MAT-756: INVESTIGATION OF THE IMPACT OF RAP GRADATION ON THE EFFECTIVE BINDER CONTENT IN HOT MIX ASPHALT

Nowadays, it is common to add a little amount of Reclaimed Asphalt Pavement (RAP) in asphalt mixes without changing too much properties such as modulus and low temperature cracking resistance. Not only will those mixes be able to make roads last longer, but they will be a greener alternative to usual mixes. In order to make a flexible pavement design, the mixture behavior is usually characterized with the complex modulus. To have a high modulus mix, you need to control the gradation precisely even when RAP is added. When performing a mix design to incorporate RAP, it is desirable to know the RAP binder characteristics and content and its gradation. In the literature, there is no clear vision of the RAP gradation impacts on the mixture properties and field performance. The objective of this study, performed at the Pavements and Bituminous Materials Laboratory (LCMB), is to evaluate the impact of RAP gradation on Hot Mix Asphalt. This is needed to understand how much binder can be transferred during mix from RAP to virgin aggregate. In this study, a single source of RAP was separated into different sizes and mixed with a specific group of virgin aggregates. Then, according to their size, the mixes were separated again into the RAP group and virgin aggregate. While these were mixed, active RAP binder transferred to virgin aggregate. Then ignition test (ASTM D6307) was adapted to separate RAP binder from virgin aggregate. With this procedure, it was possible to see that, for a given temperature and mixing time, activated binder amount of coarse RAP particles and fine RAP particles. The Ignition test result showed that coarse RAP particles have more active binder in mix but ITS test indicated that fine RAP particles have higher strength

MAT-752: FIELD TESTING AND EVALUATION OF RECLAIMED MATERIALS AS AGGREGATE FOR OPSS GRANULAR B TYPE II

In urbanized regions of Ontario, the road construction industry faces a number of challenges due to the growing scarcity of locally-sourced natural aggregate materials and increased restrictions on the approval and development of new aggregate extraction sites. In an effort to maintain sustainable and economical sources of construction aggregates, companies are increasingly seeking to supplement or replace natural aggregates with available artificial materials such as crushed reclaimed concrete aggregate (RCA), and reclaimed asphalt pavement (RAP). Currently, Ontario Provincial Standard Specification (OPSS) 1010 permits the use of processed reclaimed construction materials in a variety of road base, subbase and asphaltic concrete layers, with the exception of Granular B Type II, which is a higher-performance subbase specification that solely allows primary materials produced from crushed bedrock. Consequently, there is a need to better understand the performance of reclaimed materials as alternative aggregates in Granular B Type II. This paper focuses on a field testing program carried out at two job sites in Ontario. This testing program assessed five different aggregate blends conforming to Granular B Type II gradation requirements which vary in composition from 100% natural crushed rock to 100% processed RCA. Test pads were constructed from each blended material to assess field compactibility using a nuclear density gauge and to determine the in-situ moduli of the compacted materials using a portable lightweight deflectometer (LWD). The field testing results indicate that RCA and RAP can be successfully utilized as aggregate materials in Granular B Type II subbase applications

TRA-961: FOAM GLASS LIGHTWEIGHT AGGREGATE: THE NEW APPROACH

Foam glass lightweight aggregate (LWA) derived from mixed waste and recycled glass has great potential for use as an alternative material for several applications in building and other industrial applications. Despite the significant superior features of the current product, there is still room for further research to improve the structural performance of newly developed foam glass and foam glass-ceramics produced from waste and recycled materials. Improvements may be achieved through controlling microstructures and the distributions of pore sizes and shapes, altering chemical and phase compositions, creating reinforced structures by the inclusion of other fibrous materials as well as adding colour to the foam glass and glass-ceramics. One commercially used foam glass gravel has been selected and was the subject of a wide range of tests to determine its physical and mechanical properties and to compare them to conventional products in the industry. Results obtained from percent crushed particle content, abrasion resistance and freezing and thawing resistance testing are presented and analysed. Methods for improving foam properties and expanding its usefulness in engineering applications are proposed; adjusting the microstructure characteristics and changing the chemical and phase composition were found to be effective. A deeper examination of the microstructure by microscopy (SEM or TEM) further revealed the promising features of the evaluated material as a new versatile construction material. In addition, inclusion of colouring oxides in foam formulation was examined as an innovative way for increasing mechanical strength in a colourful product

Comportement à la fatigue des matériaux granulaires traités aux liants hydrocarbonés.

Cette thèse sur le comportement des matériaux granulaires traités aux liants hydrocarbonés a été réalisée au Département Génie Civil et Bâtiment (DGCB) de l\u27Ecole Nationale des Travaux Publics de l\u27Etat. Elle s\u27inscrit dans le cadre d\u27une collaboration avec la société TOTALFINAELF. Une partie de cette thèse a été réalisée dans le cadre du programme RILEM WG3 du TC 182 pour l\u27étude de la fatigue des enrobés bitumineux. Certains aspects ont également fait l\u27objet d\u27une collaboration avec le Laboratoire Central des Ponts et Chaussées (LCPC). La première partie de cette thèse concerne une étude bibliographique sur les matériaux bitumineux, la fatigue des enrobés bitumineux et le phénomène d\u27autoréparation. La deuxième partie présente la campagne expérimentale réalisée lors de cette thèse. On présente la mise au point et la validation d\u27un essai homogène en Traction-Compression, adapté à l\u27étude de la fatigue des enrobés bitumineux. L\u27essai est réalisé à température et à fréquence constantes (10ºC et 10 Hz), en mode de contrainte ou de déformation imposée. Seize formulations différentes ont été testées. Une étude menée sur les différents critères visant à prédire la durée de vie en fatigue des enrobés bitumineux est présentée. L\u27approche du DGCB pour le calcul des taux d\u27endommagement, a été appliquée sur les résultats de la campagne expérimentale. Grâce à cette approche, l\u27influence de plusieurs paramètres de formulation des enrobés bitumineux sur le comportement en fatigue a été mise en évidence. Parallèlement, une partie de la campagne expérimentale a été réservée pour explorer le phénomène d\u27autoréparation. Une série d\u27essais a été effectuée sur trois formulations différentes en introduisant des périodes d\u27arrêt de sollicitation. Finalement, Dans la dernière partie de cette thèse, une loi de dommage par fatigue est proposée. Cette loi est intrinsèque et basée sur la méthode du DGCB. Elle prend en considération la correction des effets parasites sur les valeurs du module et l\u27évolution non linéaire de l\u27endommagement dans les essais de fatigue

Time-Temperature Superposition of Asphalt Materials and Temperature Sensitivity of Rheological Parameters (TSRP)

Different temperature sensitivity parameters were introduced to address the temperature susceptibility of asphalt cement, all of which used a single number to define each particular material by assuming linearity in temperature sensitivity. The time-temperature superposition principle (TTS) has been used, under different circumstances, to understand the viscoelastic properties of asphalt materials. Various empirical relationships have been developed to explain the relationship between TTS shift factors and temperature. This research evaluated the suitability of such relationships to evaluate the temperature sensitivity of viscoelastic materials and found that the modified Arrhenius equation is more fundamentally appropriate for this purpose. Results of this study showed that the temperature sensitivity of rheological parameters (TSRP), introduced here, is sensitive to age hardening (for both asphalt cement and mix) and can be used to evaluate age hardening and changes in mix’s volumetric properties as well as investigating the effect of mix design properties.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Evaluation for the Leaching of Cr from Coal Gangue Using Expansive Soils

Coal gangue can cause significant heavy metal pollution in mining areas, which would have a negative impact on the environment and human health. The objective of this research is to investigate the relationship between expansive soil amount and the leaching behavior of Chromium from coal gangue and the engineering properties of coal gangue used as building materials. The leaching behavior of Chromium from coal gangue was observed using atomic absorption spectrometry. A column leaching experiment was conducted to examine the impact of leaching time and heavy metal concentration. Furthermore, the unconfined compressive strength test was employed to evaluate the engineering properties of coal gangue with expansive soil. The results of the study demonstrate that pH of leachate solutions, leaching time, and expansive soil amounts in mixtures have important influence on Chromium concentration. The leachate solutions, which behave like alkaline, provide a positive environment for adsorbing Cr. Adding expansive soil can reduce leached concentrations of Chromium from coal gangue when compared to leachate of original coal gangue. It was found that 30% expansive soil was an improved solution because it delayed the cumulative concentration to reach the limitation line. Moreover, the unconfined compressive strength of coal gangue was boosted through adding expansive soil

Rutting Behaviour of Geopolymer and Styrene Butadiene Styrene-Modified Asphalt Binder

Modifying asphalt binders is an effective method of improving the performance of asphalt pavement, such as its resistance to rutting. However, because modification changes the behaviour of binders, substantial laboratory testing is required before field application to determine the best mixtures. This research aimed to evaluate the impacts of temperature, stresses, polymer type, and modification rate on the rutting behaviour of the asphalt binder modified with fly-ash-based geopolymer (GF), styrene butadiene styrene (SBS), and a combination of SBS and GF. The rheological properties of asphalt binders were investigated using the frequency sweep test at various temperatures. Additionally, the multiple stress creep recovery test was conducted at various temperatures and stresses to calculate the non-recoverable creep compliance (Jnr) and the percent strain recovery (R). The rutting resistance of asphalt mixture was assessed using the Hamburg wheel rut test. The results revealed that the asphalt binder with 8% geopolymer (8%GF) exhibited the best response in terms of complex shear modulus (G*), rutting factor (G*/sinδ), R, and Jnr compared to the 4%GF and 12%GF at different temperatures. Another interesting finding is that GF’s use in the hybrid binder (2%SBS + 8%GF) led to a significant increase in the shear complex modulus and a decrease in the phase angle compared to the binder modified with 2%SBS. The geopolymer decreased the binder’s sensitivity to temperature for both unaged and RTFO asphalt binders. The hybrid binder would also improve strain recovery under high stress and temperatures and the ability to withstand severe traffic loads. Furthermore, there is a crucial relationship between temperature and Jnr, which could help asphalt pavement designers select suitable modifiers considering the local climate and traffic volume

Incorporation of the Multi-Layer Plastic Packaging in the Asphalt Binders: Physical, Thermal, Rheological, and Storage Properties Evaluation

The amount of residual Multi-layer Plastic Packaging (MPP) in Canada has greatly increased in the last two decades, which has economic and environmental consequences. MPP is primarily made up of two or more layers of Polyethylene (PE), Polyester (PET), Nylon (NY), and Metalized Polyester (METPET). While MPP has not been used as an asphalt modifier, some of the materials commonly found in MPP, such as PE and PET, have also been successfully used as asphalt modifiers. Nevertheless, a few recent studies have demonstrated the potential for reusing MPP as an asphalt modifier to improve asphalt pavement performance. Recycling post-industrial MPP instead of using raw polymers could lead to economic and environmental benefits. However, a comprehensive study to evaluate MPP as a viable asphalt additive is lacking. The main objective of this study is to evaluate the feasibility of using MPP as an asphalt modifier via the wet method, considering the physical, thermal, rheological, and storage properties of the MPP-modified binder at different MPP concentrations (2%, 4%, and 8%) in asphalt cement (PG 58–28). MPP-modified binders were evaluated using the following instruments: Differential Scanning Calorimeter (DSC), Thermogravimetric Analysis (TGA), Superpave Dynamic Shear Rheometer (DSR), Rotational Viscosity (RV), and Environmental Scanning Electron Microscopy (ESEM). Test results indicated that the incorporation of MPP has a strong potential to improve permanent deformation resistance at high temperatures. In addition, MPP shows a moderate impact on fatigue cracking performance at intermediate temperatures. Overall, in low-temperature climates, using less than 4% of MPP additives would offer higher fatigue damage resistance along with adequate permanent deformation. In high-temperature climates, higher concentrations of additives may be preferable to resist permanent deformation. Finally, MPP is a challenge for existing recycling systems, and its incorporation into asphalt applications may develop more sustainable materials that would contribute to circular economy principles

Predicting the Recovery and Nonrecoverable Compliance Behaviour of Asphalt Binders Using Artificial Neural Networks

Additives are widely used to enhance the rheological and performance properties of asphalt binder to satisfy the demands of extreme loading and climatic conditions. Meanwhile, adding to the complexity of asphalt binder behaviour that requires more time, effort, and material resources during laboratory work. The purpose of this research was to use Artificial Neural Networks (ANNs) to predict the recovery (R) and nonrecoverable compliance (Jnr) behaviour of asphalt binder based on mechanical test parameters and rheological properties of asphalt binder. A comprehensive experimental database consisting of the results of the frequency sweep and Multiple Stress Creep Recovery (MSCR) test using a dynamic shear rheometer (DSR) at five test temperatures (46 ∘C, 52 ∘C, 58 ∘C, 64 ∘C, and 70 ∘C). Prediction models for R and Jnr of asphalt binder modified with different contents of fly ash, fly ash-based geopolymer, glass powder/fly ash-based geopolymer, and styrene–butadiene styrene (SBS) were developed. The ANNs model was developed using five input parameters (temperature, frequency, storage modulus, loss modulus, and viscosity) and one hidden layer with five neurons. The results pointed out that the hybrid and 4%SBS binders achieved the highest ability to resist extremely heavy traffic and to recover the deformation with 60.1% and 85.5% at 46 ∘C, respectively, compared with the other modified asphalt binders. Excellent R-values for the total data set of 0.937, 0.997, 0.985, and 0.987 for Jnr3.2 of unaged binder, Jnr3.2 of aged binder, R3.2 of unaged binder, and R3.2 of aged binder, respectively. Therefore, the ANNs model is appropriate tool to predict the R3.2 and Jnr3.2 using unaged or aged binders at different temperatures

Characterization of Asphalt Mixtures Produced with Coarse and Fine Recycled Asphalt Particles

Utilizing recycled asphalt pavements (RAP) in pavement construction is known as a sustainable approach with significant economic and environmental benefits. While studying the effect of high RAP contents on the performance of hot mix asphalt (HMA) mixes has been the focus of several research projects, limited work has been done on studying the effect of RAP fraction and particle size on the overall performance of high RAP mixes produced solely with either coarse or fine RAP particles. To this end, three mixes including a conventional control mix with no RAP, a fine RAP mix (FRM) made with 35% percent fine RAP, and a coarse RAP mix (CRM) prepared with 54% of coarse RAP were designed and investigated in this study. These mixes were evaluated with respect to their rutting resistance, fatigue cracking resistance, and low temperature cracking performance. The results indicate that although the CRM had a higher RAP content, it exhibited better or at least the same performance than the FRM. The thermal stress restrained specimen testing (TSRST) results showed that the control mix performed slightly better than the CRM, while the FRM performance was adversely affected with respect to the transition temperature midpoint and the maximum tensile stress temperature. Both of the RAP incorporated mixes exhibited better rutting resistance than the control mix. With regard to fatigue cracking, the CRM performed better than the FRM. It can be concluded that the RAP particle size has a considerable effect on its contribution to the total binder content, the aggregate skeleton of the mix, and ultimately the performance of the mix. In spite of the higher RAP content in the CRM versus FRM, the satisfactory performance observed for the CRM mix indicates a great potential in producing high RAP content mixes through optimizing the RAP particle size and content. The results also suggest that the black curve gradation assumption is not representative of the actual RAP particles contribution in a high RAP mix