Fatigue Properties Of Asphalt Research Articles

Effects of cutting temperature on the genes and fatigue properties of asphalt during its refining process

Asphalt binders performance is affected by refining process and crude oil. In this work, we investigated the effect of cutting temperature on the genes and fatigue properties of asphalt during asphalt refining. Five cutting temperatures (420 °C to 440 °C, interval of 5 °C) were set during the asphalt preparation, expanded the asphalt samples through ageing method. Fourier Transform Infrared (FTIR), Gel Permeation Chromatography (GPC), Nuclear Magnetic resonance Spectrum (1HNMR), Elemental analyzer, and improved Brown-Ladner method were used to characterize the asphalt genes. The fatigue performance of asphalt through Linear Amplitude Sweep (LAS) combined with the Simplified Viscoelastic Continuum Damage (S-VECD). Finally, the Pearson correlation method was used to analyze the correlation between genes and fatigue parameters of binders. The results showed that the cutting temperature and aging process changed the genes distribution of binders and these influence the fatigue properties of binders. In addition, the fatigue life of asphalt decreased at high strain levels and increased at low strain levels as the cutting temperature and the degree of ageing increased. The Pearson correlation results indicated a significant correlation between the genes and fatigue parameters of asphalt, however, the key genes affecting low-strain (2.5% and 5 %) and high-strain (10% and 20%) level fatigue in asphalt are significantly different. The outcomes of the paper provide insights about the influence of cutting temperature on the variation of asphalt genes and fatigue parameters, to allow more informed to promote of asphalt preparation.

Utilization of high contents desulfurized crumb rubber in developing an asphalt rubber pellets modified asphalt

In this paper, two kinds of asphalt rubber modifier pellets (ARP) and asphalt desulfurized rubber modifier pellets (ADRP) that can be directly injected were prepared by a screw extruder. Scanning electron microscopy (SEM) was employed to examine the internal microstructure of the two types of modifier pellets, and the storability were further evaluated. The rotational viscosity, high and low temperature rheological behaviors and fatigue properties of asphalt with two modifier pellets were investigated by rotational viscometer, dynamic shear rheometer (DSR), and bending beam rheometer (BBR), respectively. Infrared spectroscopy was used to explore the modification mechanism. The findings reveal that the content of desulfurized crumb rubber in the ADRP can be elevated to 80%, compared with 50% of crumb rubber in ARP. The surface of crumb rubber (CR) is smooth with prominent edges and corners, while desulfurized crumb rubber (DCR) reflects the rough surface with unclear edges and corners. Micro morphology verifies that asphalt and rubber manifest a good fusion phenomenon in ADRP. Incorporating anti-sticking agent lifts the collapse height of ARP and ADRP to nearly 9 cm and prevents their complete agglomeration, endowing their excellent storability. 20% DCR-MA reveals a Nf(5%) of 106,839 and superior fatigue resistance than 20% CR-MA, while it presents lower viscosity, rutting resistance, crack resistance and anti-aging performance. ADRP-MA demonstrates higher viscosity, rutting resistance, fatigue resistance and almost equivalent low-temperature performance than that of ARP-MA under the same dosage. Action mechanism of modified asphalt with both types of modifier pellets is regarded as a physical process. The modifier pellets prepared in this study reveal the merits of easy transportation, convenient direct injection, and wide application field.

Recycle of waste tire rubber powder in a novel asphalt rubber pellets for asphalt performance enhancement

Asphalt rubber has been considered as an ideal road construction material due to its excellent rutting resistance, fatigue performance, crack resistance, and noise reduction functions. However, the preparation of asphalt rubber requires special equipment and takes higher cost. In this paper, a kind of asphalt rubber modifier pellets (ARP) that can be directly injected was prepared using a screw extruder, so as to simplify the production process and reduce equipment energy consumption during the synthesis of asphalt rubber. Industrial modifier PelletPAVE as control group, firstly, scanning electron microscopy (SEM) was employed to examine the internal microstructure of the two types of modifier pellets, and the storability were further evaluated. The rotational viscosity, High and low temperature rheological behaviors and fatigue properties of asphalt with two modifier pellets were investigated by rotational viscometer, dynamic shear rheometer (DSR), and bending beam rheometer (BBR), respectively. Finally, Infrared spectroscopy was used to explore the mechanism of modification. The findings revealed that 50% crumb rubber, 40% asphalt, and 10% calcium hydroxide are the optimal material compositions for preparing asphalt rubber pellets. The modifier particles coated with anti-sticking agent can achieve the same storability as PelletPAVE. The viscosity of the modifier pellets modified asphalt prepared is marginally higher than that of the PelletPAVE modified asphalt. Incorporating modifier pellets to asphalt demonstrates superior fatigue and crack resistance than PelletPAVE, as well as lower high temperature performance. Action mechanism of modified asphalt with both types of modifier pellets is regarded as a physical process. The asphalt rubber pellets prepared in this study reveal the merits of easy transportation, convenient direct injection, and wide application field.

Study of Asphalt-Concrete Pavement Fatigue Modeling

Deterioration of asphalt pavements due to fatigue cracking is one of the most common highway pavement failure types. If the fatigue cracks are allowed to develop and grow, the driving comfort and safety, i.e., serviceability of the pavement, decreases. Pavement fatigue behaviour is not a straightforward mechanism and involves many factors and effects, thus computational methods are developed in order to help understand how the pavement works. This paper explores the accuracy and applicability of a less computational resource demanding procedure that uses transient material mechanical behaviour to model the long-term behaviour of a pavement structure. First, the mechanical and fatigue properties of asphalt were determined at the laboratory. Then a four-layer finite-element model was created using Ansys software. Two different models – with and without infinity elements – and two different fatigue simulation procedures – full and simplified – were considered. Material parameters were obtained by the laboratory tests and material properties degraded over time. Cyclic surface loading was applied to simulate the passing of a truck – 6 million fatigue cycles were simulated.

Using Steel-Smelting Slag as a Raw Material Component in the Production of Asphalt Concrete

The possibility of using polydisperse steel-smelting slag for the production of type B asphalt concrete is investigated, the possibility of its use as a mineral powder, crushing screening and crushed stone is considered. As a result of the study, it was found that a promising area for the use of slag raw materials in the technology for the preparation of asphalt mixes is: as a mineral powder - without additional processing steps; crushing screening - with the development of additional technological operations. The use of raw materials as crushed stone is impractical because of the high average density of the final asphalt mixture. Based on the test results, the characteristics of the fatigue properties of asphalt concrete from fine-grained dense mixtures of type B made on mineral powders from slag and limestone were obtained. It was established that at the initial moment, a large number of cycles to failure are characterized by compositions on slag powder, however, samples from this series tested after 45 days showed a significant rigidity increase and were destroyed earlier than similar samples on limestone. Obviously, this phenomenon is associated with an increase in the brittle properties of the material due to the formation of crystallization-condensation bonds in the structure of asphalt concrete containing slag.

Physical properties and anti-aging characteristics of asphalt modified with nano-zinc oxide powder

Asphalt aging holds responsibility for fatigue damage of asphalt pavement. Incorporation of nano-zinc oxide (nano-ZnO) as modifier into asphalt can effectively improve anti-aging property of asphalt. In this work, different dosage of nano-ZnO was added to original asphalt to prepare modified asphalt, and physical properties of nano-ZnO modified asphalt, including storage stability, penetration (25 °C), softening point and ductility (5 °C) were tested. Effect of nano-ZnO on the rheological properties of asphalt was studied by testing rheological properties of modified asphalt before and after aging. In addition, fatigue properties of asphalt with different nano-ZnO dosage were analyzed by linear amplitude sweep (LAS) test. Furthermore, anti-aging characteristics of nano-ZnO modified asphalt were characterized by thin film oven test (TFOT) and ultraviolet aging (UV-aging) test and mechanism was interpreted by UV–visible-infrared absorption test. The results show that nano-ZnO can influence penetration (25 °C), softening point, ductility (5 °C) and storage stability of asphalt. Nano-ZnO can improve complex shear modulus (G*), phase angle (δ) and fatigue performance. Addition of nano-ZnO can evidently improve anti-UV aging ability of asphalt and make asphalt show certain viscosity recovery during aging process. In addition, nano-ZnO has strong absorption characteristics to ultraviolet light with more than 95% absorption rate, which reflects its superiority as anti-UV aging modifier for asphalt. UV absorption of nano-ZnO modified asphalt is enhanced several times than that of original asphalt. Asphalt modified with reasonable nano-ZnO dosage possesses significant and evident anti-aging characteristics.

Effect of Ultraviolet Light Aging on Fatigue Properties of Asphalt

The ultraviolet aging effects on fatigue properties of asphalt were studied by using Dynamic Shear Rheometer (DSR). The low-temperature fatigue performance of asphalt has been tested in this paper with the strain-controlled mode of DSR. The samples were compacted under the temperature of 10°C and the constant strain of 2.0% in strain-controlled mode fatigue test. And the results showed that ultraviolet aging decreases the fatigue life-span of asphalt significantly.

Differentiating between damage and thixotropy in asphalt binder’s fatigue tests

When testing asphalt binders under cyclic conditions, a drop in modulus is observed. This decrease has been explained by an increase in the temperature of materials due to energy dissipation, thixotropy, and damage. This study presents the application of a cyclic uniaxial tension–compression test to analyze the causes and effects of that behavior on the fatigue properties of asphalt binders.The authors conducted both time and strain sweep tests and concluded that the steady-state complex modulus depended only on the strain applied and was not influenced by the prior loading history, i.e. both data sets converged to the same complex modulus values after a short number of cycles when applying the same strain. In addition, by increasing and decreasing strain alternatively it was found that the initial complex modulus drop is mostly caused by thixotropic effects rather than irreversible damage and can be recovered. The recovery of material properties was faster and complete when the binder was mechanically forced to its initial state instead of allowing it to rest (healing).

Effect of ageing on fatigue properties of asphalt

The fatigue properties of asphalts were investigated after various laboratory simulation ageing tests and outdoor natural exposure ultraviolet radiation ageing, by dynamic shear rheometer (DSR) time sweep fatigue test in constant strain model and a new type of specimen which was introduced to avoid the problem of adhesion failure between rotor and asphalt binder. The results show that outdoor natural exposure ageing (NEA) causes the decrease of retained fatigue life distinctly, and photodegradation caused by outdoor NEA of 1 250 μm thin films asphalt for three months, is found to be severer than pressure ageing vessel (PAV) with respects to retained fatigue life. The effect of photodegradation increases as the time of outdoor NEA increases. DSR time sweep fatigue test in constant strain indicates that the aged styrene-butadiene-styrene (SBS) modified asphalt still displays better fatigue properties than the corresponding base asphalt after ageing.