Search Results (54)

High-friction surface treatments (HFSTs) are widely applied to improve pavement safety by enhancing long-term skid resistance. Although epoxy resins are commonly used due to their strength and durability, their high cost, susceptibility to delamination, incompatibility with substrates of flexible pavements, and adverse environmental concerns limit their long-term performance. This study presents crumb rubber modified (CRM) asphalt as a sustainable alternative binder for HFST applications. CRM binders offer high performance and compatibility with existing pavement surfaces, cost effectiveness and reduced environmental impacts as compared to epoxy binders. In addition, the binder development utilizes enhanced recycling technologies for interacting with used tire rubber with asphalt. The evaluated CRM binders were prepared under varying interaction temperatures, crumb rubber contents, and types. The developed binders were evaluated for friction performance with two aggregate sources, calcined bauxite (CB) and rhyolite (Rhy). Binder characterization included rheological testing conducted through both frequency sweep and temperature sweep procedures. HFST mixes were evaluated using the British Pendulum Test (BPT), the Dynamic Friction Tester (DFT), and the Circular Track Meter (CTM) in collaboration with the Three-Wheel Polishing Device (TWPD) to simulate the traffic-induced polishing effect. The results showed that CRM content influenced binder performance under polishing. CRM asphalt-based HFST with a relatively high CRM content (15%) maintained a greater coefficient of friction (COF) and exhibited polishing resistance, showing low reduction in the COF after the total number of polishing cycles. In contrast, mean profile depth (MPD) analysis revealed that the most macrotexture efficiency was found in binders with a lower CRM content (10%) after completing the total number of polishing cycles. Analysis of Variance (ANOVA) showed a significant effect of the interaction conditions and rheological properties of CRM binders on the British pendulum number (BPN) loss due to the polishing process. As expected, aggregate source further influenced the resistance to polishing; CB outperformed Rhy with significantly lower aggregate loss under polishing. Overall, the results confirmed that CRM asphalt binders can effectively serve as a sustainable, flexible, and cost-effective alternative binder in HFST. Full article

Pavement texture is a crucial factor influencing both skid resistance and durability. This study aims to investigate the impact of texture reconstruction on pavement performance, which holds significant scientific value for enhancing road safety and durability. The research focuses on the reconstruction of airport cement pavement textures through the design of seven solid–liquid, two-component coating formulations, comprising three types of coatings: emulsion coating (P), waterborne epoxy coating (E), and water-based coating (W). Laser texture scanning technology was employed to identify the texture characteristics, which, combined with the British pendulum test, enabled a comprehensive analysis of skid resistance. Additionally, the coating–concrete interfacial strength and frost resistance were evaluated through pull-out tests, flexural strength tests, and freeze–thaw cycle tests. The results demonstrated that, compared to uncoated concrete, the mean profile depth (MPD) of the P, E, and W coatings increased by 43.4%, 34.7%, and 21.6%, respectively. Furthermore, the peak band of the slope spectrum density (SSD) shifted from a range greater than 1 mm to approximately 0.5 mm following coating application. The British pendulum number (BPN) increased by 25%, 20%, and 15% for the P, E and W coatings, demonstrating a strong correlation with MPD (R² = 0.95). These results indicate that the coated surface texture exhibits superior properties, which explain the enhanced slip resistance from a textural perspective. Moreover, the interfacial strength between the coating and concrete initially increased and then decreased with increasing coating thickness. In comparison, the interfacial bonding strength of the E coating was significantly higher than that of the P and W coatings. Furthermore, compared to the P and W coatings, the flexural bond strength of the E coating increased by 7% and 74%, respectively. After undergoing the freeze–thaw cycle, the E coating exhibited the best freeze resistance, while the W coating exhibited the poorest performance. In summary, the P coating excelled in texture reconstruction, while the E coating provided superior bonding and freeze resistance. This paper presents a novel approach to the development of coating materials for use on airport pavements. Full article

Asphalt pavements are widely used in airports due to their excellent skid resistance, vibration damping, and ease of construction. However, traditional fog seal materials often suffer from insufficient adhesion between fine sand and the emulsified asphalt binder, resulting in limited durability of the maintenance effect. This study aims to optimize the design of traditional fog seal materials and systematically evaluate their surface and durability performance. Firstly, a composite modified emulsified asphalt was prepared as the sand suspension slurry for the sand-containing fog seal. Through the dry wheel abrasion test, the optimal fine aggregates content was determined for four different spraying amounts (0.8, 0.9, 1.0, and 1.1 kg/m²). When the proportion of fine aggregates increases, the spraying amount needs to be increased accordingly to ensure the wrapping effect. Subsequently, pavement performance evaluation was conducted based on several indicators, including surface curing time, British Pendulum Number (BPN) friction coefficient, permeability coefficient, and mass loss rate. The results showed that the designed sand-containing fog seal significantly reduced surface curing time and exhibited superior skid resistance and permeability property compared to styrene-butadiene rubber (SBR)-modified emulsified asphalt. After freeze–thaw cycles, the maximum decrease in friction coefficient was 10.2%, and the mass loss rate after abrasion was approximately 67%, which were lower than those of SBR-modified emulsified asphalt (22.2% and 81%, respectively). Finally, considering the comprehensive performance comparison and evaluation, the optimal mix proportion was determined as 1.0 kg/m² spraying amount with 30% fine aggregates content. The findings of this study provide practical support for improving the durability and service life of airport asphalt pavements. Full article

Pavement surface texture significantly affects its skid resistance. To characterize pavement surface texture and analyze its correlation with skid resistance, this paper proposes a novel three-dimensional (3D) texture evaluation index: mean texture surface area density (MTSAD). First, field tests were conducted on Chengdu Greenway pavement using a portable laser scanner to collect high-precision texture data, while a pendulum friction tester was employed to measure the British Pendulum Number (BPN). Subsequently, digital image processing technology was employed for the 3D reconstruction of pavement texture. Leveraging the high-resolution data characteristics and incorporating the concept of infinite subdivision, an innovative method for calculating the pavement texture surface area was developed, ultimately yielding the MTSAD. Finally, polynomial regression analysis was performed to examine the correlation between MTSAD and BPN, revealing a coefficient of determination (R²) of 0.8302. The results demonstrate a close relationship between MTSAD and pavement friction, while proving that texture indices that are easy to promote can be obtained through high-precision 3D point cloud images, and validating the potential of non-contact texture measurement as a viable alternative to conventional contact-based friction testing methods. Full article

In this study, the feasibility of using three-dimensional (3D) printing technology to investigate the impact of macrotexture and microtexture on the skid resistance of asphalt pavement was verified. The macrotexture characteristics of the five types of real asphalt mixtures were captured, reconstructed, and printed. The comparison analysis of the skid resistance between the pavement and printed specimens was conducted, and the correlations and contribution proportions of the macrotexture and microtexture on skid resistance were also calculated. Results show that five printed asphalt mixtures present good consistency in the microtexture with a roughness of about 100 nm. The impact of thin water film on the skid resistance is insignificant for real asphalt mixtures, while it is significant for printed mixtures. The printed specimens under dry conditions show a similar British pendulum number (BPN) with the real pavement specimens under wet conditions, while the BPN under wet conditions for printed specimens are much smaller than the real ones but follows a similar variation trend. Mean profile depth (MPD) values of four printed asphalt concrete (AC) mixtures are well linearly correlated with their BPN under dry and wet conditions, especially for wet conditions with the R² of 0.91. The contribution proportion of macrotexture to the skid resistance is nearly 90% for the dry condition and about 50% for the wet condition. Full article

To prevent traffic accidents caused by icy roads in winter and damage to roads resulting from repeated freeze–thaw cycles, this paper proposes an optimized design plan for slow-release anti-icing fog seal. The effects of the dosages of slow-release anti-icing agent, water-based epoxy resin modifier, and penetrant on the ice- and snow-melting properties, mechanical properties, and penetration properties of the fog seal were investigated. Based on single-factor experiments, a Box–Behnken model was established, and the response surface method was employed to optimize the design of the fog seal. Subsequently, wear resistance was assessed using an accelerated loading test, while anti-skid performance was evaluated through the British pendulum test and the sand patch test. The results indicate that the optimal ratio for the slow-release anti-icing fog seal is 13% slow-release anti-icing agent, 20% water-based epoxy resin modifier, and 12% penetrant. This material demonstrated excellent ice- and snow-melting performance as well as good wear and skid resistance in testing, providing valuable insights for the application of the slow-release anti-icing agent in new pavement maintenance techniques. Full article

Asphalt pavement skid resistance, governed by surface texture, is critical for traffic safety. Most research has focused on full-depth textural characteristics, often overlooking the depth of tire–pavement contact under real traffic conditions. This study introduces the concept of the Effective Depth of Skid Resistance (EDSR) to describe the effective depth of tire–asphalt contact, improving skid resistance assessment accuracy. Using blue linear laser scanning, surface textures of three common asphalt pavements with wearing courses—AC-13, AC-16, and SMA-13—were analyzed, and friction coefficients were measured using a British pendulum. After pre-processing three-dimensional texture data, fractal dimensions at various depths were calculated using the box-counting method and correlated with the friction coefficients. Previous studies show an insignificant correlation between full-depth asphalt pavement textures and skid resistance. However, this study found a significant positive correlation between skid resistance and pavement textures at specific depths or the EDSR. A depth with a correlation exceeding 0.9 was defined as the EDSR. Linear formulas were established for each pavement type within these EDSR ranges. A theoretical model was developed for predicting skid resistance, showing an over 80% accuracy against real-world data, indicating its potential for improving road surface performance detection. Full article

With the updates and differences in the usage of reclaimed asphalt pavement (RAP) separation technology, the production of fine-particle RAP exceeds their usage, resulting in an excess of fine-particle RAP. How to apply this excess RAP on a large scale in micro-surfacing technology has become a challenge. This study aims to investigate the advantages and disadvantages of incorporating RAP into micro-surfacing. To this end, a mix design process for RAP-containing micro-surfacing, based on the current gradation design procedure and existing research findings, is proposed. The study examines the influence of six different RAP contents, as well as the effects of SBR emulsified asphalt, added water, and RAP on the micro-surfacing mix design. Subsequently, the effects of RAP content on the pavement performance of micro-surfacing are evaluated through rutting deformation rate, wet wheel abrasion, and British pendulum tests. Finally, an economic analysis from a construction perspective is conducted. The results indicate that the optimized mix design process meets specific usage requirements and is effective for RAP-containing micro-surfacing. The mix design results show that the addition of RAP reduces the asphalt demand and mixing time of slurry mixtures. Increasing the amount of added water can meet mixing requirements, but it leads to a reduction in early strength. As the RAP content increases, skid resistance improves, with a maximum increase of 14.9%; the rutting deformation rate increases, and this is the main factor limiting the RAP content, restricting it to no more than 40%; water damage resistance shows an initial increase followed by a decrease, but this does not affect the RAP content. Therefore, the maximum RAP content is limited to 40% without the addition of other additives, mainly due to the phenomenon of weak agglomeration in RAP. Finally, cost calculations show that incorporating 40% RAP can save approximately 17% of the construction costs. Full article

High Friction Surface Treatments (HFSTs) are recognized for enhancing friction between tires and road surfaces, with reduced road accidents being a key benefit. Epoxy-based HFSTs, though widely used, come with challenges like compatibility issues with existing pavements, higher installation and removal costs, and reduced durability tied to substrate quality. Recently, state agencies have increasingly focused on developing asphalt-based alternative binders for HFST applications as highlighted in the National Cooperative Highway Research Program (NCHRP) RFP #NCHRP 10-145. This study introduces asphalt-based HFSTs as an alternative to traditional epoxy-based treatments. Various aggregate types were examined for friction performance and the effect of polishing cycles on asphalt-based HFST. Tests such as the British Pendulum Test (BPT), Dynamic Friction Tester (DFT), and Circular Track Meter (CTM) were conducted to assess the Coefficient of Friction (COF) and Mean Profile Depth (MPD) before and after polishing cycles. Additionally, a Life Cycle Cost Analysis (LCCA) was performed to determine the economic advantages of asphalt-based HFSTs over epoxy treatments. The goal was to develop a method to convert diverse project and material data into comparable outputs like net present value (NPV), enabling comparisons between alternatives. Results from the LCCA demonstrated that the use of specific asphalt-based binders combined with optimized aggregate gradation not only achieves performance levels comparable to traditional HFST options but also improves cost efficiency. Full article

High Friction Surface Treatments (HFST) are recognized for their effectiveness in enhancing skid resistance and reducing road accidents. While Epoxy-based HFSTs are widely applied, they present limitations such as compatibility issues with existing pavements, high installation and removal costs, and durability concerns tied to substrate quality. As an alternative to traditional Epoxy-based HFSTs, this study investigated the effects of aggregate gradation as designated by agencies on the performance of asphalt-based HFST. Various aggregate types were assessed to evaluate friction performance and the impact of polishing cycles on non-Epoxy HFST. It was found that adjustments in aggregate size and gradation may be necessary when transitioning to asphalt-based HFSTs, given the different nature of asphalt as more temperature susceptible compared to Epoxy. Various asphalt binder grades were considered in this study. A series of tests, including the British Pendulum Test (BPT), Dynamic Friction Tester (DFT), Circular Track Meter (CTM), Micro-Deval (MD), and Aggregate Imaging Measurement System (AIMS), were conducted to measure Coefficient of Friction (COF), Mean Profile Depth (MPD), texture, and angularity before and after polishing cycles. The results showed that the COF in asphalt-based slabs decreased more significantly than in Epoxy-based slabs as polishing cycles increased for HFST and medium gradations. However, in coarse gradation, the COF of slabs using asphalt-based binder matched or even surpassed that of Epoxy after polishing. Notably, the PG88-16 binder for Calcined Bauxite (CB) had the smallest reduction in COF after 140K polishing cycles, with only a 19% decrease compared to a 23% reduction for Epoxy. Full article

Pavement (or road) markings play an important role in road safety, influencing the dynamics of road users through their skid resistance properties. This study provides a comprehensive synthesis and analysis of international perspectives on the skid resistance of pavement markings and their requirements. It examines marking skid test results across various regions, including North America, Europe, and other parts of the world, and emphasizes the impact of different materials and test environments on skid resistance. The study also reviews current skid resistance standards and guidelines, from North American state-level standards to European and global specifications. Furthermore, it discusses the safety implications of these standards for diverse road users, especially motorcyclists, cyclists, and pedestrians. In conclusion, this paper highlights the importance of further innovation and consistency in skid resistance testing and standards to improve road safety. Full article

This study reports a new and simple method for applying and dispersing carbon nanotubes (CNTs) in polymers, without prior chemical treatment or functionalization. The process is innovative, fast, and carried out at room temperature, without the need for specialized labor, just using the cavitation energy of ultrasonic bath to enhance properties such as impermeability and high electrical conductivity. The time of the dispersion process is 30 min and diverse concentrations of carbon nanotubes (0.1%, 0.5%, and 2%) in the total road marking paint mass were employed. This study also demonstrates the effect of the nanostructured paint applied to roadways, based on the macro texture (sand test) and in the microstructure pattern obtained (British Pendulum Tester). In addition, this study demonstrates that achieving an effective dispersion of CNTs in road marking paints produces a conductive and thermally stable paint, which also serves as a promising waterproof layer, expanding its applications in road maintenance, for example. The results from the sample with a 2% CNT content revealed enhancements in polymer conductivity in contrast to the reference, coupled with increases of up to 20% in impermeability to water and glycerin. No alteration in wettability is noted in automotive oil upon the introduction of CNTs, implying that nanostructured road paints could augment safety, traffic flow efficiency, and the environmental sustainability of future transport systems. Full article

Runway surface friction is critically important to safe aircraft operations and mostly depends on the surface texture, which provides grip in the presence of contamination and directly affects the friction coefficient in general. Microtexture assessment is the most challenging part of texture assessment since there is no standardised pavement microtexture control method in runway maintenance and management practice. The purpose of this study was to develop a simple laser profilometer and analysis model and subsequent validation for use in runway friction surveys. To that end, a simple laser profilometer was developed, and a profile picture analysis and macrotexture filtration method were designed. Test results were compared to the stylus-based roughness tester and the British Pendulum Tester. The proposed profile picture analysis and profile smothering and filtration methodology, based on linear approximation, is simpler and more effective for the case of macrotexture filtration for the friction survey. The laser profilometer model results were highly correlated with the stylus-based roughness tester results (R² = 0.99). The average roughness of the microtexture profile, after smothering and macrotexture filtration, also showed good correlation with the British Pendulum results (R² = 0.78). The results from this study confirm the possibility of texture assessment for routine runway friction surveys using a simple and economical laser profilometer, which is not routinely available in current airport surface friction management. Full article

The waterborne epoxy resin (WER) colored antiskid thin layer has been widely used in asphalt pavement to improve driving safety. The tectonic depth determines the antiskid performance of aparticle antiskid type thin layer. The spalling of aggregate from a thin layer may reduce the tectonic depth, thus damaging antiskid performance. The spreading process of aggregate on the WER binder surface plays an important role in the spalling behavior of the thin layer. Herein, the influence of spreading processes on the ceramic aggregate spalling behavior on the WER thin layer was investigated based on laboratory experiments. The abrasion and British Pendulum Number (BPN) tests were employed to evaluate the antispalling and antiskid properties of the WER thin layers with different amounts of WER mortar, coverage rates of first-spread aggregate, and spreading orders of coarse/fine aggregates. Moreover, the tectonic depths of the layers before/after the spalling test were also investigated. The results indicated that the optimal dosage of WER mortar is 2.8 kg/m². The WER thin layer exhibited better anti-striping property when coarse ceramic aggregate was spread first. The first-spread coverage rate of the aggregate on the WER surface is 70%. The thin layer exhibited a superior antispalling performance according to the resulting scheme, with a spalling rate of 3.77%. The tectonic depth only decreased from 1.87 to 1.80 mm after the spalling test. Full article

Pavement skid resistance is significant for driving safety. British Pendulum Number (BPN) is commonly used as a low-speed skid resistance indicator, whereas sometimes it is impractical for data collection on roads in service. Since skid resistance is greatly affected by pavement surface texture, this research aims to evaluate pavement surface texture comprehensively and estimate the low-speed friction BPN from road surface texture on macro- and micro- scale. Asphalt Concrete (AC) and Stone Mastic Asphalt (SMA) were included. Road surface texture was evaluated from four aspects, texture depth, amplitude-related Root Means Square (RMS), elevation variances corresponding to different wavebands and texture spectral analysis. Texture depth indicators include Mean Texture Depth (MTD) and Mean Profile Depth (MPD). Elevation variances with three wavebands, from 5 mm to 50 mm, from 0.5 mm to 5 mm and from 0.024 mm to 0.5 mm respectively, were obtained. The results show that MPD is well correlated with MTD. Elevation variances with different wavebands demonstrates that the elevation variance of macro-texture with long wavelengths from 5 mm to 50 mm dominates the total variance. Spectral analysis shows that texture level is larger when the wavelength is beyond 4 mm, which is consistent with elevation variances. A linear regression between BPN and single texture index, as well as multiple linear regression analysis were conducted. The former regression result indicates that it is not feasible to estimate BPN using single index due to low correlation coefficient R². The latter shows that the BPN can be estimated from texture levels corresponding to 64 mm and 2 mm, and the micro-texture. The R² can be up to 0.684. This research will contribute to fast acquisition of BPN from pavement surface texture, thus improving skid resistance. Full article