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Road Surface Texture Depth (STD) is a critical aspect of a road surface. A typical STD range is between 2.0-0.8 mm. Roads with STD less than the lower threshold are more prone to traffic accidents due to aquaplaning or drop in skid resistance. Roads with STD more than the upper threshold are prone to fretting and pothole formation. In this study, a simple method to predict STD has been developed. The method utilises previous STD measurements collected by the Surface Condition Assessment for the National Network of Roads (SCANNER) method to quantify STD deterioration rate, which is the amount of increase or decrease in STD over time. The deterioration rates are then converted into Texture Deterioration Master Curves (TDMCs) which can be used in predicting STD. To demonstrate the application of this method, SCANNER data covering around 400 km of class A roads in Nottinghamshire collected between 2014 and 2018 were analysed and used to build TDMCs. STD data in 2020 were then predicted and compared to the measured STD data for validation. The results show that the developed method is simple and reliable, which makes it a valuable management tool for highway authorities enabling them predicting the STD on their road networks and assessing the risks of high or low STD on the condition and operation of their road networks.

Highway Authorities in the UK use Surface Condition Assessment for the National Network of Roads (SCANNER) in assessing and managing their road networks. This survey vehicle utilises laser measurements to detect and quantify most of the distress on the road surface, such as rutting, cracking and texture depth. It is however a data intensive and expensive approach since it is conducted annually. This study presents a simple method to predict pavement distress using previous SCANNER measurements. The previous measurements are used to develop Distress Deterioration Master Curves (DDMC) that relate distress deterioration rate with the severity of the distress. These curves can be used to predict future distress severity based on the current state without the need to provide further data such as pavement age or pavement material properties. To demonstrate the application of this method, a significant amount of SCANNER data covering around 400 km of class A roads in Nottinghamshire collected between 2014 and 2020 were analysed, and rutting, crack intensity, and texture depth were modelled in this study. DDMRs of these distress types were built based on data collected between 2014-2018, then 2020 data were used to validate the predictions. The results show that the developed method can be implemented in predicting surface distress of roads using previous measurements, which makes it a valuable addition tool for highway authorities subject to underfunding.

Potholes represent one of the dangerous distress types on roads. They form as a result of various factors, including water ingress, freeze–thaw, and pavement condition deterioration. In the UK, 1.7 million potholes were repaired in 2021; this critical number causes significant economic, social, and environmental impacts; there is no tool able to predict the number of potholes that might appear in a road network. This study aims to analyze pothole formation and its relationship with other distress types and their severity, and to develop a simple tool able to predict the number of potholes that might appear in a road network based on the network condition. Significant pothole data from the road network of Greater London between 2017 and 2020, in addition to surface distress data, were used in this study. ‘Spatial density’ and ‘join’ tools embedded in ArcGIS were used to correlate pothole spatial density (PSD) with the road condition surrounding the potholes. This analysis was then used to calculate PSD as a function of different condition indicators, such as road condition index and crack intensity, allowing prediction of the number of potholes based on the length and condition of the sections being analyzed. The results demonstrate that potholes are significantly concentrated in sections with deteriorated conditions. They also show that it is possible to predict the number of potholes using PSD with reasonable accuracy. Lastly, it was found that sections with low crossfall are more susceptible to pothole formation, presumably because of water ponding and consequent damage.

The special environment conditions in high altitude areas leads to serious cracking and peeling of road hot-melt marking coatings. In order to improve the durability of marking paint, a durable hot-melt marking paint was designed by modifying the paint with toughening-agent, rheological agent, and anti-aging agent. The modification mechanism of the modified coating was revealed through TG and FTIR analysis. The low-temperature anti cracking, adhesion, and anti-aging properties of the modified coating were studied by low-temperature bending test, interlaminar shear test and UV aging test. Besides this, the workability of modified coatings was tested onsite. The results showed that the mass loss rate of the rheological agent is 0.15% at 240 °C, the modified coating had good thermal stability within the mixing temperature range of the coating. There was no chemical change between the modifier and the coating, which was a physical blend. The modified marking paint had good fluidity, softening point and drying time, but its compressive strength was slightly reduced. With the increase of the content of the toughener, the low temperature crack resistance and adhesion of the marking coating gradually increase. When the toughener is 5%, the flexural tensile strain of the marking coating beam increased by 79.1%, and the adhesion strength of asphalt concrete increased by 53.4%. The anti-aging agent can shield most of the UV radiation and improve the anti-aging property of the coating by about 30%. The field process validation achieved the expected results. The modifier coating has excellent low temperature crack resistance, adhesion, UV aging resistance, and other properties, and has good application prospects in harsh environment areas., Pavement Engineering

This study aims to characterise the healing properties of asphalt binders at different damage levels. The healing and the damage levels were quantified by crack length (CL) in binder samples generated by rotational shear fatigue loads in strain-controlled dynamic shear rheometer (DSR) tests. For comparison, the healing was also characterised by the commonly used material parameters including pseudo shear stiffness (S) and dissipated pseudo strain energy (DPSE). A normalized healing index was formulated using the above three parameters, respectively. A healing test of polymer-modified bitumen was designed based on DSR including a strain-controlled time sweep test plus a rest duration and followed by another strain-controlled time sweep test. The healing tests were performed at different rest start times (5min, 10min and 20min), rest durations (5s, 10s, 0.5min, 1min, 2min, 5min, 10min, 20min, and 40min), and amplitudes of the shear strain (5%, 7%, and 10%) at 20°C and 10Hz. Results show that the CL-based healing index is a fundamental and accurate parameter to evaluate the healing rate and healing potential of the bitumen. DPSE-based healing index is applicable only when the energy is mainly dissipated to generate cracks. Healing is underestimated when characterised using S or DPSE-based healing indices. Healing index increases due to the advance of rest duration or the decrease of the damage level, and the healing rate can be essentially modelled by Ramberg-Osgood model. Higher damage levels (introduced by higher load levels or longer loading time) can effectively decrease the binders’ healing potentials when the binders are at the relatively low damaged levels. The healing potential becomes low when the material is at severe damage state, thus will remain at that low levels even though the damage level increases.

Fatigue resistance of bituminous binders plays a critical role in determining the fatigue performance of asphalt pavements. It is reported in the literature that, under a rotational shear fatigue load like a dynamic shear rheometer (DSR) test, the crack grows in the cylindrical bitumen sample as a circumferential crack that is initiated at the periphery of the sample and propagates toward the center of the sample. This study aims to model this crack propagation in bituminous binders under rotational shear fatigue load by time sweep (TS) fatigue test using the DSR. The crack length in the TS test is determined using a damage mechanics-based DSR-C model which is a function of the shear moduli and phase angles under undamaged and damaged conditions. The crack evolution is modeled by a pseudo J-integral based Paris’ law. Samples of virgin bitumen 40/60 and polymer-modified bitumen X-70 under unaged and aged conditions are tested by the TS tests at different temperatures, frequencies, and strain levels. Results show that the pseudo J-integral Paris’ law is able to predict accurately the crack propagation in bituminous binders under the rotational shear fatigue load. The crack grows faster in aged bitumen or at lower temperatures. The Paris’ law model parameters (A and n) are independent of loading frequency or load amplitude. They are fundamental material properties and can be determined at one loading frequency and amplitude, then can be implemented to predict the growth of cracks in bituminous binders at different loading frequencies or amplitudes.