Nonde Lushinga

Bio: Nonde Lushinga is an academic researcher from Harbin Institute of Technology. The author has contributed to research in topics: Crumb rubber & Asphalt. The author has an hindex of 3, co-authored 6 publications receiving 30 citations. Previous affiliations of Nonde Lushinga include Copperbelt University.

Effect of vehicle speed and overload on dynamic response of semi-rigid base asphalt pavement

Abstract: Premature deterioration in semi-rigid base asphalt pavement is still considered as one of the main distress related to Chinese highway pavements. There are several reasons for this premature damage...

Effect of Silicone Oil on Dispersion and Low-Temperature Fracture Performance of Crumb Rubber Asphalt

Abstract: Low-temperature cracking is one of the major pavement distresses in cold regions. To reduce the prevalence of such cracks, crumb rubber modified asphalt (CRMA) has been applied for a long time. However, CRMA experiences compatibility and segregation problems with asphalt. Silicone oil has long been seen to improve compatibility and segregation problems of polymers in asphalt, but its benefits on low temperature performance of crumb rubber asphalt have not been explored. Furthermore, silicone oil can be obtained as virgin or recycled from industrial transformers; however, the recycled silicone oil’s influence on low-temperature crack performance of asphalt has also not been explored. Therefore, the purpose of this study was to investigate the effect of recycled silicone oil (SO) on dispersion and low-temperature fracture performance of crumb rubber asphalt. The fracture mechanics-based single-edge notch beam (SENB) test was performed at temperatures of −12°C, −18°C, and −24°C. In addition, fluorescence microscopy (FM), atomic force microscopy (AFM), and Fourier-transform infrared (FTIR) experiments were also conducted. Results show that the addition of SO to CRMA increases displacement, fracture energy, and fracture toughness at low temperature while it decreases stiffness which reduces cracking. In addition, AFM results show that surface roughness increases with the addition of SO which indicates that bonding of asphalt and rubber particles had also improved. FM also confirmed that dispersion of rubber particles had improved with addition of silicone oil. FTIR results revealed that asphalt samples with SO treatment were hydrophobic which potentially repels water ingress and delays the freezing of asphalt. Lastly, statistical analysis revealed that the influence of silicone oil on low-temperature performance of rubber asphalt was significant. Therefore, the study concluded that fracture cracking resistance is improved by addition of silicone oil to crumb rubber asphalt.

Improving Storage Stability and Physicochemical Performance of Styrene-Butadiene-Styrene Asphalt Binder Modified with Nanosilica

Abstract: Due to storage stability drawbacks of polymer-modified bitumen (PMB), this study investigated the storage stability and physicochemical performance of Styrene-Butadiene-Styrene (SBS) asphalt binders (herein PMB) modified with Silicone surface-treated nanosilica (SNS). Dosages 0% (control), 1.5%, 3% and 5% SNS powder were added to PMB to prepare modified binders. Hot storage, Viscosity, Multiple Stress Creep Recovery (MSCR), Scanning Electron Microscopy (SEM), Fluorescence Microscopy (FM), Linear Amplitude Sweep (LAS), Fourier Transform Infrared (FTIR), and Proton Nuclear Magnetic Resonance (1H-NMR) tests were conducted using modified binders. The study found that adding nanosilica powder to PMB improved storage stability, increased viscosity and complex modulus, and reduced rutting of binders. However, this bitumen modification was not beneficial to fatigue cracking. The performance improvement was because of the interaction between the polymer and nanosilica, creating a new polymer-nanosilica network which lowered the dynamics around the SNS particles, thereby reducing phase separation. Further, the Silicone Si–O–Si backbone bond present in SNS modified asphalt binder reduced temperature sensitivity thereby preventing thermal degradation at high storage temperature. Nanosilica modified binders presented well-dispersed nanosilica particles in the asphalt matrix. The modification mechanism was predominantly physical. Overall, the study concluded that nanosilica improves storage stability, rutting, and morphology of PMB binders.

Performance Evaluation of Crumb Rubber Asphalt Modified with Silicone-Based Warm Mix Additives

Abstract: This research was conducted to elucidate better understanding of the performance of crumb rubber asphalt modified with silicone-based warm mix additives. Two different silicone-based warm mix asphalt (WMA) additives (herein Tego XP and Addibit) were used to prepare crumb rubber modified (CRM) warm mix asphalt binders. The viscosity of these CRM binders was measured at different temperatures and shearing rates. Furthermore, softening point and penetration tests, Multiple Stress Creep Recovery (MSCR), Time Sweep (TS), Atomic Force Microscopy (AFM), Frequency sweep (FS), and Fourier Transform Infrared (FTIR) tests were also conducted on prepared samples. Based on these robust and rigorous laboratory experiments, it was established that viscosity of CRM binders was reduced by addition of Tego XP and Addibit WMA additives. However, WMA additives had different influence on rheological properties of the binder. CRM binder with Tego XP improved resistance to rutting of the binders but would degrade the fatigue performance. On the contrary, viscoelastic continuum damage (VECD) model results and those of phase angle approach revealed that the binder with Addibit improved resistance to fatigue cracking of the binders but had no adverse effects on high temperature rutting performance. FTIR test results established a presence of polydimethylsiloxane (PDMS) in CRM binders with Tego XP and Addibit. PDMS is a well-known hydrophobic organic and inorganic polymer that is water repellent; therefore, binders containing these silicone-based warm mix additives could be beneficial in resisting moisture damage in asphalt binders and mixtures. Morphology of CRM binders with and without WMA revealed good distribution of the rubber particles in asphalt binder matrix. Further addition of WMA increased surface roughness of the binder, which can be correlated to changes in microstructure properties of the binder. Therefore, the study concluded that addition of Tego XP and Addibit reduces viscosity and improves mechanical properties of the asphalt binder.

Rheological Behaviour of WMA-Modified Asphalt Binders with Crumb Rubber

Abstract: Crumb rubber (CR) is one of the materials most widely used in the road infrastructure industry due to its mechanical and environmental benefits as an asphalt binder modifier. Nonetheless, CR decreases the workability of mixes by increasing the viscosity of the binder, leading to an increase in the production temperatures of asphalt mixes. However, warm mix technologies can reduce the temperature demand associated with these processes. The preceding explains the growing interest in producing rubberised asphalt binders incorporating warm mix asphalt (WMA) additives. In this research, the mechanical and rheological properties of a 60/70 penetration grade asphalt binder modified with CR (at a dosage of 15, 18 and 21% by the wet process) and WMA chemical additives (Evotherm M1 and Iterlow T) were investigated. Laboratory tests included penetration, softening point, rotational viscosity, frequency sweep through dynamic shear rheometer (DSR), and multiple stress creep recovery (MSCR) tests. The results indicate that CR increases the stiffness of the asphalt binder, which is reflected in a lower penetration grade and improved softening point. It also improves its rutting resistance but decreases fatigue performance. Furthermore, it has been shown that under the conditions studied, the higher the CR content, the more elevated the degree of stiffness and performance of the asphalt binder. On the other hand, WMA technology decreases asphalt stiffness and performance at high temperatures.

Finite-Element Simulation of Instrumented Asphalt Pavement Response under Moving Vehicular Load

Abstract: Understanding the structural behavior of layered asphalt pavements subjected to dynamic moving wheel loads is a crucial requirement for the future design of more-durable pavement structures...