Section 22 5—Soil -Lime Construction
225.1General Description
This work includes preparing and treating roadbed materials with lime to form a base, subbase, or subgrade. Water, mix, shape, and compact the necessary material according to these requirements and with the lines, grades, and thickness indicated on the p lans. Lime treated roadbed materials, subbases, or bases will be designated as Class A, Class B, o r Class C. The requirements of these Specifications are applicable to each course or layer, unless otherwise indicated on the plans. 225.1.01 Definitions General Provisions 101 through 150. 225.1.02 Related References
GDT 19 GDT 20 GDT 21 GDT 42 GDT 59 225.1.03 Submittals General Provisions 101 through 150.
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225.2Materials
Ensure that the soil is suitable for lime stabilization and that the materials used for stabilization meet the following requirements: Soil Section 810 or Section 814, as applicable Water Subsection 880.2.01 Lime Subsection 882.2.02 Bituminous prime Subsection 821.2.01 Blotter material (sand) Subsection 412.3.05.G.3
Use soil that consists of materials found in the roadbed, base, subbase, or added materials as specified or directed by the Engineer. Ensure that these materials meet the requirements shown on the plans or the pertinent specifications for these items. Remove the following from the soil: • Particles of aggregate too large to pass through a 3 in . (75 mm) sieve • Roots, stumps, grass turfs, and other vegetable matter
Use water without detrimental quantities of oil, salt, acid, alkalis, sugar, or vegetable matter. Do not use water with total inorganic solids exceeding 0.20 percent. Test n on-potable water prior to use and provide test results to the Engineer. Do not begin construction until the Engineer has approved the test results. Test according to Subsection 880.2.01.
The application rate for lime will be determined from laboratory tests and provided to the Contractor prior to beginning stabilization work. Hydrated lime will be used in all tests.
Use bituminous prime that consists of cutback asphalt of the following grades: • RC-30 • RC-70 • RC-250 • MC-30 • MC-70 • MC-250
Use blotter material (sand) that meets the requirements of Section 412. 225.2.01 Delivery, Storage, and Handling General Provisions 101 through 150. 260 260 260 260 260 260 260 260 260 260
225.3Construction Requirements
225.3.01 Personnel Ensure that adequate protection and safety equipment and training is provided for all personnel. 225.3.02 Equipment
Use equipment of the right size, in satisfactory mechanical condition that can produce satisfactory results. Provide a list of proposed equipment to t he Engineer prior to the beginning of construction. Provide any necessary equipment, including: • Mechanical spreaders capable of uniformly distributing bulk lime or lime slurry to the actual application rate as shown in the p lans. Do not distribute dry lime by pneumatic pressure. • Equipment capable of continuously mixing materials to a homogeneous blend and to a consistent depth. Weight all rollers sufficiently to accomplish the required compaction. • Rotary -type soil mixers capable of mixing to a minimum depth of 12 inches (300 mm) and capable of injecting mix water directly into the mixing chamber with automatic sensors to monitor water application and mixing depth. • Equipment for applying water and prime. Use a type and weight of equipment that will not damage lime- treated soil. Do not begin construction until the Engineer has approved the proposed equipment.
Alternate equipment, such as continuous or batch- type central plant or traveling mixing plants, will be approved if the equipment produces a mixture that meets this specification. 225.3.03 Preparation
Prepare for soil -lime construction as follows:
Subse ction 225.3.06.B, Finishing Requirements .
without displacement.
before placing each subsequent layer.
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The first section of each mixing operation will be a test section. The length of the test section will be the length required to use all of the lime on one truck. Demonstrate the acceptability of the equipment and methods used and provide a standard by which to ensure the finished grade elevation and compacted thickness with this method.
directed by the Engineer. 225.3.04 Fabrication General Provisions 101 through 150. 225.3.05 Construction Lime- treated roadbed materials, subbases, or bases will be designated as Class A, B, or C, as follows:
Apply the specified percentage of lime in two equal increments according to the following steps:
Subsection 225.3.06.B, Finishing Requirements, for finishing.
Apply the specifie d percentage of lime according to the following steps:
Subsection 225.3.06.B, Finishing Requirements for finishing.
Apply the specified percentage of lime according to the following steps:
Subsection 225.3.06.B, Finishing Requirements for finishing.
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• Apply lime according to the rate specified by the Engineer. • Apply lime uniformly so that the applied does not vary more than +/ - 10 percent of the quantity specified for each section. • Apply lime only to areas that can be mixed in one day. • Do not mix lime with frozen soils or with soils containing frost. Perform lime stabilization only when the air temperature is above 45 ° F (7 ° C) and only between April 1 and October 15, unless directed otherwise by the Engineer. • Distribute lime at the specified rate by making repeated passes over a section until the required amount has been spread. • After each pass, incorporate the material into the soil with mixing equipment. If necessary, add more water to the mix to accelerate mellowing.
• Provide the necessary equipment and take the necessary precautions to protect operations personnel from the hazards of lime dust or slurry. • Prevent damage, discomfort, or inconvenience to the public or to private property while preparing and distributing lime.
Spread lime on scarified areas at the specified rate. Distribute the material uniformly to avoid excessive loss. Choose one of the following three methods to apply lime:
Adjust the design application rate that was based on using hydrated lime, to reflect the properties of quicklime. Use the following formula to determine the application rate for quicklime: AR Q = AR H (1.32) (P) where; AR Q = Application Rate for Quicklime AR H = Design Application Rate Based on Hydrated Lime 1.32 = Ratio of molecular weights for hydrated lime (74) and quicklime (56) P = Certified Percent Purity of The Quicklime Do not apply quicklime if the Engineer determines that wind conditions could make blowing lime hazardous to traffic, workers, or adjacent property. Minimize lime pockets by applying lime to shaped and rolled areas that are relatively smooth. Spread uniformly at the specified rate using a mechanical spreader approved by the Engineer.
Create a lime slurry by mixing 30 percent dry lime solids, by weight, with 70 percent water. Mix slurry in agitating equipment and continue to agitate until arriving at the roadbed. Spread slurry on the scarified area with distributing equipment.
Create a lime slurry by slaking quicklime using special equipment at or near the Project site. Obtain the Engineer’s approval for all equipment and procedures before work begins
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Maintain the moisture content of the material at its specified optimum or not more than 5 percent over the optimum, at all times. Add water during mixing if necessary, even if the material has the optimum moisture content to sustain the chemical reaction between lime and water. Mix the material the same as for “Dry Application” or “Slurry Application” unless indicated otherwise.
1) Mix to the required depth and width. 2) If the depth to be treated, as shown on the Plans, is more than 12 in. (300 mm) compacted, treat in approximately equal layers of not more than 12 in. (300 mm) deep. 3) When multi -layer construction is required, blade the upper layers of the compacted soil in windrows outside the area to be treated until the low er layer is mixed, compacted, and approved by the Engineer. 4) Blade each successive layer back into place, shape and treat it with lime, mix, compact and shape to typical section. Include the cost of this manipulation in the bid price.
underneath conform as closely as possible to the crown of the finished course.
the section being processed.
finished course of lime treated material that conforms to the specified thickness and surface requirements in the plans.
1) Incorporate lime and water with rotary mixers until uniform. The mixture must pass through a 2 in. (50 mm) sieve. 2) Add the amount of water necessary to produce a moisture content of no less than 0 percent below the mixture’s optimum moisture content or no more than 5 percent above optimum moisture content. See GDT 19. 3) After mixing is complete, reshape the treated course to the approximate line, grade, and typical section. 4) Seal with a light, pneumatic- tired roller and other approved equipment, as necessary. 5) Mellow for a minimum of 12 hours and a maximum of 72 hours.
1) Incorporate lime and water with rotary mixers until uniform. Continue to mix and add water until obtaining a homogeneous mixture of soil, lime, and water that is satisfactory to the Engineer. 2) After mixing and applying water, ensure that 100 percent of the material by dry weight passes a 1.0 in. (25 mm) sieve and 60 percent by dry weight passes a No. 4 (4.75 mm) sieve.
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The following applies to Class A and Class B lime treatments only.
1.0 in. (25 mm) sieve and 60 percent passes a No. 4 (4.75 mm) sieve.
the process the next day, weather permitting.
Compact the material according to the following requirements and to Subsection 225.3.06.B, Finishing Requirements for finishing.
Compact the mixture within 4 hours after completing the final mixing. Maintain the material at a moisture content within ±2 percent of optimum.
Compact the mixture immediately after completing the first and only mixing. Maintain the material at a moistur e content within ±2 percent of optimum.
moisture content or up to two percent over the optimum content.
the entire depth of the mixture is compacted to the required density specified in Subsection 225.3.06.A.
following methods: 1) Scarify the area. 2) Add lime when required. 3) Remove the material when required. 4) Reshape and compact.
(25 mm) remains.
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7 days.
during curing.
(see Subsection 225.2.D ) according to Section 412.
sufficient moisture to prevent excessive penetration of the bituminous material.
0.15 to 0.30 gal/yd² (0.70 to 1.4 L/m²).
covered effectively during this period.
curing is not impaired and that the treated sections have hardened sufficiently to prevent marring or distorting the surface.
base or paving operations or except as may be permitted for embankment construction. 225.3.06 Quality Acceptance
After shaping the mixture to line, grade, and cross -section specifications, roll the course until uniformly compacted as determined by GDT 19. Use the percentages of maximum dry density in the following table. Determine the in- place density according to GDT 20, GDT 21, o r GDT 59, as applicable. All base, subbase, or shoulder courses 100% Top 1 ft (300 mm) of embankment (subgrade) 100% To within 1 ft (300 mm) of the top of the embankment 95%
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Ensure that the surface of the completed lime- stabilized layer conforms to the lines, grades, and cross -sections shown on the p lans or established by the Engineer and meets the following characteristics: • Uniform lime mixture • Smooth • Dense • Well-bonded • Unyielding • Free of cracks or loose material Ensure that surface requirements meet the following Specifications: Subgrade Subsection 209.3.05.E. Base, subbase, or shoulder course Section 301
If necessary, reconstruct the course or add lime to the course at no additional cost to the Department.
500 ft. (150 m).
thickness shown on the Plans.
the plans.
the specified depth and width according to this specification and the plans. 225.3.07 Contractor Warranty and Maintenance Perform the following work at no cost to the Department. Repeat this work as often as necessary to keep the lime- treated soil intact. • Maintain the lime- treated soil in good condition until the w ork is completed and accepted. • Maintain a smooth surface on the course by blading. • Immediately repair any defects that occur.
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225.4Measurement
If it is necessary to add other material to the roadbed, or to build the base or subbase entirely with new material, soil-lime material is measured by loose volume cubic yard (meter), as specified in Section 109.
If payment is specified by the square yard (meter), soil -lime treated roadbed, subbase, and base course are measured with the methods used for soil -cement specified in Section 301.
• Lime is measured by the ton (megagram). • If quicklime (Ca0) is slaked on the job in an approved mixing tank to produce a lime slurry, the pay quantity for lime is measured in ton (megagram) of hydrated lime. The pay quantity is calculated using the certified lime purity for each truckload as follows: Total Weight of Hydrated Lime Produced, ton (Mg) = (A x B x 1.32) + A (C) Where: A = actual quicklime delivered B = certified % purity C = % inert material 1.32 = ratio of molecular weights for hydrated lime (74) and pure quicklime (56) • If quicklime is spread on the roadbed in a dry application, it is measured by the ton (megagram) based on invoice weight. • The formula for converting quicklime to hydrated lime does not apply for dry applications.
Bituminous prime is not measured for separate payment. Application will be according to Section 412.
Unsuitable materials removed from the roadbed are measured according to the Earthwork Item in the Contract. 225.4.01 Limits General Provisions 101 through 150.
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225.5Payment
If material is mixed on the job, it may be necessary to add other materials to the roadbed or to build up the base or subbase entirely with new materials. Any additional soil -lime material will be paid at the Contract Price per square yard (meter) or per cubic yard (meter) when in place and accepted. Payment will be full compensation for the following: • Shaping and compacting the existing roadbed • All materials except lime • Loading and unloading materials • Hauling materials • Crushing, processing, mixing, spreading, watering, compacting, and shaping materials • Maintenance • All other incidentals necessary to complete the work
A course of soil -lime treated roadbed base and subbase will be paid for at the Contract Price per square yard
• Preparing the roadbed • Mixing on the road • Shaping, pulverizing, watering, and compacting materials • Repairing all defects • Maintenance
A course of pre- mixed soil -lime treated base and subbase will be paid for at the Contract Price per ton
Payment will be full compensation for the following: • Shaping and compacting the existing roadbed • All materials except lime • Loading and unloading materials • Hauling materials • Crushing, processing, mixing, spreading, watering, compacting, and shaping materials • Maintenance • All other incidentals necessary to complete the work
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