Study on Mechanical Properties of Basalt Fiber Shotcrete in High Geothermal Environment

With the development of infrastructure, there are growing numbers of high geothermal environments, which, therefore, form a serious threat to tunnel structures. However, research on the changes in mechanical properties of shotcrete under high temperatures and humid environments are insufficient. In this paper, the combination of various temperatures (20 °C/40 °C/60 °C) and 55% relative humidity is used to simulate the effect of environment on the strength and stress–strain curve of basalt fiber reinforced shotcrete. Moreover, a constitutive model of shotcrete considering the effect of fiber content and temperature is established. The results show that the early mechanical properties of BFRS are improved with the increase in curing temperature, while the compressive strength at a later age decreases slightly. The 1-day and 7-day compressive strength of shotcrete at 40 °C and 60 °C increased by 10.5%, 41.1% and 24.1%, 66.8%, respectively. The addition of basalt fiber can reduce the loss of later strength, especially for flexural strength, with a increase rate of 11.9% to 39.5%. In addition, the brittleness of shotcrete increases during high temperature curing, so more transverse cracks are observed in the failure mode, and the peak stress and peak strain decrease. The addition of basalt fiber can improve the ductility and plasticity of shotcrete and increase the peak strain of shotcrete. The constitutive model is in good agreement with the experimental results.

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Comparison Analysis on the Mechanical Properties of HSC and NSC after the Action of High Temperatures

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1014.49 ◽

2014 ◽

Vol 1014 ◽

pp. 49-52

Author(s):

Xiao Ping Su

Keyword(s):

Mechanical Properties ◽

High Temperature ◽

High Temperatures ◽

High Strength Concrete ◽

Elasticity Modulus ◽

Strain Curve ◽

Peak Stress ◽

High Strength ◽

Peak Strain ◽

Strength Concrete

With the wide application of high strength concrete in the building construction,the risk making concrete subject to high temperatures during a fire is increasing. Comparison tests on the mechanical properties of high strength concrete (HSC) and normal strength concrete (NSC) after the action of high temperature were made in this article, which were compared from the following aspects: the peak stress, the peak strain, elasticity modulus, and stress-strain curve after high temperature. Results show that the laws of the mechanical properties of HSC and NSC changing with the temperature are the same. With the increase of heating temperature, the peak stress and elasticity modulus decreases, while the peak strain grows rapidly. HSC shows greater brittleness and worse fire-resistant performance than NSC, and destroys suddenly. The research and evaluation on the fire-resistant performance of HSC should be strengthened during the structural design and construction on the HSC buildings.

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Numerical Simulation of the Effect of Temperature on the Failure Strength of Rock

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.690-693.1737 ◽

2013 ◽

Vol 690-693 ◽

pp. 1737-1740

Author(s):

Lin Bu ◽

Tao Xu ◽

Yun Jie Zhang

Keyword(s):

Mechanical Properties ◽

Rock Fracture ◽

Strain Curve ◽

Peak Stress ◽

Effect Of Temperature ◽

Peak Strain ◽

Failure Strength ◽

Stress Strain Curve ◽

Physical Tests ◽

Compression Condition

The mechanical properties of granite experiencing high temperatures under uniaxial compression condition were simulated in this paper. Numerically simulated stress-strain curve, peak stress, peak strain and the tangent elastic modulus were compared with the corresponding physical tests. Simulated results agree well with physical tests results, it is shown that Abaqus is suitable for the analysis of the temperature effect on rock fracture.

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Mechanical Properties of Concrete Containing Liquefied Red Mud Subjected to Uniaxial Compression Loads

Materials ◽

10.3390/ma13040854 ◽

2020 ◽

Vol 13 (4) ◽

pp. 854 ◽

Cited By ~ 1

Author(s):

Gyeongcheol Choe ◽

Sukpyo Kang ◽

Hyeju Kang

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Red Mud ◽

Construction Material ◽

Strain Curve ◽

Peak Strain ◽

Cement Type ◽

Mixing Method ◽

Relationship Of ◽

The Relationship

This study used liquefied red mud (RM) sludge, an aluminum industry by-product, as a construction material. Accordingly, various methods were examined that used the fabricated liquefied red mud (LRM) as an admixture for concrete, and the mechanical properties of concrete were then evaluated according to the cement type and the amount of LRM. The LRM mixing methods (replacement and addition) were compared, and the slump and compressive strengths of concrete were evaluated for each method. To examine the mechanical properties according to the cement type and the amount of LRM, two types of cement (ordinary Portland cement and slag cement (SC)) were used, and 20 and 40 wt% LRM (with respect to the cement weight) were added. The mechanical properties of the stress–strain curve (SSC), compressive strength, peak strain, and elastic modulus were quantified. When the slump and compressive strength of concrete were considered based on the experimental results, the addition LRM mixing method was recommended as the appropriate method for LRM. As the addition of LRM increased, the mechanical properties of concrete degraded. However, when SC was used, the mechanical properties did not significantly change when different amounts of LRM were added (up to 20%). In addition, the SSC of LRM concrete could be approximated based on the use of the relationship of the compressive strength and peak strain according to the cement type and the amount of LRM.

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Study of the Effect of Joint Trace Lengths on Failure Strength of Rock

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.501-504.603 ◽

2014 ◽

Vol 501-504 ◽

pp. 603-606

Author(s):

Yun Jie Zhang ◽

Tao Xu

Keyword(s):

Compressive Strength ◽

Process Analysis ◽

Failure Process ◽

Strain Curve ◽

Peak Stress ◽

Experimental Results ◽

Peak Strain ◽

Joint Orientation ◽

Trace Length ◽

Failure Patterns

Numerical simulations the different rock sample in the uniaxial compression have been conducted using Rock Failure Process Analysis program (RFPA2D) to evaluate the effects of joint trace lengths on the overall mechanical behaviour of jointed rock masses in this paper. Numerically simulated stress-strain curve, peak stress, peak strain and failure patterns were compared with the corresponding experimental results. We found that for a series of partially-spanning joint geometries with the same joint orientation, the projected area will be proportional to the square of the trace length. Thus, the relationship between compressive strength and partially-spanning joint geometry for the tests carried out to explore the influence of joint trace length may be expressed as a linear correlation between compressive strength and projected area.Numerical simulations agree well with experimental results.

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Mechanical and Acoustic Emission Characteristics of Limestone after High Temperature

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.446-449.23 ◽

2012 ◽

Vol 446-449 ◽

pp. 23-28

Author(s):

Gang Wu ◽

De Yong Wang

Keyword(s):

Mechanical Properties ◽

Acoustic Emission ◽

High Temperature ◽

Strain Curve ◽

Peak Stress ◽

Mechanical Parameter ◽

Emission Characteristic ◽

Uniaxial Compression Test ◽

Peak Strain ◽

Different Temperatures

The mechanical properties and acoustic emission evolution process of limestone under the action of high temperature load were investigated by combining methods of uniaxial compression test and acoustic emission (AE) technique. The temperature varies in the range of 100, 200, 400, 600 and 800°C. By analysis of AE parameters and the mechanical parameter, the relations of stress-time (strain)-accumulative counts of AE, stress-time (strain)-AE rates under different temperatures are analyzed. The results show that the temperature does not obviously affect the mechanical properties of limestone at the temperature ranging from 100 to 400°C, the accumulative ring-down counts and accumulative energy increase with the rise of temperature. However, when the temperature is above 400°C, the mechanical properties of limestone deteriorate rapidly with the increase of temperature, and also the peak stress of limestone decrease in different extents. In the meantime, the accumulative ring-down counts decrease coupled with the change of mechanical parameter. The brittle fracture is main failure mode of limestone when the temperature is below 800°C and the change of peak strain of limestone is unobvious. The stress-strain curve conforms to the acoustic emission curve which shows that changes of minerals formation and microstructure due to high temperature result in the changes of mechanical and acoustic emission characteristic of limestone.

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Effect of Basalt Fiber on Static and Dynamic Mechanical Properties of Metakaolin-Based Cement Clay

Advances in Civil Engineering ◽

10.1155/2020/1359163 ◽

2020 ◽

Vol 2020 ◽

pp. 1-14

Author(s):

Kun Huang ◽

Qinyong Ma ◽

Dongdong Ma

Keyword(s):

Mechanical Properties ◽

Basalt Fiber ◽

Deformation Modulus ◽

Strain Curve ◽

Peak Stress ◽

Dynamic Mechanical Properties ◽

Fiber Content ◽

Test Results ◽

Stress Strain ◽

Reinforcement Mechanism

To investigate the effects of basalt fiber content on the mechanical properties and microstructure characteristic of metakaolin-based cement clay, the static and dynamic uniaxial compressive and splitting tensile, nuclear magnetic resonance (NMR), and scanning electron microscope (SEM) tests were performed to study the stress-strain curves, static and dynamic peak stress, pore distribution characteristic, and reinforcement mechanism. In this research, the basalt fiber with the length of 12 mm were selected and the ratios between fiber and dry soil were 0%, 0.5%, 1.0%, 1.5%, and 2.0%, respectively. The obtained results showed a noticeable difference of stress-strain curve characteristics in the static and dynamic compressive tests. A positive correlation between deformation modulus and compressive strength was found for both static and dynamic tests. The addition of basalt fiber could efficiently increase the static and dynamic strengths of metakaolin-based cement clay, and the increment 66.15% and 74.63% was observed at 1.0% basalt fiber content for static and dynamic compressive strengths, respectively, while the corresponding increment values were 93.75% and 97.62% for its splitting tensile strengths, respectively. The basalt fiber could decrease the porosity of cement clay; moreover, the reinforcement mechanism of metakaolin and basalt fiber to cement clay was analyzed based on the SEM test results.

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Experimental Investigation on the Mechanical Properties of Self-Compacting Concrete under Uniaxial and Triaxial Stress

Materials ◽

10.3390/ma13081830 ◽

2020 ◽

Vol 13 (8) ◽

pp. 1830 ◽

Cited By ~ 2

Author(s):

Hongbo Li ◽

Jianguang Yin ◽

Pengfei Yan ◽

Hao Sun ◽

Qingqing Wan

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Failure Mode ◽

Substitution Rate ◽

Peak Stress ◽

Confining Pressure ◽

Strength Test ◽

Peak Strain ◽

Self Compacting Concrete ◽

Splitting Strength

To explore the influence of fly ash (FA) and silica fume (SF) on the mechanical properties of self-compacting concrete (SCC) under uniaxial and triaxial, the compressive strength test, splitting strength test, ultrasonic testing test, and triaxial test were performed in this paper. The results show that the 3 days compressive strength and splitting strength of SCC decreased with the increase of FA substitution rate. The 28 days, 56 days, and 91 days compressive strength and splitting strength of SCC increased first and then decreased with the increase of FA substitution rate. The peak stress and peak strain of SCC gradually increased with the increase of confining pressure. The peak stress and strain of SCC increased first and then decreased with the increase of FA substitution rate. Moreover, the relationship models between compressive strength and splitting strength, between compressive strength and amplitude, between peak stress, peak strain and confining pressure under different FA substitution rates were proposed. As a conclusion, the addition of SF can increase the strength of SCC obviously. Under uniaxial stress, SCC failure mode is splitting failure, under triaxial stress, SCC failure mode is shear failure. Based on the Mohr-Coulomb strength theory, the failure criterion of SCC with FA and SF was discussed.

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Research on Dynamic Mechanical Properties and Constitutive Model of Basalt Fiber Reinforced Concrete after Exposure to Elevated Temperatures under Impact Loading

Applied Sciences ◽

10.3390/app10217684 ◽

2020 ◽

Vol 10 (21) ◽

pp. 7684

Author(s):

Wenbiao Liang ◽

Junhai Zhao ◽

Yan Li ◽

Yue Zhai ◽

Zhou Wang ◽

...

Keyword(s):

Mechanical Properties ◽

Constitutive Model ◽

Basalt Fiber ◽

Peak Stress ◽

Confining Pressure ◽

Dynamic Mechanical Properties ◽

Fiber Content ◽

Fiber Reinforced Concrete ◽

Dynamic Mechanical ◽

Different Temperatures

The dynamic mechanical properties of basalt fiber reinforced concrete (BFRC) with different fiber contents (0.0%, 0.1%, 0.2%, 0.3%, 0.4%), confining pressures (0 MPa, 5 MPa, 10 MPa, 15 MPa) and exposed to different temperatures (20 °C, 200 °C, 400 °C, 600 °C, 800 °C) were investigated by using a 50 mm split Hopkinson pressure bar (SHPB) apparatus, and the factors such as fiber content, temperature and confining pressure effect on the dynamic mechanical properties were analyzed. The results show that the dynamic peak stress increases first and then decreases with the increase of fiber content. At different temperatures, the peak stress and its corresponding strain correspond to different fiber content, and the optimal fiber content is between 0.1% and 0.3%. When the temperature was from 20 °C to 400 °C, the dynamic peak stress decreased less, while when the temperature reached 600 °C and 800 °C, the dynamic peak stress decreased greatly. The confining pressure can significantly increase the dynamic peak stress and change the crushing morphology of specimens. The damage variable was built based on the Weibull distribution. A dynamic damage constitutive model combining statistical damage and viscoelastic model was established based on component combination model. The fitting curve of this model fitted well with test curve by identifying fewer undetermined parameters compared with Zhu-Wang-Tang (ZWT) model; therefore, this model can well describe the dynamic properties of BFRC under impact load.

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Mechanical Behavior of Brick Masonry in an Acidic Atmospheric Environment

Materials ◽

10.3390/ma12172694 ◽

2019 ◽

Vol 12 (17) ◽

pp. 2694 ◽

Cited By ~ 2

Author(s):

Shansuo Zheng ◽

Lihua Niu ◽

Pei Pei ◽

Jinqi Dong

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Fly Ash ◽

Acid Rain ◽

Cement Mortar ◽

Brick Masonry ◽

Atmospheric Environment ◽

Peak Strain ◽

Lime Mortar ◽

Attenuation Model

In order to evaluate the deterioration regularity for the mechanical properties of brick masonry due to acid rain corrosion, a series of mechanical property tests for mortars, bricks, shear prisms, and compressive prisms after acid rain corrosion were conducted. The apparent morphology and the compressive strength of the masonry materials (cement mortar, cement-lime mortar, cement-fly ash mortar, and brick), the shear behavior of the masonry, and the compression behavior of the masonry were analyzed. The resistance of acid rain corrosion for the cement-lime mortar prisms was the worst, and the incorporation of fly ash into the cement mortar did not improve the acid rain corrosion resistance. The effect of the acid rain corrosion damage on the mechanical properties for the brick was significant. With an increasing number of acid rain corrosion cycles, the compressive strength of the mortar prisms, and the shear and compressive strengths of the brick masonry first increased and then decreased. The peak stress first increased and then decreased whereas the peak strain gradually increased. The slope of the stress-strain curve for the compression prisms gradually decreased. Furthermore, a mathematical degradation model for the compressive strength of the masonry material (cement mortar, cement-lime mortar, cement-fly ash mortar, and brick), as well as the shear strength attenuation model and the compressive strength attenuation model of brick masonry after acid rain corrosion were proposed.

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Experimental Study on Biaxial Dynamic Compressive Properties of ECC

Materials ◽

10.3390/ma14051257 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1257

Author(s):

Shuling Gao ◽

Guanhua Hu

Keyword(s):

Strain Rate ◽

Lateral Pressure ◽

Deformation Modulus ◽

Strain Curve ◽

Peak Stress ◽

Pressure Level ◽

Strain Rates ◽

Peak Strain ◽

Stress Strain Curve ◽

Toughness Index

An improved hydraulic servo structure testing machine has been used to conduct biaxial dynamic compression tests on eight types of engineered cementitious composites (ECC) with lateral pressure levels of 0, 0.125, 0.25, 0.5, 0.7, 0.8, 0.9, 1.0 (the ratio of the compressive strength applied laterally to the static compressive strength of the specimen), and three strain rates of 10−4, 10−3 and 10−2 s−1. The failure mode, peak stress, peak strain, deformation modulus, stress-strain curve, and compressive toughness index of ECC under biaxial dynamic compressive stress state are obtained. The test results show that the lateral pressure affects the direction of ECC cracking, while the strain rate has little effect on the failure morphology of ECC. The growth of lateral pressure level and strain rate upgrades the limit failure strength and peak strain of ECC, and the small improvement is achieved in elastic modulus. A two-stage ECC biaxial failure strength standard was established, and the influence of the lateral pressure level and peak strain was quantitatively evaluated through the fitting curve of the peak stress, peak strain, and deformation modulus of ECC under various strain rates and lateral pressure levels. ECC’s compressive stress-strain curve can be divided into four stages, and a normalized biaxial dynamic ECC constitutive relationship is established. The toughness index of ECC can be increased with the increase of lateral pressure level, while the increase of strain rate can reduce the toughness index of ECC. Under the effect of biaxial dynamic load, the ultimate strength of ECC is increased higher than that of plain concrete.

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