02505_Gravel_and_Crush_Stone_Base_and_Subbase_Course.DOC

SECTION 02505 - GRAVEL AND CRUSH STONE BASE AND SUBBASE COURSE

This section is generic, generally requiring no modification, and requires that job specific information be placed on the Drawings. Project Managers are required to review changes. The following check list assists preparation of Drawings and should be reviewed prior to Drawing completion.

Label type subbase or base required by State Item, Local Item or sieve analysis, if required. Compare gradation of NYSDOT Type 2.

Label thickness of subbase or base. If different thickness, label different areas and tapers, if applicable.

Label type material under curbs, sidewalks, edging and gutters.

Include undercut detail as an “if required” item and include backfill material and stabilizing fabric by type. Include in Bid.

If greater than 35 percent pass 200 sieve for subgrade material, consult Project Manager on revising subbase or base course.

Specify compaction requirement of subbase or base material.

SECTION 02505 ‑ GRAVEL AND CRUSH STONE BASE AND SUBBASE COURSE

Part 1 - GENERAL

1.1. SUMMARY

A. This Section includes the following:

1. Preparing Subgrade.

2. Undercuts and Stabilizing Subgrade.

3. Placing and preparing subbase and/or base.

1.2. SUBMITTALS

A. General: Submit the following for approval.

1. Product data for the following products:

a. Subbase and Base Material

1) Hardness

2) Gradation

3) Freeze Thaw

4) Verification of State approved source where applicable

b. Woven Stabilizing Fabric

1) Tensile strength

2) Elongation

3) Puncture strength

1.3. QUALITY ASSURANCE

A. Do not place subbase or base material on wet, improperly graded, frozen or unstable subgrade.

B. Do not place frozen subbase or base material that does not conform to specifications.

C. Proof-roll subgrade in the presence of the Owner’s Representative using a 10 ton roller or a loaded 10-wheel dump truck prior to placement of subbase or base material. Limits of undercuts or other stabilization of subgrade required will be designated by the Owner’s Representative.

1.4. STORAGE

A. Storage of Subbase or Base Material: Store per manufactures recommendations.

Part 2 - PRODUCTS

2.1. MANUFACTURERS

A. Manufacturer and Source: State approved when applicable.

2.2. MATERIALS

A. Subbase or Base: If not specified on Drawings, use one of the following:

1. Subbase or Base: State approved source, produced from crushed stone with maximum size aggregate of 100 percent passing the 2 inch sieve and having a range of 0 to 10 percent passing the 200 sieve. Acceptance of gradation will be based on review of the Engineer and test results less than one (1) year old.

a. Crushed Stone: Conform to AASHTO M147-65 (1980), grading A:

Sieve %Passing 2 inch

3/8 inch 30 - 65

No. 4 25 - 55

No. 10 15 - 40

No. 40 8 - 20

No. 200 2 - 10

b. Material Sample Review: By Engineer prior to acceptance and use of material.

c. Material Change Review (from Crushed Stone to Gravel or Slag): By Engineer prior to use of material. Ensure designated material conforms to State Specification or AASHTO Specifications unless a variation in writing is provided by the Engineer.

B. Fine Crush Stone Screening: State approved source with the following gradation: Test results less than one (1) year old.

Sieve %passing ½ inch

No. 200 0-10

C. Woven Stabilizing Fabrics (Minimum Properties):

ASTM Reqmnts Modulus (load at 10% elongation)

D1682-64 115 lbs.

Grab tensile strength

D1682-64 200 lbs.

Mullen burst strength

D3786-87 400 psi

Trapezoid tear strength (when applicable)

D1117-80 115 lbs.

Coefficient of permeability K CM/Sec

D4491-85 .015

Water flow rate GPM/SF

D4491-85 60

Part 3 - EXECUTION

3.1. EXAMINATION

A. Proof-roll subgrade as described under “Quality Assurance”.

B. Review of Bottom of Undercut: By Owner’s Representative. Do not place stabilizing fabric or undercut backfill until deficiencies have been corrected.

3.2. PREPARATION

Fine grade subgrade to plus or minus 1 inch of design grades and compact to 90 percent compaction (modified proctor).

When proof-rolling indicates soft subgrade, perform undercuts in accordance with recommendations of Owner’s Representative. When undercuts are required in areas that the Contractor placed fills to establish subgrade, perform undercutting at no additional cost to the Contract.

3.3. PLACING SUBBASE OR BASE

A. Place subbase or base material in lifts not exceeding 6 inches and compact.

B. If subgrade begins to weaken under delivery vehicles or upon placement of subbase or base material, establish a placement plan to be reviewed by the Owner’s Representative. The placement plan shall include maximum weight and type of delivery vehicle, on site haul routes, and spreading and compacting equipment. Do not resume placement of subbase or base material until the plan has been reviewed and accepted by the Owner’s Representative. Include all work associated with maintaining a stable subgrade, subbase an/or base at no additional expense to the Contract.

C. Fine grade subbase or base to indicated elevations, plus or minus 1 inch, but total thickness of subbase or base will not vary more than 1 inch from design.

D. Protect subbase or base from contamination, weakening from excess hauling and other acts that could reduce the integrity of the subbase or base.

E. Fill voids in the surface with an Engineer reviewed fine crushed stone screening.

END OF SECTION

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