Mix Design & Rejuvenators

Mix Design & Rejuvenators

Grant Wollenhaupt & Jennifer Breuer Mix Design & Rejuvenators Issues with Current Designs 1

Cracking 2 Raveling How do we fix these issues? 1

Cracking Fatigue Block Reflective - Thermal Cracking Causes Block Cracking 1. Old and dried out mix 2. Mix was placed to dry 3. Fine aggregate with absorption

Fatigue Cracking 1. 2. 3. 4. 5. Excessive loading

Weak surface, base, or subgrade This surface or base Poor drainage Any combo from above Cracking Causes Thermal Cracking1. Incorrect binder grade 2. Severe climatic changes

Reflective Cracking 1. Differential movement between asphalt and concrete layers CRACKING Underlying cracking problem? Mix was placed to dry High absorption on some local

aggregates Weak base mixtures Poor drainage Incorrect binder grades 2 Raveling

Causes and Solutions Raveling Causes? 1. Asphalt Binder has hardened excessively

2. Poor Quality Mixture 3. Broken Bond between aggregate and asphalt

4. OXIDATION 5. Water / Traffic ISSUE SUMMARY

Dry Mix Poor Base / Subgrade Drainage Inadequate binder grade Increased oxidation Poor construction Recycled Materials Huge push for recycled pavements in

order to preserve the environment as well as reducing waste and aid in producing a cost effective mix to construct your roadways. Cost Savings Environmentally responsible BEST PRACTICES WITH RECYCLE

QUESTION: Can recycling can be done responsibly and still provide performance as well as cost effectiveness? ANSWER: YES with design changes and rejuvenators UNDERSTANDING YOUR INPUTS The key to effective design is understanding the products you are incorporating

Aggregate RAP RAS Liquid Binder Additives Hot Topic REJUVENATORS

Rejuvenation to restore youthful vigor; make young again Softening Agent substance added to a textile in finishing to give a softer handle Oxidation ? Asphalts exposure to oxygen begins a molecular process

that causes new polar bonding sites. The increase of the polar sites allow molecules to shuffle looking for bonds that bring it to a thermodynamic stable state. Selfassemblage makes the bonds tighter resulting in a stiffer and brittle pavement How much time do we have?

1. Exposure 2. Time 3. Temperature Where does oxidation occur? Asphalt Storage Temperatures Mixing Temperatures at Plant Silo Time

UV and Oxygen Exposure Brittle Binder Decreased Decreased Flexibility Flexibility

Decreased Decreased Elasticity Elasticity Increased Increased Stiffness/

Stiffness/ Viscosity Viscosity POOR PERFORMANCE POOR WORKABILITY OXIDATION EFFECTS

REJUVENATOR MARKET Re-Disperse the asphaltenes Counter the stiffness of RAP/RAS Help ratio of asphaltenes to resins and aromatics Improve workability of the mix Increase low temperature flexibility

Results Virgin Binder PG Grading Mixture Grading Hamburg Results SCB Results TSRST Texas Overlay

PG64-22 TRUE GRADE PG64-22 5% HYDROGREEN Base Oil w/ Hydrogreen PG64-22 8% HYDROGREEN PG64-22 10% HYDROGREEN 66.5-24.9 61.0-30.9 54.8-32.7

52.0-34.8 T5RC WITH 30% RAP PG78-20 T5RC WITH 27%RAP/3% RAS PG90-12 Field Data Add Rejuvenator T5RC WITH 27%RAP/3% RAS

T5RC WITH 25%RAP/5% RAS PG75-23 PG81-22 HAMBURG WHEEL-TRACKER Source: Laboratory Performance of Green Asphalt in Flexible Pavement Systems

HAMBURG RESULTS Source: Laboratory Performance of Green Asphalt in Flexible Pavement Systems SCB Source: Laboratory Performance of Green Asphalt in Flexible Pavement Systems SCB RESULTS

Source: Laboratory Performance of Green Asphalt in Flexible Pavement Systems TSRST Source: Laboratory Performance of Green Asphalt in Flexible Pavement Systems TRST RESULTS

Source: Laboratory Performance of Green Asphalt in Flexible Pavement Systems TEXAS OVERLAY Source: FHWA/TX-14/0-6614-3 $$$$$$$ SUMMARY

Recycle is necessary to maintain roads under current budget To uphold quality of the recycled mixes, rejuvenators are a necessity Design changes are necessary to increase effective binder in mix Final product must be fairly evaluated Questions Grant Wollenhaupt

[email protected] www.researchtoroads.com

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