367These prices shall include furnishing, hauling, placing, manipulating, and compacting material; clearing and grubbing local pits; material royalties; and access roads. Geotextile for subgrade stabilization will be measured in square yards, complete-in-place. Overlaps and seams will not be measured for separate payment. The accepted quantity of geotextile will be paid for at the contract unit price per square yard. This price shall include furnishing, placing, lapping, or seaming material. Payment will be made under: ——————————————————————————————— Pay Item Pay Unit——————————————————————————————— Borrow excavation Cubic yard Select material (Type and min. CBR) Cubic yard or ton Aggregate material (No.) Cubic yard or ton Aggregate base material (Type and no.) Cubic yard or ton Geotextile (Subgrade stabilization) Square yard——————————————————————————————— SECTION 306—LIME STABILIZATION
306.01 Description
This work shall consist of stabilizing roadbed material by constructing one or more courses of the pave - ment structure using a mixture of soil or approved aggregates, lime or lime and fly ash, and water.
306.02 Materials
a.Lime shall conform to Section 240.
b.Fly ash shall conform to Section 241. Bulk fly ash may be transported dry in bulk trucks and stored in tanks or may be transported in the dampened condition, with a maximum of 15 percent moisture, and stockpiled at the job site. The Contractor shall not use excessively wet or contaminated surface material in mixing operations. The Contractor shall cover stockpiled material with a non-absorptive cover material or periodically moisten the fly ash to prevent moisture loss and it from becoming airborne.
c.Water shall conform to Section 216.
d.Aggregates shall conform to Section 205, Section 207, and Section 208 as applicable, or other requirements as described in the Contract.
306.03 Procedures
The Engineer will not allow lime stabilization when aggregates or the surface on which the course is to be placed is frozen. Manipulation shall not be started until the surface is free from mud or frost and the ambient air temperature is at least 40 degrees F .306.03 368(a) Preparing the Roadbed: The Contractor shall cut or blade the surface of the roadbed to the approximate line, grade, and cross section shown in the plans. The Engineer will not require compaction of the roadbed for the depth of the material to be treated prior to application of lime. When the course placed directly on the roadbed is to be stabilized, the Contractor shall prepare the surface of the roadbed in accordance with Section 305. Temporary ramps constructed adjacent to existing pavements, bridges, culverts, and similar items shall be removed to the depth necessary to provide the required thickness of pavement structure. The Contractor shall cut drains through excavated shoulder material on shoulders to drain the road - bed. Drains shall be cut through windrowed base materials at sufficient intervals to prevent ponding of water. The Contractor shall move windrowed material when necessary to permit the subgrade to dry.
b.Preparing Materials: The Contractor shall scarify the prepared roadbed to the depth and width required for stabilization. The depth of scarification and the blading operation shall be controlled in such a manner that the surface of the roadbed below the scarified material shall remain undis - turbed and shall conform to the established cross section. The Contractor shall remove any material retained on the 3-inch sieve prior to the beginning of stabilization work.
c.Applying Lime: The application rate of lime shall be as shown on the plans or as directed by the Engineer. The Contractor may apply lime to the partially pulverized material as a slurry or in a dry form. When quicklime is used in a dry form, it shall be applied at the same rate as hydrated lime. Where quicklime is slaked on the project to produce a slurry, the Engineer will calculate the measurement as indicated herein for each truckload using the certified lime purity for that load. The Engineer will not measure any lime added or replaced for corrective measures during construction or for repairing damaged areas. A = Certified weight of quicklime delivered x percent purity x 1.32 B = Certified weight of quicklime delivered x percent inert material A + B = Total hydrated lime produced (pay quantity) Lime applied by slurry application shall be mixed with water in approved agitating equipment and applied to the roadbed as a thin water suspension or slurry. The distribution equipment shall provide continuous agitation of the slurry from the mixing site until applied on the roadbed. The propor - tion of lime shall be such that the “Dry Solids Content” shall be at least 30 percent by weight. The Engineer may authorize a lower percent solid provided a uniform suspension of the slurry can be maintained. A weight and purity certification shall accompany each shipment of quicklime to be used in slurry applications. Spreading equipment shall uniformly distribute the lime without excessive loss. The Engineer will not permit any equipment except water trucks and equipment used for mixing and spreading to pass over the spread lime until it is mixed. The Contractor shall immediately discontinue any procedure that results in excessive loss or displacement of the lime. When a stationary mixer is used to mix aggregate material, the lime may be added to the mix by an approved feeder.306.03 369When applied in dry form, lime shall be spread uniformly over the top of the scarified material by an approved screw-type spreader box or other approved spreading equipment. The spreading operation shall be shrouded to minimize dust. Dry lime shall not be applied pneumatically, dropped from a dump truck, front end loader or bottom dumped. A motor grader shall not be used to spread the dry lime. The Contractor shall not apply dry lime when the Engineer believes wind conditions are such that the blowing material will become objectionable to adjacent property owners or create potential hazards to traffic.
d.Adding Water: Sufficient water shall be added by means of pressure water distributors or through the mixing chamber of a rotary mixer to provide moisture content at the time of compaction of not less than the optimum for the mixture, nor more than optimum +20 percent of optimum.
e.Mixing: The Contractor shall mix lime and water throughout the scarified material as thoroughly as practicable using a self-propelled rotary mixer capable of mixing to a compacted depth of at least 12 inches. Disc harrows or motor graders shall not be used for mixing. The Contractor shall then spread the mixture over the roadbed. The surface shall be sealed with a steel wheel or pneumatic tire roller to retard the loss of moisture and then allowed to mellow for 4 to 48 hours. After mellowing, the Contractor shall remix the lime-treated material with a rotary mixer until at least 60 percent of the material, exclusive of aggregates, will pass a No. 4 sieve. The Contractor may add additional water, if necessary, during the remixing operations to ensure proper moisture for compaction. When a stationary mixer is used, the material may be placed, compacted, and finished immediately after mixing. When traveling plants are used, additional mixing with blades, tillers, or repeated passes of the plant may be required. During the interval of time between lime application and initial mixing, lime that has been exposed to the open air for 6 hours or more, or lime that has been lost because of washing or blowing will not be measured for payment.
f.Compacting and Finishing: The Contractor shall place and compact the mixture to at least 95 percent of the maximum density determined in accordance with VTM-1 or VTM-12. The Engineer may require the Contractor to lightly sprinkle the mixture during placement operations to maintain the specified moisture content. Compaction shall be accompanied by sufficient blading to eliminate irregularities. The surface shall be lightly scarified during finishing operations and bladed to eliminate imprints left by the equipment. Final rolling of the completed surface shall be accomplished with a pneu - matic tire roller or steel wheel roller. Final compaction and finishing shall be completed within 12 hours after final mixing.
g.Tolerances: The finished stabilized course shall conform to the specified thickness, subject to the following tolerances: Thickness will be determined in accordance with VTM-38A. Areas that are deficient in thickness by more than 1 inch shall be removed or reworked with an additional amount of lime equal to 50 percent of the original amount. In the case of stabilized base courses, the Contractor may correct sections deficient in depth by applying asphalt concrete provided such correction is authorized by the Engineer. Areas that are excessive in thickness by more than 2 inches shall be reworked, and an amount of lime equal to 50 percent of the original amount shall be added to the mixture. Any replacement, corrective work and additional lime required to address deficiencies shall be at the Contractor’ s expense.306.03 370(h) Protecting and Curing: After finishing of the subgrade, no vehicles except sprinkling equipment shall be permitted on the subgrade for a curing period of 7 days or until the next course is placed, whichever is less. During the curing period, the subgrade shall be lightly sprinkled with water at frequent intervals to prevent the surface from drying out and cracking. The Contractor shall plan and execute the work in such a manner as to place the next course during the curing period. If the Contractor has not placed the next course by the end of the curing period, the Contractor shall apply liquid asphalt and cover material at the rate specified on the plans. Damage to the stabilized course attributable to other phases of construction by the Contractor shall be repaired at the Contractor’ s expense. At least one subsequent course shall be constructed on the stabilized course before hauling operations for the other phases of construction are permitted on the treated course. If the material loses the required stability, density, or finish before the next course is placed or the work accepted, it shall be recompacted and refinished at the Contractor’ s expense.
306.04 Measurement and Payment
Lime stabilization will be measured in tons of lime or fly ash, square yards of manipulation, and cubic yards or tons of aggregate material, complete-in-place, and will be paid for at the contract unit price per ton of lime or ton of fly ash, per square yard of manipulation, and per cubic yard or ton of aggregate ma - terial. Weighing shall be performed in accordance with Section 109.01 except that transporting vehicles shall be tared prior to each load. Manipulation shall include preparing the roadbed, scarifying, pulverizing, drying material, mixing, com - pacting, finishing, protecting, curing, and maintaining the completed course. Payment will be made under: ——————————————————————————Pay Item Pay Unit—————————————————————————— Lime Ton Fly ash Ton Manipulation (Depth) Square yard Aggregate material (Type) Cubic yard or ton—————————————————————————— SECTION 307—HYDRAULIC CEMENT STABILIZATION
307.01 Description
This work shall consist of stabilizing roadbed material as specified or as directed by the Engineer and constructing one or more courses of the pavement structure using a mixture of soil, or approved aggregates and hydraulic cement, on a prepared surface in accordance with these specifications and in conformity with the lines, grades, typical sections, and cross sections shown on the plans or as established by the Engineer.
307.02 Materials
a.Cement shall conform to Section 214, Type I, IP , or II. Cement shall be transported, stored, and otherwise protected in accordance with Section 217.03.306.03
Source: Virginia Road and Bridge Specifications, 2020 Edition. Pages 395–397 of 1,065.