Multiscale Evaluation of Open-Graded Friction Course (OGFC) Asphalt Mixture Fatigue Damage

Open-graded friction courses is a type of asphalt mixture features good drainage and rutting resistance. However, it has a poor fatigue performance. To improve its fatigue performance, modifiers including natural rock asphalt and rubber powder are added. In this paper, we conduct a material testing system fatigue test to investigate the fatigue performance of open-graded friction courses modified with rock asphalt and rubber powder under different stress ratios. According to the test result, for open-graded friction courses with the same grade, their tensile strength increases with content of rock asphalt and rubber powder added. Besides, for open-graded friction courses with the same composition, their fatigue life is inversely proportional to the stress ratio. According to the relation between the stress ratio and fatigue life, we also obtain the fatigue equations for different open-graded friction courses.

Pore clogging in porous asphalt pavement (PAP) severely limits its functional performance and widespread application. This study systematically investigates the permeability degradation and recovery characteristics of seven porous asphalt concrete (PAC) with varying air void contents (16%, 18%, 20%, 22%, and 24%) and nominal maximum particle sizes (9.5, 13.2, and 16 mm). Three clogging materials (diabase fine aggregates, clay, and their mixture) and three cleaning methods (high‐pressure water, vacuum suction, and combined methods) were applied through repeated clogging‐cleaning cycles. Key findings reveal that PAC with higher void content (24%) and larger nominal particle size (16 mm) exhibits superior anticlogging performance, while mixtures with lower void content (16%) suffer rapid permeability loss. Critical clogging particle sizes expand with increased void content and nominal particle size. Vacuum suction and its combination with high‐pressure water achieved the highest permeability recovery rates (60%–85%), outperforming high‐pressure water alone (35%–64%). Grey correlation analysis further highlights void content as the dominant factor influencing clogging resistance. This work provides practical insights for optimizing PAP design and maintenance strategies to mitigate clogging issues.

With a production of 101.4 million tonnes (MT) in 2017, India is the third largest steel producer in the world. Electric arc furnace (EAF) steel slag is the waste/by-product generated from steel-making industries that utilise electric arc furnace process of steel production. About 12 MT of steel slag is generated annually in India, but merely 20% is put to applications and the rest is indiscriminately dumped in nearby landfills. The primary objective of this study is to evaluate performance characteristics of open-graded friction course (OGFC) asphalt mixtures with varying proportions of EAF steel slag as the coarse aggregate (>2.36 mm). OGFCs are gaining popularity in the Indian highway sector owing to their superior hydraulic (high permeability), acoustic (noise-reduction) and frictional properties that contribute towards improved road safety. The level of research on the use of EAF steel slag in OGFC is still very limited, especially in developing countries like India. Ten OGFC mix designs were investigated containing five percentage substitutions of coarse natural aggregates (0%, 25%, 50%, 75% and 100%) with the EAF steel slag and two modified asphalt binders (polymer and crumb rubber modified). Static creep test, dynamic creep test, Hamburg wheel tracking test, indirect tensile stiffness modulus test, and indirect tensile fatigue test were performed to evaluate rutting and fatigue performance of steel slag-OGFC mixtures. Results of the study reveal that the EAF steel slag-OGFC mixtures showed superior performance compared to control mixtures. The steel slag-OGFC mixtures up to 75% substitution presented the best results with both binder types.

This study investigates the effectiveness of the volumetric mix design procedure used by the New Mexico Department of Transportation based only on the tensile strength ratio (TSR) test for designing open graded friction course (OGFC) materials. It also evaluates the effects of different binders (or binder grades) and aggregate gradations on the performance of OGFC materials. Nine OGFC mixes were produced using three different binders (PG 64-28+, PG 70-28+, and PG 76-22+) and three different aggregate gradations (two of 9.5 mm nominal maximum aggregate size [NMAS] and one of 12.5 mm NMAS). Next, a thorough laboratory investigation was conducted to evaluate their various performances. This study found that the traditional volumetric mix design based solely on the TSR test cannot ensure adequate durability performance. The PG 64-28+ OGFCs, for example, met all the volumetric and TSR requirements during mix design but performed poorly in all performance tests. This suggests that additional performance testing for OGFCs is required to ensure adequate longevity. Cantabro abrasion and semi-circular bending tests are found to be useful in characterizing the durability and moisture conditioning, and the fracture performances of an OGFC, respectively. Furthermore, a new test is proposed for evaluating the durability performance of an OGFC in wet conditions using the Micro-Deval device. According to this study, OGFC's durability and fracture performance improves as the grade of binder used increases. The OGFCs prepared with aggregates of smaller NMAS outperformed the OGFCs prepared with larger NMAS aggregate in both durability and fracture tests despite having similar asphalt contents.

For a fast developing economy like India, expansion, rehabilitation, and maintenance of transportation infrastructure is crucial and require huge quantities of high quality natural aggregates. Meanwhile, vast amounts of industrial wastes accumulating in the country pose problems related to safe and sustainable disposal. The present study investigated possible utilisation of marble dust, a waste from stone industry, and fly ash, a waste from thermal power stations, as filler materials in open-graded friction course mixes. Open-graded friction course mixes incorporating fly ash, marble dust, and two sources of stone dust as filler fractions were designed and evaluated for mix design properties including draindown, abrasion loss, air void content, and permeability. Morphology of each filler was characterised through scanning electron microscopy. Physicochemical properties of fillers were examined through Rigden voids, German filler test, methylene blue, and hydrometer analysis. Analysis of variance using Fisher multiple comparison procedure was performed to evaluate the effect of filler type on design properties of open-graded friction course mixes. Regression analysis using forward selection technique was performed to identify significant filler characteristics influencing open-graded friction course properties. Results showed that filler type affected open-graded friction course design parameters significantly. Open-graded friction course mixes with marble dust showed promising performance with lowest draindown, and highest durability, air voids, and permeability. Regression analysis identified Rigden void content of filler materials as a major filler characteristic affecting the mix design parameters of open-graded friction course mixes.

Microstructure characteristics of OGFC (open graded friction course) asphalt mixture are closely related to the mechanical behavior. To study the microstructure influence mechanism to mechanical behavior of OGFC asphalt mixture, the digital image processing technology is used to process the specimen’s fault images and obtain the microstructure parameters of the OGFC asphalt mixture with different gradation. At the same time, the microstructure influence on mechanical behavior of OGFC asphalt mixture is explored by using the Grey correlation theory based on the experimental results of mechanical performance and the microstructure parameters. The influence of four key sieve passing percentage (1.18, 2.36, 4.75, and 9.5 mm) on the microstructure was discussed by using the Grey correlation theory, and the influence mechanism to mechanical behavior of OGFC asphalt mixture was further revealed. The results show that with the increase of air void content, the total void area, the equivalent pore diameter, and the number of big voids (here, “big” means voids with an area greater than 10 mm2) increase, the length of void and corresponding void area increase synchronously, the drainage performance is enhanced, and the mechanical performance is decreased. With the increase of nominal maximum particle size, the average area of single void, the percentage of number of big voids, and the equivalent diameter increase, and the drainage performance, anti-skidding performance, and mechanical performance of pavement are enhanced. It is considered that the key sieve passing percentage affects the mechanical behavior by influencing the microstructure of asphalt mixtures. The influence degree of microstructure parameters on mechanical behavior and the influence degree of the key sieve passing percentage on microstructure parameters were obtained. The research results have a certain reference value for the optimization of mechanical behavior of OGFC asphalt mixture.

Functionality of an open graded friction course (OGFC) depends on the high interconnected air voids or pores of the OGFC mixture. The authors' previous study indicated that the pores in the OGFC mixture were easily clogged by rutting deformation. Such a deformation-related clogging can cause a significant rutting-induced permeability loss in the OGFC mixture. The objective of this study was to control and reduce the rutting-induced permeability loss of the OGFC based on mixture design and layer thickness. Eight types of the OGFC mixtures with different air void contents, gradations, and nominal maximum aggregate sizes were fabricated in the laboratory. Wheel-tracking rutting tests were conducted on the OGFC slabs to simulate the deformation-related clogging. Permeability tests after different wheel load applications were performed on the rutted OGFC slabs using a falling head permeameter developed in the authors' previous study. The relationships between permeability loss and rutting depth as well as dynamic stability were developed based on the eight OGFC mixtures' test results. The thickness effects of the single-layer and the two-layer OGFC slabs were also discussed in terms of deformation-related clogging and the rutting-induced permeability loss. Results showed that the permeability coefficient decreases linearly with an increasing rutting depth of the OGFC mixtures. Rutting depth was recommended as a design index to control permeability loss of the OGFC mixture rather than the dynamic stability. Permeability loss due to deformation-related clogging can be effectively reduced by using a thicker single-layer OGFC or two-layer OGFC.

This study aims at (1) enhancing Open Graded Friction Course (OGFC) mixes durability using additives and other by-products; (2) investigating the impacts of selected factors on OGFC pavements seepage characteristics; (3) developing a quantitative tool to model the deterioration in OGFC pavements functional performance; and (4) developing new guidelines of Air Void (AV) content for OGFC for optimum functionality and durability. For the durability objective, eight mixes were prepared with a PG 76-22 binder and two sources of aggregate (i.e., # 78 limestone and # 67 sandstone). Three Warm Mix Additives (WMA), one by-product (i.e., crumb rubber [CR]), and two fillers (i.e., F1 and F2) were evaluated. Results concluded that OGFC durability can be enhanced using WMA, CR, and fillers.\nFor the second and third objectives, a 3-D Finite Element (FE) model was developed and calibrated based on field measurements. The transient analyses were used to evaluate the impacts of OGFC layer thickness, OGFC permeability, underlying layer permeability, rain intensity, and traffic volume on the seepage characteristics of OGFC. The impacts of these factors were evaluated by calculating the time at which a critical location on OGFC surface reaches overflow condition (TC). The statistical analysis showed that all these factors had a significant impact on the seepage characteristics of OGFC, except OGFC permeability.\nFurthermore, an Artificial Neural Network (ANN) model was developed for the prediction of TC without the need for FE modeling. Results indicated that the ANN model predicted TC accurately with R2 of 99 % and 98% in the training and validation stages, respectively. Moreover, this model accurately predicted the deterioration rate of OGFC functionality over time when compared to the results of the FE model. Therefore, this model can be used to determine the time at which routine maintenance should be applied for OGFC pavements. Lastly, simulation runs were conducted using the developed FE model under different AV content conditions ranging from (10 to 24 %) under varying rain intensity conditions. Results revealed that an OGFC layer with an AV content of 16% would provide adequate drainage performance of rainwater while minimizing OGFC durability issues.

In a practical scenario, it is very common that an open graded friction course (OGFC) layer is subjected to repeated traffic loadings during the rains. Even after the rain, water can be clogged inside the voids. This entrapped water can accelerate OGFC layer’s overall abrasion damage under wheel loads by causing moisture damage to the material. This study employed the Micro-Deval (MD) test to evaluate the durability performance of an OGFC material in wet conditions. It is found that the MD test is effective in measuring the durability performance of an OGFC with satisfactory repeatability. While comparing the effects of binder grade on the OGFC’s performance, it is observed that the OGFC made with a lower PG grade performs poorly than the OGFCs made with higher PG grades. While evaluating the effect of aggregate gradation on the OGFC’s performance, it is found that the OGFC made with a larger aggregate has more damage than the OGFC made with a smaller aggregate. This study found that the MD test is more effective in ranking OGFC materials based on their durability performance than the traditional Cantabro abrasion (CA) test. The correlation between MD and CA test results is also found to be poor because of the differences in loading and test conditions. As the loading and test conditions in the MD test are more field representative, this study recommends the MD test for evaluating the durability performance of OGFC materials in wet conditions.

Self-healing asphalt, which is designed to achieve autonomic damage repair in asphalt pavement, offers a great life-extension prospect and therefore not only reduces pavement maintenance costs but also saves energy and reduces CO2 emissions. The combined asphalt self-healing system, incorporating both encapsulated rejuvenator and induction heating, can heal cracks with melted binder and aged binder rejuvenation, and the synergistic effect of the two technologies shows significant advantages in healing efficiency over the single self-healing method. This study explores the fatigue life extension prospect of the combined healing system in porous asphalt. To this aim, porous asphalt (PA) test specimens with various healing systems were prepared, including: (i) the capsule healing system, (ii) the induction healing system, (iii) the combined healing system and (iv) a reference system (without extrinsic healing). The fatigue properties of the PA samples were characterized by an indirect tensile fatigue test and a four-point bending fatigue test. Additionally, a 24-h rest period was designed to activate the built-in self-healing system(s) in the PA. Finally, a damaging and healing programme was employed to evaluate the fatigue damage healing efficiency of these systems. The results indicate that all these self-healing systems can extend the fatigue life of porous asphalt, while in the combined healing system, the gradual healing effect of the released rejuvenator from the capsules may contribute to a better induction healing effect in the damaging and healing cycles.

To improve drainage properties and increase driver’s safety in wet weather, epoxy modified Open Graded Friction Course (OGFC) by post-doping methods was proposed. The predominant focus of this paper evaluated the performances of epoxy modified Open Graded Friction Course (OGFC) such as rutting resistance at high-temperature, crack resistance at low temperature, friction, moisture resistance and coefficient of permeability. For comparison, the same NMAS Open friction course with epoxy asphalt which was supplied courtesy of ChemCo Systems Ltd and SK High-Viscosity Asphalt were cited. In addition, the harsh construction requirements and application limitations caused by the residence time of epoxy asphalt were solved by the post-mixing process which was produced by two steps, First step, component B of epoxy asphalt was produced in the backyard plant, then suitable amount of component A was added and mixed evenly while paving in site, affecting the holding time only in the two links of paving and rolling, and the time was easy to control. The results show that epoxy modified Open graded friction Course reinforced with Basalt fiber produced by post-mixing methods has good friction resistance and permeability while retaining satisfactory performance and mechanical properties.

Laboratory evaluation on performance of porous polyurethane mixtures and OGFC

The permeable pavement seems to be an established stormwater management solution that may be utilized in parking and low-traffic areas. These pavements can reduce the amount of runoff that reduces the environmental impact compared with a traditional drainage system. Traditional drainage systems, which carry stormwater runoff quickly to a stream by piped systems, cause increases in runoff volume, peak flow, and pollutants are taken to rivers. This paper tests permeable asphalt pavement in a purpose-designed laboratory apparatus. To understand the hydraulic flow conditions and the runoff performance that occurred within two layers of permeable and conventional pavement. The thickness of the permeable layer is 25, 37.5, and 50 mm, and the conventional layer is 80mm. An artificial rainfall covering an area of 1.5 ×1.0 m2 is constructed to study the relationship between surface runoff and subsurface runoff from a permeable pavement under different geometric design parameters of a roadway. Five slopes set at 0.0, 2.5, 5.0, 7.5 and 10 % in a short direction, and four discharge as 20, 40,60 and 80 L/min are tested. The result demonstrated that 50 mm thickness is suitable for permeable asphalt pavement under the most slope, increasing subsurface runoff and decreasing surface runoff water.

Open-graded friction course (OGFC) is applied to pavement surfaces to increase driving safety under wet conditions, and recently, to reduce tire/pavement noise. The durability of OGFC, however, has been a concern since conventional OGFC mixes last typically less than ten years before major maintenance or rehabilitation is needed. This work investigates a new open-graded asphalt mixture that uses epoxy asphalt as binder to improve mix durability. One type of epoxy asphalt that has been successfully applied to dense-graded asphalt concrete for bridge deck paving was selected. A procedure of compacting the mix into slab specimens was developed and a series of laboratory tests were conducted to evaluate the performance of the new mix, including Cantabro loss, permeability, friction, shear strength, and wheel rutting tests. Results show superior overall performance of the open-graded epoxy asphalt mix compared to conventional open-graded asphalt mix. There are also preliminary indications that the OGFC mix with 4.75-mm NMAS gradation can improve the resistance performance to raveling, while the OGFC mix with 9.5-mm NMAS gradation can improve the performance of surface friction at a high slip speed.

Self-healing properties of ferrite-filled open-graded friction course (OGFC) asphalt mixture after moisture damage