Fatigue Life Of Asphalt Research Articles

High temperature rheological properties of surface pretreated PVA fiber modified asphalt

In order to improve the compatibility of polyvinyl alcohol (PVA) fiber and asphalt in application of asphalt pavement, the surface of PVA fiber is pretreated with KH-570 silane coupling agent. The tests such as contact angle, rotational viscosity, temperature scanning, multiple stress creep and recovery (MSCR) and the linear amplitude sweep (LAS) are conducted to study the compatibility and high temperature rheological properties of original PVA fiber (T) and surface treated PVA fiber (ST) modified asphalts with different contents, so as to evaluate the effect of surface modification process on the rheological properties of PVA fiber modified asphalt. The results show that the surface treatment process improves the compatibility of asphalt and PVA fiber. Compared with T, ST has better viscosity increasing effect, rutting resistance, and permanent deformation resistance at the same content, and can slightly improve the fatigue resistance of asphalt at the lower strain level. However, T and ST have no obvious improvement on creep deformation ability and fatigue life of asphalt at high stress level under repeated load. The surface pretreatment process can effectively improve the storage stability, viscosity and high temperature deformation resistance of the binder and the results provide reference for the preparation and application of PVA fiber modified asphalt.

Mechanical characterization of warm mix asphalt mixtures made with RAP and Para-fiber additive

Asphalt recycling can help reserve natural resources and save money. However, in producing hot mix asphalt (HMA), utilizing reclaimed asphalt pavement (RAP) high heat rate is produced which leads to the stiffening of asphalt binder and producing toxic gases. This in turn will cause massive environmental pollution. As a money-saving technology, Warm Mix Asphalt (WMA) produces asphalt mixture at lower temperatures, and reduces environmental pollution as well as ageing and stiffness of the asphalt binder. This study is aimed at investigating the use of two techniques to decrease environmental pollution, save energy and costs, and improve asphalt mixture performance: WMA technique and RAP materials in asphalt mixtures. The Para-fiber additive was also employed in different values. With respect to the RAP, the use of virgin aggregates was decreased. To compare and evaluate the mechanical performance of asphalt mixtures, tests including resilient modulus, dynamic creep, indirect tensile strength, indirect tensile fatigue, and boiling water tests were conducted. According to the results, using RAP led to an increase in resilient modulus of mixtures and improved the resistance against permanent deformation. Also, by the addition of Para-fiber, the fatigue life of asphalt was improved. Moreover, according to the results of the fatigue test, it was shown that by the addition of RAP, the fatigue life of mixtures was decreased remarkably, yet it was enhanced by using Para-fiber.

Application of Infrared Spectroscopy in Prediction of Asphalt Aging Time History and Fatigue Life

Based on attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy and principal component analysis (PCA), four kinds of asphalt (two kinds of matrix asphalts, TPC70# and JL70# and two kinds of modified asphalts, SBS-1 and SBS-2) were aged using the rolling thin-film oven test (RTFOT). The multiple stress repeated creep recovery test (MSCR) was carried out on an AR1500ex dynamic shear rheometer (DSR). The PCA was carried out on the attenuated total reflection infrared spectrum of a pretreated aged asphalt, the principal component factors (oxidation factor and component change factor) were determined, the comprehensive index F was calculated, and a prediction model of aging time history was established and verified. A prediction model for the aging asphalt recovery rate R was established based on the functional group index. The relationship between the recovery rate R and aging time history of each aging asphalt was analyzed and the fatigue life of each aging asphalt based on the rate of dissipated energy change (RDEC) was compared. The correlation between the comprehensive index F and fatigue life of asphalt was also analyzed. The results show that the order of resistance to the high-temperature deformation of each aging asphalt is as follows: SBS-2 > SBS-1 > TPC70# > JL70#; the prediction model of aging asphalt recovery rate R based on functional group index has good reliability. Taking the loading cycle corresponding to the sudden increase of the inflection point of the curve, i.e., the fatigue life NRDEC, as the evaluation index, the fatigue life order of each aging asphalt is SBS-1 > SBS-2 > JL70# > TPC70#. There is a positive correlation between the fatigue life of aged asphalt and the comprehensive index F of asphalt. The correlation degree R2 is 0.85; i.e., with the increase of the comprehensive index F of asphalt, its fatigue life also increases. It was found that it is feasible to analyze the aging time history and fatigue life of asphalt by infrared spectroscopy, and it can provide a rapid and non-destructive prediction method for the practical engineering application of asphalt.

Energy-Based Approach to Predict Thermal Fatigue Life of Asphalt Mixes Using Modified Uniaxial Test Setup

AbstractIn this paper an energy-based approach has been proposed based on the principals of nonlinear viscoelastic fracture mechanics to determine the thermal fatigue life of asphalt mixes for the short-term aging condition at a constant temperature. The approach, presented in this paper for only one aging condition at one temperature, is considered in another paper as the basis for the development of a comprehensive model (TFCMODEL) by which the thermal fatigue life of various asphalt mixes may be predicted analytically for varying aging conditions and temperatures. To this end, a modified uniaxial test setup was designed to account for the effects of the bonding/friction condition between asphalt and base layers, and nonuniform distribution of stresses/strains within the asphalt layer depth. To characterize the thermal fatigue behavior of asphalt mixes, uniaxial thermal fatigue tests were carried out on the beam specimens at two aggregate gradations, two binder contents, two air void contents, one aging...

Modelling of 3D response pulse at the bottom of asphalt layer using a novel function and artificial neural network

Fatigue life of asphalt mixes in laboratory tests is commonly determined by applying a haversine or sinusoidal load with a specific frequency. However, the frequency (time duration) and shape of horizontal tensile stress and strain pulses at the bottom the asphalt layer depend on pavement design (thickness and stiffness of layers) and loading specifications (speed and contact radius). The first objective of this paper is to introduce a novel function for a more realistic representation of 3D response (stress and strain pulses in longitudinal, transverse and vertical directions) at the bottom of the asphalt layer. The second objective is to establish a framework for determination of magnitude and shape of 3D response pulse at the bottom of the asphalt layer using artificial neural network. This framework enables designers to predict the shape and magnitude of stress and strain pulses in three directions based on some parameters related to pavement structure and loading specifications.