VOT Use of Soil Stabilizers on Highway Shoulders
J Smith
USE OF SOIL STABILIZERS ON HIGHWAY SHOULDERS
Background
General Assembly action:
VTRC shall study the use of soil stabilizers in highway s.houlders at one or more selected locations with the objective of finding a method of substantially reducing the occurrence of pavement/shoulder drop off at a reasonable cost
Research Plan
- Field study only
- No laboratory analysis involved
- Two locations
- Three stabilizers
- Test and Control Evaluation
Project Modifications
- One type of shoulder material (crushed stone).
- Two stabilizers
- Soiltac (vinyl acetate copolymer emulsion)
- Centrophase AD (soy/lecithin emulsion)
- One location (Route 522, Powhatan Co.)
Before
After
Centrophase 9/14/2005
Soiltac 9/14/2005
Hypotheses
WORKING: The addition of stabilizers to the shoulder material did affect the strength of the material
NULL: The addition of stabilizers to the shoulder materi.al did not affect the strength of the material
As measured by its stiffness and bearing capacity
Performace Data
Low shoulders, Soiltac 9/21/2004
Low shoulders, Control 9/21/2004
Other Findings Visual Inspection
- 9/14 - 12/14, the surface of both test sections were firmer th.an the control section
- 2/8, the surface of both test sections were softer than the control section
Findings - Objective Tests
- Statistically speaking, on no occasion were test section data better than the control section data
- The 2/8/2005 data supports the visual inspection data
- Overall, the data supports the null hypothesis
Null Hypothesis
The addition of stabilizers to the shoulder material did not affect the strength of the materi.al as determined by measurement of its stiffness and bearing capacity
Entrance - Control Section 2/8/2005
DCP Penetration Readings for Sample Control-6, by Date
DCP Penetration Data - 2/8/2005
Conclusions
- Equipment normally used for road stabilization is not effective or efficient for stabilization of narrow shoulders.
- Soil stabilizers mixed with crusher run stone do not increase the stiffness or bearing strength.
- Soil stabilizers mixed with crusher run stone do not prolong the period of optimum stiffness and bearing strength of the material.
- Insufficient evidence to determine if soil stabilizers improve a shoulder's short-term resistance to erosion due to the action of water or traffic.
- The cost of using soil stabilizers as short-term surface stabilizers for crusher run stone shoulders is greater than the benefit received.
Recommendations
- Shoulders should be designed for the anticipated traffic load.
- Soil stabilizers should not be used with, crushed stone with the intent of improving or prolonging the CBR of shoulder material.
- Consider additional study of soil stabilizers as a short-term solution to shoulder erosion.
Project Limitations
- Project mandated : June 2004
- Report toi GA: January 1, 2005
Installation - 9/14/2004
Control
GeoGauge measures stiffness
- Defined as force over deflection
- The higher the stiffness reading the more resistant the material is to movement (e.g., rutting, corrugation)
The DCP measures penetration
- Inches/hammer blow
- Correlates to CBR or bearing strength
- The less penetration per blow the more weight the material can carry per unit area.
2/5/2008 Soiltac - Centrophase - Control
Soiltac Section - 2/8/2005
Centrophase - 2/8/2005
DCP Penetration Readings for Sample Control-6, by Date
DCP Penetration Data 2/8/2005
