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The objective of this study is to investigate the effect of using Pozzolan as an asphalt binder modifier and assess its potential physical and rheological improvements. This research also intends to initiate a comprehensive research on the effect of Pozzolan on the rheological characteristics of asphalt binder since only limited studies have used Pozzolan as an asphalt binder modifier. Pozzolan was added to a (60/70) penetration grade asphalt binder at six different percentages in addition to the control asphalt binder. Both traditional and rheological tests on modified and control asphalt binders were performed. The traditional tests included penetration, softening point, flash and fire points, and ductility. The rheological tests, on the other hand, included rotational viscometer (RV) and Dynamic Shear Rheometer (DSR) tests. The outcomes proved that adding Pozzolan to asphalt binder enhanced high-temperature performance. 15% Pozzolan content was found to be the optimum content at which most rheological characteristics of the asphalt binder were enhanced. The experimental outcomes were contrasted and analyzed statistically by the analysis of variance (ANOVA) to discover any significant difference between the influence of Pozzolan and test temperature. The outcomes of one-way ANOVA pointed out that Pozzolan had a significant influence on the rotational viscosity and physical characteristics. Also, the change in Pozzolan content and temperature together showed a significant effect on the rutting parameter according to the two-way ANOVA outcomes.

This study aims at investigating the potential of using dry battery waste powders (DBWPs) as modifiers in asphalt binder. A 60/70 penetration grade asphalt binder was used in this study. DBWPs, which were extracted from spent batteries, were mixed with the asphalt binder at seven different percentages [0% (control sample), 2%, 4%, 6%, 8%, 10%, 15%, and 20% by weight of asphalt binder]. The mixing process was performed at 175 °C for 30 min using a high-speed mechanical mixer. To study the effect of DBWPs on asphalt binder properties, both traditional and Superpave binder tests were carried out. Consistency tests included penetration, softening point, and ductility, while Superpave tests included Rotational Viscometer (RV), Dynamic Shear Rheometer (DSR), and Bending Beam Rheometer (BBR). Flash and fire point tests were also conducted. The test results indicated that the addition of DBWP to the asphalt binder decreased ductility and penetration values and increased the softening and the flash and fire points of the asphalt binder. High-temperature rutting performance of asphalt binder, as presented by DSR rutting parameter (G*/sinδ), was improved by adding DBWP. The high-temperature performance grade of asphalt binder was raised by one grade by adding DBWP up to 10%, two grades at 15%, and three grades at 20%. On the other hand, fatigue and low-temperature performance of asphalt binder were adversely affected by adding DBWP. The Superpave fatigue parameter (G*.sinδ) was negatively increased by increasing the content of DBWP but remained less than the Superpave limit (≤ 5000 kPa). The low-temperature asphalt binder grade was decreased from − 22 °C (for control asphalt binder) to − 16 °C at 15% DBWP and then to − 10 °C at 20% DBWP. Therefore, it is recommended to use DBWP modifier in high-temperature regions to resist rutting distresses.

Bonding strength between asphalt and aggregate is considered an important feature that governs the future performance of flexible pavements. This study investigated five factors that have the poten...

There are various models for predicting the friction or skid number of asphalt pavements based on inputs such as aggregate characteristics, aggregate gradation, and traffic level. However, existing models are deterministic as they incorporate mean values of the input parameters and yield an average skid number value for a pavement section. Consequently, these models are not capable of accounting for variability in material properties and associated variation in the predicted skid number values. This study aims to develop a probabilistic approach that determines the mean as well as the variation in skid number in a pavement section. The efficacy of this approach is demonstrated by selecting one of the validated models that incorporate a wide range of aggregate characteristics. The results showed that while the average skid number predicted by the deterministic model may satisfy a required threshold/specification value, a fair percentage of the distribution could fall below the required value. The probabilistic approach is useful for engineers to determine the effect of aggregate characteristics on skid resistance distribution and to identify risks associated with the probability of skid resistance values in a pavement section fall below the required limit.

This research investigates the effect of adding three different modifiers to laboratory-prepared Superpave asphalt concrete mixtures to evaluate their ability to strengthen and reinforce asphalt co...

This study evaluated potential improvements in the physical and rheological properties of asphalt binders modified with crumb tire rubber (CTR), microcrystalline synthetic wax (MSW), and na...

The laboratory simulation of asphalt pavement surface deterioration is usually a lengthy process. In this study, a predictive tool (or equation) was developed to calculate the steady state torque-based coefficient of friction (Tfr) and the onset of steady state. To this end, nonlinear regression was utilized and a Graphical User Interface (GUI) was built in MATLAB®. The purpose of the tool is to reduce experimentation time. Eight sets of data were used. Data was obtained from laboratory testing conducted on eight Job Mix Formulas (JMFs) of highway materials obtained from the State of Ohio. The data was collected using a power unit (or motor) attached to a newly developed asphalt polishing machine to detect surface deterioration. The experiment measures torque values that are directly related to friction values; the so called torque-based coefficients of friction. The main characteristic of the equation allows for calculating the steady state Tfr and the onset of steady state. This enables the experimenter to determine when steady state is reached at a desired tolerance during the test, thus reducing the time required for testing. It was concluded that testing time can be reduced significantly (a range of 40% to 50% savings), which may be received positively by Departments of Transportation and other highway material testing laboratories around the world.

The goal of this study is to check the validity of using the waste vegetable oil as an additive to the asphalt cement, to be used later in the construction of flexible pavements. This will be considered as a proper and legal method of disposing this waste material. In this study, 1%, 2%, 4%, 6%, and 8% of waste vegetable oil by volume of the asphalt cement were used. Several laboratory tests were performed on the original and waste vegetable oil-modified asphalt cements. It was found that choosing the appropriate amount of waste vegetable oil will improve most of the tested properties. Therefore, it can be concluded that using the suitable amount of waste vegetable oil as a cement modifier is feasible, and can be considered as a proper and legal method for disposing the waste vegetable oil. Keywords: Asphalt cement, Waste vegetable oil, Asphalt cement modifier, Road construction, Waste material disposal

This study explores the effect of three types of modifiers on the rutting and resilient modulus performance of asphalt concrete mixtures using the dynamic creep test. Modifiers have been added to the asphalt binder at optimum percentages that have been chosen based on a previous study by the authors. 108 Superpave asphalt mixture specimens have been prepared. In this study, the dynamic creep test has been conducted at different temperatures (25 °C, 40 °C and 55 °C) and at three loading frequencies (1, 4 and 8 Hz). Accumulated axial micro-strain, creep stiffness modulus, and resilient modulus values have been measured. The results have showed an enhancement in the rutting resistance at high frequencies when adding the modifiers. The Crump Tire Rubber modified mixtures have showed the best results at high temperatures, and the Nano Silica modified mixtures had the best outcomes at intermediate temperatures, while the Microcrystalline Synthetic Wax modified mixtures have achieved the best results at lower temperatures. Statistical and regression analyses have showed that changing temperature, frequency, and modifier type had a significant effect on the accumulated axial micro-strain, creep stiffness modulus, and resilient modulus values. Models have been generated with relatively high coefficients of determination (R2) and adjusted R2, indicating their ability in explaining much of the variability in the response variables.

This paper investigates the potential application of wire wool in the modification of hot asphalt mixes (HMA). Wire wool material is widely available at local markets as a by-product of wire wool industry and as waste products from homes. For the purpose of this study, wire wool was cut into small pieces so that it can be placed in the asphalt mixes. Different percentages of wire wool were incorporated with the hot asphalt mixes (0.0%, 0.25%, and 0.5%) of the total weight of the asphalt binder. Various experimental tests were used to evaluate the modification effectiveness of combining wire wool with hot asphalt mixes, namely, the Marshall Stability, indirect tensile strength (ITS), dynamic creep, fatigue, and rutting tests. Test results proved that the addition of wire wool increased the tensile strength of the asphalt concrete mixes. However, rutting increased due to increasing percentage of wire wool. Therefore, mixes containing wire wool can be used in areas where rutting is not the expected predominant distress type.