Stone Matrix Asphalt Mixtures Research Articles

Cost-benefit Analysis of RAP Incorporated Stone Matrix Asphalt Mixtures

It is desirable to incorporate Reclaimed Asphalt Pavement into the asphalt mixtures, which provides several benefits i.e. economic, environmental and performance. It is necessary to study, the economic analysis of the RAP since that incur several contingencies to the asphalt mixtures. In this study, a simple approach is used to evaluate the production cost of the asphalt and RAP incorporated asphalt mixtures. Apart from that Waste Vegetable Oil (WVO) is used as a rejuvenator to enhance the properties of the mixture. In this study, asphalt mixture production cost is evaluated and cost of each material is taken from the Public Works Department Standard Scheduled of Rates (PWD – SSR) and the market survey techniques are followed. From the cost-benefit ratio, it is observed that the reduction in the Optimum Binder Content (OBC) provides great economic savings to the production cost. The incorporation of the RAP reduced the asphalt content and reduced the production cost of the asphalt mixtures. The addition of the WVO further reduced the OBC but increased the production cost compared to the non-rejuvenated mixture. The increase in the production cost is due to the extra cost invested on the WVO and other contingencies.

Investigation of fatigue behaviour of warm modified binders and warm-stone matrix asphalt (WSMA) mixtures through binder and mixture tests

ABSTRACT The purpose of this study was to investigate the effect of warm additives on the fatigue behaviour of binder and stone matrix asphalt (SMA) mixtures. To achieve this, several tests were carried out on original and modified binders such as the G*.sin δ, the multiple stress creep recovery (MSCR), and the Linear Amplitude Sweep (LAS) test. Also, in order to authenticate the binder fatigue tests the indirect tensile strength and four-point bending beam tests were performed. SMA mixtures were fabricated from one original binder type (60–70 penetration grade), one gradation by NMAS of 12.5 mm and three WMA additives (Sasobit, Rheofalt LT70, Zycotherm) with different percentages. In regard to binder and mixture fatigue test, the results of this study indicated that the G*.sin δ parameter is incapable of evaluating the fatigue behaviour of binders. It was also found that MSCR test showed the best correlation with asphalt mix fatigue resistance compared to LAS test and G*.sin δ parameter.

Determining the optimum amount of recycled asphalt pavement (RAP) in warm stone matrix asphalt using dynamic creep test

This research is conducted to investigate the use of a laboratory experiment to evaluate the influence of changes in the percentage of recycled asphalt pavement (RAP) content on rutting resistance as measured by the flow number test achieved by three-stage model and the minimum rate of total permanent deformation. In this research, only one aggregate gradation with NMAS of 19 mm, one virgin binder (AC 60–70), and one RAP material source at six levels of content (0, 10, 20, 30, 40 and 50%) have been selected to prepare the stone matrix asphalt (SMA) mixtures. Furthermore, two warm mix asphalt additives including zycotherm and sasobit have been used in manufacturing (SMA) samples to carry out dynamic creep test in two levels of stress rate (300 kPa and 650 kpa), and Topcel additive fibers have been used to prevent draindown of these types of asphalt mixtures. Then, computerized programming has been developed to obtain regression coefficient parameters of the equations in three-stage models by Matlab software. Also, the correlations have been found between flow number achieved by the three-stage model and minimum rate of total permanent deformation. The result has indicated that there are good correlations between the two methods. Also, the results of the dynamic creep test to measure the flow number in 650 kPa stress level showed that by adding RAP to control SMA specimen, the FN content increases. Moreover by adding Zycotherm to samples manufactured by SMA specimen containing the RAP, the FN content increases by increasing RAP up to 40%. Also by adding sasobit to samples manufactured by SMA specimen containing the RAP and Zycotherm, the FN content increases by increasing RAP up to 30%. The highest amount of flow number (FN) relates to a specimen containing both zycotherm and sasobit and 30% RAP.

Development of Hybrid Artificial Intelligence Approaches and a Support Vector Machine Algorithm for Predicting the Marshall Parameters of Stone Matrix Asphalt

The main objective of this study is to develop and compare hybrid Artificial Intelligence (AI) approaches, namely Adaptive Network-based Fuzzy Inference System (ANFIS) optimized by Genetic Algorithm (GAANFIS) and Particle Swarm Optimization (PSOANFIS) and Support Vector Machine (SVM) for predicting the Marshall Stability (MS) of Stone Matrix Asphalt (SMA) materials. Other important properties of the SMA, namely Marshall Flow (MF) and Marshall Quotient (MQ) were also predicted using the best model found. With that goal, the SMA samples were fabricated in a local laboratory and used to generate datasets for the modeling. The considered input parameters were coarse and fine aggregates, bitumen content and cellulose. The predicted targets were Marshall Parameters such as MS, MF and MQ. Models performance assessment was evaluated thanks to criteria such as Root Mean Squared Error (RMSE), Mean Absolute Error (MAE) and correlation coefficient (R). A Monte Carlo approach with 1000 simulations was used to deduce the statistical results to assess the performance of the three proposed AI models. The results showed that the SVM is the best predictor regarding the converged statistical criteria and probability density functions of RMSE, MAE and R. The results of this study represent a contribution towards the selection of a suitable AI approach to quickly and accurately determine the Marshall Parameters of SMA mixtures.

Evaluation of the fatigue failure and recovery of SMA mixtures with cellulose fiber and with SBS modifier

Several studies have investigated the recovery of asphalt mixtures during fatigue life; however, there is still an inadequacy of determining fatigue failure and recovery of Stone Matrix Asphalt (SMA) mixtures under repeated loading. This paper presents the results of a laboratory study which was aimed to compare the effect of cellulose fiber with SBS modifier on the fatigue failure and recovery of SMA. Three different mixtures (containing cellulose fiber, 3% SBS, and 5% SBS) were fabricated by two types of aging conditions. In addition to fatigue failure and recovery of the SMA, resilient modulus, indirect tensile strength and long-term oxidative aging of this mixture were investigated. The results indicated that using the SBS modifier enhanced indirect tensile strength, resilient modulus, resistance to fatigue failure, and recovery of the mixture. Considering aged mixtures, although the long-term aged mixtures had higher failure life, resilient modulus and indirect tensile strength, they had lower recovery potential. Also, while using SBS modifier had a positive effect on reducing the impact of aging on the indirect tensile strength and the resilient modulus, it could not reduce the detrimental impact of aging on the recovery potential of the mixtures.

Evaluation of rejuvenator’s effectiveness on the reclaimed asphalt pavement incorporated stone matrix asphalt mixtures

The need for incorporation of Reclaimed Asphalt Pavement (RAP) in the Stone Matrix Asphalt (SMA) mixtures is becoming a priority in the pavement industries. The RAP offers several benefits such as the reduction in usage of bitumen, and natural aggregates, and reduction in the landfills, emission into the environment and cost. SMA is known for its success in improving rutting resistance, durability and cracking resistance and to utilize the benefits of both RAP and SMA, it seems a logical purpose to incorporate RAP in the SMA mixtures. However, RAP contains an aged binder, which increases the stiffness of the mixtures and a rejuvenator is added to improve the rheology of the aged binder. In this study, Waste Vegetable Oil (WVO) is used as a rejuvenator in the RAP incorporated SMA mixture. In order to determine the maximum RAP content and optimum WVO dosage, four RAP contents (10, 20, 30, and 40% by weight of the aggregate) and four WVO dosages (0, 3, 6, and 9% by weight of bitumen content) are used to prepare the SMA mixtures. The laboratory tests were conducted to evaluate drain down, volumetric properties, Marshall characteristics, stripping behaviour, Retained Marshall Stability (RMS), and Tensile Strength Ratio (TSR) and they are compared statistically to each other and to the control mixture. The results indicate that RAP incorporated SMA mixtures have a substantial positive effect on the volumetric properties and it enhanced the Marshall Stability (MS), stripping resistance and RMS, however, reduced the TSR value. To the contrary, the addition of the WVO improved the TSR value to a great extent and increased the RAP content. The statistical analysis, Analysis of Variance (ANOVA) results, showed that the RAP content and WVO dosage have a significance on the properties of the SMA, and the main effect plot results concluded that it is possible to incorporate 40% of RAP content with 6% WVO in the SMA mixtures.

Effects of Loading Rate and Temperature on Cracking Resistance Characteristics of Asphalt Mixtures Using Nonnotched Semicircular Bending Tests

Abstract In this study, the effects of loading rate and temperature on the cracking resistance of asphalt mixtures under static loading were examined by a nonnotched, semicircle bending test. Twenty-four test conditions combined by eight loading rates (0.1, 0.75, 3, 7.5, 15, 30, 50, and 80 mm/min) and three temperatures (−10°C, 0°C, and 15°C) were selected to be conducted using one stone matrix asphalt mixture. Five cracking parameters, namely, peak force (Fmax), peak displacement (Dp), work of before-cracking (Wc), cracking failure displacement (Dcf), and work of cracking failure (Wcf), were proposed in order to evaluate the cracking resistance of asphalt mixtures. According to the results of this study, the cracking failure mode of asphalt mixtures can be divided into three conditions: brittle cracking, flexible damage, and fall in between. For the test condition of a higher loading rate and lower temperature, the cracking failure mode would be closer to brittle cracking. Both loading rate and temperature influence the test results of all cracking parameters in different ways. According to the statistical analysis, peak force is sensitive to loading rate, and the displacement and energy parameters are sensitive to temperature variation.

Comparative Analysis of Performance of Porous Asphalt Pavement and SMA Pavement Based on Deck Pavement Structure

Viaducts are more and more widely used in China. How to ensure the safety of the bridge deck has become a hot issue of concern? Based on the above problems, the application of porous asphalt pavement in bridge deck pavement is also increasing. Based on the porous asphalt pavement project of Shijiazhuang City Ring Road (West Second Ring of Heping West Road), the performance differences between porous asphalt pavement and stone matrix asphalt pavement were studied. By comparing the gradation characteristics and performance of porous asphalt mixture and stone matrix asphalt mixture, the advantages and disadvantages of the two mixtures in road performance were analyzed. At the same time, we carried out on-site braking test, noise test and long-term temperature monitoring on two types of pavement. By comparing the test results, we thought that porous asphalt pavement could reduce the braking distance by up to 7 m in mid-to heavy rain weather, and porous asphalt pavement could reduce 2-6 dB noise, Porous asphalt pavement has better cooling effect than stone matrix asphalt pavement, and the higher the external temperature was, the better the cooling effect of porous asphalt pavement was, and it could reduce 6-8°C in summer. Through the test comparison, we draw the conclusion that the pavement performance of porous asphalt pavement is better than that of stone asphalt pavement.

Strength and durability of dry-processed stone matrix asphalt containing cement pre-coated scrap tire rubber particles

Abstract Application of rubber particle from the scrap tire through dry-process is a practical and economical efficient way to resolve the recycling problem and environmental concern of the disposed tires. However, the added rubber aggregate reduces both the strength and durability of the rubberized asphalt mixture. This study aims to improve the strength and durability of dry-processed asphalt mixture by using the cement (Portland Type Ⅰ) coating methods and gap-gradation system (Stone Matrix Asphalt (SMA)). The cement coating was applied to enhance the bonding performance between rubber aggregate and asphalt binder, and limits its expansion due to swelling in hot asphalt binder. The SMA mixtures were prepared with different sizes and proportions of mineral aggregates. The samples with conventional aggregate and untreated rubber aggregate both serve as control samples for the sample evaluation. Finally, tests on tensile strength, moisture susceptibility, rutting resistance, anti-stripping resistance, fatigue cracking resistance, and bonding between rubber particles and asphalt binder of SMA mixtures were conducted. The results showed that SMA mixture with pre-coated rubber aggregate owns similar performance comparing to the samples prepared with conventional aggregate and also has higher strength and better performance than that of the mixture with untreated rubber aggregate. Results also clearly indicated that the asphalt mixtures with 50% of No.16 mineral aggregates replaced by pre-coated rubber aggregates performed the best-satisfied performances; while, with a further increase in replaced size or proportion, the satisfied performances of SMA mixtures would be degenerated.

Evaluation of Crumb Rubber Modification on Specification Compliance of Asphalt Mixtures

Since 2008, the Louisiana Department of Transportation and Development (LaDOTD) has allowed the use of crumb rubber modification (CRM) as per the specifications. However, the introduction of CRM has presented unique challenges during design and production. LaDOTD districts have reported early cracking for dense-graded mixtures. Adhesion and stability issues have been reported for open-graded friction course (OGFC) and stone matrix asphalt (SMA) mixtures. Currently, LaDOTD specifications allow the contractor to switch asphalt cement supplies without redesigning the mixture. This study evaluated several CRM-modified mixture designs to address design and performance concerns; it also evaluated the volumetric and mechanistic properties of dense, SMA, and OGFC mixtures designed with unmodified asphalt cement, styrene-butadiene-styrene-modified asphalt cement and five crumb rubber sources. SuperPave volumetric parameters were evaluated to ascertain the impact of CRM on the design of these mixtures. Rutting and intermediate temperature cracking susceptibility were determined using the Hamburg Loaded Wheel Tracker (LWT) and semi-circular bend test (SCB), respectively. Solvent extraction and the ignition furnace were used to determine the asphalt content of the modified mixtures. The results showed that CRM improved the laboratory rutting resistance of the mixtures. However, the laboratory cracking resistance was decreased for the CRM-modified mixtures. Based on statistical analysis, additional asphalt content, reduced CRM dosage, and the use of polymer additives may mitigate the reduced laboratory cracking performance of the CRM-modified mixtures. The volumetric parameters were also affected by CRMs. The mixtures should be re-designed if the contractor anticipates using a CRM-modified asphalt cement.

Characteristics of stone matrix asphalt by using natural fibers as additives

Abstract The increased growth of traffic and maintenance expenditures demands a great need for developing better, long-lasting, and more efficient roads that prevents or minimizing bituminous pavement distresses. The Stone Matrix Asphalt (SMA) mixtures provide a durable wearing course in the flexible pavements. This research is to study the influence of additives on the characteristics of SMA mixtures and to propose an ideal surface course for the pavements. The additives used for this investigation are natural fibres such as coir, sisal and banana fibres. A preliminary investigation is conducted to characterize the materials used in this study. Marshall Test and Indirect tensile strength tests are conducted for optimizing the SMA mixtures and to study the engineering properties of stabilized mixtures respectively. Based on the volumetric and mechanical characteristics of the various stabilized mixtures it is inferred that the optimum fibre content is 0.3% fibre by weight of mixture for all fibre mixtures irrespective of the type of fibre. But in all stabilized mixtures, the volumetric results are within the specification range. The coir fibre is the best among the fibres that are used in the investigation where as Sisal and banana fibre mixtures shows the same characteristics on stabilization. The present study is carried out to provide a brief understanding of the engineering behavior of the SMA mixture with various natural fibres as additives, which increases the level of confidence in the field application of this material.

Evaluation of the healing potential of asphalt mixtures based on a modified semi-circular bending test

Since the semi-circular bending (SCB) test has been widely used to evaluate the fatigue properties of asphalt mixtures, it has been modified in this paper by adding a certain length of rest period in each cyclic loading sequence to evaluate the healing potential of different asphalt mixtures. The digital image correlation (DIC) method was utilized to characterize the tensile strain at the bottom of specimens during the healing-based cyclic SCB test. The influence of notch depth of the specimen (0 mm, 15 mm and 25 mm) and the length of the rest period (0 s, 0.4 s, 0.8 s and 1.2 s) on the fatigue and healing behaviour were carefully evaluated. The fatigue life (Nf), total dissipated energy (Gsum), secant modulus (Ms), average deformation growth rate (Dr) and average tensile strain (εr) during the cyclic load with or without rest period were analysed. Test results show that the inserted notch reduces the fatigue life and deformation of specimens, while can hardly change the load-sensitivity and secant modulus of the specimen. Most performance recovery happens within the rest period of 0.8 s. So it is better to conduct the healing-based cyclic test with non-notched SCB specimen and 0.8 s rest period. Additionally, it is found that asphalt mixtures with modified binder present both better fatigue and healing properties than asphalt mixtures with neat asphalt, while the stone matrix asphalt mixture presents similar fatigue property but much better healing potential than one dense graded mixture with the same binder.

Laboratory Evaluation of Mixture Type on Highly Modified Asphalt Mixtures in Virginia

The work presented attempts to address reflective cracking of asphalt-surfaced pavements through binder modification with a highly polymer (HP)-modified asphalt binder. Nine asphalt mixtures ranging from fine dense-graded mixtures to stone matrix asphalt (SMA) mixtures were investigated with conventional polymer modified binders and HP binder. The dynamic modulus test, overlay test (OT), and semi-circular bend (SCB) test were used to evaluate the mixtures. In the cracking tests, HP mixtures outperformed the conventionally modified control mixtures for the same mixture type. For HP mixtures, in general, SMA mixtures performed better in the cracking test than dense-graded mixtures. One of the dense-graded mixtures having larger nominal maximum aggregate size (NMAS) performed better than the mixture with a smaller NMAS, whereas the other having a larger NMAS was not significantly different in crack testing. Further, a discussion on the calculation of bulk specific gravity and percent air voids in a cut OT and SCB specimen using saturated surface dry or vacuum sealing methods is presented.

Laboratory Investigation on the Use of Bamboo Fiber in Asphalt Mixtures for Enhanced Performance

This study evaluated the use of bamboo fiber, which is a new member in the natural fiber category, in dense-grade (DG) and stone matrix asphalt (SMA) mixtures for enhanced performance. Bamboo fiber has high tensile strength in fiber direction, and it also has rough surface texture comparable to that of a commonly used lignin fiber. Moreover, bamboo fiber exhibits sufficient thermal stability, which is a typical concern of plant-based materials. Marshall mix design procedure was followed to select optimum asphalt binder contents of DG and SMA mixtures that contain various amounts of bamboo fiber. Effects of bamboo fiber on mixture moisture susceptibility, rutting and low-temperature cracking performance were evaluated using the immersion Marshall, freeze-thaw cycling tests, wheel tracking test and three-point bending beam test, respectively. Testing results showed the use of bamboo fiber effectively enhanced the above-mentioned mixture performance. In addition, the optimum bamboo fiber contents for DG and SMA mixtures were found to be 0.2–0.3% and 0.4% (by weight of mixture). Finally, mixtures with bamboo fiber exhibited equivalent or better performance than the same mixtures with polyester fiber and lignin fiber, indicating the applicability of bamboo fiber in asphalt mixtures.

Utilization of waste nylon wire in stone matrix asphalt mixtures

A lot of waste nylon wires are produced during the production of brush wire products such as toothbrush, hairbrush, paintbrush, and so on. How to recycle and reuse waste nylon wire is a new problem This research presents a study of the behavior of waste nylon wire on Stone Matrix Asphalt (SMA) mixtures using Marshall design method. The specimens were tested using several common laboratory test procedures: Marshall stability test, rutting test, three-point flexural test and moisture susceptibility test. The related results indicate that waste nylon wire can effectively improve the high temperature stability, low temperature crack resistance and moisture susceptibility of SMA. Also, oil absorption, adhesion and the retarding effect of waste nylon wire on the crack propagation of asphalt mixture are attributed to the reinforcing mechanism. The research result can offer technical support for waste nylon wire used in road construction materials.

Analysis on influencing factors of rutting resistance for stone matrix asphalt mixtures

The rutting deformation not only shortens the service life of asphalt pavement, but also brings great risks to the drivers. The rutting resistance of Stone Matrix Asphalt (SMA) is affected by many factors. This study aims to thoroughly discuss the main factors of rutting resistance and establish the dynamic stability prediction model that based on the experimental data from Marshall testing and wheel tracking test in SMA mixtures. The results show that the optimal dosage bitumen of rutting test is 0.1~0.3% more than that of Marshall testing in SMA mixtures. With the temperature increases 0.5℃, the dynamic stability of SMA mixtures decreases by an average of 18.6%. The more amount of aggregate and mineral powder donnot mean the better rutting resistance in SMA mixtures. It causes to reduce the rutting resistance of SMA mixtures as compaction work is too much or too little. There is a positive correlation between the dynamic stability of SMA mixtures and fractal dimension, relative coefficient and asphalt content, while it is a negative correlation between the dynamic stability of SMA mixtures and rolling times, testing temperature.

Fatigue damage model of stone matrix asphalt with polymer modified binder based on tensile strain evolution and residual strength degradation using digital image correlation methods

In this paper, the residual strength degradation was termed as the damage variable to evaluate the fatigue damage process of asphalt mixtures. A non-notched semi-circular bending (SCB) residual strength test with varying pre-loading cycles was designed to capture the residual strength of one stone matrix asphalt (SMA) mixture at 15 °C. The digital image correlation (DIC) method was utilized to characterize the strain field of specimens in the semi-circular bending (SCB) fatigue test under varying loading levels at 15 °C. According to the results of this study, the residual strength decreases smoothly before faster and faster with the increase of loading cycles, which fits well with an exponential model. A non-linear damage evolution model is built by the residual strength degradation law. Based on the transverse distribution characteristics of tensile strain at the bottom of SCB specimens, a 5 cm cracking zone in the center of specimens is determined and the average tensile strain is captured by DIC systems. The curves of average tensile strain versus loading cycles could also fit well with an exponential model. By using the normalized loading cycles (N/Nf) as the intermediate variable, the relationship between tensile strain evolution and residual strength degradation could be deduced and the residual strength in fatigue damage evolution model could be substituted by tensile strain, which means the average tensile strain has the potential to be a material state that dictates accumulation of damage.

EVALUATION OF THE FATIGUE BEHAVIOR OF STONE MASTIC ASPHALT MODIFIED BY DOMESTIC WASTE BIO-ASPHALT

This paper presents the results of a laboratory study based, upon evaluating the fatigue characteristics of Stone Matrix Asphalt (SMA) Mixtures using different percent of bio-oil produced from pyrolysis process of house hold waste. The indirect tensile fatigue (ITFT) test was used to study fatigue behavior. The fatigue tests were performed at three temperatures (15, 20, and 25°C) using one asphalt binder, 80/100 penetration asphalt. The outcomes demonstrated that the addition of DWBO has slightly lowered the resilient modulus, and reduced the fatigue performance of the SMA Mixtures. For the effect of the temperature on fatigue life of 80/100 bio-binders, it is reasonable to use DWBO in asphalt mixture as an additive in cold to moderate temperature regions. The study shows that the DWBO can be used with petroleum binders in the pavement industry with a percent not exceeding 3% by weight of the base binder.

Research on the fatigue equation of asphalt mixtures based on actual stress ratio using semi-circular bending test

The semi-circular bending (SCB) strength test and fatigue test were used in this paper to evaluate the strength property and fatigue performance of asphalt mixtures. The SCB strength test was carried out at 8 loading rates and 3 temperatures, followed by the SCB fatigue test at 5 load levels on one common stone matrix asphalt (SMA) mixture. The time–temperature characteristics of strength from SCB test were studied. The fatigue performance was evaluated based on displacement development and energy consumption during the cyclic loading process. And according to the established strength-loading rate model, the fatigue equation based on actual stress ratio was obtained as well. The results showed that asphalt mixture strength was affected by loading rate and temperature significantly, the relation between strength and loading rate could be approximately expressed as a power function; the relation between fatigue life and stress level (or nominal stress ratio) could also be expressed as a power function. The lower the stress level, the longer the fatigue life was, and the fatigue life and the cumulative energy consumption showed a good linear relationship in the double logarithmic coordinates; the fatigue equation based on actual stress ratio revealed the connection between fatigue failure and strength failure.

Laboratory evaluation of the effect of styrene-butadiene-styrene – montmorillonite nanocomposite on rheological behavior of bitumen and performance of stone matrix asphalt mixtures

This study was performed to evaluate moisture susceptibility of different stone matrix asphalt (SMA) mixtures modified with styrene-butadiene-styrene (SBS) and nanoclay. Different samples with vari...