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SINTEF Building and Infrastructure
Effects of Crumb Rubber Properties on CRM Binder Performance
Carl Thodesen
SINTEF Building and Infrastructure
Outline
Introduction
Objectives
Crumb Rubber
CRM Binder Properties
Conclusions
SINTEF Building and Infrastructure
Introduction: Scrap Tire Problem
Scrap tires generated in U.S. (2005): 300x106
Scrap tire generation: 1 tire/person/year
Environmental dangers: Tire fires and runoff
Social dangers: Breeding ground for mosquitoes
Reduced landfill space
Tire disposal: non sustainable practice
Wasted resources
SINTEF Building and Infrastructure
SINTEF Building and Infrastructure
CRM Binder
SINTEF Building and Infrastructure
Introduction: Solution
Approximately 28% of all scrap tires used in construction materials are used within the field of civil engineering
Incorporation of crumb rubber with asphalt binder to produce crumb rubber modified (CRM) binder
CRM asphalt meets many of the specifications of conventional modified asphalts
CRM asphalt include improved resistance to permanent deformation, fatigue cracking, and thermal cracking.
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Overhead View of Plant Site
Hot Plant Oil Tank
Virgin Oil Tank
Hot Mix Plant
Blending Unit
Bag House
Reaction Tank
Generator
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Field Binder Testing
After Reaction Time Is Complete (30, 45, 60 Minutes)
Binder sample taken and checked for viscosity
Target: 1,500 – 4,000 cP (Centipoise) @ 350° F
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Crumb Rubber Reaction
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Crumb Rubber Reaction
SINTEF Building and Infrastructure
Outline
Introduction
Objectives
Crumb Rubber
CRM Binder Properties
Conclusions
SINTEF Building and Infrastructure
Objectives
Discuss nature of variability within crumb rubber
Examine effects of crumb rubber properties on CRM binder performance using SHRP testing procedures, and
Determine which properties of crumb rubber play the biggest role in specific binder performance parameter.
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Objectives
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CRM Binder
Grinding
Concentration
Gradation
SINTEF Building and Infrastructure
US Modified binder use
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0 %
25 %
50 %
75 %
100 %
PG 58-22 PG 58-28 PG 58-34 PG 64-22 PG 64-28 PG 70-22 PG 70-28 PG 76-22 PG 76-28
% S
tate
s re
po
rt in
use
2005 2006
SINTEF Building and Infrastructure
Outline
Introduction
Objectives
Crumb Rubber
CRM Binder Properties
Conclusions
SINTEF Building and Infrastructure
Crumb Rubber
Derived from the grinding of scrap tires
Generally produced using two methods: Ambient
Cryogenic
Fine powder like substance
Some properties depend on grinding method
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Crumb Rubber
Cryogenic at 30 x
magnification
Ambient at 30 x
magnification
SINTEF Building and Infrastructure
Outline
Introduction
Objectives
Crumb Rubber
CRM Binder Properties
Conclusions
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CRM Binder Properties: SHRP Properties
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CRM Binder Properties
Handling and Pumping
Resistance to Permanent Deformation
Resistance to Thermal Cracking
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Handling and Pumping
Rotational Viscometer
Viscosity limits set
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Handling and Pumping
Particle Size
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Handling and Pumping
Morphology
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Resistance to Permanent Deformation
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Resistance to Permanent Deformation
Particle Size
Testing at 64oC
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Resistance to Permanent Deformation
Morphology
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Resistance to Thermal Cracking
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Resistance to Thermal Cracking
Particle Size
10% CRM
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Resistance to Thermal Cracking
Morphology
SINTEF Building and Infrastructure
Outline
Introduction
Objectives
Crumb Rubber
CRM Binder Properties
Conclusions
SINTEF Building and Infrastructure
Conclusions
The addition of crumb rubber to binder: Raises the upper failure temperature
Decreases lower failure temperature
Increases viscosities
Extent of modification dependent on: Base binder properties
Crumb rubber properties
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SINTEF Building and Infrastructure
Conclusions
Ambient CRM binder viscosity is typically higher than that of cryogenic CRM binder. As concentration increases the effect of the crumb rubber becomes
more defined.
Particle size (0.18 – 0.85 mm) plays a small role in establishing the binder viscosity
Increases in the crumb rubber concentration consistently produced higher G*/sinδ values, Particle size (0.18 – 0.85 mm) was not seen to play a statistically
significant effect on the rutting susceptibility of the CRM binder.
Ambient CRM binders produced significantly higher failure temperatures than cryogenic CRM binders.
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Conclusions
As particle fineness (0.18 – 0.85 mm) increased so too did the resistance to thermal cracking. Ambient and cryogenic grinding procedures produced statistically
similar CRM binders with respect to thermal cracking.
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Future work
Studded tyre issues?
Relevance of high end PG grade to predicting rutting in Norway?
Suitability with Norwegian asphalt mixes?
More research necessary to evaluate suitability in Norway
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SINTEF Building and Infrastructure
Questions?
SINTEF Building and Infrastructure
Tayebali, A. A., Vyas, B. B., & Malpass, G. A. (1990). Effect of Crumb Rubber Particle Size and Concentration on Performance Grading of Rubber Modified Asphalt Binders. ASTM Special Technical Publication , 30-47.
Bahia, H. U., & Davies, R. (1996). Factors Controlling the Effect of Crumb Rubber on Critical Properties of Asphalt Binders. Journal of the Association of Asphalt Paving Technologists , 64, 130-162.
Bahia, H. U., & Davis, R. (1994). Effect of Crumb Rubber Modifiers (CRM) on Performance Related properties of Asphalt Binders. Journal of the Association of Asphalt Paving Technologists , 63, 414-449.
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