VDOT Use of Soil Stabilizers on Highway Shoulders (TPD0507012)

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 material did not affect the strength of the material

(as measured by its stiffness and bearing capacity)

DATA COLLECTION:

• Dynamic Cone Penetration – Measures penetration and correlates to bearing strength
• Geogauge – Measures stiffness or material’s resistance to movement.
• Visual inspection

FINDINGS:

• Statistically speaking, on no occasion were test section data better than the control section data
• The February 8th data supports the visual inspection finding that the control section was firmer than either test section.
• Overall, the data supported the null hypothesis

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 of the material or prolong the period of optimum stiffness and bearing strength.
• There is 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.

Control Section

Soiltac-treated Section

Centrophase-treated Section

Entrance 2/8/2005

DCP Penetration Readings for Sample C-6, by Date

DCP Penetration Data 2/8/2005