PhD Students

I am currently working on demonstrating the effectiveness of incorporating self-healing capsules into the asphalt surface layer to increase the lifespan of roads and offer an alternative method for road maintenance. Trials will take place at Nottingham University using an accelerated pavement testing (APT) machine and onsite testing on the M25 motorway and quarry. In addition, this research will evaluate how self-healing materials have the potential to deliver significant cost savings for road maintenance.

Railway trackbeds deteriorates over time with increasing traffic loads and harsh environmental conditions. Recently, railway instrumentation has become a vital technique to monitor the structural condition of railway tracks. My research focuses on Structural Health Monitoring (SHM) of railway track bed infrastructure. Railways can use asphalt in different layers between the sleepers and the subgrade for different beneficial purposes. Having the chance to equip the asphalt layer and subgrade layers with SHM capabilities will be of great help for infrastructure managers as they can receive early warnings of potential deterioration issues. 

It is the goal of this project to embed smart and self-powered sensors in the asphalt and subgrade layers. With the data collected from these sensors, the project will aim to develop a deterioration model to improve railway asset management. In this way, improved track design for longer life and lower maintenance is the ultimate goal. 

I am currently working on polymer modified bitumen (PMB) and its behaviour and performance under different loads and temperature conditions. The aim of this project is to improve bitumen performance by adding Recycled Low-Density Polyethylene (RLDPE) and Styrene-Butadiene-Styrene (SBS). Additionally, the storage stability of PMB is another focus of this project since polymer modified bitumen often suffers from phase separation, which leads to non-uniform mixture.

This study investigates how early traffic loading affects the curing and mechanical properties of recycled asphalt mixtures. These mixtures, containing high proportions of reclaimed asphalt and foamed bitumen as the primary binder, require time to develop strength and moisture resistance. However, allowing traffic during this crucial early phase can affect the material's evolving performance. By evaluating stiffness gain and deformation under loading scenarios, a predictive model is developed accounting for traffic effects on curing. The model informs enhanced pavement design and construction by utilising recycled materials for more sustainable pavements.

The aim of this research is to investigate the possibility of using low quality and grade construction and demolition (C&D) waste as a replacement for natural aggregate to produce sustainable hydraulic bound mixtures (HBMs) and use them in road construction applications as a base or subbase layer. This can be achieved by determining the performance of C&D waste materials in the mixtures and the mixtures’ characteristics, such as strength, fatigue and stiffness, and then comparing the outcome with natural materials. It is important to evaluate the sustainability, investigate microstructural properties and understand the behavior and how it can work and act under pavement in road construction of the chosen mixtures to achieve the main goal.

As train speed increases, dynamic responses of railway track and ground along the railway line become more substantial. For a high‐speed train running on soft soil, resonance may occur, and consequently, the dynamic responses of the track and ground are dramatically amplified. At the critical speed, train moving loads induce strong vibration in the track structure, increase the risk of train derailment and track structure damage. Slab tracks is still investigating as an unproblematic system for high‐speed rail traffic. Slab track railways have dynamic performances that are quite different from those of traditional ballasted railways, in terms of transient responses and permanent deformation. The critical speed will also be affected by the slab track structure. This research will investigate the critical speed of slab track with using numerical modelling and an extensive scale of physical demonstration to simulate the effect of various loads in the research facility.

My research work, RoboFRAC, involves fixing asphalt cracks with robotic arms without human intervention. The project involves developing a robotic arm and optimising its operational parameters and then upgrading the arm into a fully-fledged robot that can be dispatched to a demo site to follow cracks and fill them with hot bitumen, autonomously. This will be achieved through the application of AI, 3D printing, sensing and robotic technologies. Robotic repairs will mean a reduction in traffic disruption, CO2 emissions, and maintenance costs. With this novel technique, we could fix asphalt cracks with greater accuracy and at any time of the day. Moreover, the autonomous repair technique will save humans from undertaking dirty and dangerous manual jobs on our highways. All the greater, I expect that the results of this research work will have a tremendous impact on the future of road maintenance.

Aging of bitumen is one of the most important factors leading to the degradation of service performance of asphalt pavement. Reclaiming aged bitumen is an efficient way to save the costs of highway maintenance. This study aims at investigating the mechanism of the aging behaviour of bitumen in terms of rheological properties, characteristic functional groups and the micro-morphology, then, the rejuvenation of aged bitumen will be observed and the specification will be established.Firstly, multiple bitumen (neat, SBS modified and crumb rubber modified) will be aged by laboratory experiments such as RTFOT and PAV, and the properties of different bitumen, both virgin and aged, with different components, will be compared in terms of rheological properties, characteristic functional groups and the micro-morphology by DSR (BBR will be replaced by 4-mm DSR), FTIR and SEM et al, also, the bitumen will be break down into maltene (even saturates, aromatics and resins) and asphaltene and to be further studied. Next, the aged bitumen will be rejuvenated by different rejuvenators, both bio-based, petroleum-based and self-made, and (E)SEM will be employed to observe the interface between the aged bitumen and rejuvenators. Then, the bitumen will undergo several cycles of aging and rejuvenation, so that its mechanism will be detected. Afterwards, numerical investigation will be applied into bitumen aging and rejuvenation. Finally, bitumen aging and rejuvenation will be incorporated into bitumen-mineral adhesion. Several fatigue tests, pull-off tests and other tests will be conducted and the specification of rejuvenation of bitumen will be established.

The use of additives to target specific bitumen properties and enhance bitumen performance is common practice within the industry. However, most additives only disperse an additional phase into the colloidal bitumen structure which can lead to early and premature separation under adverse conditions. This research aims to assess the chemical properties, thermo-rheological and mechanical performance of bitumen modified with additives.

This project is targeted at allowing Highways England to manage their stock of concrete roads effectively. The objective is to develop a trustworthy method of predicting future performance based on known characteristics. This study will concentrate on the design and calibration of a realistic concrete pavement deterioration model, in particular joint and crack deterioration. The modelling required is anticipated to involve numerical as well as empirical modelling and finally validating the developed models.  Inputs will be related to information from in-situ monitoring. Outputs need to be formulated so as to be suited to HE’s decision-making processes. 

Infrastructure material are porous media constantly subjected to a variety of stress. Addition of self healing capabilities, potentially, reduce repair and cost.Crucial is the development of a virtual environment, based on Discrete Multiphysics, applied to assess the behaviour and durability of a new class of materials.Initially, asphalt will be modelled. Later the study will be generalized to other porous infrastructure materials.Once those models have been completed, those properties derived on computational based will be verified on laboratories analysis through analytical and physical test.

Studies on polyethylene-based bitumen modification resulted a wide potential use in field applications. My project emphasises on how the pure and recycled low density polyethylene are affecting moisture susceptibility, the bonding strength between bitumen and aggregates, and the cohesion properties of the bitumen. The cohesion work in the bitumen and the adhesion between bitumen and aggregates are analysed. The modification effect to the microstructure of the bitumen will be observed by FTIR (Fourier transform infrared spectroscopy) analysis and complemented with an atomic force microscopy analysis. The bitumen ageing is also considered as the deterioration factors and finalised with mixtures’ rutting and durability tests. The obtained findings will be used to correlate in-between bitumen properties and to the mixture performance properties thus enrich the understanding on how recycled polyethylene utilizations are compared to those of virgin ones.

Asphalt mixtures containing Natural Rubber Latex has received growing attention in the past years because of its various advantages. The added mixture can be used to improve the rheological properties of modified asphalt emulsion and has several beneficial effects of the addition on the performance-related response for fatigue damage, permanent deformation, fracture strength and thermal cracking. 

The main purpose underlying to the implementation of this study has to do with the fact that it is considered to provide valuable information to be incorporated at the early stages in the design of new pavement technology with regard of Natural Rubber Latex asphalt mixture. Accordingly, the aims of this study are to examine the energy saving and environment impact in Natural Rubber Latex asphalt mixtures by taking the fuel consumption in the usage stage into consideration. Such study is important to provide information to added at the early stages of new mixtures development. 

This research explores the intricate relationship between skid resistance, pavement materials, and the geometric design of roads. Focused on how surface contaminants and environmental shifts, particularly during seasonal weather changes, affect skid resistance, the study also considers the impact of specific driving behaviours like cornering. A newly developed accelerated wearing machine aims to enhance the ability to predict skid resistance and to deepen the understanding of how pavement textures evolve, ultimately contributing to safer and more effective transportation systems.

Encapsulated bitumen rejuvenators can strengthen the self-healing capacity of asphalt mastics, prolonging the life span of roads.

The main aim of this project is to study fatigue models and develop degradation curves for self-healing asphalts, in order to apply them into a specialized software for the implementation of novel additives for road materials, that includes the effect of changes in traffic and climate, and the value of each section of the road.

Several trial sections will be constructed and be used as an example to decide in which areas of the road the installation of capsules with rejuvenators will be worth the cost.

A new virtual asphalt mixture simulation method is introduced to obtain the micro performance data of asphalt mixture. By combining the microdata of the virtual mixture and the macro test results of the equivalent test mixture to understand the effect of the aggregate morphological properties, the viscosity of the bitumen, the geometry and density of the filler particles, and the compaction type on the topological properties of aggregate skeletons, repeated load axial test results, rutting, and stability of the asphalt mixture. The experimental results will be compared to those produced by existing software and analysed by means of multiparametric analysis. Finally, the project will explore possible methods for optimizing the stability of the asphalt mixture based on the relationship between these factors. The research method using virtual design can provide some suggestions and directions for optimizing macroscopic performance by adjusting microscopic variables in the material design and development stage in the future.

Particulate contaminants have significant lubricating and wearing effects on asphalt pavements. My research is based on the background of sand on desert roads. Typical sandy asphalt pavements are selected for field observation experiments on skid resistance, while accelerated wear tests are carried out in the lab in a simulated wild environment. The implementation of this research will provide a theoretical basis and implementation recommendations to reveal the influence of sand migration characteristics, friction formation mechanism and aeolian sand on the skid resistance of asphalt pavements.

Oxidative ageing of asphalt pavements is a multiphysics problem. Ignoring the circularly dependent of multiphysics in oxidative ageing is the main research gap in the pavement field ageing modelling. The current mechanical analyses of asphalt pavements via FEM lack the consideration of road material deterioration due to ageing, leading to an inaccurate performance prediction of asphalt pavements. Besides, the traditional time domain-based computational approach for analysing the mechanical responses of asphalt pavements is time-consuming and impossible to predict the long-term performance of asphalt pavements. In this project, a coupled multiphysics field ageing and viscoelastic-damage model of asphalt pavements will be firstly established. After that, a developed multiscale computational method will be employed to solve the high cycle fatigue problems in pavement structures with an acceptable computation efficiency. This project would contribute to the accurate long-term performance prediction of asphalt pavements.