再生粗骨料沥青混合料的动态黏弹性特性研究

Study on the dynamic viscoelastic properties of reclaimed coarse aggregate asphalt mixtures

再生骨料是一种将建筑垃圾中的混凝土块等废料加工而成的再生产品,它可以替代部分天然骨料加入沥青混合料中铺筑路面,有助于减少对天然石材的开采,降低沥青路面的成本。为了研究再生粗骨料沥青混合料的黏弹性特征,针对4种取代率的再生骨料沥青混合料,采用不同频率和温度下的动态模量试验,通过Sigmoid函数建立动态模量和相位角的主曲线,探究再生骨料的掺量(0%、17%、37%、56.7%)对AC-20沥青混合料动态黏弹性特性的影响变化。研究结果表明:在相同频率、相同温度下随着再生骨料掺量的增加,沥青混合料的动态模量减小,这种现象在低温高频条件下表现得更为明显。低温和常温条件下(–10、5、20℃),沥青混合料的相位角随着再生骨料掺量增大而减小,随着频率增加而减小,在中高温条件下再生骨料掺量的变化对沥青混合料相位角的影响规律并不统一。通过动态黏弹性拟合参数结果分析发现Sigmoid模型的拟合参数变化趋势与再生掺量增幅之间存在着较大的相关性。该研究聚焦于道路工程中建筑垃圾资源化利用的环保设计需求,可为建筑垃圾应用于道路养护工程提供试验参考,可作为教学案例应用于工程领域的研究生课程。

[Objective]With the rapid development of the Chinese national economy,the transportation and construction industries are flourishing,leading to a sharp increase in the demand for building materials such as sand and gravel.However,construction generates a large amount of waste,particularly abandoned concrete.The most effective method for managing this waste is its use as a recycled aggregate.Recycled aggregate is produced through the processing of waste concrete blocks and other construction debris,which reduces the need for natural aggregates in asphalt mixtures used for road paving.This approach minimizes the excavation of natural stone,reduces the costs associated with asphalt pavement,and promotes efficient recycling and reuse of construction waste.This study focuses on the dynamic viscoelastic properties of recycled coarse aggregate asphalt mixtures.[Methods]Dynamic modulus tests were conducted to investigate the effects of recycled aggregate dosage,experimental temperature,and test loading frequency on recycled aggregate asphalt mixtures.Changes in the dynamic modulus were observed,and the trends in the dynamic viscoelasticity of recycled aggregate asphalt mixtures at different dosages,temperatures,and frequencies were identified.Four dosages of asphalt mixtures,namely 0%,17.0%,37.0%,and 56.7%,were tested across five temperatures(–10,5,20,35,and 50℃),and six loading frequencies(0.1,0.5,1,5,10.0,25.0 Hz)to examine the impact of temperature and frequency on the dynamic viscoelasticity of asphalt mixtures containing varying levels of recycled aggregate.The shift factor was calculated using the Williams-Landel-Ferry equation to extrapolate the dynamic modulus from the limited loading frequencies to a broader range of frequencies and temperatures.[Results]The test results indicated that at a constant loading frequency,the adhesion between the recycled aggregate asphalt mixtures and aggregates deteriorated at higher temperatures,resulting in a decrease in the dynamic modulus.Similarly,under identical test temperature conditions,the dynamic moduli of the four asphalt mixtures increased at higher dynamic loading frequencies.The greatest increase in the dynamic modulus for the four asphalt mixtures occurred within the frequency range of 10–15 Hz,and the increase in the dynamic modulus trend gradually diminished with increasing recycled aggregate content.Furthermore,at higher frequencies,the dynamic modulus of the asphalt mixtures decreased significantly at medium and low temperatures(–10,5,and 20℃),whereas the decrease in dynamic modulus under high temperatures(35 and 50℃)was not significant.[Conclusions]The research findings suggest that the dynamic modulus of recycled aggregate asphalt mixtures increased at higher loading frequencies.The rate of increase was lower at both high and low frequencies,whereas it accelerated within the mid-frequency range.The influence patterns of the elastic modulus for the four dosages of the asphalt mixtures were consistent,and the main curves of the dynamic modulus were similar in shape.Specifically,at a recycled aggregate dosage of 17.0%,the main dynamic modulus curve in the mid-frequency range was higher than that of the asphalt mixture without recycled aggregate.This indicates that incorporating a suitable recycled coarse aggregate can enhance the viscosity of asphalt mixtures,thereby reducing their resistance to high-frequency,low-temperature deformation.According to the Pearson correlation coefficient and the results of the significance test,a strong correlation existed between the fitting parameters of the dynamic modulus and phase angle,and the dosage of recycled aggregate.This correlation indicates that the recycled aggregate dosage significantly influenced the dynamic viscoelastic properties of asphalt mixtures.