ITEM 205  LIME MODIFIED SOIL

205.01   Description
205.02   Materials
205.03   Limitations
205.04   Spreading
205.05   Mixing
205.06   Compacting
205.07   Contractor Designed Lime Soil
205.08   Method of Measurement
205.09   Basis of Payment

205.01  Description.  This work consists of constructing a lime modified soil mixture and, designing the lime percentage in the soil.  Drain and maintain the work according to 203.04.A.

205.02  Materials.  Furnish hydrated or quick lime conforming to 712.04.B.  Furnish suitable soil, from on or off the project site, conforming to Item 203.

205.03  Limitations.  Perform lime stabilization work when the air temperature is 40 °F (5 °C) or above and when the soil is not frozen.  Do not perform this work during wet or unsuitable weather.

205.04  Spreading.  Unless stated otherwise, spread the lime at a rate to obtain 5 percent lime per dry weight of the soil for hydrated lime and 4 percent lime per dry weight of the soil for quick lime.  Use a dry weight of 110 pounds per cubic foot (1760 kg/m³) for the soil.  Prepare a report denoting the type of equipment to be used, speed of the intended equipment usage, rate of application of the lime, and calculations to produce the required percent lime.  Submit this report 2 workdays before the work for approval.

Apply lime using either dry or slurry methods as specified in the Contract Documents.  uniformly spread the lime on the soil using distributors.  Minimize dusting when spreading dry lime.  Do not apply dry lime if wind conditions are such that blowing lime exceeds the limits in 107.19.

When using the slurry method, prepare and distribute the lime slurry using equipment and procedures capable of keeping the slurried lime in suspension and spreading the slurry uniformly over the area to be stabilized.  Use the lime slurry within 24 hours of mixing.  Re-agitate or re-circulate the lime slurry after 8 hours of undisturbed storage.

The Engineer will approve the lime content of the slurry and the lime procedures for the dry and slurry methods to obtain the required percentage.

205.05  Mixing.  For slurry methods, open the soil with a spring tooth or disc harrow prior to spreading.  Immediately after spreading the lime, mix the soil and lime.  Mix the lime and soil by using an approved power driven rotary type mixer.  If necessary, add water to bring the mixed material to optimum moisture content for hydrated lime and to +3 percent of optimum for quick lime.  Continue mixing until the lime is thoroughly incorporated into the soil, all soil clods are reduced to a maximum size of 2 inches (50 mm), and the mixture is a uniform color.

For areas not under pavements or paved shoulders, the Contractor may elect to use the spring tooth or disk harrow in place of the power-driven rotary-type mixer by modifying the procedure as follows.  Open the soil with a spring tooth or disc harrow before spreading.  Spread the lime.  Use a minimum disc harrow coverage of ten in one direction and ten in the perpendicular direction to thoroughly incorporate the lime into the soil; continue mixing until all soil clods are less than 1 inch (25 mm) and the final mixture is a uniform color.

205.06  Compacting.  The Department will perform the compaction according to Supplement 1015.  Construct and compact lime modified soil according to Item 203 for embankment construction and Item 204 for subgrade.  The Engineer will use at least 98 percent of the maximum dry weight for acceptance of the lime modified soil compaction.

205.07  Contractor Designed Lime Soil.  When specified in the Contract Documents, design the percent of lime in the soil to obtain the maximum compressive strength.  Hire a Department pre-qualified geotechnical consultant experienced in lime stabilization to recommend to the Department a minimum percentage of lime required for the project.  Take one soil sample for every 5000 cubic yards (3800 m³) of soil, one per major type of soil, or a minimum of three soil samples per project, whichever is greater.  Take soil samples in locations, such as in the shoulder area of a subgrade to be stabilized, and at approximate equal intervals along the project work.  Determine the percent of lime by using compressive strength tests performed on the soil lime cylinders prepared according to ASTM D 5102, Method B.  Perform the compressive strength test on cylinders using a 5-day cure.  Use a percentage of lime by dry weight of the soil of 0, 4, 6, and 8 for each soil sample.  Make three soil cylinders for each percentage at the optimum moisture of the lime-soil mixture.  Recommend the percentage of lime for the project that obtains the maximum strength in 5 days.

Submit four copies of a report from the geotechnical consultant with all the data suitably presented to the Engineer for acceptance.  The Engineer will determine the percentage used on the project.  The Engineer may increase the percentage of lime chosen by the laboratory data by 1 percent to meet field variations.

After the Department accepts the lime percentage, make moisture density curves for the chosen percentage of lime according to AASHTO T 99 for each soil sample taken above.  Thoroughly mix the lime in the soil, and allow the soil and lime to mellow for at least 24 hours before making the curves.  Plot the wet and dry weight on one graph, and plot the wet weight on the Ohio Typical Density Curves.  Submit this data to the Engineer 3 workdays before the work.  The Engineer will use these curves or the Ohio Typical Density Curves for compaction acceptance by using Supplement 1015.

The Contract Documents will contain an estimated quantity for the project based on using 5 percent hydrated lime per dry weight of a soil weighing 110 pounds per cubic foot (1760 kg/m³).

When the lime percentage for the project changes, re-submit the spreading procedure report required in 205.04 based on the changed percentage.

205.08  Method of Measurement.  The Department will measure Lime Modified Soil (slurry or dry method) by the number of cubic yards (cubic meters) used in the complete and accepted work, as determined by Item 203 or 204.

The Department will measure Lime by the number of tons (metric tons) incorporated in the complete and accepted work.  The contract quantities contain the amount of hydrated lime estimated to complete the work.  When the Contractor uses quick lime, the following equation is used to pay for the amount of quick lime incorporated in the completed and accepted work:

HLC = EHL = QL ´ 1.32 = Payment per Ton of Quick Lime

Where:
                   HLC =  hydrated lime in the contract
                   EHL =  quick lime equivalent in hydrated lime
                      QL =  quick lime (incorporated in the work)

The Department will measure Water by the number of M gallons (cubic meters) applied in the complete and accepted work, as determined by Item 616.  The Department will include water used for making the slurry in the slurry method.  The Department will not include water used for spreading the lime slurry that brings the soil to more than 5 percent above optimum moisture content, immediately after the application of the slurry.

The Department will not measure Contractor Designated Lime Soil.

205.09  Basis of Payment.  The Department will pay lump sum for all work, labor, and equipment described in 205.07.  The Department will pay one-third of the lump sum amount bid when the lime soil sampling and testing is complete and the report is accepted by the Department.  The Department will pay one-third of the lump sum amount bid when the moisture density curves of the lime soil are accepted by the Department.  The Department will pay one-third of the lump sum amount bid when the lime soil stabilization is completed and accepted by the Department.

The Department will pay for accepted quantities at the contract prices as follows: