Effects of filling degree on skid resistance in fluid mastic asphalt mixtures

To evaluate influence of external environment and material composition on skid-resistance durability of high viscosity modified asphalt (HVMA) mixture, the accelerated abrasion test was selected to simulate decay of skid resistance for asphalt mixture by setting different test conditions. The influence of aggregate gradation, asphalt type, ambient humidity and overload on skid-resistance durability of asphalt mixture was discussed, and the significant effect of selected factors on skid-resistance durability of asphalt mixture was revealed. The results show that the skid-resistance durability of SMA-13 (Stone Mastic Asphalt) mixture is better than OGFC-13(Open Graded Friction Course) and PA-13 (Porous Asphalt) mixture under different conditions, and attenuation rate of different indexes of SMA-13 mixture is 1.6–2.2% and 0.8–2.1% lower than compared with OGFC-13 and PA-13 mixture. The attenuation rate of texture depth for asphalt mixture is closely related to aggregate gradation and asphalt, but the attenuation rate of british pendulum number for asphalt mixture with the same mineral aggregate is only significantly affected by the asphalt. The skid resistance of SMA-13 and PA-13 mixture is improved slightly by addition of high viscosity modified asphalt. The attenuation rate of texture depth of SMA-13 and PA-13 mixture with HVMA is reduced about 0.6–3.0% and 2.2–4.2% than SBS modified asphalt, but the attenuation rate of british pendulum number of above mixtures is increased about 1.2–1.6% and 0.3–1.7%. The skid-resistance durability of asphalt mixture with TPS (TAFPACK-Super) and SINOTPS high viscosity agent is better than HVA (High viscosity additive). The skid-resistance durability of asphalt mixture based on texture depth is improved under wet condition. However, the skid-resistance durability of asphalt mixture for british pendulum number gets worse due to water intrusion. The skid-resistance durability of asphalt mixture is rapidly decreased under overload condition. The influence of overload and SBS modified asphalt on skid-resistance durability of asphalt mixture is higher than ambient humidity and HVMA. This paper will provide foundation for high viscosity modified asphalt applied in asphalt pavement.

Influence of pavement surface macrotexture on pavement skid resistance

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.

Prediction modeling of skid resistance and texture depth on flexible pavement for urban roads

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.

Testing and evaluation for long-term skid resistance of asphalt pavement composite seal using texture characteristics

Wet pavement skidding due to inadequate surface texture or friction contributes to 20% to 35% of all wet weather crashes. Many of the past studies of pavement surface texture and friction have deficiency in selecting the model forms or variables and interpreting the models and (or) the findings or have recommended further investigation. These pose a chal- lenge for the highway agencies in selecting the appropriate surface layer and (or) measuring tools. This study was under- taken to re-examine some of the pavement surface texture and skid resistance related issues and aid the highway agencies in this area. Pavement surface texture and skid resistance aspects were carefully examined using the data collected from nine asphalt concrete (AC) surfaces. Pavement surface texture was measured using the sand patch method and a high speed tex- ture laser. Skid resistance was measured using a British Pendulum and a skid trailer. The analysis has reinstated that aggre- gate quality is the predominant factor for AC surface skid resistance. Both texture depth and ribbed tire skid resistance was shown to increase with an increase in coarse aggregate (CA) content proving their interdependency. Neither the voids in mineral aggregate (VMA) or air voids (AV) contents showed a meaningful or statistically significant correlation with the surface texture or skid resistance. Fairly good correlations were found among the British Pendulum number (BPN), ribbed tire skid number (SN) and mean texture depth (MTD) rejecting the hypothesis that BPN is a measure of only surface micro- texture and ribbed tire skid number is insensitive to surface texture.

Frictional Interactions between Bovine Claw and Concrete Floor

Skid resistance is required to prevent vehicle wheels from slipping on a road surface. The skid resistance is influenced by surface texture of the road, which is a function of aggregate properties and grading characteristics. This study aimed to examine the effect of using artificial aggregates on the texture depth and the skid resistance of two asphalt concrete surface course (ACSC) mixtures (dense and open graded). The artificial aggregate, which was made from a mixture of a locally sourced fly ash geopolymer paste and an alkaline activator, was used to partially substituting the coarse aggregate in these ACSC mixtures. ACSC slab samples, without and with 25% artificial aggregate, were produced in laboratory. The texture depth and skid resistance characteristics were subsequently determined. This study found that the differences in texture depth and skid resistance of the two ACSC mixtures were contributed by the difference in gradation of the mixtures and the properties of the coarse aggregate in the mixtures. The ACSC mixture containing 100% natural coarse aggregate (crushed stone) has a deeper and rougher texture depth than those containing 25% rounded artificial aggregate. Post-wheel track loading, the texture depth and skid resistance of open graded ACSC were found to be higher than those of dense graded ACSC. These trends were consistent regardless the type of aggregates used in these ACSC samples. Overall, all tested samples showed skid resistance values meeting the requirements for heavily trafficked roads in urban areas where the traffic speed does not exceed 95 km/h.KeywordsArtificial aggregateAsphalt concreteGeopolymerSkid resistanceTexture depth

Texture depth is one of the most important indexes reflecting the skid resistance performance of asphalt pavement. Temperature has effect on the texture depth of asphalt pavement. There is no effective temperature correction method on the texture depth index in China, which leads to the phenomenon that the test texture depth could not reflect the true skid resistance performance of pavement structure. In order to effectively analyze the temperature influence on the skid resistance of asphalt pavement, a temperature correction method of sensor measured texture depth (SMTD) index was proposed based on the SMTD data and equivalent temperature of asphalt surface layer in RIOHTrack full-scale track. The annual equivalent temperature at 4cm location of asphalt surface layer was taken as the correction reference temperature. The Boltzmann function was adopted to establish the relationshi p between the SMTD index and the daily equivalent temperature of asphalt surface layer. The mean square error of temperature correction model for SMTD index is 0.977. The maximum error of temperature correction model for SMTD index is 2.601%, which meets the detection requirements on road engineering. The temperature correction method is significant to reflect the SMTD index change of pavement skid resistance performance, improve the evaluation accuracy of pavement skid resistance, and improve the safety of driving on highway.

The British pendulum tester (BPT) and the dynamic friction tester (DFT) are commonly used to evaluate the polishing effect of traffic on pavement skid resistance. The present study was conducted to answer two questions: (i) whether the directional moving traffic action results in significant directional differences in skid resistance of the pavement, and (ii) if so, whether BPT and DFT are effective tools for evaluating the skid resistance performance of polished pavements with significant directional skid resistance characteristics. Five in-service pavement sections with different degrees of polishing were examined in this study. The following findings were obtained from the study: (a) There were statistically significant differences between the longitudinal and transverse skid resistance of the polished pavements tested; (b) there were no statistically significant differences between the longitudinal and transverse skid resistance of the newly paved unpolished pavement tested; (c) BPT was able to differentiate the directional skid resistance differences of the polished pavements tested; and (d) DFT was unable to differentiate the directional skid resistance differences of the polished pavements tested. DFT produces one skid resistance value for a circular path at each test point. The test results found that DFT over-estimated the traffic-direction skid resistance of in-service pavements. The over-estimation errors ranged from 0.001 to 0.023 DFT units, and the corresponding percent errors were from 0.4% to 11.1%. This finding suggests that the over-estimation effect of skid resistance directionality of polished pavements on DFT measurements should be recognized in pavement skid resistance evaluation and pavement safety studies.

In this paper, the ultra-thin layer (UTL) is defined as the dense framework structure mixture made of asphalt binder, fine aggregate with nominal maximum aggregate size (NMAS) not greater than 13.2 mm and possible additives (mineral or organic), thickness of 2–4 cm. The study aims to investigate comprehensive performance of UTL asphalt mixture. The method of impact freeze thaw split test and the index of impact freeze–thawing damage degree (IFTDD) are proposed to reflect the durability. The indoor tire-rolling-down test system and accelerated abrasion machine are used to simulate the tire-pavement interaction and test road noise and skid resistance, respectively. Though evaluating the influencing factors (pavement thickness, gradation, asphalt binder type, and the content of KS additive) on durability, the optimum parameters with excellent durability are recommended. Combined with the test of noise and skid resistance, the factors affecting the surface function are analyzed. Moreover, the prediction mathematical model of skid resistance and the long-term safety benefit value Eeff are put forward. Results indicate that pavement thickness is the most significant factor effecting on durability, and gradation is the most significant factor affecting noise. Compared with KS additive, gradation has a greater influence on skid resistance index of Texture Depth (TD), whereas, KS additive is the most significant factor affecting British Pendulum Number (BPN). Furthermore, with the addition of asphalt rubber (AR), IFTDD and noise are reduced by 29.17% and 1.6 dB, and BPN and TD increase by 0.7 and 0.03 mm, remarkably. Compared with different asphalt types, the noise of UTL asphalt rubber mixture with 13.2 mm NMAS (UTL13 AR) is the lowest. Additionally, when KS content increases by 0.6%, the noise increases by 3 dB. Furthermore, on the basis of the calculation results of Eeff, UTL13 AR mixture with 0.5% KS has the best long-term benefit of pavement safety and is recommended for field project.

To accurately evaluate the skidding resistance of asphalt pavements, a texture imaging device was developed to realize the standardized acquisition of pavement images. Based on the gray-level co-occurrence matrix and multifractal theory of texture structure, the influence of segregation degree and gradation type on the texture properties of asphalt pavement was studied. Meanwhile, a comprehensive evaluation index of skidding resistance was proposed for asphalt pavement. Furthermore, the attenuation characteristics of the anti-skidding performance for asphalt mixture were explored, and the corresponding attenuation model of asphalt pavement was established. The results show that the segregation degree and gradation type significantly affected the texture parameters and anti-skidding performance of asphalt mixture. Specially, with an increase in the segregation degree of coarse aggregate, the parameters of energy, entropy, and multifractal spectrum width gradually increased, whereas the inertial moment gradually decreased. The variation range of the multifractal spectrum difference initially increased and subsequently decreased. For the texture parameters such as energy, entropy, inertial moment, and multifractal spectrum width Δα, the values of the asphalt mixture with larger nominal maximum particle were higher than those of the mixture with smaller nominal maximum particle, whereas the multifractal spectrum difference value showed the opposite law. In addition, the texture parameters of energy, entropy, and multifractal spectrum width exhibited good linear correlation with the texture depth (TD) of asphalt mixtures with various segregation levels and gradation types. The index based on the texture parameters of energy, entropy, and multifractal spectrum width effectively evaluated the skidding resistance of asphalt pavements, which showed the same trend as the TD with the increase of the abrasion number. The achievement provides an effective solution for the evaluation of skidding resistance and attenuation characteristics of asphalt mixtures.

The skid resistance of the surface of the highway is controlled by its microtexture and macrotexture. Microtexture refers to irregularities in the surfaces of the stone particles (fine-scale texture) that affect adhesion and make the stone particles feel smooth or rough to the touch. Macrotexture refers to the larger irregularities in the road surface (coarse-scale texture) that effect hysteresis and associated with voids between stone particles. This paper evaluates the effect of aggregate microtexture, macrotexture and influence of pavement surface under dry and wet condition to skid resistance. Three (3) different types of pavement surface were selected to obtain friction value on Continuously Reinforced Concrete Pavement (CRCP), Hot Mixture Asphalt pavement (HMA), and Ralumac Micro-Asphalt. In addition, skid resistance value was calculated from British Pendulum Tester and texture depth by using sand patch method. From the field test conducted and statistical analyses of the data, there were strong relationship between microtexture, macrotexture and types of surface pavement subjected to different dry and wet conditions.

This study analyses the skid resistance performance of rigid pavements by partially replacing fine aggregates with crumb rubber percentages in a laboratory setting. To achieve this objective, British pendulum testing is performed to examine the effects of crumb rubber on skid resistance in dry and wet conditions. In addition, mechanical properties such as compressive strength, tensile strength, and slump, are also investigated. Furthermore, a thorough literature review reveals that the relationship of skid resistance with mechanical properties is relatively scant, and a regression model is also missing that can predict skid resistance through these properties. To this end, this study presents empirical correlations, ascertaining a one-to-one relationship between skid resistance with mechanical properties. As different dosages of crumb rubber are used, this study also provides some guidelines on appropriate dosage of crumb rubber, keeping all the performance parameters in view. Findings of this study suggest that skid resistance is significantly enhanced when crumb rubber is added; however, it compromises the strength performance of rigid pavements. Therefore, an appropriate dosage of crumb rubber that balances them is required. Finally, correlations and models are evaluated and discussed in detail.