Liedi Bernucci

Monitoring the condition of roads pavement surfaces: proposal of methodology using hyperspectral images

With the current system of concession roads in Brazil, both concessionaires and regulatory agents have been charged with improving the quality of the pavement on Brazilian highways. This situation requires the search for new tools that can facilitate the survey of pavement conditions in less time and at a lower cost than traditional methods. Recently, an increasing number of high-resolution spatial images have become available on the world market following the development of new remote sensing satellites and airborne sensors. Similarly, multispectral images and even hyperspectral images are now available commercially and for scientific research. The paper presents a new methodology for the identification of asphalted pavement surfaces condition and the classification of the main types of asphalt defects using hyperspectral images from airborne digital sensors. The objective of this study was to generate indexes of pavement conditions from images that can be compared with the indicators of pavement surface conditions already used by national regulatory agencies.

Laboratory and field evaluation of cold recycling mixture with foamed asphalt

Cold recycling with foamed asphalt stabilisation has been gaining acceptance and growing steadily. This study evaluates the performance of cold recycled mixes stabilised with foamed asphalt, with respect to the effects of confining stresses, and material moisture content. An experimental test section with a foamed stabilised recycled material used as the base course was monitored through quality control and quality assurance and falling weight deflectometer (FWD) tests. In laboratory, indirect tensile strength, triaxial resilient modulus, and permanent deformation tests were performed. Based on the results obtained, one can conclude that the curing is a critical consideration in terms of timing and its influence on pavement performance. Triaxial tests showed the stress dependency of this bitumen-stabilised material, while permanent deformation results indicated some potential for damage in early stages after construction. On the field evaluation, FWD data indicated the decrease in deflection with time, as a result of the increase in the layers stiffness.

Stress relief asphalt layer and reinforcing polyester grid as anti-reflective cracking composite interlayer system in pavement rehabilitation

An anti-reflective composite interlayer system, composed by a stress relief asphalt layer and a reinforcing polyester grid, was discussed based upon the results of field and laboratory research programs. The stress relief asphalt layers dissipate the stresses in the cracks tip, and reduce vertical and horizontal displacements of the subjacent crack in the new overlay. Polyester grid is a high tensile strength material that slows or even stops the reflective crack in the overlay. The field research program consisted of a highway trial section subjected to an accelerated test by using a transit simulator (HVS – Heavy Vehicle Simulator). A wheel reflective cracking test was carried out in laboratory, using the Displacement Meter CAM (Crack Activity Meter) to measure the horizontal and vertical movements on the crack or joint slab during the wheel load cycles. The results showed that both relief asphalt layer and reinforcing polyester grid work together as composite solution, technically and economically viable, which delay or block the crack reflection.

Comparison of the n-alkanes and polycyclic aromatic hydrocarbons concentrations in the atmosphere during the preparation of warm and hot mixtures asphalt for pavements

Asphalt binder is used in the production of hot mixes asphalt (HMA) for paving and, due to the high temperatures used, generates fumes thatcontainn-alkanes and polycyclic aromatic hydrocarbons (PAH). Asphalt mixes prepared at lower temperatures, such as warm mixes asphalt (WMA), may contribute to reduce the emissions of those compounds and save energy. This paper investigatesn-alkanes and PAH in the total suspended particles during the preparation of WMA, in comparison with HMA, in laboratory. The results showed that the n-alkanes of the WMA and HMA presented Cmax at n-C26 and n-C28, respectively; also, the total content of n-alkanes was higher for the HMA than forthe WMA. Besides, benzo[b]fluoranthene and benzo[a]anthracene were the major PAH in the WMA, while the higher temperatures of the HMA were observed to volatilize all larger PAH, demonstrating higher potential of inhalation exposure.

Characterization of granite and limestone powders for use as fillers in bituminous mastics dosage

This paper discusses the importance of studies on materials known as fillers from different mineral origins, used in asphalt mixes, specifically in the formulation of mastics. The research was carried out on samples of limestone and granite rock filler and asphalt binder (50/70). The samples were evaluated through semiquantitative chemical analyses by X-ray fluorescence, granulometry by low angle laser emission, scanning electron microscopy, softening point tests, penetration tests, and aggregate-asphalt binder and aggregate-mastic adhesion tests. The results highlighted convergent trends, indicating that the active behavior of the fillers in the mastic formulation is not related to the size of the particles, but rather to their form, surface texture, specific surface area and mineralogical nature, allowing the filler activity concept to be divided into two components: physical (hardening) and chemical (adhesion).

Field Aging Evaluation of Asphalt Binders by Chemical and Rheological Characterization

Two field aged asphalt binders were evaluated in the study. The binders were extracted and recovered from samples that were collected from two 4 cm HMAs in the field at different times. Chemical and rheological tests were performed to quantify the aging. The binder’s chemical properties were evaluated by SARA fractions (saturates, asphaltenes, resins and aromatics), gel permeation chromatography (GPC), nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy. The rheological tests were carried out in a dynamic shear rheometer (DSR). Dynamic shear modulus (|G*|) and multiple stress creep and recovery (MSCR) tests were performed to evaluate the change in the binders rheological properties. Both chemical and rheological results confirm the continuous aging of the asphalt binder in the field, mostly up to 24 months after construction, although the greatest aging occurs during mixing. Rheological results indicated that after 36 months of field aging, the two binders were performed similarly even though they aged differently.

Aging Characterization of Biobinder Produced from Renewable Sources

This study aims to investigate the effect of the temperature in the aging of a biobinder obtained from vegetal source. In this sense, the Rolling Thin Film Oven Test test was performed according to the ASTM D2872 (2012), considering the standard test temperature (163 °C) and two others test temperatures (150 °C and 180 °C). The unaged and aged binders (Neat Asphalt Binder, AC 30/45, and the biobinder) had their rheological and chemical properties analyzed. Under the same aging conditions, it was found that the biobinder was more susceptible to aging than the neat asphalt binder (AC 30/45). Regarding the biobinder aged under different conditions, the incremental RTFOT temperature presented some beneficial aspects to high-temperature performance; however, it might compromise the performance at intermediate temperature which can be inferred from fatigue tests. Chemical results indicated that the carbonyl and sulphoxide indexes were not adequate for the analysis of the oxidation and aging of the biobinder.

Highly Modified Asphalt Binder for Asphalt Crack Relief Mix

Reflective cracking is a common issue with respect to rehabilitated asphalt pavements, especially when the rehabilitation is done by applying a hot-mix asphalt overlay on the existing damaged pavement. Several approaches can be adopted to delay reflective cracking. They include an increase of the overlay thickness and the use of a stress relief asphalt mixture (SRAM), which is a fine-graded, flexible, and thin asphalt interlayer. Because the efficiency of a SRAM is highly related to the properties of the asphalt binder used in the mixture, it is of interest to use a highly modified asphalt (HiMA) binder. This paper describes a field test comprising three sections at BR-116 (a heavily trafficked highway in Brazil). One of the rehabilitation strategies used for a cracked asphalt pavement was a 2.5-cm SRAM (produced with a HiMA binder) and 5-cm styrene–butadiene–styrene (SBS) hot-mix asphalt (HMA). The other two strategies were to apply SBS HMA overlays of different thicknesses (7.5 cm and 10.5 cm). The aim was to evaluate and compare the capability of these solutions to control reflective cracking. Rheological properties and multiple stress creep and recovery tests were performed on the asphalt binders, and the semicircular bending test was performed on the asphalt mixtures. The surface conditions were monitored, and the results for each section were compared. After a 29-month period, the section that received the interlayer had the lowest cracked area and showed better resistance than the overlays did to reflective cracking and better maintenance of the original thickness of the pavement.

Case history study: field monitoring and performance prediction of a field-blended rubber asphalt mixture in Brazil

ABSTRACT Among the fabrication processes available for obtaining asphalt rubber, terminal blend is the most commonly used in Brazil. On the other hand, the use of field-blended rubber asphalt has been around in the United States for decades, especially in the state of Arizona. The lack of information regarding this technique in Brazil, however, inhibits a more common use in pavement construction/rehabilitation. This case history study was conducted in order to characterise the field performance of the first pavement rehabilitation job in Brazil using a field-blended rubber asphalt mixture and attempt to predict its future performance. A 500-m test section using a field-blended rubber asphalt mixture with a gap-graded aggregate as a surface course was monitored periodically through pavement deflection tests, roughness, rutting and surface conditions. Pavement monitoring revealed good functional and structural conditions after 4 years of service life. Accelerated pavement testing (f-sAPT), conducted in a representative test section using a full scale, mobile traffic simulator, exhibited promising performance. No cracking was observed in the test section and the average maximum rut depth was below limits after simulating 7 years of service life. Results from the f-sAPT simulation were then used to calibrate the performance cracking and rutting models in the Highway Development and Management Model (HDM-4).

Adhesion between asphalt layers through the Leutner Shear Test

Reflective cracking is a common issue present in recently rehabilitated pavements, especially when hot mix asphalt overlay is applied over the cracked pavement. It can cause the cracks to propagate to the new asphalt layer in a short period of time, wasting most of the resources spent in the rehabilitation project. Among many existing techniques to control reflective cracking, there is the application of an asphalt interlayer capable of relieving the stresses that reach the overlay, also known as Stress Absorbing Membrane Interlayer (SAMI). This solution can be highly efficient but it is essential to ensure adequate adhesion at the interface between layers, otherwise movement at the interface will eventually cause cracking at the pavement surface. The described rehabilitation solution was applied in a test site at BR-116 highway. As for the SAMI, an asphalt mixture produced with fine granite aggregates and Highly Modified Asphalt (HiMA) binder was used. The hot mix asphalt (HMA) overlay was produced using SBS-modified asphalt binder and the same aggregates source. Tack coat was applied between the asphaltic layers to ensure proper bonding. In this study, field samples were taken and the Leutner Shear Test was used to assess the bond strength at the interlayer-overlay interface. Results have shown that the bond strength was adequate in the test section. Therefore, the efficiency of the solution can be studied without influence of any debonding effects. The values obtained for the shear strength were higher than recommended, so lower rates of tack coat could still be effective.