| 摘要: |
| 低密度聚乙烯（LDPE）改性沥青低温性能目前尚存争议，为准确评价LDPE改性沥青低温性能，对其进行弯曲梁流变仪试验，得到劲度模量（S）和模量变化率（m），进而计算低温累积应力和耗散能比.基于动态剪切流变仪试验和时温等效原理，获取复数模量主曲线，求得玻璃态模量和交叉频率.基于测力延度试验，测得拉力-延度曲线，求出屈服应变能和拉断功等指标值.结果表明：随着LDPE掺量的增加，改性沥青S增加，m减小，低温累积应力增大，耗散能比减小，玻璃态模量增大且交叉频率减小，表现为低温性能降低；但破坏其所需拉断功却更大，从破坏能量角度来讲，表现为低温性能改善.因此，仅基于评价LDPE改性沥青指标S，m或低估了LDPE改性沥青低温性能，应考虑将拉断功补充作为其评价指标之一. |
| 关键词: 低密度聚乙烯 低温性能 评价指标 断裂能量 |
| DOI：10.3969/j.issn.1007-9629.2021.05.018 |
| 分类号:U414.7+5 |
| 基金项目: |
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| Improvement of Low Temperature Performance Evaluation Method of LDPE Modified Bitumen |
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DU Zhenyu, YUAN Jie, XIAO Feipeng
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Key Laboratory of Road and Traffic Engineering of the Ministry of Education， Tongji University， Shanghai 201804， China
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| Abstract: |
| Low density polyethylene（LDPE） modification to improve low temperature performance of bitumen is still controversial at present. In order to accurately evaluate the low temperature performance of LDPE modified bitumen， bending beam rheometer tests were carried out to obtain stiffness modulus（S）， modulus change rate（m）， and then the low temperature accumulated stress，dissipation energy rate were calculated. Based on dynamic shear rheometer test and the principle of time temperature equivalence， the master curve of complex modulus， the glass transition modulus and crossover frequency were obtained. Based on the force ductility test， the tension-ductility curve was measured， and the yield strain energy， breaking work and other index values were obtained. The results show that with the increase of LDPE content， the S of the modified bitumen increases， the m decreases， the low temperature cumulative stress increases， the dissipation energy rate decreases， the glass transition modulus increases and the crossover frequency decreases， which shows that the low temperature performance decreases. However， the breaking work required for the failure of LDPE modified bitumen is greater than that of base bitumen， which shows the better low temperature performance of LDPE modified bitumen from the point of view of failure energy. Therefore， low temperature performance of LDPE modified bitumen may be underestimated only based on the evaluation index of S， m. So breaking work should be considered as one of the supplementary evaluation indexes. |
| Key words: low density polyethylene low temperature performance evaluation index fracture energy |
