scholarly journals Degradation of Roller-Compacted Concrete Subjected to Freeze-Thaw Cycles and Immersion in Potassium Acetate Solution

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Wuman Zhang ◽  
Jingsong Zhang ◽  
Shuhang Chen ◽  
Sheng Gong
Keyword(s):  
Mechanical Properties ◽  
Weight Loss ◽  
Compressive Strength ◽  
Impact Energy ◽  
Impact Test ◽  
Potassium Acetate ◽  
Acetate Solution ◽  
Freeze Thaw ◽  
Roller Compacted Concrete ◽  
The Impact

Two sets of roller-compacted concrete (RCC) samples cured for 28 days were subjected to freeze-thaw (F-T) cycles and immersion in laboratory conditions. F-T cycles in water and water-potassium acetate solution (50% by weight) were carried out and followed by the flexural impact test. The weight loss, the dynamic elastic modulus (Ed), the mechanical properties, and the residual strain of RCC were measured. The impact energy was calculated based on the final number of the impact test. The results show that the effect of F-T cycles in KAc solution on the weight loss and Ed of RCC is slight. Ed, the compressive strength, and the flexural strength of RCC with 250 F-T cycles in KAc solution decrease by 3.8%, 23%, and 36%, respectively. The content (by weight) of K+ at the same depth of RCC specimens increases with the increase of F-T cycles. The impact energy of RCC specimens subjected to 250 F-T cycles in KAc solution decreases by nearly 30%. Microcracks occur and increase with the increase of F-T cycles in KAc solution. The compressive strength of RCC immersed in KAc solution decreases by 18.8% and 32.8% after 6 and 12 months. More attention should be paid to using KAc in practical engineering because both the freeze-thaw cycles and the complete immersion in KAc solution damage the mechanical properties of RCC.

Frost resistance of roller compacted concrete in airport runway subjected to ethylene glycol solution

2019 ◽  
Vol 66 (1) ◽  
pp. 40-44 ◽  
Author(s):  
Wuman Zhang ◽  
Jingsong Zhang ◽  
Shuhang Chen
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Ethylene Glycol ◽  
Immersion Test ◽  
Bending Test ◽  
Content Type ◽  
Freeze Thaw ◽  
Roller Compacted Concrete ◽  
Practical Engineering ◽  
Airport Runway

Purpose Ethylene glycol (EG) solution is a common deicing fluid of the aircrafts. Roller compacted concrete (RCC) used in the runway and the parking apron will be subjected to freeze-thaw cycles in EG solution. The purpose of this study is to find whether RCC can be damaged by the action of freeze-thaw cycles or long-term immersion in EG solution. Design/methodology/approach Freeze-thaw cycles test and immersion test in EG solution by weight were used to accelerate the degradation of RCC. A compression test and a three-point bending test were carried out in the laboratory to evaluate mechanical properties of RCC. The changes of microstructure were monitored by using scanning electron microscopy and energy-dispersive X-ray analysis. Findings The results show that RCC specimens have little weight change in both freeze-thaw cycles test and immersion test. The dynamic modulus of elasticity, the compressive strength and the flexural strength of RCC with 250 freeze-thaw cycles in EG solution are decreased by 4.2, 15 and 39 per cent, respectively. The compressive strength is decreased by 35 per cent after 12 months of immersion in EG solution. Micro-cracks occur and increase with the increase in freeze-thaw cycles and immersion test. Originality/value The mass ratio of the elements in the crystal is very close to the proportion of elements in CaC2O4 (C:O:Ca = 1:1.26:1.6). More attention should be paid to using EG in practical engineering because both the freeze-thaw cycles and the complete immersion in EG solution damage the mechanical properties of RCC.

scholarly journals Experimental Study on the Mechanical Properties of Sandstone under the Action of Chemical Erosion and Freeze-Thaw Cycles

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Lizhuang Cui ◽  
Nan Qin ◽  
Shuai Wang ◽  
Xuezhi Feng
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Triaxial Compression ◽  
Rock Properties ◽  
Chemical Solution ◽  
Compression Tests ◽  
Chemical Erosion ◽  
Freeze Thaw ◽  
The Impact

In order to study the mechanical properties of sandstone under the coupling action of chemical erosion and freeze-thaw cycles, the fine-grained yellow sandstone in a mining area in Zigong, China, is collected as the research object. The changes in mechanical properties of yellow sandstone under the coupling action of chemical solution erosion and freeze-thaw cycles are analyzed based on uniaxial compression tests (UCTs) and triaxial compression tests (TCTs). The results show that, with the increase in freeze-thaw cycles, the compressive strength, elastic modulus, and cohesion of the sandstone samples decrease with varying degrees. Under constant freeze-thaw cycles, the most serious mechanical properties of degradation are observed in acidic solution, followed by alkaline solution and neutral solution. Under different confining pressures, the compressive strength and elastic modulus of the sandstone samples decrease exponentially with the increase in freeze-thaw cycles. Under the action of the chemical solution erosion and freeze-thaw cycles, the internal friction angle fluctuates around 30°. For the cohesion degradation, 35.4%, 29.3%, and 27.2% degradation are observed under acidic, alkaline, and neutral solutions. Nuclear magnetic resonance imaging shows that the chemical erosion and freeze-thaw cycles both promote the degradation of rock properties from surface to interior; after 45 freeze-thaw cycles, the mechanical properties drop sharply. To properly design rock tunneling support and long-term protection in the cold region, the impact of both freeze-thaw cycles and chemical erosion should be considered.

The impact of glutaraldehyde on the characteristics of bovine hydroxyapatite-gelatin based bone scaffold as gentamicin delivery system

2021 ◽  
Vol 32 (4) ◽  
pp. 687-691
Author(s):  
Aniek Setiya Budiatin ◽  
Maria Apriliani Gani ◽  
Chrismawan Ardianto ◽  
Samirah ◽  
Sahrati Yudiaprijah Daeng Pattah ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Weight Loss ◽  
Compressive Strength ◽  
Mtt Assay ◽  
Solid Content ◽  
Bone Scaffold ◽  
Significant Difference ◽  
Bovine Hydroxyapatite ◽  
Degradation Test ◽  
The Impact

Abstract Objectives Biomaterials are widely used as drug delivery systems targeting bone tissue, such as to treat bone infectious disease. However, the addition of drugs to biomaterials weakens their mechanical properties. Crosslinkers are compounds that improve the mechanical properties of biomaterials. This study aims to determine the effect of glutaraldehyde (GTA) as a crosslinker on the characteristics of bovine hydroxyapatite-gelatin-based bone scaffold with gentamicin as antibiotics (BHA-GEL-GEN-GTA). Methods BHA-GEL-GEN-GTA scaffold with GTA solid content ranging from 0.1 to 1.4 wt% was made by direct compression. The compressive strength test was carried out using autograph. Scaffold degradation test was carried out by dissolving the scaffolds in PBS. Scaffold toxicity was performed by MTT assay using BHK-21 fibroblast cells. Results There was a significant difference in the scaffolds’ compressive strength due to differences in GTA volume. Scaffold crosslinked using GTA with solid content 0.1 and 0.2 wt% in 2 mL solution had higher compressive strength than those in 1 mL solution. Furthermore, GTA with solid content 0.6, 1, 1.2, and 1.4 wt% showed higher compressive strength than those without GTA. Degradation test results showed that GTA increased the percentage of weight loss and swelling of the scaffold. The scaffold exhibited a nontoxic profile in MTT assay. Conclusions GTA with optimum solid content shows great compressive strength, stable swelling profile with low percentage of scaffold’s weight loss, and is considered as nontoxic.

Effects of Annealing Process on Mechanical Properties of Weather-Resistant Steel Welding Joints

2018 ◽  
Vol 777 ◽  
pp. 397-401
Author(s):  
Qiang Zhang ◽  
Zhe Wu ◽  
Hong Wu Li
Keyword(s):  
Mechanical Properties ◽  
Impact Energy ◽  
Welded Joints ◽  
Impact Test ◽  
Resistant Steel ◽  
Test Results ◽  
Before And After ◽  
Welding Joints ◽  
Weld Area ◽  
The Impact

In this paper, the mechanical properties of Q355NH resistant steel welded joints are studied. Through the analysis of mechanical properties of welded joints, the results showed that the tensile strength of the welded joints decreased after annealing and the elongation increased. The impact test results of tensile specimens before and after annealing showed that the impact energy of the weld area increased greatly after annealing, while the impact energy of the heat affected zone changed little. Furtherly, fatigue strength of specimens before and after annealing was compared, and the results showed that under the condition of high cycle fatigue, the un-annealed specimens were broken and the fracture position was located on the parent metal, whereas the annealed specimens did not break.

Effect of combined drink cans and steel fibers on the impact resistance and mechanical properties of concrete

2020 ◽  
Vol 14 (2) ◽  
pp. 6734-6742
Author(s):  
A. Syamsir ◽  
S. M. Mubin ◽  
N. M. Nor ◽  
V. Anggraini ◽  
S. Nagappan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Reinforced Concrete ◽  
Impact Resistance ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Fiber Reinforced ◽  
Indirect Tensile ◽  
The Impact

This study investigated the combine effect of 0.2 % drink cans and steel fibers with volume fractions of 0%, 0.5%, 1%, 1.5%, 2%, 2.5% and 3% to the mechanical properties and impact resistance of concrete. Hooked-end steel fiber with 30 mm and 0.75 mm length and diameter, respectively was selected for this study.  The drinks cans fiber were twisted manually in order to increase friction between fiber and concrete. The results of the experiment showed that the combination of steel fibers and drink cans fibers improved the strength performance of concrete, especially the compressive strength, flexural strength and indirect tensile strength. The results of the experiment showed that the combination of steel fibers and drink cans fibers improved the compressive strength, flexural strength and indirect tensile strength by 2.3, 7, and 2 times as compare to batch 1, respectively. Moreover, the impact resistance of fiber reinforced concrete has increase by 7 times as compared to non-fiber concretes. Moreover, the impact resistance of fiber reinforced concrete consistently gave better results as compared to non-fiber concretes. The fiber reinforced concrete turned more ductile as the dosage of fibers was increased and ductility started to decrease slightly after optimum fiber dosage was reached. It was found that concrete with combination of 2% steel and 0.2% drink cans fibers showed the highest compressive, split tensile, flexural as well as impact strength.    

scholarly journals Impact resistance of steel materials to ballistic ejecta and shelter development using steel deck plates

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Hiroyuki Yamada ◽  
Kohei Tateyama ◽  
Shino Naruke ◽  
Hisashi Sasaki ◽  
Shinichi Torigata ◽  
...  
Keyword(s):  
Impact Energy ◽  
Impact Test ◽  
Impact Resistance ◽  
Protective Layer ◽  
High Strength ◽  
Steel Plates ◽  
Corrugated Plates ◽  
Shelter Construction ◽  
The Impact ◽  
Ballistic Ejecta

AbstractThe destruction caused by ballistic ejecta from the phreatic eruptions of Mt. Ontake in 2014 and Mt. Kusatsu-Shirane (Mt. Moto-Shirane) in 2018 in Japan, which resulted in numerous casualties, highlighted the need for better evacuation facilities. In response, some mountain huts were reinforced with aramid fabric to convert them into shelters. However, a number of decisions must be made when working to increase the number of shelters, which depend on the location where they are to be built. In this study, we propose a method of using high-strength steel to reinforce wooden buildings for use as shelters. More specifically, assuming that ballistic ejecta has an impact energy of 9 kJ or more, as in previous studies, we developed a method that utilizes SUS304 and SS400 unprocessed steel plates based on existing impact test data. We found that SUS304 is particularly suitable for use as a reinforcing material because it has excellent impact energy absorption characteristics due to its high ductility as well as excellent corrosion resistance. With the aim of increasing the structural strength of steel shelters, we also conducted an impact test on a shelter fabricated from SS400 deck plates (i.e., steel with improved flexural strength provided by work-hardened trapezoidal corrugated plates). The results show that the shelter could withstand impact with an energy of 13.5 kJ (2.66 kg of simulated ballistic ejecta at 101 m/s on impact). In addition, from the result of the impact test using the roof-simulating structure, it was confirmed the impact absorption energy is further increased when artificial pumice as an additional protective layer is installed on this structure. Observations of the shelter after the impact test show that there is still some allowance for deformation caused by projectile impact, which means that the proposed steel shelter holds promise, not only structurally, but also from the aspects of transportation and assembly. Hence, the usefulness of shelters that use steel was shown experimentally. However, shelter construction should be suitable for the target environment.

scholarly journals Microstructure and Mechanical Properties of Heat-Affected Zone of Repeated Welding AISI 304N Austenitic Stainless Steel by Gleeble Simulator

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 773
Author(s):  
Y.H. Guo ◽  
Li Lin ◽  
Donghui Zhang ◽  
Lili Liu ◽  
M.K. Lei
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Impact Energy ◽  
Heat Affected Zone ◽  
Ferrite Content ◽  
Equipment Safety ◽  
Microstructure And Mechanical Properties ◽  
Δ Ferrite ◽  
The Impact

Heat-affected zone (HAZ) of welding joints critical to the equipment safety service are commonly repeatedly welded in industries. Thus, the effects of repeated welding up to six times on the microstructure and mechanical properties of HAZ for AISI 304N austenitic stainless steel specimens were investigated by a Gleeble simulator. The temperature field of HAZ was measured by in situ thermocouples. The as-welded and one to five times repeated welding were assigned as-welded (AW) and repeated welding 1–5 times (RW1–RW5), respectively. The austenitic matrices with the δ-ferrite were observed in all specimens by the metallography. The δ-ferrite content was also determined using magnetic and metallography methods. The δ-ferrite had a lathy structure with a content of 0.69–3.13 vol.%. The austenitic grains were equiaxial with an average size of 41.4–47.3 μm. The ultimate tensile strength (UTS) and yield strength (YS) mainly depended on the δ-ferrite content; otherwise, the impact energy mainly depended on both the austenitic grain size and the δ-ferrite content. The UTS of the RW1–RW3 specimens was above 550 MPa following the American Society of Mechanical Engineers (ASME) standard. The impact energy of all specimens was higher than that in ASME standard at about 56 J. The repeated welding up to three times could still meet the requirements for strength and toughness of welding specifications.

scholarly journals The Effect of Layers and Bullet Type on Impact Properties of Glass Fibre Reinforced Polymer (GFRP) Using a Single Stage Gas Gun (SSGG)

2014 ◽  
Vol 564 ◽  
pp. 428-433 ◽  
Author(s):  
S.N.A. Safri ◽  
Mohamed Thariq Hameed Sultan ◽  
N. Razali ◽  
Shahnor Basri ◽  
Noorfaizal Yidris ◽  
...  
Keyword(s):  
Impact Energy ◽  
Glass Fibre ◽  
Impact Test ◽  
Single Stage ◽  
Gas Gun ◽  
Reinforced Polymer ◽  
Glass Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Glass Fibre Reinforced ◽  
The Impact

The purpose of this work is to study the best number of layer with the higher impact energy using Glass Fibre Reinforced Polymer (GFRP). The number of layers used in this study was 25, 33, 41, and 49. The impact test was performed using Single Stage Gas Gun (SSGG) for each layers given above with different bullets such as blunt, hemispherical and conical bullets. The gas gun pressure was set to 5, 10, 15 and 20 bar. All of the signals captured from the impact test were recorded using a ballistic data acquisition system. The correlation between the impact energy in terms of number of layer and type of bullet from this test are presented and discussed. It can be summarise that as the number of layer increases, impact energy also increases. In addition, from the results, it was observed that by using different types of bullets (blunt, hemispherical, conical), there is only a slight difference in values of energy absorbed by the specimen.

Effect of Filler Compositions on the Mechanical Properties of Bamboo Filled Polyester Composite

2014 ◽  
Vol 879 ◽  
pp. 90-95 ◽  
Author(s):  
Abdul Rahman Noor Leha ◽  
Nor Amalina Nordin
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Impact Test ◽  
Compression Molding ◽  
Engineering Applications ◽  
Maximum Value ◽  
Polyester Composite ◽  
Bamboo Powder ◽  
Flexural Tests ◽  
The Impact

Biocomposite from bamboo powder was fabricated by compression molding technique. The objective of this study was to investigate the mechanical properties of bamboo compounded with epoxy with different ratio. Tensile and flexural tests were done to characterize its mechanical properties. It was observed that the strength of bamboo-polyester was increased with increasing amount of bamboo powder. The tensile and flexural strength shows the highest value at 25 wt.% bamboo. However, the impact test shows the maximum value at 20 wt.% bamboo powder. These results exhibit the bamboo-polyester can be a good candidate to be used in many engineering applications

Physical Properties of Building Blocks from Hemp Shives Aggregate and Cementitious Binder, Manufactured in the Expanded Clay (Vibro Pressing) Production Line

2017 ◽  
Vol 908 ◽  
pp. 118-122 ◽  
Author(s):  
Giedrius Balčiūnas ◽  
Viktor Kizinievič ◽  
Justinas Gargasas
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Compressive Strength ◽  
Physical Properties ◽  
Production Line ◽  
Scientific Literature ◽  
Building Blocks ◽  
Freeze Thaw ◽  
Cementitious Binder ◽  
Pressing Technology

Scientific literature mostly aims at investigation of composites with fibre hemp shives (FHS) aggregate and lime binder, although, such materials are characterised by pretty low mechanical properties. In order to obtain higher mechanical properties of a composite, it is appropriate to use cementitious binder. This work investigates physical properties of blocks from hemp shives aggregate and cementitious binder, manufactured in the expanded clay production line using vibro pressing technology. Following properties of the blocks are determined: freeze-thaw resistance, compressive strength, thermal conductivity and density. Thermal resistance according to EN ISO 6946 for the block with cavities is calculated as well. It is found that compressive strength of FHS-cement blocks may be up to 3.18 MPa when the density is of ~850 kg/m3 and thermal conductivity up to 0.135 W/(m∙K). It is found as well that the decrease of compressive strength is 8.7% after 25 freeze-thaw cycles.

Sign in / Sign up

Export Citation Format

Share Document