Influence of Soybean Oil on Binder and Warm Mixture Asphalt Properties

To produce a usual hot mix asphalt, significant amount of energy is used, which causes air pollution. As a result, warm mix asphalt (WMA) is introduced to reduce the mixing and compaction temperature of the mixture. On the one hand, accumulation of waste oil in the ground occupies a large space in the Earth. After the process of frying the oil, if the by-product is not controlled properly, it leads to the pollution of the environment. Hence, utilization of this waste oil can be considered as a sustainable path to dealing with the risk. The main goal of the current research is to evaluate the possibility of exploiting soybean oil to reduce the mixing and compaction temperature of mixtures and produce warm mix asphalt (WMA). Moreover, the rheological and performance properties of mixtures containing soybean are evaluated in this study. The AC-60/70 and 85/100 binders are modified by soybean oil (0%, 1.5%, 2.5%, and 3.5% by weight of binder). Several binder tests are used to measure the physical and rheological behaviors of binders, such as penetration grade, softening point, temperature susceptibility, rotational viscosity (RV), Multiple Stress Creep Recovery (MSCR), and Linear Amplitude Sweep (LAS) tests. Besides, several mixture tests are used to evaluate the performance of the mixture, including four-point bending beam fatigue (FPB), resilient modulus (Mr), indirect tensile strength (ITS), dynamic creep, and wheel track tests. Through MSCR test results, at two stress levels, the Jnr parameter increases as the soybean oil is added to the binder. The results of the LAS test revealed that the fatigue life of binders increases by addition of soybean oil. There is no significant difference between the results of new and waste oil. This in turn makes possible reducing soybean oil production and consumption, and instead frying oil (waste) is reused, which displays no significant difference in terms of chemical and physical properties. Also, the performance test of mixtures indicated that as the soybean oil is added to the mixture, the rutting performance decreases and fatigue performance increases. Based on the results, it is recommended to use 1.5% soybean oil in asphalt mixtures without compromising the performance of the mixture. ANOVA results showed that the warm additive had meaningful effects on MR, ITS, and FE; the same was true for the effects of the warm additive-binder type interaction.

Performance Evaluation of Fatigue and Fracture Resistance of WMA Containing High Percentages of RAP

Sustainability and durability are the key requirements of pavement structure. Sustainability of asphalt pavement structure involves utilization of Warm Mix Asphalt (WMA) technologies with the addition of Reclaimed Asphalt Pavement (RAP), where durability of asphalt involves performance parameters like fatigue and fracture resistance properties etc. Utilizing the RAP content in asphalt mix increases the mixing and compaction temperature which may degrade the performance of asphalt. Hence, numerous studies have recommended different WMA technologies to decrease mixing and compaction temperature of asphalt mix containing RAP. The present research work evaluates the fatigue and fracture performance of WMA and Hot Mix Asphalt (HMA) with varying percentages of RAP and Sasobit. Different mixes of WMA and HMA were designed with varying percentages of RAP (0, 20, 40 and 60%) through Marshall Mix design. Sasobit (organic/wax-based additive) was used as WMA technology to prepare WMA at varying percentages (0, 2, 4 and 6%). The fatigue behavior of asphalt was evaluated using four-point bending test, where fracture resistance of asphalt was determined using Semi Circular Bending (SCB) test in the laboratory. Fatigue and fracture resistance of WMA were improved with the increase in percentages of Sasobit and RAP content, while the addition of RAP in HMA showed a decreasing trend of fatigue and fracture resistance due to the stiffer nature of RAP. Furthermore, WMA was identified as economical for construction besides other benefits like improved properties and environment friendly asphalt mix. Doi: 10.28991/cej-2021-03091741 Full Text: PDF

Structure and Mechanical Properties of the 18Ni300 Maraging Steel Produced by Spark Plasma Sintering

In this work, a new approach for compaction of the gas-atomized 18Ni300 maraging steel at two different temperatures of 1050 °C and 1150 °C using a progressive SPS technology is studied. Moreover, the influence of two heat treatments combining solution annealing and aging (SAT) and simply aging treatment (AT) on the microstructure and mechanical properties is investigated. It is found that samples compacted at 1050 °C had higher porosity compared to the almost non-porous material produced at 1150 °C. In addition, the difference of 100 °C for the compaction temperature successfully reduces the porosity from 0.86% down to 0.08%. Additionally, we discovered that the higher the compaction temperature, the higher the amount of retained γ-Fe which positively affects the ductility of the samples. The subsequential heat treatment results in precipitation strengthening via the Ni3Mo precipitates. Microhardness of the SPS1050 and SPS1150 samples increase from 303 ± 13 HV0.1 and 360 ± 5 HV0.1 to 563 ± 31 HV0.1 and 606 ± 17 HV0.1, respectively. The sample compacted at 1150 °C shows the highest ultimate tensile strengths reaching up to 1940 ± 6 MPa, while also showing 4% ductility.

Study on Migratory Behavior of Aggregate in Asphalt Mixture Based on the Intelligent Acquisition System of Aggregate Attitude Data

In order to provide a new method to study the migration behavior of coarse aggregates in the compaction process of asphalt mixtures, the “Intelligent Aggregate Attitude Acquisition System (IAS)” is developed based on 3D printing technology and wireless intelligent sensing technology, and the “Intelligent Attitude Aggregate (IAA)” is prepared as the acquisition terminal. The Superpave Gyratory Compaction (SGC) test and the Internet of Things (IOT) wireless sensor technology are combined to collect and analyze the attitude data of an SMA-20 asphalt mixture built in IAA at different compaction stages, and the migration behavior of coarse aggregate in the compaction process is quantitatively characterized. The result shows that the IAA is suitable as a “tracking aggregate” to study the aggregate transfer behavior in asphalt mixtures. The IAA in the upper layer tends to move vertically downward, while the particles in the lower layer tend to move horizontally and spatial rotation in the process of rotating compaction. With the increase in asphalt content, the lubrication effect between aggregate particles is obvious, and the friction resistance of aggregate particles decreases when it is embedded downward. Affected by shear force in the process of rotary compaction, the aggregate particles are easier to overcome friction and cause large horizontal migration and spatial rotation. With the increase in compaction temperature, the viscosity of asphalt binder decreases, and the contact friction between aggregate particles decreases. The asphalt content has a significant effect on the displacement in the horizontal plane Dxoy of the aggregate. The asphalt content and compaction temperature have significant effects on the spatial rotation angle Φ of aggregate, but the asphalt content has a greater impact on it.

Mixing and Compaction Temperature of Nanosilica Composite Polymer Modified Asphalt

Recently, polymer -nanocomposites were used to manufacture durable asphalt mixtures to replace the polymer modified binder, because of the remarkable properties and unique features of nanomaterials compared to conventional materials, such as their wide surface area and small dimensions, making it possible to be utilized as an additive for asphalt paving. Nanosilica particles (NS) are one of the latest minerals which likely integrate useful characteristics, such as huge surface area, good distributions, high absorption levels, high stability, and a high level of purity. Therefore, this paper is interested in studying the characteristics of nanocomposite-polymer modified asphalt. In laboratory work, a pure asphalt 60-70 penetration grade, has been modified separately with waste polypropylene polymer (WPP), and nanosillica composite polypropylene (NS/WPP) at different concentrations. As a result, two modified binders: waste polypropylene polymer- modified asphalt (WPP-MA), and nanosillica composite polypropylene modified asphalt (NSCPMA) were obtained. Traditional asphalt binder tests were performed for pure and modified binders such as penetration, ductility, flash and fire point test, softening point, and rotational viscosity. Also, storage stability test has been conducted to ensure the storage stability of binders at high temperatures. The results showed an improvement in physical properties and increase in mixing and compaction temperature due to the increase in stiffness of (NSCPMA). The results also indicated that the nanosillica composite polypropylene modified asphalt binders have good storage stability at high temperatures.

Study on the Construction Performance of Zeolite Asphalt Mixture Based on Macro-Micro Scale

In order to explore the construction performance of zeolite asphalt mixture, the microproperties of zeolite and the macroproperties of zeolite asphalt mixture were studied. The structure composition, surface properties, and pore characteristics of zeolite were analyzed by infrared spectroscopy and pressure pump method. The structure, composition, and thermal stability of zeolite were analyzed by differential scanning calorimetry and thermogravimetry, the mechanism of moisture absorption and loss of water was explored, and the properties of moisture absorption and loss of water were studied. The effect of the type and amount of zeolite on the viscosity of asphalt was studied by the viscosity test. According to the mixing current and the compaction void ratio, the influence of zeolite on the construction performance of zeolite asphalt mixture was studied. The results show that zeolite contains special zeolite water and the pore content of zeolite is much higher than that of mineral powder. Zeolite loses water at 90°C∼120°C, which is the necessary condition for zeolite to be used in warm mix asphalt mixture. The water absorption and loss capacity of zeolite mainly depend on pore volume. The larger the pore volume is, the stronger the water holding capacity of zeolite is. Meanwhile, the water holding capacity and loss capacity of zeolite are related to pore size distribution. According to the viscosity temperature equation, the mixing and compaction temperature of the asphalt mixture are determined. The mixing and initial pressure temperature of the zeolite asphalt mixture are lower than those of the hot asphalt mixture. Based on the principle of mixing current equivalence, the mixing temperature of zeolite asphalt mixture can be reduced by 20°C compared with that of hot asphalt mixture. The better the water loss performance of zeolite is, the easier the mixture is to be compacted. For the base asphalt mixture, the compaction temperature of the mixture is 120–130°C, and, for the modified asphalt mixture, the compaction temperature is 130–140°C.

Determination of Construction Parameters of Porous Ultra-Thin Overlays Based on Laboratory Compaction Studies

To address the severe distresses of asphalt pavement, a new type of pavement maintenance treatment, porous ultra-thin overlay (PUTO) with small particle size was proposed. The PUTO has a thickness of 1.5–2.5 cm and a large void ratio of 18–25%. As a newly asphalt mixture, the structure characteristics differ from poor traditional pavement. Therefore, it is necessary to investigate the fabrication schemes in laboratory and on-site, respectively. In this study, the optimal fabrication schemes, including compaction temperature and number of blows of PUTO were determined based on Cantabro test and volumetric parameters. Then, the corresponding relationship between laboratory and on-site compaction work was then established based on the energy equivalent principle. On this basis, the numbers of on-site rolling passes and the combination method were calculated. The results show that increased compaction temperature and number of blows reduce the height and enhance the compaction of the Marshall sample. With the same temperature and number of blows, the raveling resistance of coarse gradation, Pavement Asphalt Concrete-1 (PAC-1) is better than that of fine gradation, Pavement Asphalt Concrete-2 (PAC-2), and the increased asphalt viscosity significantly improves the raveling resistance of the asphalt mixture. To ensure the scattering resistance and volumetric characteristic, the initial compaction temperature of the PAC-1 and PAC-2 should not be lower than 150 °C and 165 °C, respectively. Then, the laboratory compaction work and on-site compaction work were calculated and converted based on the principle of energy equivalence. Consequently, the on-site compaction combination of rolling machines for four asphalt mixtures was determined. According to the volumetric parameters, the paving test section proved that the construction temperature and the on-site rolling combination determined by laboratory tests are reasonable, and ultra-thin overlay has good structural stability, drainage, and skid resistance.