Proposed Changes to Asphalt Binder Specifications to Address Binder Quality-Related Thermally Induced Surface Damage

Superpave specifications address binder properties that may lead to rutting, transverse cracking, and fatigue damage with varying degrees of success. However, asphalt binder production and formulation has significantly changed and introduced much more variability in relation to quality since the development of the Superpave Performance-Grade system because of economic, technical, and environmental reasons. Consequently, aged-induced surface distresses under combined thermal and traffic loading have become the main challenge for highway agencies. Thermally induced surface deterioration appears in the form of traditional transverse cracking, block cracking, and raveling, or accelerating damage at construction joints. This study evaluated the limitations of the proposed linear viscoelastic (LVE) rheological cracking surrogates, such as ΔTc, R-value, and G-R parameters, and the ability of the Asphalt Binder Cracking Device (ABCD) failure test to overcome these limitations. ABCD is particularly appropriate to rank binder performance because the measured cracking temperature (Tcr) encompasses binder LVE properties, failure strength, coefficient of thermal contraction, and cooling rate. The proposed parameter (ΔTf = Tc(S = 300 MPa) from BBR—Tcr from ABCD) relates the failure temperature to the equi-stiffness temperature and gives credit to well-formulated and compatible polymer-modified binders expected to increase binder strength and strain tolerance. This paper proposes a specification framework based on both ΔTc and ΔTf, universally applicable, regardless of binder composition. Additionally, preliminary purchase specification limits for binders used in surface layers are proposed based on the analysis of 44 binders, 15 with corresponding field performance data. Obviously, as confirmed by a recent stakeholder workshop and industry feedback, these preliminary specification limits need further validation and possible adjustments to account for regional experience and local challenges.

Kincardine Bridge – An engineering triumph 85 years on

When construction of Kincardine Bridge was completed in 1936, it was the longest road bridge in Scotland and the largest swing-span bridge in Europe. 85 years on, the Historic Environment Scotland Category A listed bridge remains in service and carries approximately 12,000 vehicles daily across the Forth Estuary. On occasions when the Queensferry Crossing and Forth Road Bridge are closed simultaneously, the Kincardine Bridge offers the shortest available diversion route across the estuary for unrestricted traffic. A 2019 principal inspection highlighted deterioration to some structural elements and in 2020 DMRB bridge assessment standards were revised. As a result, a quantitative assessment was undertaken to provide confidence that the bridge remains safe for use and fit for purpose and to inform future maintenance requirements. This paper focuses on the multitude of structural forms that comprise the overall bridge and how they: - have comparably performed relating to durability over the past 85 years - have been quantitatively assessed - have comparably withstood present-day traffic loading criteria - will be maintained in future.

Seasonal Performance Evaluation of Pavement Base Using Recycled Materials

Using recycled pavement materials to construct new pavement base is currently an important construction strategy bringing improved sustainability. This study investigates the long-term performance of pavement bases constructed with recycled concrete aggregate (RCA), reclaimed asphalt pavement (RAP), and blends with natural aggregates in a seasonal frost region. The stabilization effect of fly ash on RAP was studied as well. In situ falling weight deflectometer (FWD) tests were routinely conducted to provide seasonal deflection data, which were used to back-calculate the layer modulus. Seasonal changes in the base layer modulus along with the pavement ride quality were monitored. One of the two lanes at the test sections was consistently subjected to traffic loading, whereas the other one was not. Findings from this field research indicated that after undergoing over 8 years of naturally seasonal freeze-thaw conditions, 100% RCA, 50% RCA, plus 50% natural aggregates, and 100% RAP, presented improved performance over 100% natural aggregates. However, 50% RAP blended with 50% natural aggregates performed comparably to natural aggregates only, and fly ash did not provide considerable improvement on the long-term performance of 50% RAP plus 50% natural aggregate base. Seasonal climatic variations turned out to affect pavement performance more critically than traffic loading.

A direct method to detect and localise damage using longitudinal data of ends-of-span rotations under live traffic loading

Existing work on rotation-based bridge monitoring has focused on indirect methods, such as bridge weigh-in-motion or influence line approaches. However, these approaches require increased instrumentation complexity, and require calibration, necessitating bridge closures. In this paper, we explore the potential of using rotation measurements to create a more practical and cost-effective monitoring system. To this end, we present a damage detection method which directly analyses bridge rotation data measured under live, free-flow traffic loading. We show how the Earth Mover’s Distance, typically used in statistics and image processing, can be applied directly on end-of-span rotation measurement data to achieve effective damage detection and localisation. Numerical simulation results demonstrate the approach’s robustness to the confounding effects of temperature variation and traffic diversity (vehicle type, loading, and velocity). The direct rotation measurement approach is applied to data from an in-service short-span bridge to demonstrate the technique’s capability with free-flow traffic loading.

Traffic Study and Analysis of Highway (NH5) from Balongi to Kharar

Evaluation of in service pavements is very vital for keeping them in good serviceable condition because pavements deteriorate with age and traffic loading. To get a complete idea of the existing condition of any pavement both structural and functional evaluation are necessary. This study aims to investigate the accidental spots, traffic volume, and pavement condition. For this survey, the location of Kharar was chosen i.e. Balongi to Kharar Bus-Stand of 7 km stretch. The road initiates with intersection near Kharar bus stand and passes through many in between intersections near Sunny Enclave, VR Punjab Mall which are prime locations in that area. This road also connects with T junction and connects to NH5 / NH7 via Airport road. The data collected was processed, categorized and analyzed to generate reports for vehicle classification, hourly traffic variation, accidental black spots, pavement condition and origin & destination of trips.