Laboratory characterization of recycled crumb-rubber-modified asphalt mixture after extended aging

2008 ◽  
Vol 35 (11) ◽  
pp. 1308-1317 ◽  
Author(s):  
Soon-Jae Lee ◽  
Hakseo Kim ◽  
Chandra K. Akisetty ◽  
Serji N. Amirkhanian

This paper presents a limited study that characterizes the recycling of artificially aged crumb-rubber modified (CRM) mixtures depending on their recycling percentage and aggregate type. Eight mixtures [six recycled mixtures containing rubberized reclaimed asphalt pavement (RAP) and two control virgin mixtures] were designed and tested. Two types of aggregates were used in this research project. The rubberized RAP used in the study was artificially aged in the laboratory using an accelerated aging processes. The percentages of the RAP, by total weight of the mix, incorporated into the recycled mixtures were 15%, 25%, and 35%. Evaluation of all mixtures included the following testing procedures: tensile strength ratio (TSR), asphalt pavement analyzer (APA), resilient modulus, and indirect tensile strength (ITS) after long-term oven aging. The results from this study showed that (i) the recycled aged CRM mixtures (with 15%, 25%, and 35% rubberized RAP) can satisfy the current Superpave mixture requirements, including moisture susceptibility and rutting resistance, and (ii) in general, there was no significant difference between the control and the recycled CRM mixtures for the properties evaluated in this study.

2012 ◽  
Vol 598 ◽  
pp. 438-443
Author(s):  
Jing Hui Liu

The advantages of using asphalt rubber pavement strategies have been validated by many research efforts. However, the most obvious disadvantage of asphalt rubber hot mix is requiring a higher mix and placement temperature in order to obtain adequate workability, which results in higher energy requirements and asphalt easy ageing. By utilizing Warm Mix Asphalt(WMA) technology the temperature requirements of the asphalt rubber hot mix can be reduced significantly. Warm mix asphalt (WMA) is the name given to certain technologies that reduce the production and placement temperatures of asphalt mixes. Asphalt Rubber Hot Mix of containing Warm Mix technology is a very promising technology whether in energy saving or improving pavement performance. One of the main concentrations of crumb rubber mix is now on the moisture damage evaluation due to WMA additives. In this study, the objective was to conduct a laboratory investigation of moisture damage in Warm Rubber Mix Asphalt(WRMA). Currently, there are no standards or laboratory test data to support the knowledge area on the susceptibility of asphalt rubber mixtures to moisture damage. The widely accepted testing procedures i.e. indirect tensile strength (ITS) and tensile strength ratio (TSR) were performed to determine the moisture susceptibility of the mixtures.


Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1266
Author(s):  
Wentong Huang ◽  
Xiao Liu ◽  
Shaowei Zhang ◽  
Yu Zheng ◽  
Qile Ding ◽  
...  

The construction of sponge city is a major green innovation to implement the concept of sustainable development. In this study, the road performance of permeable asphalt concrete (PAC), which displays pronounced water permeability and noise reduction that are favorable for sponge cities, has been improved with a two-fold modification using styrene–butadiene–styrene (SBS) and crumb rubber (CR). Four percent SBS and three different ratios (10%, 15%, and 20%) of CR have been used to modify the virgin asphalt binder. The Marshall design has been followed to produce PAC samples. To evaluate the asphalt binder performance, multiple-stress creep-recovery (MSCR) test, linear amplitude sweep (LAS) test, and engineering property test programs including softening point test, penetration test, and rotational viscosity test have been conducted. Freeze–thaw splitting test, Hamburg wheel-tracking test, resilient modulus test, and permeability coefficient test have been performed to evaluate the asphalt mixture performance. The test results show that the addition of SBS and CR reduces the permeability coefficient, but significantly improves the high temperature performance, fatigue performance, and rutting resistance as well as the resilient modulus. However, the optimum rubber content should not exceed 15%. Meanwhile, after adding CR and SBS modifier, the indirect tensile strength (ITS) and tensile strength ratio (TSR) increase. It indicates that the moisture stability and crack resistance have been improved by the composite modification effect.


Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1738 ◽  
Author(s):  
Hongyin Li ◽  
Hailong Jiang ◽  
Wenwu Zhang ◽  
Peng Liu ◽  
Shanshan Wang ◽  
...  

Resistance of asphalt mix to low-temperature cracking and rutting at high temperature is very important to ensure the service performance of asphalt pavement under seasonal changes in temperature and loading. However, it is challenging to balance the improvement of such resistance by using additives, e.g., anti-rutting agent (ARA). This study focuses on improving the flexibility of anti-rutting asphalt mix by incorporating crumb rubber (CR) and ARA. The properties of the prepared modified asphalt mix were evaluated in the laboratory by performing wheel tracking, three-point bending, indirect tensile, and uniaxial compression tests. The experimental results showed that the dynamic stability of modified asphalt mix was significantly increased due to the addition of ARA and further improved by incorporating CR. The maximum bending strain at −10 °C was increased due to the contribution of CR. The results of indirect tensile strength and resilient modulus further indicated that the CR-modified anti-rutting mixture was more flexible. Moreover, the field observation and evaluation indicated that the CR-modified anti-rutting asphalt pavement met the standard requirements, better than normal asphalt mixture in many parameters. A conclusion can be made that incorporating CR in asphalt mixture prepared with ARA can improve pavement performance at both high and low in-service temperatures.


Author(s):  
Shaban Ismael Albrka Ali ◽  
Riyadh Abdulwahid ◽  
Muhamed Laith Eidan ◽  
Nur Izzi Md Yusoff

Flexible pavements deteriorate and crack with time due to the frequent traffic load imposed upon it. Many studies have been done to predict the effects of frequent traffic load and environmental conditions on pavements in the effort to find the best pavement design which resist deterioration and ensure longer pavement service time. This study investigates the effect of mixing asphalt with varying percentages of nano calcium carbonate (CaCO3), namely 0, 2, 4, and 6 %. The mixtures were designed based on the Superpave mix design criteria. Investigation was done using several tests, namely resilient modulus, indirect tensile strength, moisture susceptibility, and dynamic modulus tests. Samples were subjected to aging to determine their resilient modulus. The results of the investigation show that resilient modulus and indirect tensile strength increased when higher percentages of nanoparticles were added to asphalt mixture, with improvement of 138 and 48.18% respectively. Modified binders showed up to 17% improvement in moisture susceptibility comparison to base asphalt mixture, while the result of dynamic modulus test showed that the stiffness of modified asphalt increased 76.69%. The investigation also found that adding 6% CaCO3 nanoparticles to asphalt produced modified asphalt with the best performance. In addition, the results show that the modified asphalt with CaCO3 is suitable for hot and humid regions (tropical countries) in the field of highways construction, as the modifier was able to mitigate the influences of high-temperature rutting and moisture damage.


2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Altan Cetin

The purpose of this study is to investigate the effect of size distribution and concentration of crumb rubber on the performance characteristics of porous asphalt mixture. The recycling of scrap tires in asphalt pavements appears as an important alternative providing a large-scale market. The characteristics of bitumen are very important with regard to service life of porous asphalt pavement. The experimental study consists of two main steps. Firstly, the mixture design was performed to determine the optimum bitumen content. In the latter step, the mixtures were modified by dry process using crumb rubber in three different grain size distributions of #4~#20, #20~#200, and #4~#200 and rubber content of 10%, 15%, and 20% as weight of optimum bitumen. The permeability, Cantabro abrasion loss, indirect tensile strength, moisture susceptibility, and resilient modulus tests were carried out on the specimens. Test results show that #20~#200 sized rubber particles reduced air voids and coefficient of permeability, while they increased the Cantabro abrasion loss. In general, increasing the crumb rubber size and content decreased the performance characteristics of the porous asphalt mixtures.


CivilEng ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 370-384
Author(s):  
Hossein Noorvand ◽  
Kamil Kaloush ◽  
Jose Medina ◽  
Shane Underwood

Asphalt aging is one of the main factors causing asphalt pavements deterioration. Previous studies reported on some aging benefits of asphalt rubber mixtures through laboratory evaluation. A field observation of various pavement sections of crumb rubber modified asphalt friction courses (ARFC) in the Phoenix, Arizona area indicated an interesting pattern of transverse/reflective cracking. These ARFC courses were placed several years ago on existing jointed plain concrete pavements for highway noise mitigation. Over the years, the shoulders had very noticeable and extensive cracking over the joints; however, the driving lanes of the pavement showed less cracking formation in severity and extent. The issue with this phenomenon is that widely adopted theories that stem from continuum mechanics of materials and layered mechanics of pavement systems cannot directly explain this phenomenon. One hypothesis could be that traffic loads continually manipulate the pavement over time, which causes some maltenes (oils and resins) compounds absorbed in the crumb rubber particles to migrate out leading to rejuvenation of the mastic in the asphalt mixture. To investigate the validity of such a hypothesis, an experimental laboratory testing was undertaken to condition samples with and without dynamic loads at high temperatures. This was followed by creep compliance and indirect tensile strength testing. The results showed the higher creep for samples aged with dynamic loading compared to those aged without loading. Higher creep compliance was attributed to higher flexibility of samples due to the rejuvenation of the maltenes. This was also supported by the higher fracture energy results obtained for samples conditioned with dynamic loading from indirect tensile strength testing.


2018 ◽  
Vol 34 ◽  
pp. 01026
Author(s):  
Ahmad Kamil Arshad ◽  
Haryati Awang ◽  
Ekarizan Shaffie ◽  
Wardati Hashim ◽  
Zanariah Abd Rahman

Reclaimed Asphalt Pavement (RAP) is old asphalt pavement that has been removed from a road by milling or full depth removal. The use of RAP in hot mix asphalt (HMA) eliminates the need to dispose old asphalt pavements and conserves asphalt binders and aggregates, resulting in significant cost savings and benefits to society. This paper presents a study on HMA with different RAP proportions carried out to evaluate the volumetric properties and performance of asphalt mixes containing different proportions of RAP. Marshall Mix Design Method was used to produce control mix (0% RAP) and asphalt mixes containing 15% RAP, 25% RAP and 35% RAP in accordance with Specifications for Road Works of Public Works Department, Malaysia for AC14 dense graded asphalt gradation. Volumetric analysis was performed to ensure that the result is compliance with specification requirements. The resilient modulus test was performed to measure the stiffness of the mixes while the Modified Lottman test was conducted to evaluate the moisture susceptibility of these mixes. The Hamburg wheel tracking test was used to evaluate the rutting performance of these mixes. The results obtained showed that there were no substantial difference in Marshall Properties, moisture susceptibility, resilient modulus and rutting resistance between asphalt mixes with RAP and the control mix. The test results indicated that recycled mixes performed as good as the performance of conventional HMA in terms of moisture susceptibility and resilient modulus. It is recommended that further research be carried out for asphalt mixes containing more than 35% RAP material.


Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7060
Author(s):  
Mohammad Alharthai ◽  
Qing Lu ◽  
Ahmed Elnihum ◽  
Asad Elmagarhe

This study investigates the substitution of conventional aggregate with a Florida washed shell in open-graded asphalt mixtures and evaluates the optimal substitution percentage in aggregate gradations of various nominal maximum aggregate sizes (NMASs) (i.e., 4.75, 9.5, and 12.5 mm). Laboratory experiments were performed on open-graded asphalt mixture specimens with the coarse aggregate of sizes between 2.36 and 12.5 mm being replaced by the Florida washed shell at various percentages (0, 15, 30, 45, and 100%). Specimen properties relevant to the performance of open-graded asphalt mixtures in the field were tested, evaluated, and compared. Specifically, a Marshall stability test, Cantabro test, indirect tensile strength test, air void content test, and permeability test were conducted to evaluate the strength, resistance to raveling, cracking resistance, void content, and permeability of open-graded asphalt mixtures. The results show that there is no significant difference in the Marshall stability and indirect tensile strength when the coarse aggregates are replaced with Florida washed shell. This study also found that the optimum percentages of Florida washed shell in open-graded asphalt mixture were 15, 30, and 45% for 12.5, 9.5, and 4.75 mm NMAS gradations, respectively.


2010 ◽  
Vol 37 (11) ◽  
pp. 1414-1422 ◽  
Author(s):  
Feipeng Xiao ◽  
Serji Amirkhanian ◽  
Bradley Putman ◽  
Junan Shen

An improved understanding of the rheological and engineering properties of a rubberized asphalt concrete (RAC) pavement that contains reclaimed asphalt pavement (RAP) is important to stimulating the use of these recycled and by-product materials in asphalt mixtures. The uses of RAP and rubberized asphalt in the past have proven to be economical, environmentally sound, and effective in hot mix asphalt (HMA) mixtures across the US and the world. The objective of this research was to investigate the binder and mixture performance characteristics of these modified asphalt mixtures through a series of laboratory tests to evaluate properties such as the fatigue factor G*sinδ, rutting resistance, resilient modulus, and fatigue life. The results of the experiments indicated that the use of RAP and crumb rubber in HMA can effectively improve the engineering properties of these mixes.


2013 ◽  
Vol 368-370 ◽  
pp. 933-938 ◽  
Author(s):  
Qi Ying Niu ◽  
Jun Yong Zhao ◽  
Ru Kai Li

Through a series of mechanical properties experiment of recycled asphalt mixture composed of waste asphalt mixture 20% and different content of rubber powder, the paper analyzes and compares the elasticity, tensile strength and bending strength of asphalt mixture and recycled asphalt mixture, concluding that recycled asphalt mixture that mixed with crumb rubber content of 20% can completely replace the new asphalt mixture in the application. It has great significance for the future to recycling waste asphalt mixture in the highway.


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