205 Lime Modified Soil
Contractor Designed Lime Soil (205.07)
Specification Changes
The specifications for this item did not change significantly. The following are some of the major changes:
- The construction procedures were slightly modified.
- The standard lime mixture of 5% lime with 110 pound material was clarified.
- Quick lime is allowed and a hydrated lime to quick lime conversion is given.
- When the Department wants the Contractor to Design the percent lime, provisions are made for this work.
Uses of Lime Modified Soil
Lime is most effective in treating soils with a PI>20. These are soils classified as A-7-6 and A-6-b’s.
Most of the time lime-modified soil is specified in situations such as detailed in Figure 205.A. This situation denotes the removal and replacement of wet soil. The soil is excavated, lime modified, and replaced in the same location. Notice the addition of drainage to the slide repair.
A brief outline of the specification requirements follows:
Materials (205.02)
Hydrated or quick lime according to 712.04.B is used.
One hundred % of the quick lime must pass the # 4 sieve.
Limitation (205.03)
Temperatures greater than > 40o.
Spreading (205.04)
Usually use 5 percent lime per 110 pound soil. To calculate the number of pounds of lime to use per square yard, use the Equation 205.1:
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Equation 205.1 – Pounds of Lime per Square
Yard |
where:
9 ft2 in a square yard
9 ft2 /yd2 x (one inch deep)/12 inches/ft = ¾ ft3/yd2 per one inch deep
D = depth (inches)
WD = average density (lb/ft3)
% = percent lime (expressed as a decimal)
For example, if using 5 % lime, 110 lb/ft3 material, at 8 inch lifts:
¾ X 8 inches X 110 lb/ft3 material X 0.05 = 33 lb/yd2 of lime
Use a square yard canvas to weight the lime once the pounds per square yards have been determined. Once you determine the amount is correct, you may want to just measure the thickness of the lime. The contractor must submit a spreading plan to obtain the correct amount of lime per square yard.
See the re-agitation requirement for the slurry method. Use the slurry within 24 hours of mixing to maximize the effectiveness.
Mixing (205.05)
- For Slurry Method.
- Open the soil up prior to applying the lime.
- Apply the lime and mix into the soil.
- Use a power driven mixer.
- All clods less than 2 inches (50mm).
- If not under a pavement.
- Discs may be used.
- Use 10 passes in one direction and 10 in the other.
- All clods less than 1 inch (25mm).
- Add water.
- Optimum for hydrated.
- + 3 % for quick lime.
1. Prevents expansion.
Compaction (205.06)
- Compact to 98% of the maximum density.
- Use the one point proctor method in Supplement 1015.
- Measure the density and take the proctor soil from under the gauge.
- Use the Ohio Typical Density Curves to pick the maximum density.
- In some rare cases, a test section may be constructed or the curves developed in section 205.07 may be used.
Contractor Designed Lime Soil (205.07)
Use this section to verify that the soil will increase in strength when the lime is added to the soil.
Unconfined strengths are determined to detail the strength gain. If problems develop in the field, this information can be used to make field adjustments.
Normal increases in strength range from 20 psi to 100 psi for Ohio soils
