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Implementation of the HMA Shear Test for Routine Mix-Design and Screening

What Was the Need?

In Texas, rutting or permanent deformation (PD) continues to be a flexible pavement failure mode of concern, particularly under heavy traffic loading, high temperature environments, and severe shear stress conditions such as highway intersections and urban stop-go sections, or where lower asphalt-binder performance grades (PG) have been used. In particular, with the record summer temperatures in recent years, several rutting failures have occurred with hot mix asphalt (HMA) mixes that had performed acceptably in the laboratory rutting susceptibility tests, namely the Hamburg wheel tracking test (HWTT).

What's the Solution?

TxDOT Project 0-6744: New HMA Shear Resistance and Rutting Test for Texas Mixes proposed several key modifications to the HWTT protocol in the view of improving its ability to simulate field rutting conditions under extreme shear environments, including testing the HMA mixes at elevated temperatures (i.e. 60 °C). Additionally, a new supplementary HMA shear test, namely the simple punching shear test (SPST) was developed that showed good potential to be considered as a supplement or surrogate to the HWTT for shear strength evaluation of HMA mixes.

Researchers (1) assisted all of the districts with their routine mix-design screening and HMA shear strength testing, (2) conducted a pilot implementation of the findings of Project 0-6744 through assisting the districts with their routine HMA mix-designs and mix screening using the proposed SPST and modified HWTT protocols, and (3) verified and refined the proposed test procedures with field performance data from in-service highway test sections.

Project Number

5-6744-01

Status

Completed

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Project Details

Start Date

9/1/2015

End Date

8/31/2018

Performing Institution(s)

Texas A & M Transportation Institute (TTI)

Research Team

RS: Lubinda Walubita

Sponsor

Project Manager

Kevin Pete

Contract Specialist

Patti Dathe

Amount Funded

FY15: $5,000
FY16: $140,693
FY17: $130,942
FY18: $127,409

Source

RTI Spreadsheet 10/8/2015

Publications from this Project

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Functional Area

Safety and Operations

Index Terms

Flexible pavements
Rutting
Deformation
Hot mix asphalt

Lead University

TTI

Researcher

Walubita, Lubinda F.

Geographic name

Laredo, Tex.
San Antonio, Tex.
Fort Worth, Tex.
Paris, Tex.

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Record Added:

10/8/2015

Record Updated:

1/25/2022 5:36 AM EST

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