ABSTRACT In order for an asphalt binder to be suitable for the conditions that it is going to be used for it should pass the various performance grading tests. The polymer modified binder in this study presented higher viscosity than unmodified binder, therefore an increase in the mixing and compaction temperature is needed to obtain the required viscosities for pumping and workability. Mixing and compacting temperatures of 180 and 165

o C,

respectively, were found. After characterization of the binder a performance grade of PG70-40 was determined.

The material presented here is based upon work supported by the National Science Foundation under Award No. EEC-0813570. Any opinions, findings, and conclusions or

recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Characterization of the Performance Grade of a Polymer

Modified Asphalt Binder Jose Hernandez, Ka Lai Ng, and Dr. Chris Williams, Department of Civil, Construction, and Environmental Engineering, Iowa State University

RESEARCH QUESTION/HYPOTHESIS Will the density of the polymer modified binder be much different than an unmodified

binder?

What are the viscosities of the polymer modified binder under study at different temperatures?

How much will the mixing and compaction temperatures increase due to the expected higher viscosity of polymer modified binder?

Will the addition of polymer increase the performance grade of asphalt binder for high, intermediate, and low temperature performance?

REFERENCES AASHTO M320, Performance-Graded Asphalt Binder Standard Specifications for Transportation Materials and Methods of Sampling and Testing, 27th Ed. Washington, D.C.: American Association of State Highway and Transportation Officials.

AASHTO R28-09, Accelerated Aging of Asphalt binder Using a Pressurized Aging Vessel (PAV) Standard Specifications for Transportation Materials and Methods of Sampling and Testing, 27th Ed. Washington, D.C.: American Association of State Highway and Transportation Officials.

AASHTO T240, Effect of Heat and Air on a Moving Film of Asphalt Binder (Rolling Thin-Film Oven Test) Standard Specifications for Transportation Materials and Methods of Sampling and Testing, 27th Ed. Washington, D.C.: American Association of State Highway and Transportation Officials.

AASHTO T313, Determining the Flexural Creep Stiffness of Asphalt Binder Using the Bending Beam Rheometer (BBR) Standard Specifications for Transportation Materials and Methods of Sampling and Testing, 27th Ed. Washington, D.C.: American Association of State Highway and Transportation Officials.

AASHTO T315, Determining the Rheological Properties of Asphalt Binder Using a Dynamic Shear Rheometer (DSR) Standard Specifications for Transportation Materials and Methods of Sampling and Testing, 27th Ed. Washington, D.C.: American Association of State Highway and Transportation Officials.

AASHTO T316, Viscosity Determination if Asphalt Binder Using Rotation Viscometer (RV) Standard Specifications for Transportation Materials and Methods of Sampling and Testing, 27th Ed. Washington, D.C.: American Association of State Highway and Transportation Officials.

Asphalt Institute. Performance Graded Asphalt Binder Specification and Testing. Lexington, KY: Asphalt Institute, 2003. Print.

"Pavement Interactive." Http://www.pavementinteractive.org. Pavement Tools Consortium, n.d. Web. 18 July 2013.

RESULTS & GRAPHICS/CHARTS

BACKGROUND There has been an increase use of polymers to make modified asphalt binders to improve performance properties. The addition of polymers modify the viscoelasticity of the binder, affecting the temperature range thus improving performance. The increased viscosity from the polymers increases resistance to rutting under heavy loads, while increased elasticity improves the fatigue resistance from repeated cycles of heavy loads over the lifetime of the pavement. Since the addition of polymers affects the properties of the binder, testing ensures that the properties have enhanced.

TEST METHODS Viscometer (RV) AASHTO T-316 - Used to determine the viscosity of asphalt binder at high temperatures.

Dynamic Shear Rheometer (DSR) AASHTO T315 - Used to measure binder stiffness and elasticity properties at intermediate to high temperatures.

Bending Beam Rheometer (BBR) AASHTO T313 - Used to measure low temperature stiffness and failure properties.

Rolling Thin Film Oven (RTFO) and % Mass Loss AASHTO T240 - Provides simulated short term aged binder for physical property testing and calculation of mass lost during RTFO aging.

Pressure Aging Vessel (PAV) AASHTO R28-09 - Provides simulated long term aged binder for physical property testing.

ACKNOWLEDGEMENT I would like to thank Dr. Chris Williams in the CCEE Department. Graduate student Ka

Lai Ng in guiding and assisting me throughout my entire research. Finally Adah Leshem

with CBIRC, granting me the opportunity to conduct research.

DISCUSSION

The density of the polymer modified binder goes along with the density of an unmodified binder; 1.01~1.03. The average viscosity of the polymer modified binder is higher than the average viscosity at the

same testing temperatures of an unmodified binder, as well as the mixing and compaction temperatures (180 and 165o

C, respectively). From the DSR results of the unaged and RTFO aged material, the

high performance grade of the binder was found to be PG70. The average mass loss was 1.35%, somewhat higher than the maximum accepted criteria. The binder meets the required criteria for the PG

grading of the PAV aged material from the standard, which is set at 19o

C. The BBR results showed that the low temperature grading of the binder is PG-40. In summary, the performance grade of the

binder under study is a PG70-40, further testing of the Multiple Stress Creep Recovery (MSCR) is needed to characterize this binder.

Experimental Plan

Sample Density RV

DSR Unaged

DSR RTFO-Aged

DSR PAV-Aged

BBR

Gap 1mm Gap 1mm Gap 2mm Temp C

-18 -24 -30

PG58-40E XXX XXX XXX XXX XXX XX XX XXXX

Sample Density

1 1.019

2 1.018

3 1.020

Average 1.019

The following charts and table summarize

the results obtained after performing the

different test methods for the

characterization of the performance grade of

a polymer modified binder layed out in the

experimental plan.