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South Dakota Department of Transportation
Project Synopsis
SD2000-02


Title: Soil Density Target Values
Project Researcher: Richard Reid, SDSU
Project Manager: Brian Hines
Research Period: 2/11/2000 - 11/30/2000
Status:
Cost: $42,540.00

Problem Statement: The South Dakota Department of Transportation (SDDOT) currently uses the Ohio Typical Moisture Density Curves to establish target moisture and density values. Field use of one-point results for a comparison to the Ohio Curves is a time-consuming process. With limited resources, the time spent by SDDOT field personnel on compaction testing reduces time available for other necessary inspection duties.

Currently, a SDDOT construction inspector is required to make a one-point proctor test for each of the in-place specified density tests. The inspector must return to the field lab to complete the one-point proctor test. The one-point proctor results are then compared to the family of curves from the Ohio Typical Moisture Density Curves to determine the target Maximum Dry Density. This is a time-consuming process, removing the inspector from the project for an extended period of time. Often, a large quantity of embankment is placed before the results of the tests are determined. If the test fails, a substantial amount of rework by the Contractor can be incurred.

A review of current procedures to improve inspector efficiency while maintaining quality is needed. A review of Federal agency and surrounding state DOT practices is desirable to assess existing ways to improve our current procedures and policies. The necessary level of training required will need to be addressed, if more efficient procedures are identified. Increased inspector efficiency and improved testing methods will not only improve contractor efficiency but will minimize construction delays due to testing. Although, significant advances in moisture/density testing of soils has not occurred in recent years, improvements have been made in procedures and use of existing equipment such as nuclear density gauges and microwave ovens for moisture determination.

The purpose of this research is to increase the efficiency of our test methods, not to change the specification of the amount of compaction required. We are confident that our current specification (95% + of Maximum Dry Density in most cases) is in line with standard practices.



Findings:

Research Objectives:
1  Determine the suitability of SDDOT current soil and granular materials compaction testing policies and procedures (with the intent of reducing and or eliminating one-point testing).
2  Develop recommendations for improving efficiency while maintaining or improving quality of soil and granular compaction testing policies and procedures.
3  Develop recommendations for a training program to address all procedural changes.

Research Tasks:
1  Review current SDDOT soil and granular material policies and procedures.
2  Meet with the technical panel to review the project scope, work plan and to receive a list of SDDOT personnel to contact.
3  Meet with Material Personnel from all four regions, some Area Personnel and the SDDOT Soil Engineer, to gain insight into SDDOT existing procedures and problems.
4  Survey surrounding State DOTs and federal agencies to assess and document their methods, frequencies, procedures, equipment and training requirements for soil and granular density testing. The product of this survey would indicate what methods are mo
5  Compare SDDOT current policies and procedures against the other surrounding State DOTs and federal agencies with regards to quality, timeliness and compaction testing differences.
6  Prepare a Technical Memorandum to include recommended modern test methods and procedures that will improve efficiency while maintaining or improving quality and analyze how these changes will impact SDDOT resources.
7  Meet with the technical panel to review the work completed on the previous tasks.
8  Provide recommendations on how to implement these changes.
9  Prepare a draft copy of the changes to SDDOT Materials Manual.
10  Review current SDDOT training related to soil and granular material compaction testing and recommend appropriate changes.
11  Prepare a final report and executive summary of the literature review, research methodology, findings, conclusions, and recommendations.
12  Make an executive presentation to the SDDOT Research Review Board at the conclusion of the project.

Documents Available:
SD2000_02_Final_Report.pdf

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