Modelling of road surface pothole formation
Lead Research Organisation:
University of Nottingham
Department Name: Faculty of Engineering
Abstract
Asphalt is a complex viscoelastic multiphase material and is known to deteriorate in a number of ways, which are dependent on the environmental and loading conditions. The frequency of potholes is observed to increase during harsh winters. This is thought to be due to a combination of the embrittlement of the asphalt matrix and the loads developed during freeze-thaw cycles. In the laboratory, however, these conditions do not induce deterioration of asphalt mixtures except under unrealistically severe conditions. The novelty of this research will be to introduce grit, representative of road surface detritus, into the modelling and experimental environment.
The hypothesis is that this will lead to accelerated crack propagation through mechanisms of abrasion and/or by preventing the relaxation of cracked material during load and freeze-thaw cycles. Modelling of this type of phenomenon has received recent attention because a similar mechanism occurs in the fracking process, where hard particles are forced under pressure into fissures in rock to keep them open permitting shale gas release. You will exploit this by applying the theoretical and/or numerical models to pothole formation, calibrating the model results using the experimental data.
The hypothesis is that this will lead to accelerated crack propagation through mechanisms of abrasion and/or by preventing the relaxation of cracked material during load and freeze-thaw cycles. Modelling of this type of phenomenon has received recent attention because a similar mechanism occurs in the fracking process, where hard particles are forced under pressure into fissures in rock to keep them open permitting shale gas release. You will exploit this by applying the theoretical and/or numerical models to pothole formation, calibrating the model results using the experimental data.
Organisations
People |
ORCID iD |
| Tony Parry (Primary Supervisor) | |
| Charles Djabatey (Student) |
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| EP/N50970X/1 | 01/10/2016 | 30/09/2021 | |||
| 2111085 | Studentship | EP/N50970X/1 | 01/10/2018 | 31/03/2022 | Charles Djabatey |
| EP/R513283/1 | 01/10/2018 | 30/09/2023 | |||
| 2111085 | Studentship | EP/R513283/1 | 01/10/2018 | 31/03/2022 | Charles Djabatey |
| Description | When first broaching the topic of road surface pothole formation, the starting point of the investigation was a significant and widely recognised observation: 'Potholes form more in the winter than in any other time of the year.' The possible peculiarities of the winter months were then considered to have a more complete sense of why the phenomenon is so. Potentially increased traffic on roads, higher precipitation, greater snow cover, freeze thaw cycles and lower temperatures, and the presence of rock salt and detritus or grit in order to melt said snow cover were all appraised. Generally, all these areas have been adequately researched into baring one: the presence of detritus and grit. This therefore became the novelty of the research project. When considering experimental or modelling methods to conduct the study, an area of chemical engineering called Hydraulic fracturing seemed to provide a robust framework that, if applied well, would aid greatly in the research. Hydraulic fracturing is a process where highly pressurised fluid cracks shale rock in order to harvest shale gas. However, once the crack are formed, they need to be kept open in order the siphon the gas. Therefore, there is a technology employed called proppants which are small incompressible particles in the pressurised fluid which prevent the crack from closing. It is envisaged that something akin to this occurs in a road. However, to successfully make this comparison, it must be proven that the cracks in the road are filled with dirt. This is the first stage of testing. In the experiments done to prove this, cracked cores are taken from an engineering consultancy and frozen in ice. Once frozen, the core in cut in slices in order to see the contents of the cracks at different depths. Then, once measured with an optical microscope, the samples are allowed to thaw and their contents are collected and graded. From the findings, just below the surface of most of the samples obtained, the crack is often full of dirt. This forms the basis of the further testing and application of Hydraulic fracturing experimental methods to the research project. |
| Exploitation Route | Although potholes are a perennial problem in UK roads, the mechanism(s) of their formation is poorly understood. As a result, there is no established experimental method to characterise the pothole resistance of an asphalt mixture or means of specification directly related to this phenomenon. Inspired by recent progress in geophysics, this research will model the potential mechanisms of crack initiation and propagation in asphalt, under the conditions considered to increase the likelihood of this form of deterioration, and develop an experimental test to validate the results. If successful, this will form the first step to developing and specifying asphalt materials that are more resistant to pothole formation. |
| Sectors | Transport |
| Title | Detritus Model |
| Description | The model is applying proppant technology to the wedging of road surface detritus in the cracks of a road, and the associated relationships |
| Type Of Material | Data analysis technique |
| Year Produced | 2020 |
| Provided To Others? | No |
| Impact | It quantifies and formalises and already prevalent phenomenon. |
| URL | https://docs.google.com/spreadsheets/d/16GwqzQ6bgTZjVx8x26TZGRmxe1iddwbPkY9y_BCVWNw/edit?usp=sharing |
| Title | Fatigue Three point Bending Model |
| Description | It is essentially the paris law model applied to a rectangular sample in the presence and absence of detritus. |
| Type Of Material | Computer model/algorithm |
| Year Produced | 2020 |
| Provided To Others? | No |
| Impact | It is a measure of crack propagation and the different factors that either accelerate or retard it and the extent to which that also occurs. |
| URL | https://docs.google.com/spreadsheets/d/16GwqzQ6bgTZjVx8x26TZGRmxe1iddwbPkY9y_BCVWNw/edit?usp=sharing |
| Title | Freeze Thaw Cycle Modelling |
| Description | it describes and predicts the extent of opening and closing of cracks, in both restrained and unrestrained cases. |
| Type Of Material | Computer model/algorithm |
| Year Produced | 2020 |
| Provided To Others? | No |
| Impact | It can predict the extent of crack widening, similar to how expansion joints in rail tracks or concrete design are calculated for. |
| URL | https://docs.google.com/spreadsheets/d/16GwqzQ6bgTZjVx8x26TZGRmxe1iddwbPkY9y_BCVWNw/edit?usp=sharing |
| Title | Hydraulic Fracturing model |
| Description | It is a model to simulate the increase in pore water pressure in a pavement when pressurised with a moving vehicle tyre. |
| Type Of Material | Computer model/algorithm |
| Year Produced | 2020 |
| Provided To Others? | No |
| Impact | Essentially it will simulate the contribution of pore water pressure to crack propagation in the pavement. |
| URL | https://docs.google.com/spreadsheets/d/16GwqzQ6bgTZjVx8x26TZGRmxe1iddwbPkY9y_BCVWNw/edit?usp=sharing |