Art. 302.12 Lime Stabilized Soil Mixture the modified soil layer as shown on the plans, this extra earth excavation and embankment will not be measured for payment.
302.13 Basis of Payment. This work will be paid for at the contract unit price
per square yard (square meter) for PROCESSING MODIFIED SOIL, of the thickness specified and per ton (metric ton) for LIME, FLY ASH, PORTLAND CEMENT, or SLAG-MODIFIED PORTLAND CEMENT. SUBBASE SECTION 310. LIME STABILIZED SOIL MIXTURE
310.01 Description. This work shall consist of the construction of a lime
stabilized soil mixture, composed of soil, lime, and water which shall be considered as subbase.
310.02 Materials. Materials shall be according to the following.
Item Article/Section
a.Water ....................................................................................................... 1002
b.Hydrated Lime .................................................................................... 1012.01
c.By-Product, Non-Hydrated Lime ........................................................ 1012.03
d.Lime Slurry ......................................................................................... 1012.04
e.Soil for Lime Stabilization .................................................................. 1009.02
f.Bituminous Materials (Note 1) ................................................................. 1032 Note 1. The bituminous materials used for curing shall be emulsified asphalt RS-2, CRS-2, HFE 90, or HFE 150; rapid curing liquid asphalt RC-70; or medium curing liquid asphalt MC-70 or MC-250.
310.03 Equipment. Equipment shall be according to Article 302.03, except a
disk harrow may be used when permitted by the Engineer. CONSTRUCTION REQUIREMENTS
310.04 General. The lime stabilized soil mixture shall be constructed when
the temperature of the soil measured 6 in. (150 mm) below the surface is above 50 F (10 C) and the ambient air temperature in the shade is above 45 F (7 C). The quantity of lime stabilized soil mixture constructed shall be limited to that which can be covered by the full thickness of PCC pavement or HMA binder during the same construction season.
310.05 Proportioning. Proportioning shall be as follows.
a.Samples. Samples of the lime and the project soil(s) shall be obtained and submitted to the Engineer at least 45 days prior to the construction of the lime stabilized soil mixture. Sample sizes shall be a minimum of 25 lb (11 kg) for the lime and 200 lb (90 kg) for the project soil(s). Lime Stabilized Soil Mixture Art. 310.08
b.Mix Design. The actual proportions of lime, soil, and water will be determined by the Engineer prior to construction using the submitted samples. The Engineer reserves the right to make such adjustments in proportions as are considered necessary during the progress of the work. In no case shall proportions or type of lime be changed during the progress of the work without permission from the Engineer.
310.06 Preparation of Subgrade. The area to be processed shall be shaped
to the proper grade and cross section. All vegetation and other objectionable material shall be removed from within the limits of lime treatment. In cut or at grade sections, the subgrade shall be prepared according to Articles 301.03 and 301.04; except the minimum immediate bearing value (IBV) of the soil below the soil to be stabilized, shall be 3.0.
310.07 Application of Lime. The lime (slurry or dry) shall be applied
uniformly on the soil. The application of lime shall be limited to that area where the initial mixing operations can be completed during the same working day. After application of dry lime, but before the addition of any water, the surface of the subgrade shall be lightly scarified or disked. When lime slurry is used, the surface of the subgrade shall be lightly scarified or disked prior to the application of the slurry. Dry lime shall not be applied when wind conditions are such that blowing lime becomes objectionable to adjacent property owners or creates a hazard to traffic on adjacent highways, as determined by the Engineer. Lime slurry shall be applied within 30 days of preparing and mixing the slurry, and shall be thoroughly agitated prior to application. Lime (slurry or dry) that has been exposed to the open air for a period of six hours or more shall be replaced. Lime (slurry or dry) which has been damaged by hydration due to rain prior to or during the mixing operations, or has been displaced by the Contractor’s equipment or other traffic after application, shall be replaced.
310.08 Mixing. Mixing shall be performed in two stages as follows.
a.Initial Mixing. The lime, soil, and water shall be thoroughly mixed until a uniform mixture throughout the required depth and width is obtained. All clods and lumps shall be reduced to a maximum size of 2 in. (50 mm). The moisture content of the stabilized soil shall be above optimum moisture content with a maximum of three percent above optimum. After mixing, the surface shall be sealed with a light rolling. The mixture shall then be left to undergo a conditioning period of at least 48 hours. The mixture shall be maintained in a moist condition throughout the entire conditioning period.
b.Final Mixing. After the required conditioning period, the mixture shall be uniformly mixed and maintained at approximately optimum moisture content. Art. 310.08 Lime Stabilized Soil Mixture If the mixture contains clods, they shall be pulverized to meet the following requirements. Sieve Size Minimum % Passing 1 in. (25 mm) 100 No. 4 (4.75 mm) 60 Mixing may be performed in a single stage when permitted by the Engineer, provided that the final mixing requirements are met.
310.09 Compaction. After final mixing, compaction shall be completed within
the same day. The compacted, lime stabilized soil mixture shall have a minimum dry density of 95 percent of the laboratory standard dry density. The in-place dry density will be determined according to Illinois Modified AASHTO T 191, or Illinois Modified AASHTO T 310 (Direct Transmission Density/Backscatter Moisture). The laboratory standard dry density will be determined according to Illinois Modified AASHTO T 99.
310.10 Finishing and Curing. When compaction of the lime stabilized soil
mixture is nearing completion, the surface shall be shaped to the required lines, grades, and cross section shown on the plans. For HMA base course and pavement (full-depth) and portland cement concrete base course and pavement, the surface of the lime stabilized soil mixture shall be brought to true shape and correct elevation according to Article 301.07, except that well compacted earth shall not be used to fill low areas. The surface shall be maintained in a moist condition by means of a fine spray during all finishing operations. Construction of pipe underdrains shall follow the requirements of Article 407.07. The surface of the lime stabilized soil shall be kept drained according to
Article 301 — 09 and shall maintain a maximum moisture content of three percent above
optimum prior to pavement construction. The lime stabilized soil mixture shall be cured for a period of seven days and maintained at optimum moisture content by sprinkling with water or applying bituminous materials according to Article 352.13, except the method of moisture control for curing shall be applied as soon as possible after completion of final rolling. During this period, no equipment or traffic will be permitted on the completed work beyond that required for maintenance of curing.
310.11 Subgrade Stability. Following curing, the Engineer will determine the
stability of the lime stabilized soil mixture in terms of the immediate bearing value (IBV) according to Illinois Test Procedure 501. The IBV shall be a minimum of 23.0 measured within 10 calendar days prior to pavement construction. No equipment or traffic shall be on the lime stabilized soil mixture after compaction until the required IBV is attained.
310.12 Construction Joints. Construction joints will not be required between
each day’s work, unless there is a time lapse of seven days or more between the processing of adjacent sections. When construction joints are required, they shall be Lime Stabilized Soil Mixture Art. 310.15 formed by cutting back 3 ft (1 m) into the completed work to form a vertical face. Otherwise, damage to completed work shall be avoided.
310.13 Maintenance. The lime stabilized soil mixture shall be maintained in a
manner satisfactory to the Engineer. Maintenance shall include immediate repairs of any defective or damaged portions.
310.14 Method of Measurement. This work will be measured for payment as
follows.
a.Contract Quantities. The requirements for the use of contract quantities shall conform to Article 202.07(a).
b.Measured Quantities. Processing lime stabilized soil mixture will be measured for payment in place and the area computed in square yards (square meters). The width of measurement will be as shown on the plans. Lime will be measured for payment in tons (metric tons). The lime will be measured in trucks or freight cars. The Contractor shall furnish or arrange for use of scales of a type approved by the Engineer. When the lime is shipped in trucks, it will be measured at the place of loading, at the place of unloading, or at such other place as the Engineer may designate. The Engineer may accept original signed freight bills in lieu of determining the weight (mass). Should the Contractor’s method of construction require additional earth excavation or embankment due to requiring more than one lift to construct the lime stabilized soil mixture as shown on the plans, this extra earth excavation and embankment will not be measured for payment.
310.15 Basis of Payment. This work will be paid for at the contract unit price
per square yard (square meter) for PROCESSING LIME STABILIZED SOIL MIXTURE, of the thickness specified; and per ton (metric ton) for LIME. Art. 311.01 Granular Subbase SECTION 311. GRANULAR SUBBASE
311.01 Description. This work shall consist of furnishing, placing, and
compacting granular material on the prepared subgrade as shown on the plans.
311.02 Materials. Materials shall be according to the following.
Item Article/Section
a.Coarse Aggregate .............................................................................. 1004.04
311.03 Equipment. Equipment shall be according to the following.
Item Article/Section
a.Steel Wheel Rollers ....................................................................... 1101.01(e)
b.Pneumatic-Tired Rollers .................................................................... 1101.01
c.Vibratory Machine (Note 1)
d.Subgrade Planer ................................................................................ 1103.08
e.Subgrade Machine ............................................................................. 1103.09 Note 1. The vibratory machine shall meet the approval of the Engineer. CONSTRUCTION REQUIREMENTS
311.04 Subgrade. The subgrade shall be prepared according to Section 301,
except Articles 301.05 and 301.06 will not apply, or according to Section 302 when soil modification is used.
311.05 Placing and Compacting Subbase Materials. The granular material
shall be placed and compacted as specified for the particular type of granular subbase. If any earth is worked into the granular material during the compacting or finishing operations, all granular material within the affected area shall be removed and replaced with new granular material. The Engineer may restrict hauling over the completed or partially completed work after inclement weather or at any time when the earth subgrade is soft and there is a tendency for the earth to work into the granular material. The granular material shall be placed and compacted at least three days prior to the placement of pavement or base course. Except where required for temporary access, the quantity of subbase granular material Types A or B to be placed shall be limited to that which can be covered by the full thickness of PCC pavement or HMA binder during the same construction season. If the moisture content is insufficient to maintain satisfactory compaction or to prevent segregation or raveling when hauling is permitted over the granular material, water shall be added as directed by the Engineer. When construction of the granular subbase has been completed at a location, or when directed by the Engineer, the Contractor shall salvage the excess granular material outside the construction limits of the granular subbase. The salvaged granular material shall be carried forward and utilized in the construction of the
Referenced in this section
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Source: Illinois Standard Specifications for Road and Bridge Construction, 2022 Edition. Pages 167–171 of 1,217. View official source ↗