FDOT_Specifications_Section_911.pdf

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Attached to
On-Site Concrete Crushing with Multi-Size Aggregate Output and Contaminant Removal
Solicitation number
26-06
Issued by
Walton County, Florida

About this file

This is a technical specifications document from the Florida Department of Transportation (FDOT) governing the composition, quality, and testing requirements for base and stabilized base materials used in flexible pavement construction. The specification covers six material types: limerock, shell (both bank-run and dredged), shell-rock, cemented coquina shell, calcarenite, and recycled concrete aggregate (RCA). Each material category has defined composition standards, with limerock consisting of unconsolidated or partly consolidated limestone of marine origin, shell materials composed of naturally occurring broken mollusk shells and marine invertebrate remains, and RCA derived from crushing hard portland cement concrete. All materials must comply with FDOT testing protocols including Limerock Bearing Ratio (LBR) tests per FM 5-515, liquid limit and plasticity tests per AASHTO standards, carbonate content analysis per FM 5-514, and gradation requirements per AASHTO T 27 and FM 1-T11. Materials must meet specified minimum LBR values ranging from 90 to 150 depending on material type, contain minimum carbonate percentages between 45 and 70 percent, and comply with strict gradation requirements with maximum particle sizes not exceeding six inches and well-graded composition down to dust.

The specification explicitly prohibits mixing approved materials with other approved or non-approved materials and identifies deleterious substances that render materials unacceptable, including cherty pieces, clay lumps, organic matter, loose sand, free shells, and water-sensitive clay minerals. RCA materials face additional restrictions including asbestos-free requirements and specific contamination limits for bituminous concrete, bricks, glass, ceramics, wood, reinforcing steel, and plaster not exceeding defined percentages by weight. Mineral aggregate sources require approval in accordance with FDOT procedures outlined in section 6-2.3, and all materials must prevent adhesion issues with bituminous prime coats while maintaining strength and performance characteristics suitable for base course applications under construction traffic loads.

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FLEXIBLE-PAVEMENT MATERIALS

(INCLUDING MATERIALS FOR STABILIZING)

SECTION 911

BASE AND STABILIZED BASE MATERIALS

911-1 Description.

This Section governs materials to be used in the construction of base and subgrade stabilization including limerock, shell, shell-rock, cemented coquina shell, calcarenite, and recycled concrete aggregate (RCA).

911-2 Materials.

911-2.1 General:

911-2.1.1 Approval of Material: Approval of mineral aggregate sources shall be in accordance with 6-2.3.

911-2.1.2 Deleterious Substances: Materials shall not contain deleterious substances that would result in: prevention of the bituminous prime coat from adhering to the base course; a detriment to the finishing, strength, or performance of the base; or a surface which is susceptible to distortion under construction traffic. Such substances include, but are not limited to: cherty or other extremely hard pieces, lumps, balls or pockets of sand or clay size material, organic matter, loose sand, loose, free shells, corals or skeletal remain of other marine invertebrates retained on the No. 4 sieve, or water sensitive clay minerals.

911-2.2 Limerock Composition: Limerock material shall consist of unconsolidated or partly consolidated limestone of marine origin.

911-2.3 Shell Material: Composition: Shell materials shall consist of naturally occurring deposits formed essentially of broken mollusk shell, corals and the skeletal remains of other marine invertebrates. Live or steamed shell, or man-made deposits as a by-product of the shellfish industry will not be permitted.

911-2.3.1 Bank Run Shell: Shell materials meeting the requirements of this

Section which are presently found as “dry land” deposits.

911-2.3.2 Dredged Shell: Shell materials meeting the requirements of this

Section which are dredged from ocean, bay or lake deposits.

911-2.4 Shell-Rock Material Composition: Shell-rock materials shall consist of naturally occurring heterogeneous deposits of limestone with interbedded layers or lenses of loose and cemented shell, to include cemented sands (calcitic sandstone). This material shall be mined and processed in a manner that will result in a reasonably homogenous finished product.

911-2.5 Cemented Coquina Shell Material Composition: Cemented coquina shell materials to be used as cemented coquina base or stabilized base, shall be defined as naturally occurring deposits formed essentially of broken mollusk shell, corals and the skeletal remains of other marine invertebrates, which are presently found as “dry land” deposits and which have been cemented together by carbonates or other natural cementing agents.

911-2.6 Calcarenite Composition: Calcarenite material shall consist of calcareous clastic sedimentary rock, formed by compaction and cementation of carbonate clasts of size between 0.06 and 2 mm. It also contains a calcareous cementing material that binds the sand grains together.

1003 FY 2026-27Return to Table of Contents

911-2. 7 Recycled Concrete Aggregate (RCA) Composition: RCA shall consist of concrete material derived from the crushing of hard portland cement concrete. In addition to the deleterious materials noted in 911-2.1.2, RCA shall be asbestos free. The following limits shall not be exceeded:

Bituminous Concrete ...................................... 1% by weight

Bricks .............................................................. 1% by weight

Glass and Ceramics ......................................... 1% by weight

Wood and other organic substances ............. 0.1% by weight

Reinforcing steel and welded wire fabric .... 0.1% by weight

Plaster and gypsum board ............................ 0.1% by weight

911-3 Material Requirements.

911-3.1 Limerock Bearing Ratio (LBR): Materials shall meet the requirements in

Table 911-1 in accordance with FM 5-515:

Table 911-1

Limerock Bearing Ratio (LBR)

Material Requirement

Limerock

Average Results per LOT - 100, minimum

Individual Results - 90, minimum

Shell

Shell-Rock

Cemented Coquina Shell

Calcarenite

RCA Individual Results - 150, minimum

911-3.2 Liquid Limit and Plasticity: Materials shall meet the requirements in

Table 911-2 in accordance with AASHTO T 89 and AASHTO T 90:

Table 911-2

Liquid Limit and Plastic Properties

Material Liquid Limit Plastic Properties

Limerock Base Not to exceed 35 Non-Plastic (NP)

Stabilized Base Plasticity not to exceed 10

Shell

- NP

Shell-Rock

Cemented Coquina Shell - NP

Calcarenite - NP

RCA - NP

911-3.3 Carbonates: Materials shall meet the carbonate requirements in Table 911-3 in accordance with FM 5-514:

1004 FY 2026-27Return to Table of Contents

Table 911-3

Percentage of Carbonates (Calcium and Magnesium)

Material Requirement

Limerock minimum - 70%

Shell minimum - 50%

Shell-Rock minimum - 50%

Cemented Coquina Shell minimum - 50%

Calcarenite minimum - 45%

RCA Not Applicable

911-3.4 Gradation and Size Requirements: Materials shall meet the gradation and size requirements in Table 911-4 in accordance with AASHTO T 27 and FM 1-T11:

Table 911-4(1)

Gradation Requirements

Material Requirement

Limerock Base Passing 3-1/2 inch sieve - 97%, minimum(2)

Stabilized Base Passing 3-1/2 inch sieve - 97%, minimum(2)

Shell

Dredged shell

Passing 3-1/2 inch sieve - 97%, minimum

Passing No. 4 sieve - 50%, maximum

Passing No. 200 sieve - maximum 7.5% (washed)

Bank-run shell

Passing 3-1/2 inch sieve - 97%, minimum

Passing No. 4 sieve - 80%, maximum

Passing No. 200 sieve - 20%, maximum (washed)

Shell-Rock Passing 3-1/2 inch sieve - 97%, minimum

Passing No. 4 sieve - 70%, maximum

Passing No. 200 sieve - 20%, maximum (washed) Cemented Coquina Shell

Calcarenite Passing 3-1/2 inch sieve - 97%, minimum(2)

RCA

Sieve Size Percent by Weight Passing

2 inch 100

3/4 inch 65 to 95

3/8 inch 40 to 85

No. 4 25 to 65

No. 10 20 to 50

No. 50 5 to 30

No. 200 0 to 10

(1) The maximum dimension shall not exceed six inches.

(2) The material shall be well graded down to dust. The fine material shall consist entirely of dust of fracture.

911-4 Exceptions, Additions, and Restrictions.

Approved materials shall not be mixed with other approved or non-approved materials.

1005 FY 2026-27Return to Table of Contents

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