Attachment A.pdf

South Carolina Department of Transportation

STANDARD

SPECIFICATIONS

FOR

HIGHWAY

CONSTRUCTION

305.1 305.2.3

SECTION 305

GRADED AGGREGATE BASE

305.1 Description

This section contains specifications for the materials, equipment, construc tion, measurement, and payment for construction of a base course composed of the graded aggregate materials specified herein on a properly prepared foundation (subgrade or subbase) in conformance with the lines, grades, di mensions, and cross-sections shown on the Plans or as directed by the RCE.

When the Contract specifies a graded aggregate base course, the following base courses listed below may appear on the proposal as alternates:

• Macadam Base Course,

• Marine Limestone Base Course, or

• Recycled Portland Cement Concrete Base Course.

When alternates appear in the proposal, select the intended bid alternate and provide unit bid prices only on that alternate.

Marine limestone aggregate is generally found in the coastal plain area of the state and is defined as any limestone aggregate not meeting the classifi cation of dolomitic limestone. Fossiliferous limestone aggregate and recrys tallized limestone aggregate are considered marine limestone aggregates.

305.2 Materials

305.2.1 Macadam Base Course

Use base course material composed of crushed stone, excluding marine limestone, filled and bound with screenings. Ensure that the aggregate is free from vegetable matter, sand, lumps or balls of clay, or other deleterious mat ter.

305.2.2 Marine Limestone Base Course

Use limestone base course materials produced from a single source or de posit that yields a satisfactory mixture conforming to all requirements of these specifications. Ensure that the Limestone Base Course does not contain clay, sand, organics, or other materials in sufficient quantity to be considered det rimental to the proper bonding, finishing, or strength of the base course.

305.2.3 Recycled Portland Cement Concrete Base Course

Use aggregate in the base course consisting of coarse aggregate of crushed, graded, recycled Portland cement concrete mixed together with sand, sand-gravel, soil or other approved materials having similar characteris tics and combined as necessary to give a mixture conforming to the require ments given below.

2 Use aggregate that is free from lumps or balls of clay or other objectionable matter and does not contain metals, wood, brick, plastics, or other unaccept-

305.2.3 305.2.5.2 able debris.

3 When Recycled Portland Cement Concrete Base Course is selected, have the source inspected, sampled and tested, and approved by the MRE and RCE before any material is used in the work. Allow a minimum of 4 weeks for this sampling, testing, and approval.

305.2.4 Coarse Aggregate

305.2.4.1 General

Use material retained on the No.4 sieve consisting of hard, durable aggre gate particles that are reasonably free from thin or elongated pieces, disinte grated particles, vegetable matter, or other deleterious substances. Ensure that the maximum abrasion loss for coarse aggregate is 65% when subjected to the Los Angeles Abrasion Test (AASHTO T 96).

305.2.4.2 Coarse Aggregate for Macadam Base Course

Use coarse aggregate for Macadam Base Course consisting of hard, dura ble particles of crushed slag or stone, excluding marine limestone. Ensure that the aggregate is free from vegetable matter, sand, lumps or balls of clay, or other deleterious matter.

Ensure minimum weight for crushed slag used in Macadam Base Course, when dry and rodded, is 70 pounds per cubic foot. Use crushed slag that consists of angular fragments, reasonably uniform in density and quality, and reasonably free from glassy, thin or elongated pieces, dirt, or other objection able material.

305.2.4.3 Coarse Aggregate for Marine Limestone Base Course

Use coarse aggregate for Marine Limestone Base Course consisting of sound, durable particles of marine limestone aggregate.

305.2.4.4 Coarse Aggregate for Recycled Portland Cement Concrete Base Course

Use coarse aggregate for Recycled Portland Cement Concrete Base Course consisting of sound, durable particles of recycled Portland cement concrete aggregate, excluding crushed concrete block or pipe.

305.2.5 Fine Aggregate

305.2.5.1 General

Use fine aggregate or binder material passing the No.4 sieve subject to the requirements in this subsection.

305.2.5.2 Fine Aggregate for Macadam Base Course

Use fine aggregate for Macadam Base Course consisting of material pro duced by crushing operations, excluding marine limestone.

305.2.5.3 305.2.5.5

305.2.5.3 Fine Aggregate for Marine Limestone Base Course

Use fine aggregate for Marine Limestone Base Course consisting of marine limestone produced by mining or crushing operation. Sand will not be permit ted as fine aggregate.

305.2.5.4 Fine Aggregate for Recycled Portland Cement Concrete Base Course

Use fine aggregate for Recycled Portland Cement Concrete Base Course consisting of material produced by the crushing operation, sand, soil, or other acceptable material. Ensure that these materials are obtained from sources approved by the MRE.

305.2.5.5 Composite Mixture

After the base course material is spread on the subgrade, mixed, and shaped, but prior to the beginning of compaction operations, make certain that the composite mixture conforms to the requirements in the following ta ble.

Macadam Base Course

Sieve Designation Percentage by Weight Passing

2-inch 100

1/t,-inch 95 -100

1-inch 70 -100

Y>-inch 48 -75

No.4 30-60

No. 30 11 - 30

No. 200* 0-12

Liquid Limit 25 Max.

Plasticity Index 6 Max.

Marine Limestone Base Course

Sieve Designation Percentage by Weight Passing

2- inch 100

1Y>-inch 95 -100

1-inch 70 -100

Y>-inch 50 -85

(table continued on the next page)

305.2.5.5 305.3

(table continued from the previous page)

Marine Limestone Base Course

Sieve DeSignation Percentage by Weight Passing

No.4 30 -60

No. 30 17 - 38

No. 200* 0-20

Liquid Limit 25 Max.

Plasticity Index 6 Max.

*AASHTO T 11 is used to determine the amount passing the No. 200 sieve.

Recycled Portland Cement Concrete Base Course

Sieve DeSignation Percentage by Weight Passing

2-inch 100

1}~-inch 95 - 100

1-inch 70 - 100

%-inch 48 -75

No.4 30 - 60

No. 30 11 - 30

No. 200* 0-12

Liquid Limit 25 Max.

Plasticity Index 6 Max.

*AASHTO T 11 is used to determine the amount passing the No. 200 sieve.

305.2.5.6 Asphalt Materials

Use EA-P Special for priming the base course conforming to the require ments specified in Section 407.

305.3 Equipment

Ensure that the equipment necessary for the proper construction of the work is on site, in acceptable working condition, and approved by the RCE as to both type and condition before the start of work under this section. Provide sufficient equipment to enable prosecution of the work in accordance with the project schedule and completion of the work in the specified time.

2 Use a steel wheel roller capable of developing a pressure of 250 to 350 pounds per inch of roller width in the compression wheel for compaction. If necessary, use other rollers in conjunction with the steel wheel roller. Ac-

305.4 305.4.3 ceptable additional rollers are self-propelled or tractor drawn pneumatic tired rollers or vibratory rollers. Use a combination of the above rollers as neces sary to produce a finished product that complies with these specifications.

305.4 Construction

305.4.1 Preparation of Subgrade

Construct the foundation for the graded aggregate base course in accor dance with the requirements as specified in Section 208. Roll and compact the subgrade for at least 500 feet ahead of the placing of base course materi als where feasible.

2 Construct shoulders in accordance with the requirements of Section 209, accurately trimmed to the alignment and grade of the base course to form a trench or channeled section as prescribed on the Plans.

305.4.2 Placing of Base Course Material

Deliver base course materials to the project with the necessary fines al ready included. Alternatively, add fines if necessary to obtain the desired density and stability. However, in any case provide material whose final gra dation meets the requirements shown in Subsection 305.2.5.

Place the base course aggregate on the prepared foundation. Perform the spreading so that the finished base course conforms to the lines, grades, di mensions, and the typical cross-sections shown on the Plans or as directed by the RCE.

3 When the required compacted thickness is 10 inches or less, construct the base course in one layer. Where the required thickness is more than 10 inches, construct the base course in two or more layers of approximately equal thickness, and ensure that the maximum compacted thickness of any one layer does not to exceed 10 inches. Construct and compact each layer as specified before placing the succeeding layer.

Take care to prevent segregation of the fines from the coarse aggregates during the handling, spreading, or shaping of the materials. Correct all areas of segregated fine or coarse material before subsequent placement of overly ing lifts.

If the foundation becomes unstable after the base course has been placed, repair the affected section. Repair the section by removing the base course material and unsatisfactory foundation material and replacing it with approved foundation material. Reconstruct the foundation to the required compaction and shape and then replace the base course at the required cross-section, grade, and compaction.

305.4.3 Compaction, Rolling, and Finishing

After the base course material is spread, continually machine it with motor graders or other suitable equipment and maintain the required section until the base course is thoroughly compacted. Compact each layer by the use of equipment specified in Subsection 305.3. If the foundation becomes unsta-

305.4.3 305.4.5 ble after the base course has been placed, repair the affected section. After removing the base course material and the unsatisfactory foundation material, place suitable subgrade material at the required compaction and shape and then, replace the base course material to the required cross-section, grade and compaction.

Start rolling the base course at the edge and proceed toward the center, except on superelevated curves where rolling operations proceed from the lower to the upper side. On areas not accessible for the operation of standard rollers, perform compaction using RCE approved rollers. Continue rolling until the layer is satisfactorily compacted for the full width and depth. Wet the base course when necessary. Extend rolling over the edges of each layer of base course materials for a distance of 2 feet on the shoulders. Continue blading and rolling until a dense, smooth, unyielding, and well-bonded base course is obtained.

If initial compaction has been performed and the voids are not filled, place fine aggregate on the base course in an amount only sufficient to fill the voids.

Broom, wet, and roll the base course until the coarse aggregate is firmly set, bonded, and the base course is thoroughly compacted for the full width and depth. Compact each layer of the macadam base course while near optimum moisture with equipment capable of obtaining the required density for the full depth. Continue the rolling until the entire base course is compacted to not less than 100.0% of maximum laboratory density as determined by SC-T-140.

When the total compacted thickness of the graded aggregate base course is more than 10 inches, place the materials in layers as specified in Subsection

305.4.2 and compact each layer to the density specified above, regardless of layer thickness.

Determine the in-place density and moisture content of the graded aggre gate base course with a nuclear moisture-density gauge or by other approved means.

5 On shoulder work or other applicable construction, do not use steel wheel rollers on the finished pavement, except at locations necessary for turning around. During all phases of the work, take extreme care to protect struc-tures. .

305.4.4 Surface Smoothness

Ensure that the finished surface of the base course varies neither more than % inch from a straight edge 10 feet long when applied parallel to the cen terline of the road, nor more than Yz inch from the typical cross-section shown on the Plans. Provide necessary materials and perform such corrective work to repair any deviations exceeding the limits given above without additional compensation.

305.4.5 Thickness Tolerance of Base Course

The thickness of the completed base course is measured at staggered in tervals not to exceed 250 feet for two-lane roads. Depth measurements are made by test holes through the base course. Where the base course is less

305.4.5 305.4.6 than the specified thickness by more than % inch, correct such areas by scari fying, adding base course material, and re-compacting as directed by the

RCE.

2 When the base course is paid for on a square yard basis, any measure ment that exceeds the specified thickness by more than % inch is considered as the specified thickness plus % inch. The average job thickness is the av erage of the depth measurements. When the average job thickness is less than the specified thickness by more than Yo. inch and payment is by the square yard, an adjusted unit price is used for calculating payment. This ad justed unit price bears the same ratio to the contract unit price bid as the av erage job thickness bears to the specified thickness.

When the Contract includes more than one road, each road is considered separately.

No additional payment over the contract unit price is made for any base course where the average job thickness, determined as provided, exceeds the specified thickness.

305.4.6 Application of Prime Coat

When hot mix asphalt or an asphalt surface treatment is specified as the subsequent layer on a Graded Aggregate Base Course, apply a prime coat to the base course in accordance with Subsection 401.4.18. Before applying the prime coat, repair all irregularities in the base course and ensure that the base course has seasoned sufficiently to permit a uniform penetration and that the RCE has approved the density of the base course. Clean the base course of all mud, dirt, dust, and caked or loose material of any description by brooming, blowing, or other methods to expose the coarse aggregate in the base course.

2 When, in the opinion of the RCE, the asphalt material used to prime coat the base course may present a hazard to adjacent properties, the RCE may opt to delete the prime coat from a section of roadway.

3 Ensure that the rate of application of the prime coat material conforms to the application rates in the following table.

Application Rate in Gallons per

Base Course Material Square Yard of Asphalt (gal/yd2)

Min. Max.

Macadam Base Course 0.25 0.30

Marine Limestone Base Course 0.10 0.15

Recycled Portland Cement

0.25 0.30

Concrete Base Course

4 Perform the application using the methods and requirements prescribed in pertinent portions of Section 406.

305.4.6 305.6

5 When it is necessary to maintain traffic on a road or a section of road be-fore the prime coat has had time to sufficiently dry to prevent pickup, apply sand or some other approved granular material as a cover as directed by the RCE. The cost of furnishing this material and performing this work is included in the price of the base course or other items of work and no direct payment is made.

305.4.7 Weight Tickets

When the base course is measured by the ton, the requirements set forth in Subsection 302.4.2 regarding weight tickets apply in all respects.

305.4.8 Maintenance

Machine the base course as often as is necessary to maintain it smooth and true to grade and cross-section and apply water as required to prevent raveling and keep the base course tightly bound until the prime coat is ap plied. Repair any defects or damage that develops.

305.5 Measurement

The quantity for the pay item Graded Aggregate Base Course is measured by the pay unit, either square yard or ton, specified in the Contract.

When paid by the square yard, the quantity for the pay item Graded Aggre gate Base Course (of the required uniform thickness) is the surface area of the base constructed as specified and measured by the square yard (SY) of base course in-place, complete and accepted. The area of base course con structed outside the area designated is disregarded in computing the quantity.

3 Base course of variable thickness or base course of thickness for which there is no unit bid price bid is converted to square yards of equivalent area of a base course of a thickness for which there is a contract unit bid price. The conversion is based on the base course whose thickness is nearest to that of the base course without a unit price.

When paid for by the ton, the quantity for Graded Aggregate Base Course is the weight of the base course constructed as specified, measured by the of ton (TON), including water contained in the delivered base course material, weighed on approved scales and actually incorporated in the work, complete and accepted. If a visual inspection indicates excessive moisture in the base course, a deduction is made for the weight of water applied in excess of 2% above optimum moisture as determined by the RCE. The weight of base course constructed outside the area designated, wasted or lost due to the negligence of the Contractor, and applied in excess of the rate specified or directed in writing is disregarded in computing the quantity.

Measurement of Prime Coat is in accordance with Subsection 401.5.

305.6 Payment

Payment for the accepted quantity of Graded Aggregate Base Course, measured in accordance with Subsection 305.5, is determined using the

305.6 305.6 contract unit price for the item. Payment is full compensation for constructing the graded aggregate base course as specified or directed and includes pre paring the foundation, furnishing, hauling, placing, spreading, mixing, adding water, shaping compacting, finishing, applying prime coat, maintenance, re construction (if necessary) of the base course, and all other materials, labor, equipment, tools, supplies, maintenance, and incidentals necessary to com plete the work in accordance with the Plans, the Specifications, and other terms of the Contract.

2 Base course specified on a square yard basis and is deficient in thickness is paid for at the adjusted unit price in accordance with Subsection 305.4.5.

3 Payment for Prime Coat is in accordance Subsection 401.6.

4 Payment for each item includes all direct and indirect costs or expenses required to complete the work.

5 Pay items under this section include the following:

Item No. Pay Item Unit

3050104 Graded Aggregate Base Course (4" Uniform) SY

3050105 Graded Aggregate Base Course (5" Uniform) SY

3050106 Graded Aggregate Base Course (6" Uniform) SY

3050107 Graded Aggregate Base Course (7" Uniform) SY

3050108 Graded Aggregate Base Course (8" Uniform) SY

3050110 Graded Aggregate Base Course (10" Uniform) SY

3050112 Graded Aggregate Base Course (12" Uniform) SY

3050199 Graded Aggregate Base Course TON