Investigating the Rheological Properties of Carbon Nanotubes/Polymer Composites Modified Asphalt

Effect of different waste plastic modifiers on conventional asphalt performance: optimal preparation parameters determination and mechanism analysis

The typical treatment of waste plastics has become a global environmental problem. In light of recent developments, waste plastics used as asphalt modifiers offer an efficient approach to solve this problem. This paper studied the effects of three kinds of waste plastic-modified asphalts (WPMA), with polypropylene (PP), polyethylene (PE) and ethylene-vinyl acetate copolymer (EVA) as their respective modifiers, on the conventional asphalt performance. Furthermore, an orthogonal experimental design (OED) was used to determine the preparation parameters of WPMA. Thereafter, thermogravimetric-differential scanning calorimetry (TG-DSC) and Fourier transform infrared spectroscopy (FTIR) were employed to expound the mechanism of WPMA. It was then subsequently ascertained that the optimum preparation parameters of PP-modified asphalt (PPMA) and PE-modified asphalt (PEMA) were 170 °C, 3000 rpm, and 30 min, while the optimum preparation parameters of EVA-modified asphalt (EVAMA) were 180 °C, 3000 rpm, and 30 min. In addition, WPMA displayed better high-temperature performance and are inherently more suitable for pavement in high-temperature regions. Ultimately, this study will effectively solve the disposal of waste plastic and promote the research and application of WPMA in the future.

Analysis of the Influence of Production Method, Plastic Content on the Basic Performance of Waste Plastic Modified Asphalt

The sustainable reuse of waste plastic as an alternative construction material has numerous environmental and economic advantages. New opportunities to recycle waste plastic in asphalt for road construction would mitigate landfill issues and significantly reduce global carbon emissions. With a clear aim to contribute to a more efficient reuse of waste plastic, this paper reutilized two types of waste plastic (polypropylene (PP) and polyethylene (PE)) as asphalt modifiers to improve the performance of asphalt pavement as well as to achieve the purpose of sustainable recycling waste plastic. Therefore, the optimal preparation parameters of plastic-modified asphalt were recommended by the orthogonal test. Then, the dispersion and modification mechanisms of plastic particles in plastic-modified asphalt were further studied by Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Differential Scanning Calorimetry (TG-DSC). The results show that the asphalt containing PP and PE shows better overall performance at high temperatures compared with the base asphalt. Furthermore, PE-modified asphalt and PP-modified asphalt exhibited optimal properties when prepared at 3000 rpm for 30 min at 170 °C. Moreover, the results of the expansion mechanism show that the main reaction process of plastic asphalt is a physical change. Finally, PP-modified asphalt and PE-modified asphalt generally perform well and are suitable for high-temperature areas. Consequentially, the results of this research promote the recycling of waste plastic, ultimately advocating the recycling of waste materials and environmental protection of pavement construction.

Study on Storage Stability of Activated Reclaimed Rubber Powder Modified Asphalt

The purpose of this research was to make full use of waste lubricating by-products (LBP) and reclaimed rubber powder (RR) to modify asphalt by a one-pot approach, so as to achieve the dual purpose of solving the poor storage stability of reclaimed rubber powder modified asphalt (RRMA) and the realization of solid waste recycling. A variety of characterization techniques were performed to analyze storage stability, conventional properties and microstructure of LBP-activated reclaimed rubber powder modified asphalt (Blend). Fourier transform infrared spectroscopy illustrated that not only the chemical composition of LBP was very similar to that of asphalt, but also the activation of LBP improved the compatibility of RR with asphalt and enhanced the storage stability of Blend. Fluorescence spectrum and scanning electron microscopy results indicated that the RR without LBP activation was aggregated and dispersed as blocks in asphalt, while the LBP activated RR was uniformly dispersed in the asphalt phase. The segregation test demonstrated that Blend exhibited outstanding storage stability, in which the softening point difference was within 2.5 °C and the segregation rate was -0.2-0.2. In addition, the conventional properties of Blend have been significantly improved, especially in penetration and ductility. More importantly, the short-term aging results demonstrated that, compared with RRMA, Blend possessed excellent anti-aging performance.

Investigation on Preparation and Properties of Crack Sealants Based on CNTs/SBS Composite-Modified Asphalt

Crack is the main distress of asphalt pavement. Sealant is one of the most commonly used crack repair materials, and its performance is the key to affect the service life of asphalt pavements. In order to find an efficient modifier and optimize the performances of crack sealants. In this paper, carbon nanotubes (CNTs) and styrene-butadiene-styrene (SBS) were used as modifiers to prepare CNTs/SBS composite-modified asphalt crack sealant. The properties of the sealant were tested to evaluate its suitability for crack repair, which included the viscosity, softening point, resilience recovery, cone penetration, flow value, penetration, aging resistance, and fatigue resistance. The results showed that the conventional properties of the sealants meet the requirements of the specification. In addition, after heating aging, the elastic recovery rate of the sealant containing more CNTs decreased only slightly. The sealant containing 1 wt% CNTs exhibited a higher viscosity, fatigue resistance, thermal aging resistance.

Analysis of the Storage Stability Property of Carbon Nanotube/Recycled Polyethylene-Modified Asphalt Using Molecular Dynamics Simulations

Carbon nanotubes (CNTs) can improve the storage properties of modified asphalt by enhancing the interfacial adhesion of recycled polyethylene (RPE) and base asphalt. In this study, the interaction of CNT/RPE asphalt was investigated using molecular dynamics simulation. The base asphalt was examined using a 12-component molecular model and verified by assessing the following properties: its four-component content, elemental contents, radial distribution function (RDF) and glass transition temperature. Then, the adhesion properties at the interface of the CNT/RPE-modified asphalt molecules were studied by measuring binding energy. The molecular structural stability of CNTs at the interface between RPE and asphalt molecules was analyzed through the relative concentration distribution. The motion of molecules in the modified asphalt was studied in terms of the mean square displacement (MSD) and diffusion coefficient. The results showed that CNTs improved the binding energy between RPE and base asphalt. CNTs not only weakened the repulsion of RPE with asphaltenes and resins, but also promoted the interaction of RPE with light components, which facilitated the compatibility of RPE with the base asphalt. The change in the interaction affected the molecular motion, and the molecular diffusion coefficient in the CNT/RPE-modified asphalt system was significantly smaller than that of RPE-modified asphalt. Moreover, the distribution of the asphaltene component was promoted by CNTs, resulting in the enhancement of the storage stability of RPE-modified asphalt. The property indexes indicated that the storage stability was significantly improved by CNTs, and better viscoelastic properties were also observed. Our research provides a foundation for the application of RPE in pavement engineering.