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SWUTC Ph.D. Candidate Assistantship Project Description

Flexible Base Course Performance Prediction of Roadway Infrastructures through Nondestructive Tests

University: Texas A&M University

Principal Investigator:
Hakan Sahin
Zachry Department of Civil Engineering

Faculty Supervisor:
Bruce X. Wang
Zachry Department of Civil Engineering
(979) 845-9964

Funding Source: USDOT Funds

Total Project Cost: $36,279

Project Number: 600451-00035

Date Started: 9/1/13

Estimated Completion Date: 12/31/14

Project Summary

Project Abstract:
Pavement performance and life cycle costs depend very strongly on the proper functioning of the base course, the most important supporting layer in a pavement. The likelihood of the base course performing well is greatly increased if the properties it was assumed to have when the pavement was designed match the properties it has when it is actually built in-place. However, it turns out that the properties of the base course layer that are measured during construction are never the same as the layer properties used in the design. For decades, it has been recognized that there is a need to assure that the properties of base courses used in design are what have actually been placed. The layer modulus and permanent deformation properties are the primary design properties that can be directly related to the subsequent performance of the pavement and ultimately to the costs which are passed on to the taxpaying public for using a cost-effective in-service pavement.

A major obstacle to controlling these design parameters is the difficulty of measuring the modulus, and more so the permanent deformation characteristics of the base course. Quality assurance of the compacted base course must be conducted in a timely and efficient manner so as to not retard the pace of construction, and also with a high degree of accuracy and precision that can reasonably assure that the pavement will perform as it was meant to while being designed. This challenge is attempted to be addressed in this study by establishing some simple and quick laboratory test protocols to measure essential attributes of the base course that can be extended for use in the field.

Project Objectives:
The focus of this research is to develop a quick, accurate and simple process for determining reliable values of the in-place as compacted base course modulus and permanent deformation properties. In addition, the measurements that are made should also contribute to the assurance of quality during the cycle of operations in the process of taking the base course from its quarry, transferring it to a job site, and compacting it in-place.

The unbound aggregate properties which are related to Quality Control (QC) and Quality Assurance (QA) are sought to be determined accurately regardless of whether they are measured in the field or through laboratory experiments.

Hence, the primary objective of this work is to determine an improved performance protocol regarding base course properties and subsequently develop mathematical relationships which can be used in engineering design and construction using the proposed protocol. This work will develop new and innovative methods to determine QC and QA for base course materials in-place.

Task Descriptions:

Task 1Developing Experimental Program

Task 2Develop a Model to Determine Fundamental Base Course Properties

Task 3Model for Modulus and field Verification

Task 4Model for Permanent Deformation and Field Verification

Task 5 – Document the Dissertation and Final Report