Rutting in flexible pavements is primarily governed by permanent strain accumulation in unbound layers and subgrade soils. Laboratory repeated load triaxial (RLT) tests are commonly used to characterize this behavior; however, differences in confinement, stress paths, and loading frequency often lead to discrepancies between laboratory predictions and field observations. Conventional calibration approaches typically rely on constant scale factors, which cannot adequately capture variations in the empirical transfer function relating resilient strain to allowable load cycles.This study proposes a parametric transformation of laboratory transfer functions via rotation and translation to reconcile laboratory results with full-scale tests, such as those conducted in a Heavy Vehicle Simulator (HVS). The methodology preserves the functional structure of the empirical relationship while allowing slope adjustments associated with scale effects and loading frequency. Results show that the slope of the transfer function varies with the allowable permanent strain level, indicating that a single scale factor is insufficient to account for laboratory–field discrepancies. Although the validation is limited to the tested SM subgrade soil and the specific RLT and HVS conditions considered, the proposed framework provides a general method for transforming laboratory into full-scale mechanistic–empirical transfer functions.

Subgrade soil performance and flexible pavement system responses are significantly influenced by loading parameters and environmental factors. The structural rutting in subgrades is especially important, as inadequate permanent strain rates may cause drainage issues that require costly rehabilitation. Unpaved roads are generally located in remote areas and characterized by heavy vehicles, exacerbating this problem. This study emphasizes how crucial load parameters-like amplitude and frequency-impact the accumulation of permanent strain under cyclic loading for different pavement subgrade soils. The research offers comprehensive insights into the behavior and interaction of two distinct subgrade materials, clay and silty sand, through cyclic triaxial testing under varying stress and moisture conditions. Analysis of the transfer curve reveals that frequency is critical in altering the function form, regardless of soil type, water content, or imposed load size. The findings underscore that frequency, more than any other factor, significantly impacts the behavior and characteristics of the pavement structure, making it a key parameter in understanding and predicting structure responses. Furthermore, for a maximum allowable resilient strain, the number of cycles may vary up to 70 times for frequencies ranging from 0.1 Hz to 0.3 Hz. This implies that damage can be accelerated by fewer heavy vehicle passes, especially when the road condition forces the speed to moderate speeds (low frequencies). Assessing the soil stability and rutting potential in situations involving large trucks travelling at slow speeds while carrying heavy loads is crucial. Designers should thus modify their damage criteria to account for these circumstances.

The use of high-inflation pressure and heavily loaded tires on aircraft induce high stresses at the surface of runway pavements. High compressive, tensile and shear stresses at or near pavement surface are likely to induce rutting and surface-initiated fatigue cracking (top-down cracking) in asphalt concrete. Tire-pavement interaction has been extensively studied using finite element modelling but has not been experimentally documented due to the limitations of conventional pavement instrumentation technology. During construction cycle 7 (CC7), five flexible pavements were constructed. Four of the five test sections include 200 mm, 250 mm, 300 mm and 375mm of P401 hot mix asphalt (HMA) concrete over a P154 subbase (thickness varying between 890 and 965 mm) resting on a CBR 5.5 subgrade soil. The proposed paper describes experimental investigation of near-surface strains induced under Heavy Weight Deflectometer (HWD) and aircraft tires using an innovative instrumentation technique based on fiber optic sensors. Four “strain plates” supporting an array of 24 Fabry-Perrot fiber optic sensors were retrofitted in the HMA layers of four test sections at the Federal Aviation Administration (FAA) National Airport Pavement Test Facility (NAPTF) in Atlantic City, New Jersey. The proposed paper will describe the strain plate technology and the installation of the sensors, and results of pavement response under the HWD and aircraft wheel loads).

Accurate prediction of permanent deformation in granular materials under cyclic loading is essential for ensuring the long-term performance of flexible pavements. The Pérez-Bilodeau-Doré model is based on a mechanistic-empirical approach and allows permanent deformation to be predicted using the plastic deformation rate but requires the calibration of three parameters (β1, β2, and c1) using triaxial tests. This study establishes correlations between these parameters and granulometric indicators obtained from particle size distribution. Tests conducted on seven materials from Quebec show that c1 and β2 can be predicted with high accuracy (R2≈0.97), while β1 (normalized as Ncβ1) is more variable. The proposed correlations reduce laboratory requirements, enable preliminary evaluation of materials, and support performance-based pavement design.

Road infrastructure built over permafrost is increasingly vulnerable to climate change, with seasonal thawing causing significant degradation in mechanical performance. Variations in moisture content, active layer thickness, and freeze-thaw cycles can compromise structural integrity, especially in granular embankments without asphalt surfacing. Understanding how these environmental changes affect stress distribution and stiffness is critical for maintaining long-term road stability in northern regions. This study monitored the mechanical response of a granular road embankment along a permafrost-affected corridor during the thawing seasons of 2022 and 2024. Field instrumentation, including pressure cells and strain gauges installed in site, captured stress and deformation data under controlled truck loading at multiple speeds. Seasonal site visits were conducted in June, August, and September each year. Elastic modulus was calculated from stress-strain relationships and interpreted alongside temperature and moisture content profiles obtained during testing. The results revealed strong seasonal trends: in 2022, the modulus increased from 86.3 MPa in June to over 300 MPa in September, indicating progressive stiffening as the embankment dried. In 2024, modulus values were significantly lower across all months, suggesting deeper thaw penetration and a weaker subgrade layer. Higher stress magnitudes and pulse widths in August reflected dry, compacted conditions, while June responses showed energy dissipation in wetter, softer soils. These findings demonstrate the impact of permafrost degradation on embankment stiffness and stress transmission, emphasizing the need for improved monitoring and design adaptations in cold regions.

In cold regions, flexible pavements are vulnerable to frost-induced damage, necessitating effective insulation strategies. Foam glass aggregate (FGA) insulation layers, made from recycled glass, offer promising thermal insulation properties but are mechanically fragile and susceptible to permanent deformation under repeated loading. Manufacturers provide technical recommendations, particularly regarding load limits for installation and the dimensions of the thermal protection layer. These are considered insufficient to assist pavement designers in their work. The definition of critical criteria for permissible loads was deemed necessary to design mechanically durable structures using this alternative technology. This study investigates the critical stress conditions that FGA layers can tolerate within flexible pavement systems to ensure long-term structural integrity. Laboratory cyclic triaxial tests and full-scale accelerated pavement testing using a heavy vehicle simulator were conducted to evaluate the resilient modulus and permanent deformation behavior of FGA. The results show that FGA exhibits stress-dependent elastoplastic behavior, with resilient modulus values ranging from 70 to 200 MPa. Most samples exhibited plastic creep or incremental collapse behavior, underscoring the importance of careful stress management. A strain-hardening model was calibrated using both laboratory and full-scale data, incorporating a reliability level of 95%. This study identifies critical deviatoric stress thresholds (15–25 kPa) to maintain stable deformation behavior (Range A) under realistic confining pressures. FGA performs well as a lightweight, insulating, and draining layer, but design criteria remain to be defined for the design of multi-layer road structures adapted to local materials and traffic conditions. Establishing allowable critical stress levels would help designers mechanically validate the geometry, particularly the adequacy of the overlying layers. These findings support the development of mechanistic design criteria for FGA insulation layers, ensuring their durability and optimal performance in cold climate pavements.

This laboratory study investigates the use of softwood Kraft lignin as a bitumen additive to reduce its environmental footprint and modify bitumen's properties. However, the lignin addition in bitumen can lead to some adverse effects, such as increased viscosity. Sasobit (R) was used to remedy those effects. This study evaluates the separate and synergistic effect of varying concentrations of Kraft lignin and Sasobit on the properties of bitumen. The chemo-thermal and rheological properties of the modified bitumens were investigated using the Fourier-transform infrared spectroscopy (FTIR) technique, thermogravimetric analysis (TGA), and Brookfield rotational viscometer (BRV), dynamic shear rheometer (DSR), multiple stress creep recovery (MSCR) and bending beam rheometer (BBR) tests. FTIR spectra demonstrate that no chemical reactions occur between additives and bitumen. Adding Sasobit increases the thermal stability of lignin-modified bitumen. Sasobit mitigates lignin-modified bitumen's viscosity. The Sasobit-lignin combination enhances bitumen's rutting resistance and viscoelastic properties, but adversely affects the low-temperature performance.

A full-scale study was conducted at Universit & eacute; Laval's indoor accelerated pavement facility in order to document the mechanical behaviour of a flexible pavement structure affected by an idealised transverse crack. The constructed pavement structure was subjected to different temperature conditions and loading repetitions using the Accelerated Transportation Loading System (ATLaS). Various sensors, in particular strain gauges, were embedded at precise positions around the idealised crack. The paper presents the methodology undertaken, and a comparison of longitudinal strains measured in the reference area to measurements around the crack. The study demonstrated that a transverse crack fundamentally alters longitudinal strain and bottom-up fatigue damage patterns compared to uncracked sections, leading to accentuated bottom-up cracking at a distance from the crack.

Electric Road Systems (ERS) are pivotal in advancing Electric Vehicle (EV) technology by enabling dynamic wireless charging through integrated elements in roadway infrastructure. These systems extend EV range and reduce the need for frequent recharging, while supporting smaller batteries. In contactless ERS, inductive coils are embedded in pavement layers, leaving the road surface unaltered, unlike ground-based conductive systems. However, the long-term effects of embedded coils on the mechanical response and integrity of pavement structures, particularly under Canadian climatic and traffic conditions, remain underexplored. This study evaluates the mechanical performance of electrified road (eRoad) pavements with inductive coils, compared to traditional pavements (tRoad). Sensor-based monitoring assessed the performance of three full-scale pavement structures (two eRoad and one tRoad) built at Laval University's accelerated pavement test facility, under varying loads and environmental conditions. Results show different strain distribution in eRoad pavement, suggesting possible bonding issues between coil casing material and asphalt concrete.

This study investigates the feasibility of using Kraft lignin in Hot and Warm Mix Asphalt (HMA and WMA), with a particular focus on its integration alongside Sasobit®. The research aims to evaluate the impact of Kraft lignin and Sasobit, individually and in combination, on the construction temperatures, compactability, and physical properties of asphalt mixtures. The experimental program included a reference HMA and modified mixes with 20% Kraft lignin, 3% Sasobit, and their combinations. These mixes were designed and subjected to tests to assess their volumetric and mass properties and to determine the construction temperatures using the Superpave Gyratory Compactor (SGC). The results demonstrated that adding Kraft lignin increased construction temperatures, while Sasobit effectively reduced these temperatures by lowering binder viscosity. When used together, Sasobit offset the increase in construction temperatures caused by Kraft lignin, resulting in compaction temperatures similar to the reference HMA mix. Additionally, Kraft lignin increased air voids, leading to reduced compactability at higher gyration levels. It also exhibited indications of a dual role, functioning as both a binder replacement and a filler. In conclusion, the combination of 20% Kraft lignin with 3% Sasobit offers a promising solution for enhancing the sustainability of asphalt mixtures.

The rise in electric vehicle (EV) adoption has spurred the integration of inductive charging systems into road pavements. However, the impact of the inclusion of inductive charging coils in the pavement structure on the overall performance and structural integrity of the road needs to be characterized. This study evaluates this impact using a heavy vehicle simulator on a pavement structure built in a laboratory test pit at Laval University. The test pit comprises a control section representing the standard Québec pavement structure and two sections incorporating inductive charging coils. Various sensors such as strain gauges and load cells were used to monitor the behaviour of each pavement component during dynamic loading tests, from the surface course to the underlying soil. This paper outlines stress measurements at the top of the granular base layer in all sections exposed to different load amplitudes, positions of the load, temperatures, and two water table conditions: high and low.

Embankment dams primarily serve as structures for water containment. However, there is a growing demand for alternative usage, particularly from energy, mining, and forestry sectors. Allowing heavy vehicle transit on dam crests would improve access to the structures and the surrounding areas. Nonetheless, concerns arise regarding the safety and efficiency of embankment dams under heavy vehicle loads. There is a demand for innovative tools to facilitate decision-making processes by assessing the performance of embankment dams when subjected to heavy vehicle traffic. In the realm of unpaved road engineering, it is firmly established that the accumulation of permanent deformation under repeated loading is a key indicator of the performance of granular materials and soils. The paper aims to establish a model predicting the plastic strain rate in dam cores subjected to repeated heavy traffic, utilizing field measurements and laboratory testing of permanent deformation.

Pavement design in cold regions is challenging due to the difficult conditions of soils, humidity, and temperatures. Insulation layers have been identified as a suitable solution for these conditions. Due to their unique engineering properties, foam glass aggregates (FGAs) are a promising material for use as an insulating granular layer in pavement design. However, understanding their mechanical performance is critical for predicting long-term layer and pavement behavior. In this laboratory study, an empirical transfer function was developed using an environmental and heavy vehicle simulator and an experimental pavement built in an indoor test pit. The study aimed to determine the allowable number of load repetitions for an FGAs insulation layer and to develop an empirical transfer function that can be used as part of a mechanistic-empirical pavement design procedure. This article proposes a linear relationship between permanent deformation, the number of load cycles, and the equivalency factor between the effect of resilient strain, or vertical stress, and allowable damage. The proposed empirical transfer functions allow defining an allowable number of load repetitions for a characteristic resilient strain or vertical stress and an allowable damage. The allowable damage can be modulated with respect to road classification, and a damage value of 0% to FGAs layer can be considered as a safety factor. The findings of this study provide valuable insights into the use of FGAs as an insulating granular layer in pavement design in cold regions.

The AASHTO93 guide is widely used in pavement design and is considered the primary reference in road construction and management for many countries worldwide. One important parameter used in the AASHTO93 design method is the drainage coefficient, which considers the impact of saturation on the stiffness of granular materials. However, selecting this parameter can be associated with high uncertainty in practice. With the knowledge gained from applying this methodology and advancements in current research on granular materials, it is possible to revise this parameter to achieve optimal results. This work aims to review the basics of the drainage coefficient and introduce a more logical approach to define the proper parameter for local conditions. The goal is to enhance pavement design practices in administrations that utilize the AASHTO93 method, particularly those with no intention of transitioning to advanced techniques like the mechanistic-empirical approach or where alternative approaches are still minimal.

Accurately characterizing permanent deformation in granular materials subjected to cyclic loading is crucial for pavement design. This paper introduces an alternative approach to characterizing permanent deformation in a framework that reduces the number of load cycle repetitions by applying an alternative analytical strategy based on plastic strain rate variation over time. The methodology uses a cycle-hardening approach to establish correlations between short-term (post-compaction) and long-term (shakedown state) plastic strain accumulation. This alternative approach provides an efficient means to accelerate the characterization of permanent deformation, ensuring the integrity and validity of the assessment in a more time-efficient and resource-optimized way.

This study aims to quantify the susceptibility of granular materials used in pavements to changes in moisture content and propose a correlation model to incorporate this susceptibility into seasonal analyses. The fines content and the percentage of fractured coarse aggregates were identified as direct indicators of the resilient modulus susceptibility to changes in water content. The results showed that the percentage of fractured coarse aggregates particles (FR) has a more significant impact on the resilient modulus (Er) of crushed granular materials used in pavement construction than the combined indicator of the fines content and sample volumetrics (nf). Crushed granular materials with a higher percentage of fractured coarse aggregates are relatively insensitive to changes in the degree of saturation, but become more sensitive as the fine fraction porosity decreases. An adjusted model was proposed based on the existing formulation, but considers a complex parameter to describe and adjust the sensitivity of base granular materials to variations in moisture content with respect to fabrication characteristics, fines content and volumetric properties. The model shows that the variation of Er values is below ±10% for fully crushed granular materials. However, it reaches approximately ±12% for materials with 75% of crushed coarse aggregates and +40% and -25% for materials with FR=50%. This model could help select good aggregates characteristics and adjust grain-size distribution for environments where significant moisture content variations can occur in the pavement system, such as in the Province of Quebec (Canada). As it is based on parameters that can be easily determined or estimated, it also represents a valuable tool for detailed design and analysis that can consider material characteristics.

Aiming to address the lack of available and accurate runoff coefficients of various roads in urban flooding simulations and effectiveness assessments of permeable pavement on runoff reduction, the rainfall-runoff response characteristics of typical urban road pavements were investigated by laboratory-scaled tests. The results showed that average runoff coefficients and initial runoff times of pervious road pavements were almost 0.1 0.2 and 7 20 times those of impervious pavements, respectively. Moreover, permeable brick (PB) pavement presented better capacity for runoff mitigation than permeable asphalt concrete (PAC) pavement when the average rainfall intensity was 1.11 or 1.80 mm/min. The average runoff coefficient of cement concrete (CC) pavement ranged from 0.939 to 0.985 under all rainfall intensity and longitudinal slope combinations, while that of asphalt concrete (AC) was between 0.907 and 0.961. These results may be beneficial to improving the precision of runoff computation generated from roads or other site areas in urban flooding simulations.