307Hydrated Lime Stabilized Subgrade

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307-1 DESCRIPTION. Hydrated lime stabilized subgrade shall consist of the in-place subgrade soil

mixed uniformly with hydrated lime and moistened, compacted and cured in accordance with these specifications, the plans and as specified by the Engineer.

307-2 Materials.

307-2.01 Lime Stabilization. Materials for lime stabilization shall meet the requirements of the

following: Water 712-01 Hydrated Lime 712-04

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NEW YORK STATE DEPARTMENT OF TRANSPORTATION Sections 200 - 599 STANDARD SPECIFICATIONS (USC) January 1, 2026 Volume 2 Hydrated lime which has slaked prior to mixing, for any reason, shall not be incorporated in the work.

307-2.02 Surface Treatment. When a surface treatment is required to protect the completed lime

stabilized course as specified in §307-3.11, the materials for surface treatment shall meet the following requirements: Asphalt Emulsion - (RS-2) 702-3101 Coarse Aggregate - 1A size 703-02

307-3 Construction Details.

307-3.01 Equipment. No work will be permitted until all necessary equipment is on hand, inspected and

approved by the Engineer.

307-3.02 Weather Limitations. Lime stabilization of the subgrade shall not be done when the subgrade

temperature is below 40°F, nor in the period from October 15 to May 15, except by written permission of and under such special limitations as set forth by the Deputy Chief Engineer (Technical Services). The hydrated lime shall not be mixed with frozen subgrade soil or when the subgrade contains frost. Lime shall not be applied when wind conditions, as determined by the Engineer, are such that blowing lime becomes objectionable or hazardous to traffic, workers, and adjacent property owners.

307-3.03 Protection and Safety. Before lime is spread, the Contractor shall take necessary precautions

and provide necessary equipment to protect all personnel and adjacent properties from lime dust created by the lime application and mixing operations. Safety goggles and lightweight filter masks shall be provided by the Contractor to all working personnel and shall be worn at all times during these operations.

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NEW YORK STATE DEPARTMENT OF TRANSPORTATION Sections 200 - 599 STANDARD SPECIFICATIONS (USC) January 1, 2026 Volume 2

307-3.04 Preparation of Foundation. Prior to the addition of any lime to the subgrade, the area to be

stabilized shall be graded and shaped in close conformity to the typical sections, lines and grades as shown on the plans or as specified by the Engineer. Where the depth of lime stabilization exceeds 6 inches, the subgrade soil in excess of the 6 inches depth shall be removed, placed in windrows and processed as an additional lift.

307-3.05 Scarifying. The subgrade soil shall be scarified 6 inches deep to the width required for

stabilization. The scarified material shall be partially pulverized by making one pass through the area with a pulverizing rotary mixer. The pulverizing portion of the scarifying operation may be deleted in some areas, where, as determined by the Engineer, the subgrade soils are excessively wet and sticky so that pulverizing with a rotary mixer is impractical.

307-3.06 Application of Lime. The hydrated lime shall be applied to the scarified material by an

approved method and at the rate stipulated in the plans or as specified by the Engineer. A lime slurry, applied by an approved method and suitable equipment, will be permitted. Spreading equipment shall uniformly distribute the lime without excess loss. No equipment except that used for spreading and mixing shall be permitted to pass over the spread lime until it is mixed. The Engineer may require the spread lime to be sprinkled with water to reduce dusting.

307-3.07 Primary Mixing. After the required amount of lime has been uniformly spread, it shall be

mixed into the subgrade to the full depth of treatment using a traveling rotary mixing machine or heavy plow. A minimum of three passes will be required to assure uniform incorporation of the hydrated lime. Water shall be added at the rate of up to 500 gallons/ton of lime as required for the proper consistency. The primary mixing operation shall be completed within four hours after application of the lime. At this time, all of the lime shall be thoroughly and uniformly incorporated into the subgrade to the full depth of treatment in such a manner that the result is a homogeneous, friable mixture of subgrade soil and lime, free from clods or lumps exceeding 2 inches in size. Where the required depth of stabilization exceeds 6 inches, the windrowed material in excess of the 6 inches depth shall be spread to the required lift thickness and processed, by the addition of lime and primary mixing, as specified for the first layer. Each additional layer, where required, shall be processed similarly. Immediately after the primary mixing operations are completed for the full depth of treatment, the surface of the subgrade shall be shaped and lightly sealed with a pneumatic tired or smooth steel wheel roller. The surface shall be crowned so as to properly shed water if rain occurs.

307-3.08 Curing. Following primary mixing operations, the stabilized course shall be allowed to cure

for at least 24 hours plus any additional time required for the lime to properly react with the subgrade soil. Curing periods in excess of 24 hours shall be as determined and specified by the Engineer. During the curing period, the surface of the material shall be kept moist to prevent drying and cracking, and maintained in a properly sealed and crowned condition as specified by the Engineer.

307-3.09 Secondary Mixing. Immediately after the completion of the curing period, the stabilized

course shall again be completely mixed and pulverized to the full depth of stabilization by a rotary pulverizing mixer. Secondary mixing shall continue for at least three passes or until, as determined by the Engineer, the material is properly mixed and blended. Adjustments in water content shall be made during the secondary mixing operation to obtain the proper moisture content required for compaction.

307-3.10 Compaction, Shaping and Finishing. Compaction of the mixture shall begin immediately

after completion of the secondary mixing operations and after the proper moisture content for compaction has been obtained. Compaction shall be in accordance with the requirements of Section 203, Compaction. After compaction and shaping, the surface of the course shall be finished-rolled by a smooth steel wheel tandem roller weighing between 8 to 10 tons. The secondary mixing, compaction,

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NEW YORK STATE DEPARTMENT OF TRANSPORTATION Sections 200 - 599 STANDARD SPECIFICATIONS (USC) January 1, 2026 Volume 2 shaping and finishing operations shall be completed within eight hours after the start of the secondary mixing. The surface of the finished stabilized subgrade course shall not extend above design grade at any location. The thickness of the complete hydrated lime stabilized subgrade will be determined from measurements made in test holes located at random intervals not to exceed 500 feet. The measured thickness shall not deviate from that shown on the plans or specified by the Engineer, by more than plus 1 1/2 inches or minus 1 inch. Areas of hydrated lime stabilized subgrade not meeting the specified thickness requirements shall be reconstructed. The subbase course material shall be placed and compacted within two days after the lime stabilized subgrade course has been compacted, shaped and finished at that location. The surface of the treated subgrade shall be kept continuously moist up to the time of subbase material placement.

307-3.11 Surface Treatment Option. The Contractor may elect to defer placement of the subbase

materials up to two weeks by placing a bituminous membrane, cationic asphalt emulsion, over the treated subgrade. The bituminous membrane must be placed within two days after the stabilized subgrade has been compacted and finished. The stabilized subgrade must be kept continuously moist prior to application of the bituminous membrane. The bituminous material shall be applied at a uniform rate of 0.2 gal/sy of treated subgrade. Where traffic is to operate on the treated subgrade, the bituminous membrane shall be chipped with a uniform coating of Size 1A aggregate applied at a rate of 15 lb/sy of treated subgrade.

307-4 Method of Measurement.

307-4.01 Hydrated Lime Stabilized Subgrade. The quantity of hydrated lime stabilized subgrade to be

paid for will be the number of cubic yards of lime stabilized subgrade computed within the payment lines shown on the plans or otherwise specified in writing by the Engineer.

307-4.02 Furnishing and Applying Hydrated Lime. The quantity of hydrated lime to be paid for will

be the number of tons of hydrated lime furnished and applied. Lime that has slaked prior to application and additional lime applied because of reduced lime content resulting from excessive thickness of the lime stabilized layer will not be measured for payment.

307-5 Basis of Payment.

307-5.01 Hydrated Lime Stabilized Subgrade. The unit price bid per cubic yard shall include the cost

of furnishing all labor, equipment and materials necessary to complete the work, except that furnishing and applying water and hydrated lime will be paid for separately. No payment will be made for the asphalt emulsion or 1A stone chips, nor for any maintenance, repairs or reconstruction of the stabilized subgrade made before acceptance, nor for any losses of material which may result from compaction, erosion or any other causes.

307-5.02 Furnishing and Applying Hydrated Lime. The unit price bid for hydrated lime shall include

the cost of all material, labor and equipment necessary to furnish, store, handle and apply hydrated lime in accordance with these specifications. Payment will be made under: Item No. Item Pay Unit 307.01 Hydrated Lime Stabilized Subgrade Cubic Yard 307.02 Furnishing and Applying Hydrated Lime Ton

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NEW YORK STATE DEPARTMENT OF TRANSPORTATION Sections 200 - 599 STANDARD SPECIFICATIONS (USC) January 1, 2026 Volume 2