Surface Macrotexture Research Articles

Characteristics of Open-Graded Friction Course Macrotexture and Macrostructure and Its Effect on Skid Resistance under Rainfall.

An Open-Graded Friction Course (OGFC) presents a rough surface and a porous structure and provides skid resistance under wet conditions, differing from that of a dense graded mixture. This study explored the distribution of surface macrotexture with depth in OGFC. Using cross-sectional images and semantic image segmentation techniques, the internal structure, porosity, and void size distribution were analyzed to assess the effectiveness of rainfall drainage. Skid resistance was evaluated with a British Pendulum Tester, focusing on the influence of surface macrotexture and internal macrostructure, particularly with regard to contact depth. Results show that finer gradations increase surface roughness peaks, which are concentrated near the top surface. In contrast, coarser mixtures exhibit a greater effective contact depth and more peaks with higher curvature. Finer gradations also result in lower porosity, greater void dispersion, and smaller average void diameters. During heavy rainfall, OGFC-13 exhibits the highest friction coefficient due to its effective contact, surface roughness, and internal voids, which facilitate water expulsion. This research provides insights into the skid resistance mechanism of OGFC in wet conditions and offers practical guidance for selecting the optimal gradation.

One-year results of the first road surface with the addition of sunflower oil porous capsules

This paper presents findings from the first surface course in the UK employing sunflower oil-filled porous capsules as a self-healing additive. The capsules, designed to mitigate ravelling, were tested on a road constructed at an asphalt plant and subjected to a year of traffic in temperatures ranging from below 0°C to 35°C. Spherical in shape with a diameter of about 1.5 mm, the capsules possess a porous structure filled with sunflower oil. Each tonne of asphalt contained 5 kgs of capsules. The material used was Stone Mastic Asphalt (SMA), one of the UK's most utilised surface course materials. Eight sections were built, with four varying binder contents (6.4 %, 5.9 %, 5.5 % and 5.2 %), each with and without capsules. The road performance was evaluated by measuring two indicators: rut depth and surface macrotexture. Results show that the capsules delay fretting progression in wearing courses. Fretting could have resulted from the complex interaction between early life wearing and asphalt compaction by traffic that caused the mastic to move to the road surface. In addition, no considerable difference in rutting was observed between the different materials. Moreover, core samples were extracted from the road before and after traffic and age exposure for further laboratory analysis to assess the long-term performance. Results showed that stone loss resistance in asphalt-containing capsules was 30.02 % lower before ageing and 25.92 % lower after ageing. Furthermore, the stiffness ageing factor was 15–20 % lower in materials with capsules, while the fatigue life remained consistent across all materials.

Development of Macrotexture Test Method for Dense-Graded Asphalt Mixtures

The design and construction of pavements necessitate careful consideration of longevity, cost-effectiveness, sustainability, and safety, with a focus on enhancing the durability and lifespan of dense-graded asphalt (DGA) surface mixtures. This paper discusses a research project the Federal Highway Administration (FHWA) initiated to assess the macrotexture characteristics of DGA mixture pavement—particularly concerning safety at higher speeds. The project aims to develop an efficient testing procedure for measuring macrotexture during mixture design and field-testing processes, striking a balance between longevity, cost-effectiveness, sustainability, and safety in pavement design and construction. The study began with a comprehensive review of existing practices, leading to the selection and testing of a unique laser texture scanner capable of noncontact macrotexture measurement. The subsequent phase involved validating the suggested macrotexture measurement system through data collected from State-sponsored projects under the FHWA Mobile Asphalt Technology Center program. Macrotexture measurements were collected from field cores and laboratory-compacted specimens from various State departments of transportation projects and analyzed. Preliminary analysis of the limited dataset to date revealed a positive correlation between average macrotexture measurements from gyratory specimens’ top surface and field core macrotexture measurements. The FHWA developed a draft test method for measuring macrotexture on laboratory specimens and field cores, thereby aiming to reduce procedural variability. Interlaboratory macrotexture test results demonstrated good reproducibility, with an average coefficient of variation of approximately 20%. Overall, this research project seeks to advance the understanding and measurement of macrotexture in DGA mixture pavements and thereby contribute to the development of safe pavements.

Measuring the Macrotexture of Pavement Surface Using an Image Processing Technique

The objective of this study was to propose an image processing-based index for measuring pavement macrotexture at the network level. This index enables macrotexture to be measured easily and inexpensively using images collected at traffic speed. The study involved collecting pavement surface images at a constant traffic speed on a test section specifically designed and constructed for this purpose, with three surface course mixes that are commonly used in India, namely, bituminous concrete, stone matrix asphalt, and gap-graded rubberized bituminous mix. Additionally, macrotexture data with regard to mean texture depth (MTD) from the sand patch test and mean profile depth (MPD) from laser sensor-based measurements were obtained at the locations where the images were captured. The surface macrotexture index (SMI), which was derived from wavelet transform-based image texture analysis, was compared with the MTD and MPD data. The results showed that the SMI is an accurate indicator of pavement surface macrotexture. In addition, the study showcased the application of an unsupervised machine learning algorithm to identify and replace outliers in the SMI data that resulted from isolated spots with dirt, pavement markings, and wet surfaces. The research also established relationships between the proposed SMI and MTD/MPD. These relationships are reliable and can be used to predict the commonly used pavement surface construction quality measure MTD and the network-level skid resistance indicator MPD.

Enhancing Quality Control of Chip Seal Construction through Machine Learning-Based Analysis of Surface Macrotexture Metrics

Efforts to enhance quality control (QC) practices in chip seal construction have predominantly relied on single surface friction metrics such as mean profile depth (MPD) or friction number. These metrics assess chip seal quality by targeting issues such as aggregate loss or excessive bleeding, which may yield low friction numbers or texture depths. However, aggregate loss, particularly due to snowplow operations, does not always result in slippery conditions and may lead to uneven surfaces. The correlation between higher MPD or friction number and superior chip seal quality is not straightforward. This research introduces an innovative machine learning-based approach to enhance chip seal QC. Using a hybrid DBSCAN-Isolation Forest model, anomaly detection was conducted on a dataset comprising 183,794 20 m MPD measurements from actual chip seal projects across six districts in Indiana. This resulted in typical 20 m segment MPD ranges of [0.9 mm, 1.9 mm], [0.6 mm, 2.1 mm], [0.3 mm, 1.3 mm], [1.0 mm, 1.7 mm], [0.6 mm, 1.9 mm], and [1.0 mm, 2.3 mm] for the respective six districts in Indiana. A two-step QC procedure tailored for chip seal evaluation was proposed. The first step calculated outlier percentages across 1-mile segments, with an established limit of 25% outlier segments per wheel track. The second step assessed unqualified rates across projects, setting a threshold of 50% for unqualified 1-mile wheel track segments. Through validation analysis of four chip seal projects, both field inspection and friction measurements closely aligned with the proposed methodology’s results. The methodology presented establishes a foundational QC standard for chip seal projects, enhancing both acceptance efficiency and safety by using a quantitative method and minimizing the extended presence of practitioners on roadways.

Image-based indices of aggregates for predicting the initial skid resistance of bituminous pavements

The objective of this study is to propose image-based indicators of microtexture and macrotexture for pavement surfaces that can predict the initial skid resistance. To achieve this objective, images of different types of aggregates that were collected from quarries were processed. Based on the outcome of the image processing, suitable indicators of shape, angularity, and surface texture of coarse aggregates were proposed. Skid resistance data were collected from pavements constructed with the aggregates used in the image processing, as well as with different surface course mixes commonly used in India, such as Bituminous Concrete (BC), Stone Matrix Asphalt (SMA), and Gap-Graded Rubberized Bituminous mix (GGRB).Through a detailed investigation of the image processing outcome and field data, this study introduces the Aggregate Surface Texture Index (STI) as a means of quantifying microtexture, which can be obtained by processing images of the aggregate using wavelet decomposition technique. Additionally, the study proposes Shape Index (SI) and Angularity Index (AI) as indicators for macrotexture, which can be obtained from the processing of digital images of aggregates. For determining the skid resistance of newly constructed pavements, the study suggests using the Surface Macrotexture Index (SMI), which can be obtained by processing digital images of the pavement surface. Furthermore, this study proposes statistical models for predicting the initial skid resistance of pavement based on these indicators. Overall, the proposed image-based indicators of microtexture and macrotexture have the potential to provide valuable insights for designing and maintaining safe and durable pavement surfaces.

Analysis of tyre-pavement contact behaviour of heavy truck in full-scale test

ABSTRACT Tyre-pavement contact behaviour is one of the core issues in pavement engineering. In this study, the tyre-pavement contact behaviour was investigated in full-scale tests. The pavement texture was characterised by a 3D scanner and the sand patch method. The data of tyre-pavement contact stress were collected by a pressure distribution measurement system. The characteristics of the tyre-pavement contact stress distribution were explored by introducing the Boltzmann model. The feasibility of the Hertz model in assessing the tyre-pavement contact behaviour was evaluated. The results showed that the tyre-pavement carries a larger load by extending the contact area in longitudinal direction and increasing the contact stress mainly at the lateral edges. The pavement texture has significant effects on the contact behavior. Under the regular tyre vertical force range, the value of contact stress is within 1000 kPa for about 80% of the tyre-pavement contact area, but the maximum contact stress can be up to 3000 kPa. The Boltzmann model can be used to fit the contact stress distribution, and some parameters of the model have linear relationships with pavement surface macrotexture. The Hertz model can reflect the average state of tyre-pavement contact behaviour.

Experimental analysis of long-term skid resistance of steel slag asphalt mixture based on differential wear

ABSTRACT This study aimed to analyse the attenuation law of skid resistance of steel slag asphalt mixture (SSAM) based on differential wear. In this study, an indoor accelerated wear instrument was used to accelerate the wear of the SSAM surface. A pavement laser scanner and a dynamic friction tester measured the three-dimensional morphology and dynamic friction coefficient (μ) of SSAM. Then, the improvement mechanism of steel slag on the skid resistance of SSAM was expounded by analysing the surface microtexture, mineral composition, and chemical composition of aggregates. The results showed no linear relationship between the amount of steel slag and the improvement of SSAM skid resistance. The SSAM with 50% steel slag maximised the differential wear effect and had the largest μ and the richest surface macrotexture. It was recommended that the steel slag content in the SSAM should not exceed 50%. The more mineral composition and higher average hardness of steel slag were the sources of its excellent skid resistance. In addition, it is suggested that the differential wear between mixed aggregates should be considered in the design of skid resistance pavement, and the proportion of different aggregates should be reasonably distributed.

Road pavement macrotexture estimation at the design stage

Road performance (e.g., rolling resistance, friction, noise, and hydroplaning) is affected by surface macrotexture. The characteristics above need to be controlled and predicted at the design stage because of the consequences on sustainability and safety. However, macrotexture is quite difficult to govern when designing a mixture and this fact poses many issues, especially when focusing on Low-nominal maximum aggregate size, NMAS, mixtures. Consequently, tools are needed, at the design stage, to better predict a pavement surface macrotexture (e.g., mean texture depth, MTD). For these reasons, the main objective of this study is to set up and implement a model to predict MTD at the design stage. To this end, three main data sets of bituminous mixtures were taken into account. The first data set was created considering technical specifications limits, the second one consisted of data from the literature, and the third one consisted of mixtures especially created in the laboratory (low- NMAS mixtures). Modelling was carried out by setting up several equations, which are based on the sphere packing model and on the concept of filling volume, FV, herein introduced. Results demonstrate that (1) NMAS and FV can explain up to 88 % of MTD variance, (2) the lower specification limits set up in technical specifications must not be considered as good descriptors of the expected MTD, and (3) for low-NMAS mixtures the impact of FV appears less important, while the impact of NMAS seems to be still important. Results can benefit both researchers and practitioners.

Evolution of tire-pavement friction with the regular surface macro-texture characteristics and environmental factors using three-dimensional (3D) printing technology

Conventional gradation-based pavement design makes the constructed pavement surface too complex to quantify the contribution of texture on the tire-pavement friction accurately. This study aims to investigate the influence of regular macro-texture characteristics and environmental factors on friction using three-dimensional (3D) printing technology. The variation of friction with different texture shapes, heights, and gaps was investigated under dry and wet conditions. The evolutions of friction under different water film thicknesses and temperatures were also quantitatively analyzed. The results show that all specimens with different texture shapes, heights, and gaps can contribute to large friction under dry conditions, where the British pendulum number (BPN) is larger than 90. The friction sharply decreases under wet conditions, especially for the semi-circular texture specimens. The specimens with positive textures are much better than those with negative textures. The impact of texture shapes is more significant than texture height and gaps under wet conditions, where the texture gaps are relatively insignificant. The friction is slightly linearly increased with the water film thickness while slightly decreasing with the temperature. This study provides a friction-oriented pavement texture design method and manufacturing techonology.

Establishment and Analysis of the Relationship Model between Macro-Texture and Skid Resistance Performance of Asphalt Pavement

Pavement surface texture evaluation is mainly analyzed based on elevation data in previous research, and attention also need to be paid to wavelength information. Furthermore, a well-established relationship model between surface texture and skid resistance for real road sections still needs further investigation to help provide useful information on appropriate maintenance time considering skid resistance attenuation. In this research, the macro-texture of asphalt pavement was evaluated from different aspects, including elevation, wavelength information, and geometry, and the relationship models between the macro-texture and skid resistance (at both low and high speeds) were established and compared using the multiple linear regression (MLR) and back propagation (BP) neural network to recommend a suitable one. In order to achieve this, this study monitored anti-skidding performance and the macro-texture of six road sections for 18 months. Firstly, the Dynamic Friction Coefficient (DFC) test and core drilling were conducted on site at three different service times. Additionally, a laboratory accelerated loading test was carried out on specimens prepared by similar material composition to one of the road sections, and the British Pendulum Number (BPN) was tested after different passes of loading. Secondly, 3D laser scanning was carried out on core samples from road sections and laboratory specimens after different passes of loading. The correlation degree between macro-texture indexes and anti-skidding performance was analyzed with the grey correlation entropy analysis method. Finally, the relationship models between the anti-skidding performance at high and low speeds and macro-texture were established based on the MLR and BP neural network. The results indicate that the macro-texture indexes calculated based on elevation data to characterize vertical irregularities have a good correlation with the skid resistance despite the different service times and pavement types. Compared with the BP neural network model, the MLR model has low correlation and noticeable error. The relationship model between F60 (DFC at the speed of 60 km/h) and macro-texture could be well established by the BP neural network. In addition, the relationship between F20, BPN, and pavement surface macro-texture is poor, making it impossible to establish a model with good correlation. Generally, it is recommended to use the BP neural network to establish the relationship model between macro-texture and skid resistance.

Performance of Porous Asphalt Mixtures Containing Recycled Concrete Aggregate and Fly Ash.

This study investigates the effects of two waste materials from construction and industry, namely recycled concrete aggregate (RCA) and Type C fly ash, on the overall performance of a special type of pavement surface mixture, porous asphalt mixture. Mixtures of different combinations of RCA (for partial aggregate replacement) and fly ash (for filler replacement) were prepared in the laboratory and tested for a variety of pavement surface performance parameters, including air-void content, permeability, Marshall stability, indirect tensile strength, moisture susceptibility, Cantabro loss, macrotexture, and sound absorption. The analysis of the results showed that incorporating RCA or fly ash in a porous asphalt mixture slightly reduced the air-void content, permeability, and surface macrotexture of the mixture. A 10% replacement of granite aggregates with RCA in the porous asphalt mixtures led to a reduction in mixture stability, indirect tensile strength, resistance to raveling, and sound absorption. The further substitution of mineral filler with fly ash in the mixture, however, helped to offset the negative impact of RCA and brought the mechanical properties of the mixture with 10% RCA to levels comparable to those of the control mixture.

Comparative Evaluation of Pavement Macrotexture Measurements from Different Devices

Ride quality, safety, and tire pavement noise are functional performance measures of concern to highway motorists. Owing to the significant influence of surface macrotexture on wet-weather skid resistance, splash and spray, and highway traffic noise, a need exists for reliable and repeatable methods to measure pavement macrotexture over the road network. To address this need, the National Cooperative Highway Research Program sponsored a project that developed draft protocols for test methods, equipment specifications, and data quality assurance practices for network-level macrotexture measurement. The project conducted three field experiments to evaluate available technologies in regard to repeatability, agreement, and accuracy. This paper focuses on the field experiment conducted at the Texas A&M University RELLIS Campus, which aimed to validate macrotexture measurements from high-speed laser equipped devices suitable for network-level macrotexture data collection and processing. To accomplish this objective, the RELLIS experiment included test speed and laser exposure time in the test matrix, fabricated a measurement beam to collect static reference texture data using a high-resolution laser, and compared texture measurements from different devices with corresponding reference values. This paper presents the findings and conclusions drawn from the RELLIS experiment.

An energetic approach to model the relationship between tire rolling friction and road surface macrotexture

To investigate the relationship between tire rolling friction and road surface texture, a model based on the energy dissipated by a rubber block when it is deformed cyclically by road surface asperities is proposed. The effects of speed and temperature are considered using time-temperature superposition and the Williams-Landel-Ferry equations. The model is applied to texture profiles, measured using a laser profilometer, and filtered to simulate the envelopment of road surfaces by a tire, to estimate the dissipated energy and deduce the coefficient of rolling friction. The comparison between the model and the experiments, obtained by measurements performed on road samples in the laboratory, shows a fair correlation between the predicted and measured coefficients of rolling friction, this depending on the type of surface studied. Discussions are made to explain the gap between the model and the experiments and identify perspectives for future investigations.

Application of friction–speed model to evaluate runway surface microtexture and macrotexture: a case study

ABSTRACT Runway skid resistance should be evaluated and maintained periodically to sustain aircraft operation safety. This study focuses on evaluating runway skid resistance in terms of surface microtexture and macrotexture and determining how aircraft operations affect these characteristics. The friction–speed model developed by the Harmonisation of European Routine and Research Measuring Equipment for Skid Resistance of Roads and Runways–Laboratoire Central des Ponts et Chaussées was selected due to its consistent and rational results. The grip number values measured using a grip tester for 19 continuous months on 2 runways of the Taoyuan International Airport were analysed as a case study. Research outcomes showed that the microtexture of dense grade asphalt concrete was not considerably different from that of stone mastic asphalt concrete, but the latter exhibited markedly better macrotexture than the former. Aircraft landing operation significantly reduced skid resistance at the touchdown zone. In particular, macrotexture was decreased. However, aircraft behaviour at high-speed exits exerted more negative influences on microtexture than on macrotexture. Accordingly, designing a runway surface layer with improved macrotexture at the touchdown zone is recommended and special attention should be given to the microtexture evaluation of the area located immediately before a high-speed exit point.

Investigation to the skid resistance of asphalt pavement based on the movement of aeolian sand

Particulate contaminants that adhere to the surface have a major impact on asphalt pavement skid resistance. In this investigation, the skid resistance analysis system for the contaminated road was used to look at the decay characteristics of the pavement friction and the movement behavior of sand particles. To analyze the effect of aeolian sand on the skid resistance, the handheld laser scanner was used to collect the road surface macrotexture and then rebuilt the 3D model. The surface roughness of the contaminated road can be jointly characterized via the centreline average (Sa), the profile root-mean-square deviation (Sq), the height distribution symmetry (Ssk), and the height distribution kurtosis (Sku). The results show that aeolian sand has shear lubrication and rolling lubrication at the contact interface between the tire and the road. It fills the macrotexture and weakens the road's skid resistance. When there is aeolian sand adhering to the pavement, sliding and rolling friction provides the skid resistance of the asphalt road. Excessive aeolian sand has adverse long-term effects on skid resistance. It is recommended to routinely clean the road surface to maintain its original skid resistance when the amount of sand reaches to 0.625 kg/m2.

Estimating the Potential of Skid Incident at Airport Runway – A Case Study

Skid resistance or friction on airport pavement plays an essential role in runway safety to ensure safe stopping distance. It also provides safety margins during take off and landing of aircraft especially in directional control by reducing the occurrence of overrun and veer-off incidents. The friction between pavement and tire is related to multiple factors such as pavement surface characteristics (microtexture and macrotexture), material intruded between tire and pavement surface (water, snow, and contaminants), tire conditions (types, wear, and inflation pressure), and vehicle operating conditions (vehicle speed and whether the wheel is rolling or locked). Skid incidents due to wet pavement surface at airport runway is a major concern especially in regions of wet-tropical climate countries such as Malaysia. Thus, this study was undertaken to measure the potential of skid incident at airport runway by collecting data on pavement surface characteristics. Field data collection on pavement surface microtexture was conducted using the British Pendulum Tester at a local airport runway to obtain data for the estimation of the skid number (SN). Due to constraints, pavement surface macrotexture test was unable to be conducted at site. However, the pavement surface macrotexture was able to be estimated based on previous research. The potential of the skid incident was estimated by calculating the SN using the aircraft’s touch down speed at the airport runway, varies from 50 to 70 knots (57.5 – 80.6 mph or 92.6 – 129.6 km/h). The results of the estimation indicated that the possibility of the skid incident occurrence was high. This study provides useful insights for airport authority to investigate the potential of overrun and veer-off incidents of aircraft at the airport runway.

Characterization of Sustainable Asphalt Mixtures Containing High Reclaimed Asphalt and Steel Slag.

Policymakers are implementing the transition to a circular model in all economic sectors to drastically mitigate the effects of climate change. In this regard, the producers of paving products should promote the reuse and recycling of solid waste in the design of sustainable asphalt materials. This study evaluated the performance-based properties of three highly recycled mixtures for wearing courses of asphalt pavements containing steel slag and varying amounts (25, 40, and 50%) of fractionated reclaimed asphalt (RA). In addition, the mixtures incorporated a warm mix asphalt (WMA) organic additive to lower production temperatures compared to a reference hot mix asphalt (HMA). Based on the experimental results, the warm recycled asphalt mixtures show equivalent or better performance compared to HMA in terms of moisture susceptibility, stiffness, rutting and fracture resistance, and surface macrotexture. Therefore, the combined incorporation of RA and steel slag with WMA was proven to be an effective option in designing environmentally friendly and high-performance wearing course mixtures.

Why do clogged porous asphalt pavements give better traffic noise reduction than a dense-graded asphalt pavement?

In Europe, porous asphalt concrete pavements (PAC) are commonly used to reduce traffic noise. Especially the double-layer type (DPAC) provides substantial traffic noise reduction. Unfortunately, PAC pavements compared to dense asphalt pavements have reduced acoustic longevity; the main reason being clogging of the pores and voids, sometimes also more ravelling. The dense-graded pavements considered here are stone mastic asphalts (SMA, in the US known as stone matrix asphalt) which often have surface macrotexture of the same size as the PAC. The main difference is that the PAC has accessible pores/voids providing sound absorption, while the SMA has practically no porosity. One would expect that when the pores in the PAC have become clogged while ravelling is not yet substantial, that the noise property of the PAC would approach that of the SMA. But experimental studies suggest that even when PAC:s are effectively clogged, they retain a certain noise reduction compared to SMA:s. This paper examines this feature of clogged PAC versus SMA and reasons for this unexpected property, for a few Swedish DPAC pavements compared to SMA pavements, with due consideration of possible difference in maximum aggregate size and macrotexture as represented by mean profile depth (MPD) and grading curves.

An Investigation of the Relationship among Skid Resistance, Mean Texture Depth and Abrasion Resistance for Different Macrotextures of Concrete Pavements

Road accidents are one of the ten major causes of death in the world. Lack of enough friction and skid resistance of the pavement surface are known as important factors in traffic accidents. In this study, to evaluate the relationship between skid resistance and pavement surface macrotexture, five methods of creating macrotexture on concrete pavements were used. Sand Patch test, British Pendulum and Wide Wheel Abrasion tests were employed to obtain mean texture depth, skid resistance and abrasion resistance of the surface, respectively. Results showed that brushing on fresh concrete surface (parallel or perpendicular to the traffic direction) can improve frictional properties of pavement surface, drastically. This method increased British Pendulum Number (BPN) and friction coefficient by 32% and 38% (in average), respectively. Friction coefficient of parallel brushing was quite similar to perpendicular (0.2% discrepancy), while its abrasion resistance was 4% higher. Hence, as a finding, parallel brushing is the most recommended texturing technique in respect to friction. Generally, concrete pavement texturing decreases surface abrasion resistance, but burlap dragging improved this index by 2.5%. Nevertheless, burlap dragging results could be deceptive due to the high sensitivity to initial setup conditions. In other words, measurement scale of the studied testing procedures are small in respect to the scale of protuberances caused by burlap dragging method.