SKID RESISTANCE AND TEXTURE OF COMPACTED ASPHALT MIXES EVALUATED FROM THE IFI IN LABORATORY PREPARATION (original) (raw)
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Skid resistance and texture are important safety characteristics which need to be considered in flexible pavement design, maintenance and rehabilitation. The main objective of this paper is to optimize surface texture characteristics in asphalt rubber pavements, mainly macrotexture to reduce splash, spray and hydroplaning and microtexture to increase friction at low and high speeds. The objective was accomplished by measuring the friction surface with two different tests: (i) British pendulum; (ii) Volumetric Method. The specimens prepared in the laboratory represent the as-constructed pavement surface. In this study, two different mixtures grading (dense and gap) were produced using three types of binders: (i) conventional asphalt; (ii) asphalt rubber using terminal blend process; (iii) asphalt rubber using continuous blend process. The binder content influence in functional quality was tested by using the same configuration for mixtures with more 1% of asphalt rubber content. The results of this study were carried out to evaluate the effect of asphalt rubber production process and mixtures gradation on the pavement surface characteristics. The results showed that the mixture with gap grading exhibit higher texture in comparison of mixtures with a dense grade gradation. The asphalt rubber mixtures improved the skid resistance compared to conventional mixtures. This research indicates that the CRM (crumb rubber modified) production with rubber from the different processes have significant differences in pavement surface characteristics.
Quantifying the effect of modified mixture volumetrics and compaction effort on skid resistance of asphalt pavements Quantifying the effect of modified mixture volumetrics and compaction effort on skid resistance of asphalt pavements, 2022
This paper aims to quantify the effect of modified mixture volumetrics and compaction effort on surface characteristics of asphalt pavements. Specimens were prepared using PG 64-10 asphalt binder mixed with crushed limestone aggregate. Three types of asphalt modifiers were added; Crumb Tire Rubber (CTR), Microcrystalline Synthetic Wax (MSW) and Nano Silica (NS). In addition, specimens were adjusted at 4% air void and were compacted at Design Number of Gyrations (Ndes) = 119 and 82 to simulate high and low levels of traffic, respectively. Research findings revealed that Air Voids Volume (V a) and Effective Binder Volume (V be) exert a significant effect on the surface frictional properties. Additionally, the ratio of V a to V be , expressed as P v , was also investigated to study the combined effect of V a and V be on surface friction results. It was concluded that P v has a considerable role in the evaluation process. It was also shown that increasing the level of compaction would result in a positive effect on British Pendulum Number (BPN) measurements and the opposite is true in terms of macrotexture measurements. Furthermore, CTR-modified mixtures exhibited the highest values of friction and macrotexture followed by NS-modified mixtures. MSW-modified and unmodified mixtures exhibited the least fractional characteristics. ARTICLE HISTORY
Evaluating skid resistance of different asphalt concrete mixes
Building and Environment, 2007
At all stages of pavement life, the highway surface should have some sort of roughness to facilitate friction between car wheels and pavement surface. Skid resistance is a measure of the resistance of pavement surface to sliding or skidding of the vehicle. It is a relationship between the vertical force and the horizontal force developed as a tire slides along the pavement surface. The texture of the pavement surface and its ability to resist the polishing effect of traffic is of prime importance in providing skidding resistance. Polishing of the aggregate is the reduction in microtexture, resulting in the smoothing and rounding of exposed aggregates. This process is caused by particle wear on a microscopic scale. It is a common fact that the lower the skid resistance value, the higher the percentage of the traffic accidents, especially during the wet seasons. Having a low skid resistance value at an asphalt concrete surface might be attributed to one or more of the following reasons: (1) use of higher asphalt content than recommended by the mix design procedure, (2) the Marshall mix design procedure itself, (3) used aggregate gradation, and (4) aggregate quality. To evaluate these factors, a comparative study was performed to find the British Pendulum Skid Resistance Number for a number of mixes. These mixes included, an asphalt concrete mix using local aggregate at the optimum Marshall asphalt content, mixes with 0.5% and 1.0% asphalt contents higher than Marshall optimum asphalt content, a mix designed using Superpave design procedure, a mix with steel slag to replace 30% of limestone aggregate, and a mix with stone matrix aggregate gradation. It was found that the mix with 30% slag has the highest skid number followed by Superpave, SMA, and Marshall mixes, respectively. It was also observed that increasing the asphalt content above the optimal asphalt content value decreases the skid resistance of these mixes.
Civil engineering infrastructures journal, 2021
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 find...
Asphalt pavements surface texture and skid resistance — exploring the reality
Canadian Journal of Civil Engineering, 2012
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 challenge for the highway agencies in selecting the appropriate surface layer and (or) measuring tools. This study was undertaken 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 texture laser. Skid resistance was measured using a British Pendulum and a skid trailer. The analysis has reinstated that aggregate 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 microtexture and ribbed tire skid number is insensitive to surface texture.
Effect of Asphalt Mix Properties on Surface Texture: An Experimental Study
Applied Mechanics and Materials, 2013
Pavement surface characteristics play an important role in accident occurring, especially in wet conditions: the optimization of surface performance starting from hot mix asphalt (HMA) design phases is a fundamental requirement in road construction techniques. Although such relevance, the prediction of surface properties based on HMA composition and construction still calls for further research. Indeed, there is not a clear framework for a mix design oriented to surface properties. In the light of the abovementioned facts authors' efforts were focused into the analysis of the most significant factors influencing pavement surface macrotexture, by analyzing the main variables of existing macrotexture prediction models. Many experimental mixes were designed and produced. Some statistical correlations between macrotexture data and mixes grading and volumetric properties were also carried out. Outcomes of this study are expected to benefit both practitioners and researchers.
The Open Civil Engineering Journal
Background: Micro-texture and macro-texture are two essential parameters that functionally evaluate friction on asphalt pavement surface. While micro-texture indicates the irregularity of aggregate using British Pendulum Tester (BPN), macro-texture shows the larger irregularity of asphalt mix surface using Mean Texture Depth (MTD). Both micro-texture and macro-texture contribute to increased skid resistance value, which is needed for road to meet the safety qualification. Aim: This study aims to investigate the effect of local aggregate types and aggregate proportion (%) on asphalt mix on pavement textures (micro and macro-texture). Methods: Laboratory experiments were conducted on four types of local aggregates (A, B, C, and D), which were carried from West Java, Indonesia, and aggregate has a different characteristic to each other. In addition, three asphalt mix types (SMA-fine, AC-WC, and HRS-WC), each containing varying proportion (%) of aggregates, were investigated to analyze ...
Predicting Asphalt Mixture Skid Resistance Based on Aggregate Characteristics
2009
The objective of this research project was to develop a method to determine the skid resistance of an asphalt mixture based on aggregate characteristics and gradation. Asphalt mixture slabs with different combinations of aggregate sources and mixture designs were fabricated in the laboratory, and their skid resistance was measured after different polishing intervals. The wheel-polishing device developed by the National Center for Asphalt Technology (NCAT) was used for polishing the slabs. Frictional characteristics of each slab were measured by sand patch method, British Pendulum, Dynamic Friction Tester (DFT), and Circular Texture Meter (CTMeter). Aggregates were characterized using a number of conventional test methods, and aggregate texture was measured using the Aggregate Imaging System (AIMS) after different polishing intervals in the Micro-Deval device. Petrographic analyses were performed using thin sections made with aggregates from each of these sources. Petrographic analyses provided the mineralogical composition of each source. The aggregate gradation was quantified by fitting the cumulative Weibull distribution function to the gradation curve. This function allows describing the gradation by using only two parameters. The results of the analysis confirmed a strong relationship between mix frictional properties and aggregate properties. The main aggregate properties affecting the mix skid resistance were Polish Stone Value, texture change before and after Micro-Deval measured by AIMS, terminal texture after Micro-Deval measured by AIMS, and coarse aggregate acid insolubility value. The analysis has led to the development of a model for the International Friction Index (IFI) of asphalt mixtures as a function of polishing cycles. The parameters of this model were determined as functions of (a) initial and terminal aggregate texture measured using AIMS, (b) rate of change in aggregate texture measured using AIMS after different polishing intervals, and the (c) Weibull distribution parameters describing aggregate gradation. This model allows estimating the frictional characteristics of an asphalt mixture during the mixture design stage.
Influence of pavement surface macrotexture on pavement skid resistance
Transportation Research Procedia, 2020
Pavement skid resistance is one of determining road features that contributes to traffic safety. Several influencing factors govern the skid resistance, amongst which the pavement surface texture is the one that could be designed and controlled by the pavement engineers. Pavement surface texture is classified into four categories, where microtexture and macrotexture level affect the pavement skid resistance. Microtexture contributes to skid resistance at low traffic speed, while macrotexture governs skid resistance at high speed. Macrotexture is a result of asphalt mixture properties, mostly the aggregate gradation, maximum aggregate size, binder and air voids content. Macrotexture is usually measured using different volumetric or optical devices, and the measuring results are expressed as texture depth or profile depth values. Several studies showed that macrotexture level can be correlated to pavement skid resistance performance. Previously conducted small-scale case study performed on road network in City of Rijeka analyzed the influence of pavement surface renewal treatment on macrotexture values increase and its influence on skid resistance values. In this paper, an analysis of measured macrotexture and skid resistance values is shown for a greater set of data. The measurements were conducted on selected highway section in Croatia, using laser profilometer for macrotexture determination and surface friction trailer for skid resistance determination. Both pavement surface performance indicators-Mean profile depth (MPD) for the macrotexture and longitudinal friction coefficient (LFC) for the skid resistance were measured before and after the renewal treatment in order to determine the influence of the renewal treatment on the surface performance improvement. The measured values were then correlated, showing that skid resistance is connected to the level of pavement surface macrotexture.
Characterization of the Skid Resistance and Mean Texture Depth in a Permeable Asphalt Pavement
IOP Conference Series: Materials Science and Engineering
Road pavements need a deep characterization of the surface layer, with which the vehicles have direct contact and, therefore, must provide security to the users. The use of permeable asphalt pavements (PAP) with porous layers has provide obvious advantages in reducing runoff and the rainwater infiltration into the soil or for storage. However, the study of the interaction between the pavement surface layer and the tire rubber requires additional tests in terms of texture and friction, since they are important parameters for the design, construction, management, maintenance and roads safety. Considering the application of a PAP in a parking lot, the study objective was to characterize in the field the pavement surface in terms of mean texture depth (MTD) and skid resistance (Pendulum test value, PTV). The methods used were the volumetric technique by the patch test and the pendulum test, according to EN 13036-1 and EN 13036-4, respectively. The double layer porous asphalt (DLPA) at the surface is characterized by having a structure with high voids content that led to results of clearly rougher macrotexture and good skid resistance. The normalized limit values were met, however, a very strong correlation between MTD and PTV was not observed. A comparison was also made with porous surfaces of other studies and it was found that porous asphalt has a good behaviour at the start of construction which may tend to improve in the long term. From the study, it is concluded that the PAP presents good performance of the surface layer, providing road safety to users.