The effects of diacetyl tartaric acid ester of monoglycerides (DATEM), ascorbic acid (AA), urea, and dithiothreitol (DTT) on viscoelastic properties of commercial hard red winter wheat gluten were investigated. A cons...The effects of diacetyl tartaric acid ester of monoglycerides (DATEM), ascorbic acid (AA), urea, and dithiothreitol (DTT) on viscoelastic properties of commercial hard red winter wheat gluten were investigated. A constant shear stress of 40 Pa was applied to gluten during creep-recovery test. Experimental creep-recovery compliance responses were fitted into a Burgers model with four elements accounting for characteristics of pure elastic (spring), viscoelastic (spring-dashpots elements), and viscous flow (dashpot). DATEM decreased the elasticity and viscoelasticity, but increased viscosity of gluten. The addition of AA, urea, and DTT, resulted in opposite rheological properties when compared with DATEM. Relationship among physical properties was also studied with principal component analysis (PCA) including gluten viscoelasticity, dough mixing and baking properties. Regressed coefficients from Burgers model accounted for higher percent of explained variance and were independent from flour content, baking and dough mixing properties.展开更多
本研究利用70号道路石油沥青和SBS改性沥青,将温拌剂(Sasobit)、氢氧化铝(ATH)和有机蒙脱土(OMMT)与沥青复配,制备成三种不同阻燃剂掺量(质量分数)的温拌阻燃沥青,采用多应力蠕变恢复(MSCR)试验开展对温拌阻燃沥青高温性能的评价。分别...本研究利用70号道路石油沥青和SBS改性沥青,将温拌剂(Sasobit)、氢氧化铝(ATH)和有机蒙脱土(OMMT)与沥青复配,制备成三种不同阻燃剂掺量(质量分数)的温拌阻燃沥青,采用多应力蠕变恢复(MSCR)试验开展对温拌阻燃沥青高温性能的评价。分别对温拌阻燃沥青在60℃下的应变变化、蠕变恢复率(R)、不可恢复蠕变柔量(J_(nr))及其相应应力敏感性指标(R_(diff)、J_(nrdiff))进行分析,并依据AASHTO M 332-20标准对不同阻燃剂掺量的温拌阻燃沥青进行交通分级。结果表明:随着阻燃剂掺量的提高,两种类型沥青的应变值减小,J_(nr)值呈减小趋势,R值呈增大趋势;阻燃剂掺量较低时,提高其掺量对沥青结合料的高温性能改善效果更加明显;温拌阻燃沥青(道路石油沥青)的J_(nr3.2)值不满足AASHTO标准中“≤4.5”的要求。温拌阻燃沥青的J_(nrdiff)值均能满足AASHTO标准中“≤75%”的要求。温拌阻燃沥青(道路石油沥青)未达到标准交通要求而无法分级,温拌阻燃沥青(SBS改性沥青)在4%阻燃剂掺量下达到特重交通的标准,在8%、12%掺量下达到极重交通的标准,因此温拌阻燃沥青(SBS改性沥青)的高温性能更好。基于对温拌阻燃沥青蠕变力学指标、高温交通分级和经济性的综合考虑,推荐复配阻燃剂(ATH、OMMT的质量比为3∶1)的最佳掺量为8%。展开更多
This paper discusses a visco-elastoplastic constitutive model to analyze the creep deformability of asphalt concretes at high service temperatures, finalized to improve the interpretation of permanent deformation phen...This paper discusses a visco-elastoplastic constitutive model to analyze the creep deformability of asphalt concretes at high service temperatures, finalized to improve the interpretation of permanent deformation phenomenon and performance design of road pavements. A three dimensional constitutive visco-elastoplastic model is introduced, in tensor as well as in numerical form. The associated uniaxial model is used to arrange a plastic element in series with the viscoelastic component. The latter is defined by an elastic spring placed in parallel with three Maxwell elements. Three different hardening laws, namely isotropic, kinematic and mixed hardening, are included in the constitutive model to compare the creep deformability. The proposed constitutive model has been calibrated and validated on the basis of uniaxial creep-recovery test results at 40℃. This is performed with a high performance hot mix asphalt concrete （HP-HMA） at different stresses and loading times. Depending on the hardening law considered, permanent deformation data predicted by the proposed model results are reasonably consistent with the experimental creep-recovery data. A rational constitutive model that is physically congruent with the creep phenomenon of asphalt concretes was developed and calibrated to achieve a deeper understanding of the stress-strain response of such materials. The fundamental relevance of an appropriate plastic response modeling, in the study of the creep behavior of asphalt concretes for highway and road pavements.展开更多
文摘The effects of diacetyl tartaric acid ester of monoglycerides (DATEM), ascorbic acid (AA), urea, and dithiothreitol (DTT) on viscoelastic properties of commercial hard red winter wheat gluten were investigated. A constant shear stress of 40 Pa was applied to gluten during creep-recovery test. Experimental creep-recovery compliance responses were fitted into a Burgers model with four elements accounting for characteristics of pure elastic (spring), viscoelastic (spring-dashpots elements), and viscous flow (dashpot). DATEM decreased the elasticity and viscoelasticity, but increased viscosity of gluten. The addition of AA, urea, and DTT, resulted in opposite rheological properties when compared with DATEM. Relationship among physical properties was also studied with principal component analysis (PCA) including gluten viscoelasticity, dough mixing and baking properties. Regressed coefficients from Burgers model accounted for higher percent of explained variance and were independent from flour content, baking and dough mixing properties.
文摘本研究利用70号道路石油沥青和SBS改性沥青,将温拌剂(Sasobit)、氢氧化铝(ATH)和有机蒙脱土(OMMT)与沥青复配,制备成三种不同阻燃剂掺量(质量分数)的温拌阻燃沥青,采用多应力蠕变恢复(MSCR)试验开展对温拌阻燃沥青高温性能的评价。分别对温拌阻燃沥青在60℃下的应变变化、蠕变恢复率(R)、不可恢复蠕变柔量(J_(nr))及其相应应力敏感性指标(R_(diff)、J_(nrdiff))进行分析,并依据AASHTO M 332-20标准对不同阻燃剂掺量的温拌阻燃沥青进行交通分级。结果表明:随着阻燃剂掺量的提高,两种类型沥青的应变值减小,J_(nr)值呈减小趋势,R值呈增大趋势;阻燃剂掺量较低时,提高其掺量对沥青结合料的高温性能改善效果更加明显;温拌阻燃沥青(道路石油沥青)的J_(nr3.2)值不满足AASHTO标准中“≤4.5”的要求。温拌阻燃沥青的J_(nrdiff)值均能满足AASHTO标准中“≤75%”的要求。温拌阻燃沥青(道路石油沥青)未达到标准交通要求而无法分级,温拌阻燃沥青(SBS改性沥青)在4%阻燃剂掺量下达到特重交通的标准,在8%、12%掺量下达到极重交通的标准,因此温拌阻燃沥青(SBS改性沥青)的高温性能更好。基于对温拌阻燃沥青蠕变力学指标、高温交通分级和经济性的综合考虑,推荐复配阻燃剂(ATH、OMMT的质量比为3∶1)的最佳掺量为8%。
文摘This paper discusses a visco-elastoplastic constitutive model to analyze the creep deformability of asphalt concretes at high service temperatures, finalized to improve the interpretation of permanent deformation phenomenon and performance design of road pavements. A three dimensional constitutive visco-elastoplastic model is introduced, in tensor as well as in numerical form. The associated uniaxial model is used to arrange a plastic element in series with the viscoelastic component. The latter is defined by an elastic spring placed in parallel with three Maxwell elements. Three different hardening laws, namely isotropic, kinematic and mixed hardening, are included in the constitutive model to compare the creep deformability. The proposed constitutive model has been calibrated and validated on the basis of uniaxial creep-recovery test results at 40℃. This is performed with a high performance hot mix asphalt concrete （HP-HMA） at different stresses and loading times. Depending on the hardening law considered, permanent deformation data predicted by the proposed model results are reasonably consistent with the experimental creep-recovery data. A rational constitutive model that is physically congruent with the creep phenomenon of asphalt concretes was developed and calibrated to achieve a deeper understanding of the stress-strain response of such materials. The fundamental relevance of an appropriate plastic response modeling, in the study of the creep behavior of asphalt concretes for highway and road pavements.
