Arkansas Experience with Crumb Rubber Modified Mixes Using Marshall and Strategic Highway Research Program Level I Design Methods

Author(s):  
Gary V. Gowda ◽  
Kevin D. Hall ◽  
Robert P. Elliott

Unmodified and crumb rubber modified mixes conforming to the Arkansas State Highway and Transportation Department Type II surface course specifications were designed for heavy traffic conditions and environmental conditions typical to Arkansas by using the Marshall and Superpave Level I methods. Specimens prepared at appropriate design asphalt contents were evaluated for both volumetric and performance considerations. Three mix types, an unmodified hot-mix asphalt concrete, a dry process rubber modified asphalt, and a wet process asphalt rubber, were included in the investigation. For the asphalt cement, crumb rubber, aggregate type, and aggregate gradation used, the design asphalt content and the VMA were reduced for the SHRP Level I method relative to the Marshall method. Incorporation of crumb rubber into hot-mix asphalt concrete provided increased rutting resistance; however, the rubber modified mixes did not show enhanced resilient and tensile properties when tested at 25°C. Also, the performance-related properties of the SHRP Level I asphalt-rubber mixes (5, 10, and 15 percent A-R blends) evaluated did not differ significantly at 5 percent level of significance.

Author(s):  
Raghu Ram Madapati ◽  
K. Wayne Lee ◽  
Francis J. Manning ◽  
Colin A. Franco

There are two processes of adding crumb rubber modifier (CRM) to hot mix asphalt (HMA), that is, the wet process and the dry process; and different technologies are available for each process. On the basis of the results of the binder study and producer's practices, HMA specimens were prepared using two selected AR binders with Producer R and A CRMs for Rhode Island (RI) dense-graded and dense-graded friction course (DGFC) mixtures, respectively. Aggregates procured from four local asphalt contractors were used. In addition, gap-graded HMA specimens were prepared with 3 percent CRM and control AC-20 binder with two typical local aggregates using the dry process. Marshall mix design was performed on all mixtures to determine optimum binder content and Marshall properties. Mechanical properties were evaluated for the mixtures with and without CRM. Superpave Level I mix design was also performed for dense-graded, DGFC, and gap-graded mixtures with aggregates procured from Contractor C. Finally, the performance of pavements with and without CRM was predicted using the computer program VESYS. Results of this study indicated that the use of CRM is feasible for RI dense-graded and DGFC mixtures utilizing the wet process.


2011 ◽  
Vol 243-249 ◽  
pp. 4201-4206 ◽  
Author(s):  
Jing Hui Liu

Low temperature cracking is the main distress in asphalt pavements in winter. As asphalt rubber course is increasing, there is no standard method to characterize the resistance to cracking of asphalt rubber mixtures. This paper investigates the use of a Semi Circular Bend (SCB) test as a candidate for a low-temperature cracking specification. Based on the SCB test, this paper presents the findings of a laboratory study that aimed to evaluate the effects of recycled tire rubber on the Low temperature cracking properties of asphalt mixtures. Three mix types, a conventional hot-mix asphalt concrete, a dry process rubber modified asphalt concrete, and a wet process asphalt-rubber asphalt concrete, were included in the investigation. It is found that the asphalt mixtures produced by the wet process showed much better low temperature crack resistance, the binder effect modified by rubber was significant.


2011 ◽  
Vol 255-260 ◽  
pp. 3444-3449 ◽  
Author(s):  
Jing Hui Liu

The Semi-Circular Bending (SCB) test, which is chosen as the best inspecting method for pavement cores, is of great significance. Based on the SCB test and flexure beam test, this paper presents the findings of a laboratory study that aimed to evaluate the effects of recycled tire rubber on the fatigue properties of asphalt mixtures. Three mix types, a conventional hot-mix asphalt concrete, a dry process rubber modified asphalt concrete, and a wet process asphalt-rubber concrete, were included in the investigation. It is found that the asphalt mixtures produced by the wet and dry process showed better fatigue performance, which is the same conclusion from the SCB test and flexure beam test. The SCB test can be an effective evaluation means for the pavement service performance of asphalt rubber mixtures.


2020 ◽  
Vol 259 ◽  
pp. 119662 ◽  
Author(s):  
Israel Rodríguez-Fernández ◽  
Farrokh Tarpoudi Baheri ◽  
Maria Chiara Cavalli ◽  
Lily D. Poulikakos ◽  
Moises Bueno

2016 ◽  
Vol 78 (7-3) ◽  
Author(s):  
Md. Maniruzzaman A. Aziz ◽  
Zohair Ahmed Altieb ◽  
Khairul Anuar Bin Kassim ◽  
Hauwa Baffa Jibrin

The increasing consumption of waste tire has generated many problems such as increasing landfill space, environmental pollution and causing health hazards. Parallel to this is the increasing of roads construction as a result of heavy traffic on roads. This study reviews to the use of crumb rubber (waste tires in powder form) in bitumen using the wet process. The study focuses on the crumb rubber as a replacement to the total weight of bitumen. The design or life span for all highways and urban roads is 10 – 20 years. Unfortunately, damages or distresses on pavements are still occurring before reaching the maximum period of the designed road serviceability. Among the major influencing factor that is contributing to this distress is the repeated heavy traffic loading on the road surfaces. Moreover, the use of waste crumb rubber in road construction as a pavement surface has a better skid resistance, fatigue crack resistance and increased rut resistance. The review includes physical tests that are used to determine the physical properties of bitumen and modified crumb rubber mix. The physical tests involve penetration test, softening point test and viscosity test. The second stage is rheological tests like rolling thin film oven test (RTFOT), pressure aging vessel (PAV) and dynamic shear rheometer (DSR) tests. The expectations from the study are to develop bitumen with waste crumb rubber that would minimize the costs of bitumen and providing better physical and rheological properties compared to the convention bitumen based on the tests that was conducted. Crumb rubber modifier as improved resistance to rutting due to high viscosity, Improved resistance to surface initiated, reduce fatigue/ reflection cracking, lower pavement maintenance costs, and saving in energy and natural resource.


Since 1960 Using crumb rubber modifier (CRM) in hot asphalt mixtures has become a frequent practice in road construction. Using the CRM by the dry process method is not commonly used, although it has great advantages such as it is less fuel consuming and it does not require storage container like the wet process method. This research evaluates the mechanical properties of dense graded asphalt rubber mixtures manufactured using the dry process. The results obtained from this mixture compared with similar asphalt mixture without CRM. The mechanical properties of all mixtures evaluated using a set of tests such Marshall Stability and flow test, moisture susceptibility test, indirect tensile strength test, dynamic modulus and flow number test. The research results showed that using CRM with 0.75% of aggregate’s weight increased the mixture’s stability, flow and enhanced its cracking and permanent deformation resistance.


Author(s):  
John A. Hinrichsen ◽  
John Heggen

The use of voids in mineral aggregate (VMA) criteria for proper mix design of hot-mix asphalt is a time-honored and fairly successful tool. Recent developments in the field of asphalt mix design have encouraged the use of mixtures with a coarse aggregate structure to resist the effect of heavy traffic loads. By using the equations presented, which account for both aggregate gradation and the volumetric properties of the materials, the mix designer is able to judge the proper VMA requirement for each unique blend of materials. By applying the new equations, the most economical mix may be selected without great risk of reduced durability. Supporting data from field application are presented to illustrate the use of the equations.


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