Abstract
Previous studies have indicated that steel slag can be used as a substitute for natural aggregates in asphalt mixture, while little attention has been paid to systematic investigation of the influences of various external environmental factors on deformation resistance of steel slag asphalt mixture. In order to understand the service behavior of steel slag asphalt mixture, its permanent deformation under different condition was investigated based on an indoor simulation test. The chemical composition, microscopic structure, surface texture, and volume stability of steel slag were firstly characterized. The uniaxial repeated loading test and standard wheel‐tracking test were applied to evaluate the effect of temperature, stress levels, and water damage on the permanent deformation of AC‐16 and AC‐20 steel slag asphalt mixtures. The results indicate that a higher content of alkaline oxide and high‐grade texture index existing in steel slag contribute to its strong absorptivity and adhesion of asphalt. The steel slag demonstrates fine volume stability due to its lower free‐CaO (f‐CaO) content, autoclave chalked ratio, and immersion expansion ratio. The permanent deformation of steel slag asphalt mixtures increases rapidly under higher stress and temperatures in contrast to lower increment at lower stress and temperatures. Asphalt mixtures at higher stress and higher temperatures and water condition exhibit larger rutting deformation and inferior rutting resistance. AC‐16 steel slag asphalt mixture has superior resistance to permanent deformation than AC‐20 asphalt mixture. Rutting factors show different degrees of impact in a decreasing order of temperature, water damage, and stress levels. The findings have significant implications for providing a theoretical basis for reusing steel slag in pavement construction and facilitating engineering application of steel slag asphalt mixture.
Highlights
Li et al [15] employed an advanced repeated load permanent deformation (ARLPD) test to investigate the rutting resistance of asphalt pavements, and they found that laboratory results and long-term pavement performance data demonstrated better coincidence, which validated the repeatability of the ARLPD test. e effect of confinement, moisture, stress, and temperature on the three-stage rutting behavior of asphalt mixtures was conducted by Fang et al [16]. e results indicated that a higher primary rutting rate implied a lower flow number (FN) and faster failure rate
It can be inferred that the chemical composition of steel slags mainly contains CaO, SiO2, and Fe2O3, which accounts for approximately 80% of the total composition, while the highest contents of basalt are SiO2, followed by Al2O3 and CaO. e composition difference of steel slag and basalt is attributed to the discrepancy in the molding process
Results of Uniaxial Repeated Loading Test. e permanent deformation of asphalt pavement is divided into three stages. e primary stage is corresponding to the compaction stage, in which the deformation rate of asphalt mixture decreases with the increase of cycle times. is is mainly due to the compaction effect of vehicle load on the pavement and the decrease of pavement layer thickness. e secondary stage is corresponding to the plastic flow stage, in which the deformation rate remains unchanged with the increase of cycle times
Summary
Asphalt pavement during service life is prone to crack and damage due to heavy load, overload, high temperature, and water erosion, resulting in rutting disease and affecting its driving comfort and safety [1, 2]. en, the further development of rutting will cause other diseases such as network cracks and pits, which will seriously reduce the structural performance and service performance of asphalt pavement [3, 4]. erefore, the characterization of permanent deformation of hot-mix asphalt mixture becomes currently a research hotspot.Causing factors of permanent deformation of asphalt mixture were divided into internal factors and external factors [5, 6]. e internal reasons mainly included the properties of asphalt, aggregate, gradation composition, and asphalt-aggregate ratio [7]. e external elements mainly referred to repeated vehicle loads, temperature, and rainwater [8]. Evaluation method of the permanent deformation of asphalt mixture focused on wheel-tracking test, uniaxial repeated loading test, and static loading test [9, 10]. Wheeltracking test and uniaxial repeated loading test demonstrated better correlations between simulation results of rutting development and field performance, so they were commonly applied to characterize the permanent deformation of asphalt mixture [11, 12]. Li et al [15] employed an advanced repeated load permanent deformation (ARLPD) test to investigate the rutting resistance of asphalt pavements, and they found that laboratory results and long-term pavement performance data demonstrated better coincidence, which validated the repeatability of the ARLPD test. A multisequenced repeated load (MSRL) test with a fixed number of repeated loads in each sequence was used to characterize the permanent deformation behavior of asphalt mixture [13]. Yu et al [11] proposed the indicators called FN index, accumulated strain to differentiate the impacts of several factors, and found that FN index was suitable for representing the high-temperature performances of asphalt mixtures
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