Shu Wei Goh

Rheological Properties and Chemical Bonding of Asphalt Modified with Nanosilica

AbstractThe objective of this study is to evaluate the rheological properties and chemical bonding of nano-modified asphalt binders blended with nanosilica. In this study, the nanosilica was added to the control asphalt at contents of 4% and 6% based on the weight of asphalt binders. Superpave binder and mixture tests were utilized in this study to estimate the characteristics of the nano-modifed asphalt binder and mixture. The rotational viscosity (RV), dynamic shear rheometer (DSR), bending beam rhometer (BBR), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), asphalt pavement analyzer (APA), dynamic modulus (DM) and flow number (FN) tests were used to analyze rheological properties and chemical bonding changes of the nano-modified asphalt binder and the performance of the nano-modified asphalt mixture. In addition, the performance of nano-modified asphalt after rolling thin-film oven (RTFO) short-term and pressure-aging vessel (PAV) long-term aging was assessed as well...

Evaluation of Low-Temperature Binder Properties of Warm-Mix Asphalt, Extracted and Recovered RAP and RAS, and Bioasphalt

This research project evaluates the low-temperature performance of energy-efficient and environmentally friendly hot-mix asphalt (HMA) paving materials. Innovative materials gaining interest in the asphalt pavement industry includes warm mix asphalt (WMA), recycled asphalt shingle (RAS), reclaimed asphalt pavement (RAP), and bioasphalt. The materials are used as modifiers in typical HMA to enhance low-temperature field performances. Sasobit compounds at 0.5, 1.0, and 1.5%, by weight of performance grade (PG) 52-34 asphalt binder, are used to design the WMA. Five and 10% of RAS were also added to a PG 52-34 asphalt binder. 50% of RAP combined with 50% of the base PG 58-28 binder, and 100% RAP extracted from the PG 58-28 HMA, were prepared and tested. Bioasphalt was produced from swine waste and used to modify PG 64-22 asphalt binder. By using the Superpave bending beam rheometer (BBR) and the new asphalt binder cracking device (ABCD) method, the thermal cracking performance of the samples were tested. The ...

Preliminary Dynamic Modulus Criteria of HMA for Field Rutting of Asphalt Pavements: Michigan’s Experience

This paper presents a comparative study of laboratory results of both dynamic modulus testing and field rutting performances of hot-mix asphalt (HMA) in the state of Michigan. Fourteen field-produced mixtures at various traffic levels and aggregate sizes were evaluated and compared to those of field rutting. These mixtures were collected from job sites and compacted with a Superpave gyratory compactor to imitate the common air void level used in Mich., which is 7%. Dynamic modulus E∗ was measured at temperatures ranging from −5 to 39.2°C and frequencies ranging from 0.1 to 25 Hz. The results show that the dynamic modulus values increased when the designed traffic level for HMA mixtures increased. The field rutting performance was evaluated based on theoretical pavement rutting life index. Two parameters, | E∗ | and | E∗ | /sin (φ) , were compared to the theoretical pavement rutting index. Based upon the preliminary study, it was found that E∗ was a suitable parameter in comparing the field and laboratory ...

Mechanical Properties of Porous Asphalt Pavement Materials with Warm Mix Asphalt and RAP

The objectives of this paper are (1) to characterize the mechanical properties of porous asphalt pavement mixtures containing reclaimed asphalt pavement (RAP) and a WMA additive (Advera® WMA) using Superpave™ gyratory compactor and dynamic modulus testing. Four types of porous asphalt mixtures were evaluated in this study. They are 1) control mixture, a conventional porous asphalt mixture; (2) porous asphalt mixture with WMA additive (Advera® WMA in this case); (3) porous asphalt mixture containing 15% reclaimed asphalt pavement (RAP); and (4) porous asphalt mixture containing 15% RAP and additional WMA additive. This study evaluated com- paction energy index (CEI), permeability, indirect tensile strength, and dynamic modulus (E � ) for all types of porous asphalt mixtures. All of the porous asphalt mixtures meet the typical minimum coefficient of permeability in this study. Compaction energy required for the WMA containing 0.25% Advera® WMAwas found to be lower compared with the control mixture (HMA). The results from the dynamic modulus test show that WMA made with 0.25% Advera® WMA had significantly lower values than the control HMA mixture. In addition, only a slight decrease in Ewas found when WMA additive was added to the porous asphalt mixture containing RAP. For indirect tensile strength testing, WMA containing RAP was found to have the highest tensile strength among all of the mixtures tested. DOI: 10.1061/(ASCE)TE .1943-5436.0000307.

Exploring the Interactions of Chloride Deicer Solutions with Nanomodified and Micromodified Asphalt Mixtures Using Artificial Neural Networks

The objectives of this research are to modify an asphalt mixture with two materials—nanoclay and carbon microfiber—and to investigate the interactions of chloride deicer solutions with nano- and/or micromodified and unmodified asphalt mixtures in terms of indirect tensile strength (ITS) and fracture energy. Artificial neural networks (ANNs) were used in this study to establish predictive models and quantify the complex cause-and-effect relationships between the nano- or micromodification and conditioning of asphalt mixtures and the resulting mechanical properties. Four influential variables (nanoclay content, microfiber content, deicer type, and deicer dilution ratio) were collectively examined to predict the ITS and fracture energy of asphalt mixtures, and a back-propagation neural network of three layers with seven or nine hidden nodes was employed respectively. The established ANN models were then successfully used for numerical in- vestigations on the parameters affecting the asphalt properties. The addition of polysiloxane-modified montmorillonite and/or carbon micro- fiber (both at less than 2% by weight of asphalt binder) can enhance the tensile strength fracture energy of asphalt concrete mixtures and reduce their moisture susceptibility and cracking risk, and such benefits are especially significant when the asphalt concrete is conditioned in water or chloride-based deicer solutions. This evaluation makes it possible to design asphalt mixtures for a desired level of ITS or fracture energy in the absence or presence of common chloride-based deicer solutions. DOI: 10.1061/(ASCE)MT.1943-5533.0000452.

Evaluation of Asphalt Blended With Low Percentage of Carbon Micro-Fiber and Nanoclay

The objectives of this study are to investigate the applicability of carbon micro-fiber and nanoclay in asphalt binders and to evaluate the performance of micro- and nano-modified asphalt (NMA) binders in terms of rheological properties. Due to their unique characteristics, micro- and nanomaterials were hypothesized to play a critical role in enhancing the performance behavior of asphalt binders. In light of existing research, carbon micro-fiber (MCF) and Nanomer I.44P (NI.44P) were selected as the micro- and nanomaterials for this research. Then, these materials were added into the PG 58-34 control asphalt binder at the concentrations of 2 % and 4 % by weight. Superpave™ binder tests—rotational viscosity (RV), dynamic shear rheometer (DSR), and bending beam rheometer (BBR)—were then conducted for evaluating the performance of each modified asphalt binder. Also, the characterization tests were run on the aged samples prepared using the rolling thin film oven (RTFO) and pressure aging vessel (PAV) to simulate the short-term and long-term aging. Subsequently, the viscosity, dynamic shear modulus (|G*|) and phase angle (δ) of asphalt binders were analyzed, and the dissipated energy per load cycle was introduced to estimate the asphalt binders’ rutting and fatigue cracking resistance. It was found that the dynamic shear modulus of asphalt binders can be improved by the selected micro- and nanomaterials. Furthermore, the NI.44P modified asphalt showed better properties relative to the other modified asphalt binders or the control (PG 58-34) binder.

Moisture Damage and Fatigue Cracking of Foamed Warm Mix Asphalt Using a Simple Laboratory Setup

Warm mix asphalt (WMA) appears to allow a reduction in the temperature at which asphalt mixes are produced. This technology is rapidly gaining prominence due to its uniqueness compared with hot mix asphalt (HMA). In this study, the WMA was produced using the foaming method under a simple laboratory setting, and evaluated by the indirect tensile strength and four-point beam fatigue testing. A control mixture, WMA with 1.0%, 1.5% and 2.0% water based of asphalt binder weight were used in the test. These WMAs were produced at production temperatures of 100°C, 115°C and 130°C. The details of the method used to produce the foamed WMA were discussed in this study. Tensile strength and four-point beam fatigue tests were carried out to evaluate the moisture damage and fatigue characteristics of WMA. Generally, when lower production temperature was used, the WMA had higher fatigue potential based on four-point beam fatigue testing. The findings from this study were summarized in the paper.

Evaluation of Recycled Asphalt Shingles in Hot Mix Asphalt

The objective of this study was to evaluate the performance of asphalt mixtures containing different dosages of recycled asphalt shingles (RAS) using the dynamic modulus (|E*|) test with a universal testing machine and rutting test with the asphalt pavement analyzer (APA). In this study, 5% and 10% RAS were used in the Superpave mixtures. A mixture without RAS was used as the control mixture. All the mixture samples were compacted at 86 gyrations under different temperatures. The 10% RAS had the highest air void level and the control mixture had the lowest air void level. The dynamic modulus and rutting tests were conducted to evaluate the performance of the mixtures with RAS. The results show that the |E*| for RAS mixtures were higher as compared to the control mixture when tested at high temperature (i.e. 39.2°C). Additionally, the added RAS decreased the rut depth significantly after 8000 cycles using the APA.

Evaluation of Warm Mix Asphalt Produced at Various Temperatures through Dynamic Modulus Testing and Four Point Beam Fatigue Testing

The potential for using Warm Mix Asphalt (WMA) in reducing the mixing and compacting temperatures of asphalt mixes is becoming more and more attractive nowadays. In this study, two WMA technologies — Sasobit® and Advera® were used. These WMAs were produced at different dosages and different production temperatures. Dynamic modulus testing and four-point beam fatigue testing were carried out to evaluate the rutting and fatigue characteristics of WMAs. In the dynamic modulus test, it was found that when the compaction temperature is higher, the overall values of |E*| for WMA were higher. Based on the four-point beam fatigue testing, most of the WMAs fatigue life were similar or higher than the control Hot Mix Asphalt (HMA) except for the WMA produced at 130°C; and it was found that the fatigue life for the WMA produced at temperature at around 115°C were the highest among all the samples tested.

Determination of Flow Number in Asphalt Mixtures from Deformation Rate During Secondary State

Numerous research studies have been conducted on the connection between asphalt material properties and pavement performance. Asphalt mixture performance tests (AMPTs) have been part of these efforts in the past few years. One such test is the flow number test, the output of which is the flow number. Recent studies have found that flow number correlates well with the rutting potential of asphalt pavement. However, the current method used in AMPTs to examine the flow number also was highly sensitive to the variation of testing data (resulting in inaccurate flow number values) and time-consuming, especially when used on stiff asphalt mixtures. The main goal is to determine the flow number with the use of the deformation rate at the secondary state from the result of the flow number test. One hundred twenty-two flow number tests were conducted. A stepwise method was used to overcome variations in results from the flow number test. The flow number was determined with the stepwise method, then compared with the flow deformation rate. A strong correlation between flow number and deformation rate was found. Therefore, the deformation rate can be used to estimate flow number, which significantly reduces testing time. The proposed method also allows the flow number test to be terminated as soon as the permanent strain reaches 1.2%.