302Sand-Bituminous Stabilized Base Course

302.1General Description

This work includes constructing a base course composed of sand, or a mixture of sands that is stabilized with bituminous materials. Construct the base course according to these specifications and to the lines, grades, and typical cross-sections shown on the plans or established by the Engineer. All of the provisions of Section 300 apply to this Item. 302.1.01 Definitions General Provisions 101 through 150. 302.1.02 Related References

AASHTO T 191 ASTM D 1138 GDT 7 GDT 8 GDT 59 GDT 67 302.1.03 Submittals General Provisions 101 through 150. 301 301 301 301 301 301 301 301 301

302.2Materials

Ensure that materials meet the requirements of the following Specifications: Material Specification Sand for Bituminous Base Subsection 814.2.03 RC-800 Subsection 821.2.01 Bituminous Prime: Cutback Asphalt, RC-30, RC-70, RC-250, or MC-30, MC-70, MC-250 Subsection 821.2.01 Emulsified Asphalt, EAP-1 Subsection 822.2.01 Cutback Asphalt Emulsion, CBAE-2 Subsection 823.2.01 Blotter Materials (Sand) Subsection 412.3.05.G.3 Produce a sand-bituminous mixture with a resistance to plastic flow of 200 lbs. (90 kg) minimum when tested according to ASTM 1138. Produce a sand-bituminous mixture with a maximum 4 percent, 7-day absorption when tested according to GDT 8. 302.2.01 Delivery, Storage, and Handling General Provisions 101 through 150.

302.3Construction Requirements

Use the central plant mixing method when the sand-bituminous stabilized base course is to be paid for by the ton (megagram). Mix, spread, and compact the material according to Section 400, with the following exceptions: • No test strip is required. • The Compaction Acceptance Schedule does not apply. Use either the central plant or traveling plant mixing method when the sand-bituminous stabilized base course is to be paid for by the square yard (meter). Use the central plant mixing method when the sand-bituminous stabilized base course is used for widening in addition to the use of suitable special rollers for compaction. Use plow and harrow mixing only for aeration according to Subsection 302.3.05.D.1, Preparing Mixture for Compaction.

Do not apply bituminous materials when the air temperature is less than 60 oF (15 oC) in the shade nor when the temperature of either the subgrade, subbase, or soil to be used in the mixture is below 50 oF (10 oC). 302.3.01 Personnel General Provisions 101 through 150. 302.3.02 Equipment Provide all necessary equipment (in satisfactory condition) on the Project before work commences. Use applicable equipment specified in Subsection 412.3.02, Equipment for bituminous prime. 302 302 302 302 302 302 302 302 302

302.3.03 Preparation When constructing the base from new materials, prepare the subgrade or subbase as specified in Subsection 300.3.03.C, Preparing the Subgrade or Subsection 300.3.03.D, Preparing the Subbase. Prepare the subgrade or subbase by scarifying a minimum of 2 ft. (600 mm) on each side of the Plan width and to the depth of material when the Engineer determines that any existing roadbed materials are suitable for mixed-in-place base construction. Blend new materials with the prepared roadbed thoroughly before adding bituminous material. 302.3.04 Fabrication General Provisions 101 through 150. 302.3.05 Construction

roadbed during processing.

the Plan thickness of the compacted base course. Place materials only on dry, unfrozen subgrade or subbase.

subgrade or subbase. Add water as needed to assist pulverization. • 100 percent of material shall pass the 1.5 in (37.5 mm) sieve. • A minimum of 80 percent of the soil (exclusive of stones or gravel) shall pass the No. 4 (4.75 mm) sieve.

material. The moisture content shall be adjusted under the Engineer’s direction. 1) Add water at the mixer using accurate gauging devices. 2) Ensure that the moisture is uniformly distributed.

uniformly only if the mixing plant operation requires.

completed.

Minimum Maximum RC-800 Cutback Asphalt 160 °F (70 °C) 210 °F (100 °C)

in one operation. Ensure that a uniform mixture is produced. 303 303 303 303 303 303 303 303 303

80 percent of the soil, excluding any stone or gravel, will pass through a No. 4 (4.75 mm) sieve.

1) Proportion the sand-bituminous material and water separately. 2) Charge all materials into the mixer together and mix immediately.

for mixing.

the finished base course. • Use an approved spreader. • Place sand-bituminous material only on a dry subgrade or subbase.

The Engineer will determine the quantity of bituminous material required. Apply the bituminous material uniformly, using an amount within 5 percent of the required quantity. If bituminous material is applied at a rate more than 5 percent in excess of the required amount and it is considered detrimental, remove and reconstruct the section. If the application rate is more than 5 percent and the material is left in place, no payment will be made for bituminous material in excess of the 5 percent tolerance. Correct any shortage of bituminous material more than 5 percent less than the required amount by applying additional bituminous material. The cost of reapplying, remixing, and compacting will be included in this Pay Item at no additional cost to the Department.

Limit the application of the bituminous material so that aeration and compaction can begin immediately after mixing.

1) Begin aeration as soon as the prepared base is long enough to permit the operation of aeration equipment. 2) Loosen and turn the mixture with harrows, blades, or the equivalent, until the volatile solvents and water evaporate, and the mixture is tacky.

aeration as soon as weather permits.

1) Spread to a maximum compacted lift thickness of 8 in. (200 mm). 2) Lay the maximum lift thickness for which the specified compaction is obtained, otherwise lay the base in more than one course. 304 304 304 304 304 304 304 304 304

Compact as soon as the condition of the material and the weather permit. Bring the base to line, grade, and cross- section. Roll until the full depth of the course is compacted to 95 percent of the maximum dry density of the sand, without bituminous material.

After the base has been compacted, do the following:

the edges and work toward the center until the surface is smooth, closely knit, free from cracks, and in conformance with the proper line, grade, and cross section.

After compacting the first course, do the following:

Compact irregular areas inaccessible to a roller by using mechanical tampers approved by the Engineer. Density requirements are unchanged from above.

Apply bituminous prime according to Section 412.

Maintain the base in a smooth and acceptable condition until it is covered by other construction.

it is accepted as specified in Section 105. 302.3.06 Quality Acceptance

Test compaction as follows:

material by GDT 7 or GDT 67.

Check the finished surface of the base, subbase, or shoulder course as follows:

sections

305 305 305 305 305 305 305 305 305

do not exceed 1/4 in. (6 mm) at any point. Rod readings shall not deviate more than 0.02 ft. (6 mm) from required readings.

Repairing Defects.

Determine the thickness of the base, subbase, or shoulder course, by making as many checks as necessary to determine the average thickness.

determine the deficient area.

of the following methods according to these Specifications:

• Apply Asphaltic Concrete 9.5 mm Superpave.

• Leave in place and accept payment for the materials and area (if the course is mixed in place) at ½

the Contract Unit Price for the deficient area.

9.5 mm Superpave or removing the material to the full depth of the course and reconstructing to the

required thickness in accordance with these specifications.

Superpave to correct deficiencies will be made at the Contract Unit Price that applies to the course

needing correction. Payment for additional material used in reconstructing an area will be made at the

Contract Unit Price, but the removed material removed will be deducted from payment.

to correct deficiencies or reconstructing deficient work.

Average thickness is measured as follows:

increment will be deducted from the Contractor’s payments.

(13 mm) tolerance by the surface area of the base, subbase, or shoulder, as applicable.

302.3.07 Contractor and Warranty and Maintenance

General Provisions 101 through 150. 306306306306306306306306306

302.4Measurement

When a mixed-in-place construction method is used, any additional materials necessary to add to the roadbed will

be measured by loose volume in cubic yards (meters) of additional material added according to Section 109.

When payment is by the square yard (meter), measure length along the centerline in feet (meters) and use the plan

width to calculate area. Use actual dimensions of irregular areas placed to calculate the number of square yards.

When payment is by the ton (megagram), measure the actual weight of the sand-bituminous mixture on

approved scales.

Measure bituminous materials incorporated into the mixture according to Section 109.

No separate measurement will be made for bituminous prime.

Measure unsuitable material removed according to the Earthwork Item in the Contract.

302.4.01 Limits

General Provisions 101 through 150.

302.5Payment

Sand Bituminous Stabilized Base Course materials, in place and accepted, will be paid at the Contract Unit Price

per cubic yard (meter), which shall be full compensation for furnishing the material where specified in the Pay Item,

mixing the pit, for all loading, unloading, spreading as here specified, and for hauling where specified in the

Pay Item.

Sand-Bituminous Stabilized Base Course, complete in place and accepted, will be paid for at the Contract Unit

Price per square yard (meter), which shall be full compensation for preparation of the roadbed, for mixing on the

road, shaping, pulverizing, hauling, watering, compaction, repair of all defects, and maintenance

Sand-Bituminous Stabilized Base Course, complete in place and accepted, will be paid for at the Contract Unit

Price per ton (megagram) or per square yard (meter), which shall be full compensation for preparation of the

roadbed, for all materials except bituminous materials, and for loading, unloading, all hauling, mixing, spreading,

watering, rolling, shaping, and maintenance.

The number of gallons (liters) of bituminous material, except bituminous material in excess of the 5% tolerance

and except that used as Bituminous Prime, will be paid at the Contract Unit Price per gallon (liter), complete and

in place.

Payment is full compensation for providing bituminous material, hauling, heating, and applying the material.

Removal of unsuitable material will be paid for according to the Earthwork Item in the Contract. 307307307307307307307307307

Payment will be made under:

Item No. 302 Sand-bituminous stabilized base course material, including material

and haul

per cubic yard (meter)

Item No. 302 Sand-bituminous stabilized base course material, including haul per cubic yard (meter)

Item No. 302 Sand-bituminous stabilized base course, ___ inch (mm) per square yard (meter)

Item No. 302 Pre-mixed sand-bituminous stabilized base course, including

material

per ton (megagram) or

per square yard (meter)

Item No. 302 Bituminous materials per gallon (liter)

302.5.01 Adjustments

General Provisions 101 through 150.. 308 308 308 308 308 308 308 308 308