 to 2.Conclusions. Some orthodontic acrylics disinfection caused significant changes of determined parameters. Changes were specific for the applied disinfectant and tested orthodontic acrylic. Further studies should verify the impact of long-term disinfection intervals. Thus, from manufacturers of orthodontic acrylics recommendations for appropriate disinfectants would be desirable.

A Simplified Method to Assess the Risk of Geotechnical Engineering under Hydro-Chemical Corrosion

2011 ◽  
Vol 243-249 ◽  
pp. 2952-2957
Author(s):  
Peng Li ◽  
Guo He Li ◽  
Jian Liu
Keyword(s):  
Mechanical Properties ◽  
Chemical Kinetics ◽  
Geotechnical Engineering ◽  
Damage Index ◽  
Chemical Thermodynamic ◽  
Chemical Corrosion ◽  
Long Term Stability ◽  
Physical And Chemical ◽  
Reaction Direction

Rock mass are subject to continuous changes induced by physical and chemical processes of natural and anthropic origin. Such changes affect their mechanical properties. To quantitatively evaluate the hydro-chemical corrosion, the theories of chemical thermodynamic and chemical kinetics are introduced. An index was proposed, which provides a criterion to judge whether the corrosion would be happened and indicated the reaction direction. Then based on theoretical and testing results, a hydro-chemical damage index was proposed. And a series of damage degrees of sandstone under different circumstances, which consider the variations of pH values, temperatures, ions species and ions concentrations, were calculated by chemical kinetics method. Based on the results, the sensitivity of influencing factors was discussed. According to the calculation and the theory of poromechanics or testing results, the mechanical properties of geotechnical materials under hydro-chemical corrosion process can be predicted, so can assess the risk of geotechnical engineering long-term stability.

scholarly journals Effects of TiO2 Nanoparticle Addition on Microstructure and Selected Properties of Ag–xTiO2 Composites

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4846
Author(s):  
Anna Wąsik ◽  
Beata Leszczyńska-Madej ◽  
Marcin Madej
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Nitrogen Atmosphere ◽  
Contact Boundary ◽  
Powder Metallurgy Method ◽  
Tem Analysis ◽  
Single Action ◽  
Steel Balls ◽  
Positive Effect ◽  
Made In

The paper presents the results of a study of the microstructure and selected properties of silver-based composites reinforced with TiO2 nanoparticles, produced by the powder metallurgy method. Pure silver powders were mixed with TiO2 reinforcement (5 and 10 wt%) and 5 mm steel balls (100Cr6) for 270 min in a Turbula T2F mixer to produce a homogeneous mixture. The composites were made in a rigid die with a single-action compaction press under a pressure of 400 MPa and 500 MPa and then sintered under nitrogen atmosphere at 900 °C. Additionally, to improve the density and mechanical properties of the obtained sinters, double pressing and double sintering operations were conducted. As a result, compacts with a density of 90–94% were obtained. The microstructure of the sintered compacts consists of uniform grains, and the TiO2 reinforcement phase particles are located on the grain boundaries. There were no discontinuities at the Ag–TiO2 contact boundary, which was confirmed by SEM and TEM analysis. The use of a higher pressure had a positive effect on the hardness and flexural strength of the tested materials. It was found that the composites with 5 wt% TiO2 pressed under 500 MPa are characterized by the highest level of mechanical properties. The hardness of these composites is 57 HB, while the flexural strength is 163 MPa.

scholarly journals Effect of Temperature and Strain Rate on the Flexural Behavior of Wood-Polypropylene Composites

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3987 ◽  
Author(s):  
Wei Wang ◽  
Xiaomin Guo ◽  
Liu Liu ◽  
Ruiyun Zhang ◽  
Jianyong Yu
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Strain Rate ◽  
Storage Modulus ◽  
Master Curve ◽  
Wood Powder ◽  
Polypropylene Composites ◽  
Long Term Performance ◽  
Term Performance

The mechanical properties of wood-polypropylene composites exhibit typical viscoelasticity. However, there is little information on the mechanical properties of wood-polypropylene composites related to temperature and time, which limits the use of wood-polypropylene composites as structural components. Here, the effect of time (strain rate) and temperature on the flexural properties and the master curve of the storage modulus used to predict the long-term performance of wood-polypropylene composites were investigated. The results showed that the flexural strength and modulus increased linearly with the increase of wood contend, which can increase by 134% and 257% respectively when the mass fraction of wood powder reached 45%. Moreover, there was a positive linear relationship between flexural strength and ln strain rate, while the flexural strength and modulus decreased as temperature elevated. The storage modulus as a function of frequency (time) and temperature confirmed this trend. To evaluate the long-term performance, the storage modulus master curve was constructed and the respective activation energy was calculated, which revealed that the long-term performance of the samples depended on the matrix and the addition of an appropriate amount of wood powder was beneficial to improve their durability.

scholarly journals Comparison of Long-Term Strength Development of Steel Fiber Shotcrete with Cast Concrete Based on Accelerator Type

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5599
Author(s):  
Kyong Ku Yun ◽  
Seunghak Choi ◽  
Taeho Ha ◽  
Mohammad Shakhawat Hossain ◽  
Seungyeon Han
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Steel Fiber ◽  
Strength Reduction ◽  
Strength Development ◽  
Fiber Reinforced ◽  
Cast Concrete ◽  
Long Term Performance ◽  
Term Performance

This study analyzed the effect of accelerating agents, such as aluminate, cement mineral, and alkali-free accelerators, on the long-term performance of steel-fiber-reinforced shotcrete. The shotcrete performance was studied based on the type and amount of steel fiber added. Performance tests were performed to identify the accelerator providing better long-term performance to the steel-fiber-reinforced shotcrete. Changes in strength and flexural performance over time were investigated. The compressive strength and flexural strength tests on 1-, 3-, 6-, 12-, and 24-month-old test specimens were performed, wherein 37 kg of steel fiber was added to the cement mineral and aluminate mixes, and 40 kg of steel fiber was added to the alkali-free mix. The 1-month compressive strength result of all the test variables satisfied the Korea Expressway Corporation standard. The compressive strength of the cast concrete and shotcrete specimens increased with age, demonstrating a strength reduction, particularly in the 24-month-old shotcrete specimens. Thus, the shotcrete performance may deteriorate in the long-term. In the 24-month-old specimen, substantial flexural strength reduction was observed, particularly in the aluminate and alkali-free specimens. The relative strength of the specimens was compared with that of the cast concrete mold specimens. The results suggest the use of alkali-free accelerators, considering the long-term performance of tunnels and safety of workers. Moreover, increasing the steel fiber performance rather than the amount of low-performance steel fiber must be considered.

Strength Development of Concrete Incorporating Metakaolin and PVA Fibres

2014 ◽  
Vol 567 ◽  
pp. 505-510 ◽  
Author(s):  
Sadaqat Ullah Khan ◽  
Muhd Fadhil Nuruddin ◽  
Nasir Shafiq
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Aspect Ratio ◽  
Flexural Strength ◽  
Volume Fraction ◽  
Splitting Tensile Strength ◽  
Strength Development ◽  
Increasing Trend ◽  
Better Than

Study has been conducted to investigate the effect of aspect ratio and volume fraction of PVA fibres on the mechanical properties of concrete. Total eighteen (18) mixes of concrete have been examined using metakaolin up to 5% and PVA fibres of aspect ratio 45, 60, 90 and 120 with volume fraction 1 to 2%. Compressive strength, splitting tensile strength and flexural strength at 7 days and 28 days have been determined to check the effect of volume fraction and the aspect ratio of PVA fibres. It has been found that 2% volume fraction is better than 1% and there is increasing trend up to a certain value of aspect ratio in the strengths of concrete.

scholarly journals Characterization of High Strength Concrete Pavement with steel fibre & silica fume

2020 ◽  
Vol 9 (1) ◽  
pp. 2087-2090
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Silica Fume ◽  
Steel Fibre ◽  
High Strength ◽  
Steel Fibre Reinforced Concrete ◽  
Term Operation ◽  
Strain Limit

Steel Fibre reinforced concrete (SFRC) are maximizes the ductility of Concrete after adding in Concrete and Silica fume increases the density of Concrete[2]. In this investigation we have to determine the combined effect of Steel fibre and silica fume, the main focus of this studies is that to improve the mechanical properties here we use 80 aspect ratio of steel fibre [1] Expansion diverse level of steel fibre and distinctive rate silica smoulder by weight of concrete substance. The droop cone strategy is utilized to decide usefulness [2].By Conducting the experimental test we can determine the flexural strength of steel fibre which is harden concret test[3]. Plain solid asphalts have low flexural quality and strain limit; By utilizing fibre basic qualities are improved and likewise permits decrease of the thickness of the asphalt layer. These better properties are impressive and constrained by qualities of fiber and rate by reducing the thickness of pavement we can minimize the thickness of pavement and gives solidness. Fragility of cement diminished by expansion of steel fiber and density of concrete improves by addition of silica fume. Else it will be brittle in nature. Improvement in such mechanical properties like flexural strength gives better performance in their life span. It will be beneficial for long term operation on Concrete roads[10].

scholarly journals Mechanical properties of an experimental resin based composite containing silver nanoparticles and bioactive glass

2020 ◽  
Vol 36 (4) ◽  
Author(s):  
Amjad Hanif ◽  
Fazal Ghani
Keyword(s):  
Mechanical Properties ◽  
Silver Nanoparticles ◽  
Elastic Modulus ◽  
Flexural Strength ◽  
Bioactive Glass ◽  
Vickers Hardness ◽  
Control Group ◽  
The Difference ◽  
Hardness Values ◽  
Made In

Objective: To compare the elastic modulus, flexural strength, and hardness of an experimental resin based composite (RBC) with and without containing silver nanoparticles (AgNPs) and bioactive glass (BAG) with a commercially available RBC. Methods: This study was conducted, during the period August 2016-May 2018, at the Department of Dental Materials, Peshawar Dental College, Peshawar (Pakistan) and Department of Chemistry, University of Montreal, Canada. Test specimens made in the commercial RBC acted as Group-1 (G1). An experimental RBC containing 70 wt % filler content was synthesized. It was first used as such to prepare test specimens to act as the experimental control group (G2). This RBC was then modified by adding various amounts of BAG (5%, 10% and 15%) and a fixed amount of 0.009% AgNPs to use the so modified RBCs for preparing the test specimens to belong to three groups (G3, G4 & G5). The AgNPs had been synthesized in situ by reduction of salt during photo-polymerization. Flexural strength (FS), elastic modulus (EM) and Vickers hardness were determined using universal testing machine and hardness tester respectively. Data were analyzed using one-way ANOVA and Tukey post-hoc test. Results: Except for G3 restorations showing significantly lower mean FS value, the FS for those in the other groups were not significantly different (p>0.05). Elastic modulus of the experimental RBC restorations was though higher than those of the others but the difference was statistically insignificant (p>0.05). Reduced Vickers hardness values were documented for the restorations in the G4 and G5 compared to those in the G3 but again the difference was insignificant (p>0.05). Flexural strength and hardness values of the test specimens in the experimental RBCs were significantly lower than those made in the commercial hybrid RBC (p<0.05). Conclusion: BAG and AgNPs addition to the experimental RBC in the mentioned concentration adversely affected the tested mechanical properties. doi: https://doi.org/10.12669/pjms.36.4.1913 How to cite this:Hanif A, Ghani F. Mechanical properties of an experimental resin based composite containing silver nanoparticles and bioactive glass. Pak J Med Sci. 2020;36(4):---------. doi: https://doi.org/10.12669/pjms.36.4.1913 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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