Effect Of Vehicle Speed And Weight On Raveling Of Chip Seal Constructed Using Mineral And Tire Derived Aggregate

The characteristics of the load applied by traffic, namely, vehicle speed and load magnitude, play a critical role in the raveling performance of chip seal pavement, which is often overlooked in literature. Furthermore, a sustainable chip seal constructed out of tire derived aggregate (TDA) has been recently introduced. Unlike mineral aggregate, rubber is a time-dependent material, and its properties are greatly influenced by the magnitude and rate of loading. Introducing TDA in chip seal has increased the significance and need to investigate the effects of vehicle speed and load on chip seal. This study investigated the raveling performance of different chip seal specimens constructed out of mineral and TDA, as well as a hybrid tire derived–mineral aggregate, under various loading speeds and magnitudes using a small-wheel traffic simulation device. The findings revealed that both load and speed significantly affect the texture loss of conventional and TDA chip seals, but in opposite ways. Conventional chip seals experienced increased texture loss with higher load and speed, while TDA chip seals showed a decrease. The use of TDA as an aggregate in chip seal resulted in a 23% reduction in macrotexture loss under increased load and a 56% reduction in macrotexture loss under increased speed compared with conventional chip seal. This improved performance is attributed to the dynamic properties of TDA, such as internal hysteresis, time-dependent behavior, and load transmissibility

Using photogrammetry to obtain pavement profiles over large surface areas – a feasibility study

Pavement profiles have been consistently used to determine texture and a variety of factors related to pavement performance such as pavement condition, roughness, and friction characteristics. There are a multitude of different methods that can be used to obtain either a two-dimensional or three-dimensional pavement profile for further analysis. The main objective of this study was to determine whether photogrammetry could be used to determine larger three-dimensional pavement profiles along with the respective cross sections of those three-dimensional pavement profiles using traditionally available computers, cameras, and computational platforms. 3DF Zephyr, a photogrammetry program was used to convert the two-dimensional photos of the pavement surfaces into three-dimensional point clouds and meshes. Photos of four different pavement surfaces were taken across the Austin, Texas area. Of the surfaces selected for testing, two were asphalt, and two were concrete to include both material types using photogrammetric analysis. Additionally, each pavement surface selected had defining elevation features to test the validity and accuracy of the photogrammetric program. A plate with a truncated pyramid geometry of known dimensions was placed inside each of the pavement surface test areas and was used to calibrate the model during the photogrammetric process to evaluate sensitivity and accuracy of the final profile measurements. The results of the study found that each of the pavement profiles and their major distresses were successfully determined by photogrammetry and could be exported and graphed using computational platforms. Furthermore, the results showed that not only was photogrammetry viable to determine larger pavement profiles, but also that it could be done without highly complex equipment and systems. Finally, the analysis determined that using photogrammetry and computational platforms two-dimensional cross sections of the pavement could be determined at any plane of interest to gather further knowledge of a pavement surfaceCivil, Architectural, and Environmental Engineerin

The evolution of macrotexture on asphalt pavements using non-contact field techniques

Adequate skid resistance is required to ensure vehicle safety on pavements in wet conditions and depends upon road surface characteristics, particularly texture. Texture is composed of a range of different scales each of which contributes differently to the generation of adequate friction at the tyre-road interface. Macrotexture acts to disperse water, under wet conditions, through the gaps in between road aggregates, and influences the way skid resistance reduces with increasing speed in wet conditions. Increasingly, correlations between macrotexture measurements captured using non-contact techniques and tyre-pavement contact friction are being investigated. There is a notable scarcity of research into the respective accuracy of the non-contact measurement techniques at these scales. This thesis compares three non-contact techniques: a laser profile scanner, Structure from Motion photogrammetry (SfM) and Terrestrial Laser Scanning (TLS). Spectral analysis, areal surface texture parameters and 2D cross-correlation analysis are used to evaluate the suitability of each approach for characterising and monitoring pavement macrotexture. The results show that SfM can produce successful measures of the areal root mean square height (Sq), which represents pavement texture depth and is positively correlated with skid resistance. Significant noise in the TLS data prevented agreement with the laser profiler but new filtering procedures result in improved values for the peak density (Spd) and the arithmetic peak mean curvature (Spc), which together define the shape and distribution of pavement aggregates forming macrotexture. However, filtering the TLS data results in a trade-off with vertical accuracy, thus altering the reliability of Sq. The work undertaken reveals that the functional areal parameters Spd and Spc are sensitive to sample size. This means that pavement specimen size of 150 mm x 150 mm or smaller, when used in laboratory or field observations, are inadequate to capture the true value of areal surface texture parameters. Therefore, the deployment of wider scale approaches such as SfM are required in order to successfully capture the functional areal parameters (Spc and Spd) for road surfaces. This thesis also provides the first meaningful analysis of a long-term study of legacy texture data obtained using TRACS (TRAffic Speed Condition Survey). A new data analysis approach utilising time series data with spectral analysis and spatial filtering procedures is presented, to determine long term rates of change in road surface macrotexture and compared with meteorological and traffic datasets. The results reveal for hot rolled asphalt (HRA) surfaces that changes to Sensor Measured Texture Depth (SMTD) follow a linearly increasing trend with time. The ‘rate of change’ is influenced by the order of magnitude of annual average daily traffic (AADT), when factored for the percentage of heavy goods vehicles. This linear trend is disrupted by environmental parameters such as rainfall events and seasonal conditioning. In the summer this signal is evident as a transient peak in the ‘rate of change’ of texture greater than 0.04 mm, and in the winter as a reduction. The transient changes in texture corresponded to above average rainfall occurring in the week prior to SMTD measurement. The signal observed demonstrates an inverse pattern to the classically understood seasonal variation of skid resistance in the UK, where values are low in the summer and high in the winter. The findings demonstrate for the first time that texture measurements experience a seasonal signal, and provide compelling evidence pointing toward surface processes (such as polishing and the wetting and drying of surface contaminants) causing changes to texture that are affecting seasonal variation in skid resistance. Furthermore, results expose a systematic periodicity occurring each year within the SMTD data studied, corresponding to longitudinal oscillations with wavelengths between 33 m to 62 m. The time-invariant periodicity of these oscillations suggests that it is ‘imprinted’ in the early life of the pavement. ‘Imprinting’ may theoretically arise with cyclic tyre loading applied by the suspension systems of heavy vehicles or during road construction. Finally, this thesis contributes to understanding of the role of the different scales of texture on the development of skid resistance. A signal processing technique termed Empirical Mode Decomposition was used to decompose the texture measurements into a set of component profiles of different wavelengths. The Dynamic Friction Model, a computational friction model already validated on real road surfaces, was then used to determine the relative effect of partially recomposed profiles with their components on skid resistance. The results demonstrate the importance of not only “small-scale” and “large-scale” textures but also their spatial arrangement and shape. Indeed, on wet road surfaces, “small-scale-texture” was found to be key to achieving good skid resistance at low speeds, whilst “large-scale-texture” was found to be crucial to maintaining it with increasing speed. The distribution of the summits of the large-scale-textures was established as being able to compensate for a lack of small-scale-texture. Conversely, the reverse was established as also being true, with the small sharp local summits of small-scale-texture being found to compensate for a lack of large-scale-texture. The work undertaken in this PhD scrutinises the measurement of pavement macrotexture using non-contact techniques and defines new approaches to analyse legacy data sets to visualise spatially macrotexture evolution. Significantly, the work provides compelling evidence of a ‘seasonal signal’ in texture data, linked to environmental conditions, particularly precipitation. These results place a new emphasis on the future need to quantify the contribution of pavement surface processes to the phenomenon of seasonal variation of skid resistance, to improve texture evolution assessment and frictional measurement on road networks

Development of New Methodologies for Prediction of Performances of Asphalt Mixtures

This thesis proposes the use of new methodologies for prediction of performances of asphalt mixtures. Recent improvements in technology make it possible to adopt new methods of investigation with the dual objective of improving the performance in the survey of the parameters and investigate new properties so far not analyzed. In particular, the image analysis and the tyre/surface interaction belong to an innovative framework, which is next to flank, if not replace, the classic measurements so far employed. The thesis deals with the use of these technologies for the analysis of three rubberized stone mastic asphalts, which were laid on a stretch of road close to Bologna, Italy. Three different surveys were carried out on site during the first year of service. The surveys included the change in texture and skid resistance due to the traffic, along with the acoustic properties of the pavement. Local as well as dynamic continuous measurements were carried out, involving the use of a profilometer and a skiddometer. A second phase involved the prediction of the surface parameters with different stages of simulated trafficking on Road Test Machine. At each stage change in macrotexture, skid resistance, adhesion between bitumen and aggregates, contact pressures and areas were assessed. The image analysis is used for the assessment of the adhesion between the bitumen and the aggregate. The images are then processed in order to create 3D models of the asphalt specimens and investigate the surface and volume properties. The tyre/pavement interaction is another fundamental phenomena that received little considerations from the research, given its importance. A final discussion summarizes these investigations by separately review three different simulated periods, i.e. the early life, the in-service equilibrium and the end of life. In order to accelerate the distress, one slab was subjected to Immersion Wheel Track test

3D surface profile equipment for the characterization of the pavement texture - TexScan

Loads from vehicles alter the functional and structural characteristics of road pavements that directly affect the loss of resistance of the pavement and the users’ comfort and safety. Those alterations require constant observation and analysis of an extensive area of road surface with high precision. For such it was developed a new scanning prototype machine capable of acquiring the 3D road surface data and characterize the road texture through two algorithms that allows calculate the Estimated Texture Depth (ETD) and Texture Profile Level (L) indicators. The experimental results obtained from nine road samples validate the developed algorithms for the texture analysis and showed good agreement between the scanning prototype equipment and the traditional Sand Patch Method.Fundação para a Ciência e a Tecnologia (FCT) through the PhD Grant referenced SFRH/BD/18155/200

Microsurfacing Pavement Solutions with Alternative Aggregates and Binders: A Full Surface Texture Characterization

The road surface texture is responsible for controlling several quality/safety road indicators, such as friction, noise, and fuel consumption. Road texture can be classified into different wavelengths, and it is dependent on the material used in the paving solution. With the aim of evaluating and characterizing the surface texture of a microsurfacing road pavement, six microsurfacing samples were made in the laboratory with both traditional materials (basaltic aggregates and bituminous emulsion) and with innovative materials from recycling procedures (crumb rubber (CR) and artificial engineered aggregate (AEA)). The characterization was performed through the use of a conoscopic holography profilometer with high precision and post-processing of the profiles detected through consolidated algorithms (ISO standards). We found that the aggregate type plays a very important role in the pavement texture. The binder agent seems to be highly important, but more studies regarding this are necessary. The use of crumb rubber as an aggregate proved to be feasible, and the texture parameters that were obtained were in accordance with the benchmark ones. In addition, the study shows that the use of artificial engineered aggregates does not impair the surface texture. Finally, the use of the texture parameters defined by the ISO standards, together with a statistical analysis, could be useful for defining the surface texture characteristics of microsurfacing

Achievements and Prospects of Functional Pavement

In order to further promote the development of functional pavement technology, a Special Issue entitled “Achievements and Prospects of Functional Pavement” has been proposed by a group of guest editors. To achieve this objective, the articles included in this Special Issue are related to different aspects of functional pavements, including green roads to decrease carbon emissions, noise, and pollution, safety pavements to increase skid resistance through water drainage and snow removal, intelligent roads for monitoring, power generation, temperature control and management, and durable roads to increase service life with new theories, new design methods, and prediction models, as highlighted in this editorial

Feasibility and assessment of using recycled rubber for infrastructure applications

“The United States needs to mine billions of tons of raw natural aggregate each year. At the same time, millions of scrap tires are stockpiled every year. Therefore, replacing natural aggregate with recycled crumb rubber aggregate will be beneficial to the construction industry and environment. This research aimed to investigate the feasibility of using recycled rubber in new construction applications. Based on size, recycled rubber was selected to match its natural counterpart. Different ratios of recycled crumb rubber were used as a fine aggregate replacement in concrete masonry units (CMUs) where the rubberized units showed a lower unit weight, higher ultimate strain, and better durability. In addition, the thermal conductivity of rubberized masonry units decreased with increasing the rubber content resulting in a reduction in heating energy consumption. In a different application, recycled crumb rubber was used as a full or partial replacement of coarse aggregate in chip seal surfacing where it shows better retention especially with longer curing time. The rubberized chip seal had a rougher surface which increases driving safety. Environmentally, the toxic heavy metals leached from the rubberized chip were below that of the EPA drinking water standards with a significant reduction of heavy metal leaching when rubber was used with emulsion in the form of chip seal. The third application was utilizing the waste of scrap tire processing in a form of rubber- fiber powder (RFP) as a sand replacement within cement mortar. RFP was used as an additive to provide more corrosion resistance and less heat of hydration of cement mortar. Incorporating RFP within plastering mortar disclosed that RFP can be used as an eco-friendly additive to provide better crack resistance, thermal and acoustical insulation as well as noise reduction”--Abstract, page iv