Unified Strength Model of Asphalt Mixture under Various Loading Modes

Abstract

Although the rutting resistance, fatigue cracking, and the resistance to water and frost are important for the asphalt pavement, the strength of asphalt mixture is also an important factor for the asphalt mixture design. The strength of asphalt mixture is directly associated with the overall performance of asphalt mixture. As a top layer material of asphalt pavement, the strength of asphalt mixture plays an indispensable role in the top structural bearing layer. In the present design system, the strength of asphalt pavement is usually achieved via the laboratory tests. The stress states are usually different for the different laboratory approaches. Even at the same stress level, the laboratory strengths of asphalt mixture obtained are significantly different, which leads to misunderstanding of the asphalt mixtures used in asphalt pavement structure design. The arbitrariness of strength determinations affects the effectiveness of the asphalt pavement structure design in civil engineering. Therefore, in order to overcome the design deviation caused by the randomness of the laboratory strength of asphalt mixtures, in this study, the direct tension, indirect tension, and unconfined compression tests were implemented on the specimens under different loading rates. The strength model of asphalt mixture under different loading modes was established. The relationship between the strength ratio and loading rate of direct tension, indirect tension, and unconfined compression tests was adopted separately. Then, one unified strength model of asphalt mixture with different loading modes was established. The preliminary results show that the proposed unified strength model could be applied to improve the accurate degree of laboratory strength. The effectiveness of laboratory-based asphalt pavement structure design can therefore be promoted.

A Unified Strength Model of Asphalt Mixture Considering Temperature Effect

“…The suitability of UST for asphalt mixtures has been verified. However, it has mostly been carried out at specific temperatures (Suo et al, 2015;Yang et al, 2015;Xia et al, 2019). Considering the objectivity of temperature sensitivity of asphalt material, this section attempts to establish a unified strength model of asphalt mixture considering the temperature effect.…”

“…To establish an accurate theoretical model to describe the effect of intermediate principal stress on asphalt mixture strength. Some scholars explored and achieved important results under the unified strength model framework (Suo et al, 2011;Yu et al, 2011;Xia et al, 2019). Suo et al (2015) conducted orthogonal tests and confirmed the influence of the second principal stress, loading rate and temperature on the strength of asphalt mixture.…”

“…The criterion confirmed that the tension-compression strength ratio had a significant influence on pavement stress and its distribution, and the pavement stress level would be significantly increased after considering intermediate principal stress. Xia et al (2019) established a unified strength model of asphalt mixture under different loading modes by using the relationship between strength ratio and loading rate indirect tensile test, unconfined compression test and indirect tensile test. This model solves the uncertainty of strength performance of asphalt mixture under different loading models.…”

Investigating the Effect of Aggregate Characteristics on the Macroscopic and Microscopic Fracture Mechanisms of Asphalt Concrete at Low-Temperature

“…The fracture failure of asphalt concrete at low-temperature is complex, because it essentially depends on complex microstructures, temperature and fracturing modes, causing complex fracture patterns consisting of the main crack, crack branching and crack deflection [9,10]. Granting laboratory experiments have been widely adopted to investigate the fracture resistance [4,11] and cracking process [12,13] of asphalt concrete, which analyze the effect of temperatures [1,14,15,16], environmental factors [17,18] and fracturing modes [2,9,14,19], it is difficult to clearly reveal the effect of some important aggregate characteristics (e.g., morphological features and distribution), and require a high-cost and a lot of time for manufacturing samples. To contrast, the numerical simulation method has the advantage of characterizing these complex microstructures, saving research time and reducing experimental samples [20].…”

Sustainable Designed Pavement Materials

“…They concluded that asphalt mortar could be the closest subscale in terms of performance to that of asphalt mixtures, making it a vital scale to bridge the gap between asphalt binder and asphalt mixtures in multiscale performance analysis. A unified strength model, which can be used to overcome the design deviation caused by the randomness of the laboratory strength test and improve the accuracy degree, was described by Xia et al [28]. Different loading stresses were investigated to conclude the unified strength model, as well as to study the asphalt mixture moduli in the research presented by Fan et al [29].…”