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Low-noise asphalt mixtures are characterized by increased air void content. Their more open structure contributes to faster degradation within the operating temperature range. For this reason, binder modification is used in their production. The correct selection of modifiers allows one to significantly improve the technical properties of the mixtures. The article presents the results of tests of six types of mixtures: stone mastic asphalt (SMA8), porous asphalt (PA8), stone mastic asphalt reducing tire/road noise (SMA8 LA) and stone mastic asphalt reducing tire/road noise, with 10%, 20% and 30% content of rubber granulate (RG). Bitumen 50/70 modified with copolymer styrene butadiene styrene (SBS) and crumb rubber (CR) was used for the production of the mixtures. In order to determine the differences in the technical properties of the mixtures, the following parameters were tested: stiffness modules by indirect tensile testing of cylindrical specimens (IT-CY) in a wide range of positive temperatures, and resistance to permanent deformation using the British and Belgian methods with the use of double wheel tracker (DWT). The test results and their analysis confirmed that there was a significant improvement in the IT-CY stiffness modules of SBS and CR modified mixtures. Replacing more than 20% of coarse aggregate with RG causes a significant decrease in the stiffness of the mixture (by 90% in relation to the reference mixture SMA8 LA). The SMA mixtures obtained lower values of rutting resistance parameters (WTS and PRD) in water (Belgian method) compared to the results obtained in the air tests (British method). On the other hand, mixtures of PA, thanks to the compression of stresses in pores filled with water, obtained better results when the rutting resistance test was performed in the water (Belgian method).

To evaluate the durability of bamboo fiber asphalt mixture using four gradation schemes, the durability of the bamboo fiber asphalt mixture is studied considering three aspects: ageing durability, freeze-thaw cycle durability and fatigue durability through the Marshall test, indoor ageing test, uniaxial compression test, low-temperature bending test, immersion Marshall test, freeze-thaw splitting test and four-point bending fatigue test. Nonfiber asphalt mixture and lignin fiber asphalt mixture were used as control groups. The results show that the addition of plant fiber can effectively improve the durability of asphalt mixture. Bamboo fiber modified asphalt mastic has good ductility and adhesion due to its rough surface and good oil absorption performance. Bamboo fiber asphalt mixture has better and more stable low-temperature ageing durability and moisture ageing durability than lignin fiber asphalt mixture, but its mechanical property is weaker than the latter. The improvement effect of the two fibers on the freeze-thaw cycle durability of asphalt mixture is basically the same. Bamboo fiber can improve the flexibility of the mixture and delay the development of cracks so that the mixture has good fatigue durability. The smaller the void ratio, the thicker the asphalt film, and the denser the structure of the mixture, the better the durability. The durability of the stone mastic asphalt (SMA) gradation mixture is better than that of asphalt concrete (AC) gradation. The material composition and aggregate gradation of plant fiber asphalt mixture have a great influence on its durability. In the future, it is necessary to establish a multiparameter comprehensive evaluation index system among fiber type and properties, mixture gradation and durability so as to realize the directional regulation of the durability of different fiber asphalt mixtures. Bamboo fiber is a reliable substitute for lignin fiber, and further research on improving its surface properties and dispersion uniformity can be carried out in the future.

Durability is one important problem that pavement engineers need to address in pavement&rsquo, s long service life. Furthermore, easily recycled pavement materials, and safe and efficient pavement construction are also important areas for development in road engineering. For these reasons, a new asphalt steel plastic (ASP) pavement structure was proposed with an asphalt mixture forming the surface layer, and steel plate and plastic materials functioning as the main load-bearing layers. Based on a comprehensive performance review and cost-benefit analysis, stone mastic asphalt (SMA) is recommended to be used as the surface layer, and A656 steel plate and acrylonitrile butadiene styrene (ABS) plastic materials should be the main load-bearing layer, on top of a foundation layer made with graded crushed stones. A glass fiber reinforced polymer (GFRP) insulation layer is recommended for use between the steel plate and ABS. Mechanical properties of the ASP pavement were analyzed using the finite element method. Laboratory tests were conducted to verify the thermal insulation performance of GFRP, the high-temperature stability and the fatigue resistance of ASP pavement. Results show that some of the mechanical properties of ASP pavement (with a structure of 80 mm SMA asphalt mixture, 8 mm steel plate, 140 mm ABS and 200 mm crushed stones) are comparable with conventional long-life pavement (with 350 mm asphalt layer overlaying 400 mm graded crushed stones). Dynamic stability of the ASP slab specimens can reach 10,000 times/mm, and the fatigue life is about twice that of SMA. Besides, the ASP pavement can be prefabricated and assembled on-site, and thus can greatly improve construction efficiency. From the lifecycle perspective, ASP pavement has many advantages over traditional pavements, such as durability, lower environmental footprint and recyclability, making it is worth further research.

Many airports are surfaced with grooved Marshall-designed dense graded asphalt. Grooving is required to satisfy regulatory aircraft skid resistance requirements, but introduces the risk of groove-related distress, such as groove closure. Consequently, airports seek an ungrooved runway surface option that performs similarly to dense graded asphalt but allows grooving to be avoided. Stone mastic asphalt is the most viable ungrooved runway surface solution and has been used on runways in Europe and China. However, before being accepted as an ungrooved runway surface in Australia, stone mastic asphalt must be shown to meet regulatory runway aircraft skid resistance requirements, and to otherwise perform similarly to typical dense graded asphalt mixtures for runway surfacing, including deformation resistance, fatigue cracking resistance and durability. Based on laboratory performance-related testing, 10-mm and 14-mm sized stone mastic asphalt mixtures, produced with four different aggregate sources, were found to generally meet the airport asphalt performance requirements. The 14 mm mixture was found to perform better than the 10 mm mixture, particularly regarding surface macrotexture and deformation resistance. It was concluded that airports should consider 14 mm sized stone mastic asphalt as an ungrooved runway surface in the future.

Various additives to asphalt binders and asphalt mixtures improving their properties are being used more and more frequently in order to improve the durability of road pavements. Such additives include various types of fibres, including aramid fibres. Tests concerning the impact of aramid fibre addition on the properties of selected asphalt mixtures have been described herein. Two types of asphalt mixtures were assessed: high modulus asphalt concrete (HMAC) and stone mastic asphalt (SMA). The examined asphalt mixtures were assessed with regard to: resistance to rutting, resistance to water and frost as well as fatigue resistance. The conducted tests showed relatively small impact of aramid fibre addition on the improvement of some assessed properties of the analysed asphalt mixtures. The obtained results were also compared to results of the tests conducted by the other research team concerning the impact of aramid fibre addition on the properties of the other types of asphalt mixtures.

Construction and demolition waste material is of great potential for use in pavement engineering. This paper aims to investigate the feasibility of ceramic waste aggregate (CA) used in cooling asphalt pavement through a series of test methods and simulation techniques. Stone mastic asphalt (SMA) containing 10%, 20%, 30%, 40%, and 50% coarse ceramic waste aggregate (CASMAs) was first designed using the Marshall method. Afterward, the road performance and thermal insulation performance of the five different CASMAs were assessed by a comprehensive lab test, including a wheel rutting test, moisture susceptibility test, bending beam test, fatigue beam test, and indoor thermal insulation test. Finally, a 2D finite-element (FE) model was developed to investigate the transient thermal field and rutting deformation response of the cooling asphalt pavement with CASMAs. Results show that CASMAs experienced degradation of rutting resistance, moisture susceptibility, and anti-cracking performance while still meeting technical requirements with CA content of up to 40%. On the other hand, CASMAs can cool the pavement&rsquo, s temperature by 11.5 &deg, C at the bottom of asphalt layers. The permanent rutting deformation of cooling asphalt pavement was 45.36% smaller than that of conventional asphalt pavement without CASMAs. Based on the test results and numerical simulation results, the optimum content of ceramic waste aggregate in stone mastic asphalt was recommended as 40%.

Strength is an important parameter for the design of asphalt pavement materials and structures. To study the influence of various factors on the three-dimensional strength of asphalt mixtures, three aggregate gradations (dense-graded bituminous mixture AC-13, stone mastic asphalt SMA-13 and bituminous stabilization aggregate paving mixture OGFC-13) and two binders (SBS modified bitumen and 70# base bitumen) were used to prepare the asphalt mixture specimens. Among them, SBS+SMA-13 asphalt mixture has the best performance. On this basis, the uniaxial compressive test, uniaxial tensile test and confining triaxial test were conducted on the SBS+SMA-13 asphalt mixture under six oil-stone ratios conditions (5.5%, 5.7%, 5.9%, 6.1%, 6.3%, and 6.5%), six temperatures conditions (5 &deg, C, 10 &deg, C, 15 &deg, C, 20 &deg, C, 25 &deg, C, and 30 &deg, C), and five loading rates conditions (1 mm/min, 2 mm/min, 3 mm/min, 4 mm/min, and 5 mm/min). In addition, a unified three-dimensional strength calculation model considering the influence of temperature, loading rate, and oil-stone ratio was proposed, and the change law of the three-dimensional strength with these above factors was revealed. Furthermore, two sets of three-factor three-level orthogonal tests were carried out on the SMA-13 asphalt mixture. The sensitivity analysis and strength regulation research between three-dimensional strength and each factor were carried out. The results show that the type of asphalt has the greatest influence on the strength of the mixture, the temperature has the second most influence, the loading rate has less influence, and the oil-stone ratio has the least influence. The strength regulations proposed to improve the strength of the asphalt mixture include the use of modified asphalt, high-temperature stability high-quality asphalt, and the lower oil-stone ratio than the Marshall optimal oil-stone ratio. The strength control measures proposed from the perspective of the three-dimensional stress state, the joint failure of each stress components and real stress states are taken into consideration.

Stiffness is an important mechanical characteristic of asphalt mixtures used in the wearing course. It is one of the determining factors in the generation of tyre/road noise. The dynamic stiffness of the upper layer of the road surface depends on the physical and mechanical properties of the materials it is composed of, and traffic load. Determination of dynamic stiffness, both in laboratory conditions and in situ, requires consideration of many other factors. Tests of dynamic properties of road surfaces in field conditions are most often conducted with the help of modal hammers. Impulse excitation results are usually less accurate than those in the application of modal exciters. The test stand was constructed, comprising a tripod, 32-channel and 24-bit data acquisition system, exciter, signal amplifier, impedance head, single-axis piezoelectric accelerometers and a stinger. The test stand and the proposed method of measuring dynamic stiffness do not require the determination of the resonance frequency of the tested specimen and can be used both on various types of bituminous mixtures of varying shape and dimensions, as well as directly on the upper surface of the wearing course of bituminous pavements. The test results showed that the type of bituminous mixture used in the wearing course significantly affects its dynamic stiffness. The dynamic stiffness level of asphalt concrete, stone mastic asphalt and porous asphalt layers was determined to be similar. The addition of rubber granulates significantly reduced its rigidity, which is very beneficial from the point of view of reducing the tyre/road noise.

Basalt fiber has been widely used in asphalt mixture due to its excellent mechanical properties and good combination with asphalt. In order to systematically evaluate the enhancement effect of basalt fiber on the fatigue performance of the mixtures, gradations of Stone Mastic Asphalt and Superpave with different nominal maximum aggregate sizes, namely SMA-13, SUP-20 and SUP-25, were prepared, and a four-point bending beam fatigue test was adopted under the strain control mode. The fatigue damage mode was assessed based on the phenomenology theory, energy dissipation theory and change rate of dissipated energy. The results showed that basalt fiber could well increase the fatigue life of the mixtures. Basalt fiber could also increase the cumulative dissipated energy of the mixtures, and it was linearly correlated with the fatigue life in double logarithmic coordinates. In the meantime, adding basalt fiber could increase the change rate of dissipated energy of the mixtures. Furthermore, it is not appropriate to take the stiffness modulus declined to 50% of the original as the fatigue failure criterion of the mixture, this paper suggested that it is reasonable when the stiffness modulus was 15–25% that of the initial. These findings provide a theoretical basis for exploring the fatigue failure of asphalt pavements.

In most cases, stone mastic asphalt (SMA) mixtures placed in thin layers and subjected to stress develop early cracks (potentially resulting from being improperly affixed to the underlying layer, placed over previously cracked asphalt pavement, or placed over Portland cement concrete slabs). However, the filler used in SMA production is very influential on the performance of the mix. Fillers used in this type of mixture have a low plastic index or are inert (calcium carbonate or lime), so it is important to understand the effect of each material on the possible fissuring and cracking process of the SMA mixture. The objective of this study is to present an evaluation of the behavior of SMA asphalt mixtures with different types of filler and at different temperatures using the semicircular bend (SCB) fracture energy test. This research compares results between fracture energy and different types of filler in SMA asphalt mixtures at temperatures ranging from &minus, 10 to 25 &deg, C.

Materials 12(1), 146 (2019). doi:10.3390/ma12010146 special issue: "Special Issue "Sustainable Designed Pavement Materials" / Special Issue Editors: Prof. Dr. Sandra Erkens, Guest Editor; Prof. Dr. Yue Xiao, Guest Editor; Assoc. Prof. Dr. Mingliang Li, Guest Editor; Prof. Dr. Tao Ma, Guest Editor; Dr. Xueyan Liu, Guest Editor", Published by MDPI, Basel

Low-temperature cracking is one of the most common road pavement distress types in Poland. While bitumen performance can be evaluated in detail using bending beam rheometer (BBR) or dynamic shear rheometer (DSR) tests, none of the normalized test methods gives a comprehensive representation of low-temperature performance of the asphalt mixtures. This article presents the Bending Beam Creep test performed at temperatures from −20 °C to +10 °C in order to evaluate the low-temperature performance of asphalt mixtures. Both validation of the method and its utilization for the assessment of eight types of wearing courses commonly used in Poland were described. The performed test indicated that the source of bitumen and its production process (and not necessarily only bitumen penetration) had a significant impact on the low-temperature performance of the asphalt mixtures, comparable to the impact of binder modification (neat, polymer-modified, highly modified) and the aggregate skeleton used in the mixture (Stone Mastic Asphalt (SMA) vs. Asphalt Concrete (AC)). Obtained Bending Beam Creep test results were compared with the BBR bitumen test. Regression analysis confirmed that performing solely bitumen tests is insufficient for comprehensive low-temperature performance analysis.