Department of transportation state of georgia supplemental specification




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November 17, 2006

Revised: May 30, 2012

Revised: November 16, 2012

July 10, 2013

February 27, 2014


DEPARTMENT OF TRANSPORTATION

STATE OF GEORGIA
SUPPLEMENTAL SPECIFICATION
Section 812—Backfill Materials

Delete Section 812 and substitute the following:



812.1 General Description

This section includes the requirements for four types of material used as backfill: foundation backfill, Types I and II, imperfect trench backfill, Type III, and mechanically stabilized wall backfill.

812.1.01 Related References

A. Standard Specifications

Section 810—Roadway Materials



B. Referenced Documents

AASHTO T 11

AASHTO T 27

AASHTO T 96

AASHTO T 104

GDT 4


GDT 6

GDT 7


GDT 24a

GDT 24b


GDT 67

GDT 75


GDT 98

SOP 1


812.2 Materials

812.2.01 Foundation Backfill, Type I



A. Requirements

Use natural or artificial mixtures of materials consisting of hard, durable particles of sand or stone, mixed with silt, clay and/or humus material for Type I backfill.

Have the final blend of material meet the requirements of Class I or II soils in Subsection 810.2.01.

B. Fabrication

General Provisions 101 through 150.



C. Acceptance

Test as follows:



Test

Method

Soil gradation

GDT 4

Volume change

GDT 6

Maximum density

GDT 7 or GDT 67

D. Materials Warranty

General Provisions 101 through 150.

812.2.02 Foundation Backfill, Type II

A. Requirements


  1. Type

Use material meeting the requirements of Section 800, Class A or B aggregate, and SOP 1. Crushed concrete may be used provided it meets the requirements of Section 800 that are applicable to Group 2 Aggregates.

Do not use backfill aggregate containing soil or decomposed rock.

Gradation

Use material meeting the following gradation requirements:



Sieve Size

% Passing by Weight

1-1/2 in (37.5 mm)

100

1 in (25 mm)

80-100

No. 8 (2.36 mm)

0-5

B. Fabrication

General Provisions 101 through 150.



C. Acceptance

Test as follows:



Test

Method

Sieve analysis

AASHTO T 27

D. Materials Warranty

General Provisions 101 through 150.

812.2.03 Imperfect Trench Backfill, Type III

A. Requirements


  1. Type

Use material made from either of the following for Type III backfill:

  • A natural soil with a density of less than 95 lb/ft³ (1520 kg/m³) when tested with GDT 7

  • An artificial mixture of soil and organic material, such as hay, leaves, or straw

B. Fabrication

General Provisions 101 through 150.



C. Acceptance

The laboratory will:



  1. Test the soil density with GDT 7.

  2. Review the mixture and the percentages of each material, and approve a mixture suitable for the Project.

D. Materials Warranty

General Provisions 101 through 150.



812.2.04 Mechanically Stabilized Embankment Backfill

A. Requirements

Use material comprised of crushed stone, natural sand, or a blend of crushed stone and natural sand free of soils, organic or any other deleterious substances meeting the following additional requirements:



  1. Crushed Stone

Use a material manufactured from Class A or B stone that is free of soil overburden, has a soundness loss of not more than 15 percent, and conforms to the requirements of SOP 1.

2. Natural Sand

May be used in conjunction with an approved, non-corrodible, extensible reinforcement. Use non-plastic material consisting of strong, hard, durable particles having a durability index of at least 70.

3. Gradation



Sieve Size

% Passing by Weight

4 in (100 mm)

100

2 in (50 mm)

80 -100

No. 10 (2 mm)

20 - 90*

No 200 (75 mm)

0 - 12

* Natural Sand may be 20 - 100

  1. Chemical

Ensure the material meets the following chemical requirements:

Test Method

Requirement

pH

*5.0 – 9.5

Resistivity

>3000 ohms/cm

Chlorides

<100 ppm

Sulfates

<200 ppm

Note: These chemical requirements are not applicable to MSE walls stabilized with an approved, non-corrodible, extensible reinforcement.

*Sources of select backfill material having a pH between 4.5 and 5.0 may be used provided the interior face of the MSE wall panels have 3 inches of concrete cover over the reinforcement and the concrete used in the panels contains the following ingredients and proportions:

Material

% by Weight

Minimum

Maximum

Cement

30

--

Type F Fly Ash

10

20

Slag

50

60

Type F Fly Ash and Slag

--

70

  1. Maximum Dry Density

Use backfill material with a maximum dry density equal to or greater than the design unit weight shown on the plans. If no maximum dry density of the backfill material is shown, use a weight of 125 lb/ft3 (2000 kg/m3).

B. Fabrication

General Provisions 101 through 150.



C. Acceptance

Test the material as follows:



Test Method

Requirement

Percent Wear

AASHTO T96 (“A” Grading)

Sieve Analysis

AASHTO T 27

Material Passing No. 200 (75 mm) Sieve

AASHTO T 11

Durability Index

GDT 75

Maximum Dry Density

GDT 7 or GDT 24a, GDT 24b

Soundness (Magnesium Sulfate)

AASHTO T 104

pH

GDT 98

Resistivity

GDT 98

Chlorides

GDT 98

Sulfates

GDT 98


D. Materials Warranty

General Provisions 101 through 150.



Office of Materials and Testing



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