8/12/2019 14 048 Pavement Base Strengthening

1/2

FY 2014 Research Problem Statement

ODOT Research Section

555 13thStreet NE; Ste 2

Salem OR 97301-5192

Phone (503) 986-2700

Fax (503) 986-2844

I. TITLE

II. PROBLEM

The State of Oregon controls a significant number public highways, totaling thousands of miles, which are subjectedto a broad range of environmental and traffic-loading conditions. Increased demand for access and usage of these

highways has resulted in an increase in the wear on its pavements, and the need for widened corridors. Whenwidening and rehabilitation is required, particularly in those segments that exhibit poor performance, the sub-base

and base course of the pavement structure often requires reworking and/or replacement to re-establish the strengthand stiffness of the material, resulting in a significant amount of construction effort and increased construction

duration. For example, a preferred remediation used by ODOT consists of (1) removing the pavement layer, (2)

tilling the base and sub-base layers, (3) mixing the tilled base and sub-base with cement, (4) wait for curing of thecement-stabilized soils, (5) regarding and leveling, and (6) paving. Additionally, increased duration of constructionand use of new aggregate materials results in a larger carbon footprint per mile of rehabilitation, due to the fuel

required to power mining, hauling, and placement activities.

III. PROPOSED RESEARCH, DEVELOPMENT, OR TECHNICAL TRANSFER ACTIVITY

Research on a relatively new ground improvement method, termed Geo-Base, is proposed to evaluate its

effectiveness in the in-place stiffening and strengthening of sub-base and base course materials that are notsusceptible to pumping failure, such as loess soils in Eastern Oregon, dune sands along the coast, and dredge sand

fills along the Columbia River. The Geo-Base ground improvement method consists of a track-ho mounted stiffenedsteel plate, 2.5 in diameter, fixed to a hydraulically powered concrete breaker. The steel plate tamping foot is

placed on the surface the existingbase course following removal of the deteriorated pavement and tamped under

high-frequency, high-energy percussive blows until the plate no longer moves downward, as indicated by on-boardinstrumentation, resulting in a stiffened, densified base course layer. The process is repeated along a pre-determinedgrid of improvement points to achieve the required coverage. Since this method is relatively new, research is

required to evaluate variables controlling the performance of the improved ground.

The research program proposed to evaluate the in-place sub-base and base improvement offered by this new methodconsists of:

1. Perform literature review to identify and compare the performance of somewhat similar ground improvemenmethods, such as deep dynamic compaction (dropped dead weight) and rapid impact compaction.

2. Develop an experimental program for a field evaluation of the GeoBase ground improvement method. Thiswork includes the:

a.

Identification of a test site: the Geotechnical Engineering Field Test Site at Oregon State Universityprovides a suitable, controlled test site that offers both fine grained soils and a stock pile of granular soils

to simulate both common subgrade materials found in Oregon as well as the typically specified sub-baseand base course materials.

b. Conduct field trials to evaluate the effect of: (1) the duration of compaction, (2) the area improvementratio (essentially, relative area of improvement), (3) the depth of improvement, and (4) the effect of soil

type/moisture sensitivity on improvement performance. The test bed would be evaluated before and afterimprovement using in-situ and field compaction testing.

3. Evaluate the impact of the improved sub-grade, sub-base, and base course improvement on the anticipatedservice life of typical pavement sections.

4. Document findings and submit final report.

14-048 Accelerated In-Place Pavement Base and Sub-base Strengthening A Sustainable Approach

8/12/2019 14 048 Pavement Base Strengthening

2/2

IV. POTENTIAL BENEFITS

Research on this relatively new ground improvement method will offer ODOT a green alternative for the economica

and effective reconstruction and rehabilitation of its numerous highways. The duration of rehabilitation could besubstantially reduced, resulting in shorter duration of lane closures and impact on traffic congestion. The cost o

pavement reconstruction could be reduced significantly with the decrease in material quantities. Additionally, thissystem could be used by ODOT Maintenance to effectively treat small problem areas without major excavation and

replacement. Finally, Oregon could improve its already high standing as a proponent of Sustainable practices byinvestigating and implementing this new green construction technology.

V. IMPLEMENTATION

This technological advance will be transferred through presentations given in meetings and workshops with ODOT

personnel. Findings will be summarized in technical reports, conference proceedings, and journal papers. Designexamples will be generated to provide ODOT a methodology for the evaluation of the improvement in its existing

pavement section and the possible cost benefits for in-place stiffening and strengthening. Justin Moderie, PavemenDesign Engineer, will oversee technical transfer and implementation within ODOT.

VI. LIST OF REFERENCES(optional)

VII. CONTACT INFORMATION

Your name: Armin W. Stuedlein, PhD, P.E.______ Person Responsible for Implementation: Justin G. Moderie, P.E., G.E.

Affiliation: Oregon State University Affiliation: Oregon Department of Transportation

Telephone: 541-737-3111 Telephone:(503) 986-3122Email: armin.stuedlein@oregonstate.edu Email: Justin.G.MODERIE@odot.state.or.us