The steady and dynamic rheological behaviors of precipitated calcium carbonate (PCC) suspension in polyethylene glycol (PEG) were investigated on a TA AR2000ex rheometer. Under steady shear consistency index K and flo...The steady and dynamic rheological behaviors of precipitated calcium carbonate (PCC) suspension in polyethylene glycol (PEG) were investigated on a TA AR2000ex rheometer. Under steady shear consistency index K and flow exponent N of suspensions with different volume fractions were determined. The shear-thinning and the discontinuous shear-thickening behavior were observed at different constant frequencies from 10 to 100 rad/s. The relationship between the complex viscosity and the constant frequency were determined. As the volume fraction increases,flow exponent N shows a rapid increase,and it increases dramatically when the discontinuous shear-thickening takes place,while consistency index K decreases. Dynamic oscillatory shear experiments were conducted at constant strain amplitude and constant frequency,respectively. For the frequency sweep,the system shows viscous property in entire range of the frequency investigated,and the complex viscosity shows discontinuous jump at a critical frequency of 10 rad/s. For the strain sweep,on the other hand,at low strain the elastic modulus is strongly dependent on the strain,and the viscous modulus is independent of the strain. But at the critical strain point both of the moduli show an abrupt jump and the system transits from elastic to viscous at a strain of 0.1.展开更多
The characters of basalt fiber are analyzed and compared with commonly used fibers. The rheological behaviors of the basalt fiber reinforced asphalt mastic are investigated by the dynamic shear rheological tests and t...The characters of basalt fiber are analyzed and compared with commonly used fibers. The rheological behaviors of the basalt fiber reinforced asphalt mastic are investigated by the dynamic shear rheological tests and the repeated creep tests. The results show that basalt fiber has excellent reinforced performances, such as high asphalt absorption ratio, low water absorption ratio, high tensile strength, high elastic modulus and high temperature stability. The rutting factor of the fiber reinforced asphalt mastic is higher than the plain asphalt mastic and the reinforced effects are more remarkable under high temperature. The rheological performances of the asphalt mastic demonstrate a good linear relationship between different temperature and loading frequency. The creep stiffness modulus of the asphalt mastic at different loading time can be expressed by power function. Improved Burgers model is used to represent the rheological behaviors of the asphalt mastic with basalt fiber and the model parameters are estimated.展开更多
In order to study the chemical modification mechanism and rheological properties of polyphosphoric acid (PPA)-modified asphalt,asphalt modified with different PPA contents were characterized by four-component test,ato...In order to study the chemical modification mechanism and rheological properties of polyphosphoric acid (PPA)-modified asphalt,asphalt modified with different PPA contents were characterized by four-component test,atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR).In the test,changes in asphalt chemical composition and colloidal structure were analyzed for different PPA contents,and infrared spectra were fitted with a Gaussian function.The reaction mechanism of PPA and matrix asphalt was also discussed.Based on dynamic shear rheometer (DSR) test and bending beam rheometer (BBR) test,rheological index G~*/sinδ and S/m were used to evaluate the modification effect of PPA on asphalt.The results show that,with an increase in PPA content,both large and small honeycomb structures increased in the three-dimensional topography seen in the atomic force microscope (AFM).In a certain space range,some of the micelles in the asphalt are connected each other to form interlocking skeleton structures,and locally form dense spatial network structures.The added PPA does not chemically react with the functional groups in the functional-group area of the infrared spectra (3 100-2 750 cm^(-1),1 800-1 330 cm^(-1)),and the structure is very stable.However,there is an obvious new absorption peak below 1 330 cm^(-1) in the fingerprint area,that is,the chemical reaction between PPA and the matrix asphalt generates a new compound,inorganic phosphate.Infrared spectra of PPA-modified asphalt with different contents were fitted by a Gaussian function,which makes up for the limitation that the absorption intensity information of each superimposed functional group cannot be obtained directly from the original infrared spectra.Results of this qualitative analysis were further verified by quantitative analysis.The addition of PPA can effectively improve the high and low-temperature performance of asphalt,and the lower the temperature is in the negative temperature zone,the more obvious the improvement is.When PPA content is more than 1%,the improvement of asphalt low-temperature performance is not obvious.展开更多
海底表层的结构物在使用中可能受到动荷载作用,为保证其的长期稳定性,有必要对海床表层的深海超软土动力学特性展开研究。使用Anton Paar MCR302流变仪,采用应变控制模式,对含水率高于液限的深海超软土进行动态剪切测试,研究动态流变参...海底表层的结构物在使用中可能受到动荷载作用,为保证其的长期稳定性,有必要对海床表层的深海超软土动力学特性展开研究。使用Anton Paar MCR302流变仪,采用应变控制模式,对含水率高于液限的深海超软土进行动态剪切测试,研究动态流变参数、动剪切模量G和阻尼比λ的变化规律。结果表明,随着剪切应变的增大,深海超软土的变形由可恢复的弹性变形主导逐渐过渡为不可恢复的黏性变形主导。通过建立动态流变参数与动剪切模量G和阻尼比λ的关系,探讨了深海超软土的动力特性。根据深海超软土动剪切模量G的变化特征,提出了峰值参考应变的概念,建立了最大动剪模量G_(max)与归一化含水率w/w_(p)(w为含水率,w_(p)为塑性含水率)的关系。结果还显示,相较于常规黏土,深海超软土的G/G_(max-γ)(γ为剪切应变)曲线衰减较快,且受塑性指数影响较小。深海超软土的阻尼比整体偏高,并随剪切应变的增大快速上升。根据试验结果,给出描述深海超软土G/G_(max-γ)、λ-γ曲线的数学模型。展开更多
基金Projects (50774096, 50606017) supported by the National Natural Science Foundation of China
文摘The steady and dynamic rheological behaviors of precipitated calcium carbonate (PCC) suspension in polyethylene glycol (PEG) were investigated on a TA AR2000ex rheometer. Under steady shear consistency index K and flow exponent N of suspensions with different volume fractions were determined. The shear-thinning and the discontinuous shear-thickening behavior were observed at different constant frequencies from 10 to 100 rad/s. The relationship between the complex viscosity and the constant frequency were determined. As the volume fraction increases,flow exponent N shows a rapid increase,and it increases dramatically when the discontinuous shear-thickening takes place,while consistency index K decreases. Dynamic oscillatory shear experiments were conducted at constant strain amplitude and constant frequency,respectively. For the frequency sweep,the system shows viscous property in entire range of the frequency investigated,and the complex viscosity shows discontinuous jump at a critical frequency of 10 rad/s. For the strain sweep,on the other hand,at low strain the elastic modulus is strongly dependent on the strain,and the viscous modulus is independent of the strain. But at the critical strain point both of the moduli show an abrupt jump and the system transits from elastic to viscous at a strain of 0.1.
基金Funded by The National Natural Science Foundation of China(No.51108082)
文摘The characters of basalt fiber are analyzed and compared with commonly used fibers. The rheological behaviors of the basalt fiber reinforced asphalt mastic are investigated by the dynamic shear rheological tests and the repeated creep tests. The results show that basalt fiber has excellent reinforced performances, such as high asphalt absorption ratio, low water absorption ratio, high tensile strength, high elastic modulus and high temperature stability. The rutting factor of the fiber reinforced asphalt mastic is higher than the plain asphalt mastic and the reinforced effects are more remarkable under high temperature. The rheological performances of the asphalt mastic demonstrate a good linear relationship between different temperature and loading frequency. The creep stiffness modulus of the asphalt mastic at different loading time can be expressed by power function. Improved Burgers model is used to represent the rheological behaviors of the asphalt mastic with basalt fiber and the model parameters are estimated.
基金Funded by National Natural Science Foundation of China (No. 11962024)Inner Mongolia Transportation Technology Project (No. NJ-2014-9)Research Fund for the Doctoral Program of Higher Education of China (RFDP)(No. BS2020042)。
文摘In order to study the chemical modification mechanism and rheological properties of polyphosphoric acid (PPA)-modified asphalt,asphalt modified with different PPA contents were characterized by four-component test,atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR).In the test,changes in asphalt chemical composition and colloidal structure were analyzed for different PPA contents,and infrared spectra were fitted with a Gaussian function.The reaction mechanism of PPA and matrix asphalt was also discussed.Based on dynamic shear rheometer (DSR) test and bending beam rheometer (BBR) test,rheological index G~*/sinδ and S/m were used to evaluate the modification effect of PPA on asphalt.The results show that,with an increase in PPA content,both large and small honeycomb structures increased in the three-dimensional topography seen in the atomic force microscope (AFM).In a certain space range,some of the micelles in the asphalt are connected each other to form interlocking skeleton structures,and locally form dense spatial network structures.The added PPA does not chemically react with the functional groups in the functional-group area of the infrared spectra (3 100-2 750 cm^(-1),1 800-1 330 cm^(-1)),and the structure is very stable.However,there is an obvious new absorption peak below 1 330 cm^(-1) in the fingerprint area,that is,the chemical reaction between PPA and the matrix asphalt generates a new compound,inorganic phosphate.Infrared spectra of PPA-modified asphalt with different contents were fitted by a Gaussian function,which makes up for the limitation that the absorption intensity information of each superimposed functional group cannot be obtained directly from the original infrared spectra.Results of this qualitative analysis were further verified by quantitative analysis.The addition of PPA can effectively improve the high and low-temperature performance of asphalt,and the lower the temperature is in the negative temperature zone,the more obvious the improvement is.When PPA content is more than 1%,the improvement of asphalt low-temperature performance is not obvious.
文摘海底表层的结构物在使用中可能受到动荷载作用,为保证其的长期稳定性,有必要对海床表层的深海超软土动力学特性展开研究。使用Anton Paar MCR302流变仪,采用应变控制模式,对含水率高于液限的深海超软土进行动态剪切测试,研究动态流变参数、动剪切模量G和阻尼比λ的变化规律。结果表明,随着剪切应变的增大,深海超软土的变形由可恢复的弹性变形主导逐渐过渡为不可恢复的黏性变形主导。通过建立动态流变参数与动剪切模量G和阻尼比λ的关系,探讨了深海超软土的动力特性。根据深海超软土动剪切模量G的变化特征,提出了峰值参考应变的概念,建立了最大动剪模量G_(max)与归一化含水率w/w_(p)(w为含水率,w_(p)为塑性含水率)的关系。结果还显示,相较于常规黏土,深海超软土的G/G_(max-γ)(γ为剪切应变)曲线衰减较快,且受塑性指数影响较小。深海超软土的阻尼比整体偏高,并随剪切应变的增大快速上升。根据试验结果,给出描述深海超软土G/G_(max-γ)、λ-γ曲线的数学模型。
