scholarly journals Assessment of Thermal Stresses in Asphalt Mixtures at Low Temperatures Using the Tensile Creep Test and the Bending Beam Creep Test

2019 ◽  
Vol 9 (5) ◽  
pp. 846 ◽  
Author(s):  
Marek Pszczola ◽  
Mariusz Jaczewski ◽  
Cezary Szydlowski
Keyword(s):  
Thermal Stress ◽  
Low Temperature ◽  
Creep Test ◽  
Thermal Stresses ◽  
Test Methods ◽  
Asphalt Mixtures ◽  
Tensile Creep ◽  
Rheological Parameters ◽  
Uniaxial Tensile ◽  
Failure Temperature

Thermal stresses are leading factors that influence low-temperature cracking behavior of asphalt pavements. During winter, when the temperature drops to significantly low values, tensile thermal stresses develop as a result of pavement contraction. Creep test methods can be suitable for the assessment of low-temperature properties of asphalt mixtures. To evaluate the influence of creep test methods on the obtained low-temperature properties of asphalt mixtures, three point bending and uniaxial tensile creep tests were applied and the master curves of stiffness modulus were analyzed. On the basis of creep test results, rheological parameters describing elastic and viscous properties of the asphalt mixtures were determined. Thermal stresses were calculated and compared to the tensile strength of the material to obtain the failure temperature of the analyzed asphalt mixtures. It was noted that lower strain values of creep curves were obtained for the Tensile Creep Test (TCT) than for the Bending Beam Creep Test (BBCT), especially at lower temperatures. Results of thermal stress calculations indicated that higher reliability was obtained for the viscoelastic Monismith method based on the TCT results than for the simple quasi-elastic solution of Hills and Brien. The highest agreement with the TSRST results was also obtained for the Monismith method based on the TCT results. No clear relationships were noted between the predicted failure temperature and different methods of thermal stress calculations.

scholarly journals Assessment of Thermal Stresses in Asphalt Mixtures at Low Temperatures Using the Tensile Creep Test and the Bending Beam Creep Test

2019 ◽  
Author(s):  
Marek Pszczola ◽  
Mariusz Jaczewski ◽  
Cezary Szydlowski
Keyword(s):  
Thermal Stress ◽  
Low Temperature ◽  
Creep Test ◽  
Thermal Stresses ◽  
Test Methods ◽  
Asphalt Mixtures ◽  
Tensile Creep ◽  
Rheological Parameters ◽  
Uniaxial Tensile ◽  
Failure Temperature

Thermal stresses belong to the leading factors that influence low-temperature cracking behavior of asphalt pavements. During winter, when temperature drops to significantly low values, tensile thermal stresses develop as a result of pavement contraction. Creep test methods can be suitable for the assessment of low-temperature properties of asphalt mixtures. To evaluate the influence of creep test methods on the obtained low-temperature properties of asphalt mixtures, three point bending and uniaxial tensile creep tests were applied and the master curves of stiffness modulus were analyzed. On the basis of creep test results, rheological parameters describing elastic and viscous properties of the asphalt mixtures were determined. Thermal stresses were calculated and compared to tensile strength of the material to obtain the failure temperature of the analyzed asphalt mixtures. It was noted that lower strain values of creep curves were obtained for the Tensile Creep Test (TCT) than for the Bending Beam Creep Test (BBCT), especially at lower temperatures. Results of thermal stress calculations indicated that higher reliability was obtained for the viscoelastic Monismith method based on the TCT results than for the simple quasi-elastic solution of Hills and Brien. The highest agreement with the TSRST results was also obtained for the Monismith method based on the TCT results. No clear relationships were noted between the predicted failure temperature and different methods of thermal stress calculations.

scholarly journals Influence of Bitumen Type and Asphalt Mixture Composition on Low-Temperature Strength Properties According to Various Test Methods

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2118 ◽  
Author(s):  
Marek Pszczola ◽  
Cezary Szydlowski
Keyword(s):  
Tensile Strength ◽  
Low Temperature ◽  
Cooling Rate ◽  
Strength Properties ◽  
Test Methods ◽  
Asphalt Mixtures ◽  
Bending Test ◽  
Mixture Composition ◽  
Tension Stress ◽  
Strength Reserve

In regions with low-temperatures, action transverse cracks can appear in asphalt pavements as a result of thermal stresses that exceed the fracture strength of materials used in asphalt layers. To better understand thermal cracking phenomenon, strength properties of different asphalt mixtures were investigated. Four test methods were used to assess the influence of bitumen type and mixture composition on tensile strength properties of asphalt mixtures: tensile strength was measured using the thermal stress restrained specimen test (TSRST) and the uniaxial tension stress test (UTST), flexural strength was measured using the bending beam test (BBT), and fracture toughness was measured using the semi-circular bending test (SCB). The strength reserve behavior of tested asphalt mixtures was assessed as well. The influence of cooling rate on the strength reserve was investigated and correlations between results from different test methods were also analyzed and discussed. It was observed that the type of bitumen was a factor of crucial importance to low-temperature properties of the tested asphalt concretes. This conclusion was valid for all test methods that were used. It was also observed that the level of cooling rate influenced the strength reserve and, in consequence, resistance to low-temperature cracking. It was concluded that reasonably good correlations were observed between strength results for the UTST, BBT, and SCB test methods.

scholarly journals Tensile Creep of Cement and Concrete Composites: Monitoring by Means of 2D-Digital Image Correlation

2021 ◽  
Vol 11 (18) ◽  
pp. 8334
Author(s):  
Andina Sprince ◽  
Tomass Kozlovskis ◽  
Rihards Gailitis ◽  
Juozas Valivonis ◽  
Kinga Korniejenko ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Compact Tension ◽  
Test Methods ◽  
Image Correlation ◽  
Tensile Creep ◽  
Uniaxial Tensile ◽  
2D Digital Image Correlation ◽  
Cement And Concrete ◽  
Creep Deformations

Creep and shrinkage of Cement and Concrete Composites (CCC) are significant properties that need to be considered to use these materials in practice. Many previous scientific studies revealed CCC creep characteristics under sustained compression and shrinkage, using traditional test methods from design standards. Because of the complexity of experimental procedures, CCC creep in tension has not been studied as close. Furthermore, there is no unified standard that proposes applicable testing methods or specific testing apparatus. This study examines the suitability of 2D—Digital Image Correlation (DIC) to observe the creep deformations of specimens under tension. Ordinary Portland cement (OPC) mortar with 1% polyvinyl alcohol (PVA) fibres has been investigated in the research. Compact tension (CT) specimens 150 × 150 × 12 mm (with a notch) were used. Creep deformations under sustained uniaxial tension (applied loading corresponding to 60% of the ultimate strength) were measured. DIC images were captured using an entry/mid-level DSLR camera. Results show that DIC is suitable for studying uniaxial tensile creep of cement and concrete composites. Deformation of specimens in tension was similar to that measured using the conventional method (using surface-attached gauges).

scholarly journals Influence of Bitumen Type and Asphalt Mixture Composition on Low-temperature Strength Properties

2018 ◽  
Author(s):  
Marek Pszczola ◽  
Cezary Szydlowski
Keyword(s):  
Tensile Strength ◽  
Low Temperature ◽  
Cooling Rate ◽  
Strength Properties ◽  
Test Methods ◽  
Asphalt Mixtures ◽  
Bending Test ◽  
Mixture Composition ◽  
Tension Stress ◽  
Strength Reserve

In regions with low-temperature action transverse cracks can appear in asphalt pavements as a result of thermal stresses that exceed the fracture strength of materials used in asphalt layers. To better understand thermal cracking phenomenon, strength properties of different asphalt mixtures were investigated. Four test methods were used to assess the influence of bitumen type and mixture composition on tensile strength properties of asphalt mixtures: tensile strength using the Thermal Stress Restrained Specimen Test (TSRST) and the Uniaxial Tension Stress Test (UTST), flexural strength using the Bending Beam Test (BBT) and fracture toughness using the Semi-Circular Bending Test (SCB). The strength reserve behavior of tested asphalt mixtures was assessed as well. The influence of cooling rate on strength reserve was investigated and correlations between results from different test methods were also analyzed and discussed. It was observed that the type of bitumen is a factor of crucial importance to low-temperature properties of the tested asphalt concretes. This conclusion was proved by all test methods that were used. It was also observed that the level of cooling rate influences the strength reserve and, in consequence, resistance to low-temperature cracking. It was concluded that reasonably good correlations were observed between strength results for the UTST, BBT and SCB test methods.

scholarly journals Elevated Temperature Tensile Creep Behavior of Aluminum Borate Whisker-Reinforced Aluminum Alloy Composites (ABOw/Al–12Si)

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1217
Author(s):  
Yameng Ji ◽  
Yanpeng Yuan ◽  
Weizheng Zhang ◽  
Yunqing Xu ◽  
Yuwei Liu
Keyword(s):  
Elevated Temperature ◽  
Creep Test ◽  
Load Transfer ◽  
Elevated Temperatures ◽  
Tensile Creep ◽  
Uniaxial Tensile ◽  
Fracture Mechanisms ◽  
Transfer Model ◽  
Unreinforced Alloy ◽  
The Matrix

In order to evaluate the elevated temperature creep performance of the ABOw/Al–12Si composite as a prospective piston crown material, the tensile creep behaviors and creep fracture mechanisms have been investigated in the temperatures range from 250 to 400 °C and the stress range from 50 to 230 MPa using a uniaxial tensile creep test. The creep experimental data can be explained by the creep constitutive equation with stress exponents of 4.03–6.02 and an apparent activation energy of 148.75 kJ/mol. The creep resistance of the ABOw/Al–12Si composite is immensely improved by three orders of magnitude, compared with the unreinforced alloy. The analysis of the ABOw/Al–12Si composite creep data revealed that dislocation climb is the main creep deformation mechanism. The values of the threshold stresses are 37.41, 25.85, and 17.36 at elevated temperatures of 300, 350 and 400 °C, respectively. A load transfer model was introduced to interpret the effect of whiskers on the creep rate of this composite. The creep test data are very close to the predicted values of the model. Finally, the fractographs of the specimens were analyzed by Scanning Electron Microscope (SEM), the fracture mechanisms of the composites at different temperatures were investigated. The results showed that the fracture characteristic of the ABOw/Al–12Si composite exhibited a macroscale brittle feature range from 300 to 400 °C, but a microscopically ductile fracture was observed at 400 °C. Additionally, at a low tensile creep temperature (300 °C), the plastic flow capacity of the matrix was poor, and the whisker was easy to crack and fracture. However, during tensile creep at a higher temperature (400 °C), the matrix was so softened that the whiskers were easily pulled out and interfacial debonding appeared.

Thermal stresses in carbon-coated optical fibers at low temperature

1997 ◽  
Vol 12 (9) ◽  
pp. 2493-2498 ◽  
Author(s):  
Sham-Tsong Shiue ◽  
Wen-Hao Lee
Keyword(s):  
Thermal Stress ◽  
Low Temperature ◽  
Glass Fiber ◽  
Young’S Modulus ◽  
Optical Fibers ◽  
Poisson’S Ratio ◽  
Carbon Coating ◽  
Thermal Stresses ◽  
Poisson's Ratio ◽  
Carbon Coated

The thermal stresses in carbon-coated optical fibers at low temperature have been analyzed. The thermally induced lateral pressure in the glass fiber would produce microbending loss. In order to minimize such a microbending loss, the thickness, Young's modulus, and Poisson's ratio of the carbon coating should be decreased. On the other hand, the maximum thermal stress is the tangential stress in the carbon coating that occurs at the interface of the carbon coating and glass fiber. It was experimentally observed that if the maximum thermal stress is larger than the tensile strength of the carbon coating, the carbon coating will be broken along the axial direction. In order to minimize such a maximum thermal stress, the thickness of the carbon coating should be increased, but Young's modulus, thermal expansion coefficient, and Poisson's ratio of the carbon coating should be decreased. Finally, an optimal selection of the carbon coating for optical fiber is discussed.

scholarly journals Performance-Based Asphalt Mix and Pavement Design

2013 ◽  
Vol 2 (1) ◽  
pp. 21-38 ◽  
Author(s):  
Ronald Blab
Keyword(s):  
Low Temperature ◽  
Deformation Behavior ◽  
Elevated Temperatures ◽  
Permanent Deformation ◽  
Flexible Pavements ◽  
Test Methods ◽  
Service Performance ◽  
Triaxial Tests ◽  
Uniaxial Tensile ◽  
Induced Stresses

Abstract Prediction and optimization of in-service performance of road pavements during their live time is one of the main objectives of pavement research these days. For flexible pavements the key performance characteristics are fatigue and low-temperature, as well as permanent deformation behavior at elevated temperatures. The problem facing pavement designers is the need to fully characterize the complex thermo-rheological properties of hot mix asphalt (HMA) over a wide temperature range on the one hand, while on the other also providing a realistic simulation of the traffic- and climate-induced stresses to which pavements are exposed over their design lives of 20 to 30 years. Where heavily trafficked roads are concerned, there is therefore an urgent need for more comprehensive test methods combined with better numerical forecast procedures to improve the economics and extend the service lives of flexible pavements under repair and maintenance programs. This papers therefore focus on performance-based test methods on the basis of existing European standards that address effective mechanical characteristics of bituminous materials and which may be introduced into national requirements within the framework of European HMA specifications. These test methods comprise low temperature tests, i.e. the tensile stress restrained specimen test or the uniaxial tensile strength test, stiffness and fatigue tests, i.e. the four point bending beam test or the uniaxial tension compression test, as well as methods to determine permanent deformation behavior by means of dynamic triaxial tests. These tests are used for the performance-based mix design and subsequently implemented in numerical pavement models for a reliable prediction of in-service performance, which, in combination with performance-based tests, enables a simulation of load-induced stresses and mechanogenic effects on the road structure and thus improved forecasts of the in-service performance of flexible pavements over their entire service lives.

Design and Evaluation of Asphalt Mixtures for Stress Absorbing Pavement Layers

2015 ◽  
Vol 764-765 ◽  
pp. 116-121
Author(s):  
Ondrej Dasek ◽  
Pavel Coufalik ◽  
Petr Hyzl ◽  
Jan Kudrna ◽  
Jaroslava Daskova ◽  
...  
Keyword(s):  
Low Temperature ◽  
Test Methods ◽  
Asphalt Mixtures ◽  
Fatigue Properties ◽  
Rubber Mixture ◽  
Stiffness Modulus ◽  
Theoretical Part ◽  
Asphalt Rubber ◽  
Absorbing Layer ◽  
Tensile Relaxation

This paper deals with the use of special asphalt-rubber mixture, the Stress Absorbing Layer (SAL). Description of SAL and test methods is given in theoretical part of this paper. Several different mixtures were designed and selected ones subsequently tested. Low-temperature properties, rutting test, bending tensile relaxation, stiffness modulus and fatigue properties were determined. These parameters are stated for asphalt-rubber mixtures with aggregate sizes up to 5 mm, 8 mm or 16 mm.

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