Reclaimed asphalt pavement with waste frying oil and crumb rubber

The application of Reclaimed Asphalt Pavement (RAP) has become a relatively standard material in the road industry in most countries. However, some of the problems associated with the addition of RAP to asphalt mixtures are the increase in moisture and cracking damage. The addition of rejuvenators into the recycled mixture containing RAP is also needed to enhance its performance although the rutting resistance remains a major issue. Therefore, there is a need to investigate the incorporation of other materials in the design of the asphalt mixture to achieve improved properties and better performance. This study was carried out to investigate the performance of the recycled asphalt mixture that consists of the conventional asphalt binder with 60/70 penetration grade, 25% and 40% RAP, and the incorporation of waste materials comprising 2.6% and 4.7% Waste Frying Oil (WFO) as the rejuvenator and 1.5% Crumb Rubber (CR) with sieve size of 0.15 mm as the modifier. The study was divided into three stages, namely evaluation of material properties, analysis of the asphalt binder properties, and determination and analysis of the asphalt mixture performance. Based on the results, the addition of 25% and 40% RAP in the asphalt mixture along with WFO and CR lowered the Indirect Tensile Strength (ITS) by 31.1% and 47.3%, respectively, which fulfilled the requirement of the ITS ratio test. The resilient modulus pattern for the recycled asphalt mixture containing WFO and CR was identical at 25 and 40 °C. When tested at 40 °C, the 25% and 40% RAP with incorporated WFO and CR generated a significant resilient modulus of 848 and 901 MPa, respectively. The recycled asphalt mixture with WFO and CR also exhibited a lower permanent strain than that of the virgin asphalt binder. The rutting values of all asphalt mixtures in the wheel tracking test demonstrated a similar pattern at 45 and 60 °C test temperatures. The rutting resistance of the recycled asphalt mixture with WFO and CR slightly improved compared to the virgin asphalt binder at 60 °C. Therefore, the incorporation of WFO and CR has a considerable influence on the RAP performance while preserving the environment and reducing pollution through the recycling of waste materials

Performance of Aged Asphalt Binder Treated with Various Types of Rejuvenators

High demand for asphalt binders in road construction verifies the need of finding alternative materials through asphalt pavement recycling. This paper investigated the impact of different rejuvenators on the performance of an aged asphalt binder. Virgin Olive oil, virgin cooking oil, waste cooking oil, virgin engine oil, and waste engine oil were added to a 30/40 penetration grade aged asphalt binder at a fixed oil content of 4% for all types. The wet method was used to blend the rejuvenators and aged asphalt binder. The physical, rheological, and chemical properties of the rejuvenated asphalt binder were evaluated using several laboratory tests which include penetration, softening point, bleeding, loss on heating, storage stability, penetration index, ductility, viscosity, dynamic shear rheometer, and Fourier transform infrared spectroscopy. The outcomes of the physical properties showed that the olive, waste, and virgin cooking rejuvenators can restore the aged asphalt binder to a penetration grade of 60/70. In contrast, the virgin and waste engine oil required a more quantity of oil to rejuvenate the aged asphalt binder. A sufficient amount of rejuvenator could regenerate the (G*/sin δ), (δ°), and (G*) for the aged asphalt binder. The addition of virgin olive and cooking oils in aged asphalt led to a rutting issue. No chemical reactions were observed with the addition of rejuvenators but they give an impact on reducing the oxidation level of the aged asphalt binder. As a result, further research should be performed on waste cooking oil given that it is inexpensive and provides excellent performance results. Doi: 10.28991/cej-2021-03091669 Full Text: PD

Moisture sensitivity of crumb rubber modified modifier warm mix asphalt additive for two different compaction temperatures

Crumb rubber obtained from scrap tires has been incorporated with asphalt binder to improve the performance of asphalt mixtures in the past decades. Pavements containing crumbrubber modified (CRM) binders present one major drawback: larger amounts of greenhouse gas emissions are produced as there is rise in the energy consumption at the asphalt plant due to the higher viscosity of these type of binders compared with a conventional mixture. The objective of this paper is to calculate the optimum bitumen content for each percentage and evaluate the moisture sensitivity of crumb rubber modified asphalt at two different compacting temperatures. In this study, crumb rubber modified percentages was 0%, 5%, 10% and 15% from the binder weight, with adding 1.5% warm mix asphalt additive (Sasobit) and crush granite aggregate of 9.5mm Nominal maximum size was used after assessing its properties. Ordinary Portland Cement (OPC) used by 2% from fine aggregate. The wet method was using to mix the CRM with bitumen, the CRM conducted at 177°C for 30 min with 700rpm and Sasobit conducted at 120°C for 10 min with 1000rpm. As a result, from this study the optimum bitumen content (OBC) was increased with increased crumb rubber content. For performance test, it was conducted using the AASHTO T283 (2007): Resistance of Compacted Bituminous Mixture to Moisture-Induced Damage. The result was as expected and it was within the specification of the test, the result show that the moisture damage increased with increased the crumb rubber content but it is not exceeding the limit of specification 80% for indirect tension strength ratio (ITSR). For the temperature was with lowing the temperature the moisture damage increased

Influence of crumb rubber size particles on moisture damage and strength of the hot mix asphalt

Tropical countries such as Malaysia experience a high amount of rainfall that can lead to a common type of distress on the roads known as moisture damage. Using waste materials as additives in the asphalt mixture is an innovative measure to improve the quality and strength of the mixture. In this study, 5% of crumb rubber (CR) by the total weight of binder was added to the asphalt mixture in three different sizes of 0.075 mm, 0.15 mm, and 0.3 mm. The wet method was applied to blend the CR with virgin asphalt binder grade 60/70. The aggregate gradation applied in this study was 9.5 Nominal maximum aggregate size. The samples were produced with the Superpave gyratory compactor. Moisture sensitivity (ASSTHO T-283) and indirect tensile strength (ITS) tests were performed to evaluate the impact of the CR sizes on the asphalt mixture. The findings showed that the CR addition improved the strength of the asphalt mixture. Furthermore, there was an increment in the ITS with an increasing size of CR. The addition of 5% CR resulted in a minor reduction of the moisture resistance. Thus, a slight improvement in the moisture resistance was detected with a reduction in CR size. Overall, all asphalt mixtures in this study had TSR of more than 80%, thus passing the moisture damage test requirements

Encouraging Sustainable Use of RAP Materials for Pavement Construction in Oman: A Review

The Sultanate of Oman has experienced rapid development over the last thirty years and has constructed environmentally friendly and sustainable infrastructure while it continues to find economical alternative resources to achieve the goals of the Oman 2040 vision. The primary concerns are preserving natural resources and reducing the impact of carbon dioxide (CO₂) emissions on the environment. This review aims to encourage the sustainable use of reclaimed asphalt pavement (RAP) materials in pavement construction and focuses primarily on employing RAP materials in new pavement projects. Currently, new construction projects utilise a significant percentage of demolished asphalt pavement to save costs and natural resources. The key issue that arises when mixing RAP into new asphalt mixtures is the effects on the mixtures’ resistance to permanent disfigurements, such as fatigue cracks, that influence asphalt mixture performance. Numerous studies have assessed the impact of using RAP in asphalt mixtures and found that RAP increases the stiffness of asphalt mixtures, and thus improves rutting resistance at high temperatures. Nevertheless, the findings for thermal and fatigue cracking were found to be contradictory. This review will address the primary concerns regarding the use of RAP in asphalt pavements, and aims to encourage highway agencies and academic researchers in the Gulf countries to develop frameworks for the practical usage of RAP in the construction of sustainable pavement systems

Encouraging Sustainable Use of RAP Materials for Pavement Construction in Oman: A Review

The Sultanate of Oman has experienced rapid development over the last thirty years and has constructed environmentally friendly and sustainable infrastructure while it continues to find economical alternative resources to achieve the goals of the Oman 2040 vision. The primary concerns are preserving natural resources and reducing the impact of carbon dioxide (CO₂) emissions on the environment. This review aims to encourage the sustainable use of reclaimed asphalt pavement (RAP) materials in pavement construction and focuses primarily on employing RAP materials in new pavement projects. Currently, new construction projects utilise a significant percentage of demolished asphalt pavement to save costs and natural resources. The key issue that arises when mixing RAP into new asphalt mixtures is the effects on the mixtures’ resistance to permanent disfigurements, such as fatigue cracks, that influence asphalt mixture performance. Numerous studies have assessed the impact of using RAP in asphalt mixtures and found that RAP increases the stiffness of asphalt mixtures, and thus improves rutting resistance at high temperatures. Nevertheless, the findings for thermal and fatigue cracking were found to be contradictory. This review will address the primary concerns regarding the use of RAP in asphalt pavements, and aims to encourage highway agencies and academic researchers in the Gulf countries to develop frameworks for the practical usage of RAP in the construction of sustainable pavement systems

Computational modelling for predicting rheological properties of composite modified asphalt binders

The complicated viscoelastic characteristics of asphalt binders make it a challenging task to precisely predict their rheological behavior. This study aims to investigate and compare the suitability of response surface methodology (RSM) and machine learning (ML) modeling approaches in predicting the complex modulus (G*), phase angle (δ), and rutting parameter (G*/sinδ) of Nano Silica (NS) and/or waste denim fiber (WDF) modified asphalt binders before and after short-term aging. To achieve this, an experimental scheme was designed for RSM and ML modeling with three variables including NS contents (0–6%), WDF contents (0–6%), and testing temperature (40–76 °C) as the inputs, and provided the G*, δ and G*/sinδ before and after short-term aging as the outputs. A wide range of ML algorithms was evaluated to determine the optimum ML model that can be used to accurately predict the rheological properties of NS/WDF-modified asphalt binders. RSM analysis results indicated that the G*, δ, and G*/sinδ of NS/WDF composite asphalt are significantly affected by the %NS, %WDF, and test temperatures. The RSM-developed models showed coefficient of determination (R2) values exceeding 0.97 for all responses, indicating adequate agreement between experimental results and models developed by RSM. From ML algorithms optimization and among all evaluated ML models, it was found that Gaussian process regression (GPR) exhibited the highest R2 with a value of (0.99) and the lowest Root Mean Square Error (RMSE) with a value of approximately 1%. The performance evaluation of the GPR model for predicting all responses showed a very small difference between the predicted and experimental results, highlighting the prediction accuracy of the developed ML models

Image processing procedure to quantify the internal structure of porous asphalt concrete

Purpose: In order to fully understand the properties of porous asphalt, investigation should be conducted from different point of views. This is from the fact that porous asphalt mixture designed with the same aggregate gradation and air void content can give different infiltration rate due to the different formation of the internal structure. Therefore, the purpose of this paper is to investigate the micro-structural properties and functional performance of porous asphalt simultaneously. Design/methodology/approach: The aim is to develop imaging techniques to process and analyze the internal structure of porous asphalt mixture. A few parameters were established to analyze the air void properties and aggregate interlock within the gyratory compacted samples captured using a non-destructive scanning technique of X-ray computed tomography (CT) throughout the samples. The results were then compared with the functional performance in terms of permeability. Four aggregate gradations used in different countries, i.e. Malaysia, Australia, the USA and Singapore. The samples were tested for resilient modulus and permeability. Quantitative analysis of the microstructure was used to establish the relationships between the air void properties and aggregate interlock and the resilient modulus and permeability. Findings: Based on the results, it was found that the micro-structural properties investigated have successfully described the internal structure formation and they reflect the results of resilient modulus and permeability. In addition, the imaging technique which includes the image processing and image analysis for internal structure quantification seems to be very useful and perform well with the X-ray CT images based on the reliable results obtained from the analysis. Research limitations/implications: In this study, attention was limited to the study of internal structure of porous asphalt samples prepared in the laboratory using X-ray CT but can also be used to assess the quality of finished asphalt pavements by taking core samples for quantitative and qualitative analysis. The use of CT for material characterization presents a lot of possibilities in the future of asphalt concrete mix design. Originality/value: Based on the validation process which includes comparisons between the values obtained from the image analysis and those from the performance test and it was found that the developed procedure satisfactorily assesses the air voids distribution and the aggregate interlock for this reason, it can be used

A comparative assessment of the physical and microstructural properties of waste garnet generated from automated and manual blasting process

Cold mix asphalt (CMA) is an eco-friendly sustainable asphalt mixture, mostly for asphalt surface treatments (ASTs). However, material compatibility and poor adhesion leading to high voids, moisture damage susceptibility, and weak early strength remain challenging. Efforts to solve this limitation is beamed towards binder improvement and modification with modifiers, adhesion promoters, or polymers. Other forms of AST mixture improvement entail supplementary cementitious reinforcing or pozzolanic agents in the form of by-products. In this study, the physio-mechanical and microstructural desirability of spent garnet for use as fine aggregate in CMA was explored. Spent garnet is a by-product of abrasive blasting, often produced in large quantities and disposed of in landfills. Often, spent garnet waste gets contaminated with toxic elements either during usage or in landfills. This study aimed to investigate the properties of Automatically (AG) and Manually generated (MG) spent garnet grades. The physio-mechanical, morphologic, and chemical parameters of spent garnet were assessed to achieve this aim. The result compared with relevant specifications on cold mixtures plus Jabatan Kerja Raya (JKR) requirement. Moreover, crystallinity and composition were studied using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and X-ray Fluorescence (XRF). The presence of toxic heavy metals that often contaminate spent garnet deposits in landfills was evaluated too. Results suggested that both AG and MG’s high sand equivalent and least water absorption of 98 %, 89 %, and 0.14 %, 0.23 % accordingly, and can replace sand in CMA. However, MG spent garnet is not desirable for chemically sensitive materials. The AG garnet was found to be Pyrope while the MG spent garnet is largely Almandine garnet – the strongest form of garnet, including traces of other garnet forms

A new approach to enhance the reclaimed asphalt pavement features: role of maltene as a rejuvenator

The properties of aged asphalt can be renewed using rejuvenating agents. Rejuvenators can improve the performance of reclaimed asphalt pavement (RAP) by reducing the asphaltene-to-maltene ratio back to their initial state. This study assessed the function of maltene as a rejuvenator to renew aged asphalt. Penetration, softening point, ductility and viscosity tests were performed to determine the ideal maltene content to be incorporated into RAP. The rejuvenated asphalt samples were evaluated using rolling thin film oven (RTFO), dynamic shear rheometer (DSR), bending beam rheometer (BBR), Fourier transform infrared (FTIR), thermogravimetric (TGA) and atomic force microscopy (AFM) measurements. The outcomes were compared with virgin and aged asphalts. Both oxygenated groups and asphaltene content decreased by adding 12% maltene. Essentially, DSR, BBR, TGA, and AFM analyses divulged the comparable performance of rejuvenated asphalt with virgin asphalt, signifying the potency of maltene for practical applications