LIGHTWEIGHT FILL SPECIFICATIONS - GeoTech · PDF filelightweight fill november 2012 page 1 of 54 r02 geotechnical solutions for soil improvement, rapid embankment construction, and

LIGHTWEIGHT FILL

November 2012 Page 1 of 54 R02 GEOTECHNICAL SOLUTIONS FOR SOIL IMPROVEMENT, RAPID EMBANKMENT CONSTRUCTION, AND STABILIZATION OF PAVEMENT WORKING PLATFORM

SPECIFICATIONS

The specification guidance and discussion provided herein is divided into several sections that each address a specific type of lightweight fill. For each type of lightweight fill, this document provides a review of existing specifications, example specifications, and comments about the example specifications. The six types of lightweight fill are aggregate (includes slag, pumice, scoria, and ESCS, which stands for Expanded Shale, Clay, and Slate), fly ash, wood fiber, shredded tire, cellular concrete, and geofoam. All of the example specifications are attached at the end of this document.

Note: Specifications that are mentioned but not included in this document can be found under the Additional Information link on the Lightweight Fill SHRP2 website page.

Table 1 identifies the example specifications contained in this document.

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Table 1. Specification identification table.

Specification Name/Number

Sec

tion

023

32S

Lig

htw

eigh

t Agg

rega

te B

orro

w

Spe

cial

Pro

visi

on: L

ight

wei

ght A

ggre

gate

s

Spe

cial

Pro

visi

on f

or B

ackf

ill,

Lig

htw

eigh

t, S

lag

Agg

rega

te

Fly

Ash

Del

awar

e –

DO

T S

peci

fica

tion

Woo

d F

iber

- W

ashi

ngto

n D

OT

Shr

edde

d T

ire

- M

odel

Spe

cifi

cati

on

Tir

e D

eriv

ed A

ggre

gate

(T

DA

)

Lig

htw

eigh

t Con

cret

e F

ill (

Typ

e A

& B

)

EI

08-0

14: R

evis

ed S

peci

al S

peci

fica

tion

For

Exp

ande

d P

olys

tyre

ne F

ill

Spe

cial

Pro

visi

on f

or G

eom

embr

ane

Sp

ecif

icat

ion

typ

e Method approach

Performance approach

Combined performance/method approach

└Performance level 4 4 4 4 3/4

Performance level: 1 - Actual performance measured after construction (e.g., settlement at a specific time) and warranty provisions might be included 2 - Performance-related properties measured at end of construction (e.g., CPT, vane shear, etc.) 3 - Design properties measured during construction (e.g., modulus measured for each lift) 4 - Design-related properties measured during construction (e.g., density and water content measured for each lift)

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-Aggregate-

Review of Existing Specifications

The specifications in this assessment can generally be grouped into three sets. The first set of specifications is applicable for multiple types of lightweight aggregate materials. This includes slag, pumice, scoria, and ESCS. Three general lightweight aggregate specifications were reviewed as part of this assessment. The second set of specifications is applicable only for ESCS materials. Three ESCS specifications were reviewed as part of this assessment. The third set of specifications is applicable only for blast furnace slag. Only one blast furnace slag specification was reviewed, Special Provision for Backfill, Lightweight, Slag Aggregate. All the assessed specifications are either method approach specifications or combined performance/method approach specifications. In addition to method approach requirements, the specifications that incorporated performance requirements included values for the compacted density of fill materials.

Depending on the project and application, it may be more desirable to use either a general lightweight aggregate specification or a material-specific specification. General lightweight aggregate specifications allow for a wide variety of materials, including ESCS and slag, but typically have fewer material requirements and lack explicit construction requirements. Specialized ESCS and slag specifications typically have more extensive material requirements and explicit construction requirements.

No general guide specifications were reviewed for lightweight aggregate fill, but if such guide specifications are developed, they should be generated for the three categories described above: general lightweight aggregates (including ESCS and slag), exclusive for ESCS aggregates, and exclusive for slag aggregate. This would provide the user with specifications that could easily be adapted for a variety of lightweight aggregate projects and applications.

The specification Section 02332S Lightweight Aggregate Borrow provides the most suitable basis for developing a general lightweight aggregate guide specification. It could be adapted to resolve some ambiguous language, improve clarity, and include sections on measurement and payment. It contains all applicable QC/QA requirements and acceptance criteria.

The ESCS specifications are generally well written and provide sufficient detail. The specification Special Provision: Lightweight Aggregates provides the most suitable basis for developing an ESCS guide specification. Acceptance criteria, QC/QA requirements, and definitions from the other two ESCS specifications should be added to this specification.

The specification Special Provision for Backfill, Lightweight, Slag Aggregate was the only blast furnace slag specification reviewed. This specification was generally well written but could be improved by clarifying sampling and construction requirements. Currently, sampling procedures

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SPECIFICATIONSare provided in a separate manual. Spreading and compaction methods are not specified and are subject to Engineer approval.

Many of the assessed specifications lacked adequate QC/QA requirements. QC/QA requirements for lightweight fills include material testing, surveying methods, test sections, density testing, and construction monitoring.

Summary of Example Specifications

In the following section, three examples of typical aggregate lightweight fill specifications are provided. These specifications should be modified based on project specific parameters and in accordance with the recommended Design Guidance and QC/QA Procedures for lightweight fill.

Specification Name/Number: Section 02332S Lightweight Aggregate Borrow Source(s):

Utah DOT

This specification is applicable for many types of lightweight aggregate materials, including scoria, pumice, slag, and ESCS. The material source must have been tested to meet specification requirements and Utah State Environmental Laws for embankment fill. Material requirements include compacted density, gradation, durability, and chemical inertness; however, requirements for durability and chemical inertness should be more clearly explained or quantified. Clarification of the QA Manager’s affiliation and of the target moist unit weight required during compaction should be included. This specification mandates a test section to determine approved compaction methods, but it also includes requirements for final compacted density of materials. This has the potential to unfairly allocate risk to the contractor because both method and performance become the contractor's responsibility. Therefore, it is recommended that either an approved compaction method or the final required compacted density be included in the specification, but not both. Compacted density is verified using a calibrated nuclear density gauge. This specification does not include sections on measurement and payment.

This specification is to be used in conjunction with the latest versions of Utah DOT Standard Specifications, available online at:

http://www.udot.utah.gov/main/f?p=100:pg:0::::V,T:,1925

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SPECIFICATIONS Specification Name/Number: Special Provision: Lightweight Aggregates Source(s):

South Carolina DOT

This specification is only applicable for ESCS lightweight fill materials. Material requirements are fairly extensive and include particle shape, cleanness, soundness, abrasion, chloride content, absorption, density, friction angle, resistivity, and pH. This specification is clearly written and contains simple and straightforward construction requirements with lift thickness, equipment, and number of passes well defined. This specification could be improved by including more detailed QC/QA guidance and acceptance criteria.

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SPECIFICATIONS Specification Name/Number: Special Provision for Backfill, Lightweight, Slag

Aggregate Source(s):

Michigan DOT

This specification is only applicable for iron blast furnace slag lightweight fill materials. Material requirements include gradation, density, and leachate determination. Construction requirements include placement of a stabilization geotextile, lift thickness, and protection of placed materials. Methods for spreading and compacting are not specified but need to be approved by the Engineer. QC/QA includes sampling and testing of placed materials to verify compliance with gradation requirements and unit weights. Sampling requirements are specified in the Michigan DOT Materials Quality Assurance Procedures Manual, but it would be helpful for other projects if they were contained within the specification. The leachate determination is verified by Michigan DOT prior to placing materials.

This specification is to be used in conjunction with the latest versions of the Michigan DOT Materials Quality Assurance Procedures Manual and Standard Specifications, which are available online at:

http://www.michigan.gov/mdot/0,1607,7-151-9622_11044_11367-207980--,00.html

http://mdotwas1.mdot.state.mi.us/public/specbook/

-Fly Ash-


The specification Fly Ash Delaware – DOT Specification would benefit from improvement in some areas, but it could be used in developing a combined performance/method approach guide specification for fly ash. It should be noted that the Fly Ash Delaware – DOT Specification is to be used in conjunction with Delaware DOT Standard Specifications, and it may be important to include some of this information in the guide specification. In addition, ambiguous language should be clarified and, when appropriate, responsibilities could be transferred from the Owner’s Engineer to the Contractor. All relevant QC/QA requirements for lightweight fill are included in the specification.


Only one fly ash lightweight fill specification was available at the time of this assessment. This specification should be modified based on project-specific parameters and in accordance with the recommendations found in the Design Guidance and QC/QA Procedures documents for lightweight fill.

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SPECIFICATIONS Specification Name/Number: Fly Ash Delaware – DOT Specification Reference(s):

Elias et al. (2006a)

This specification is only applicable for fly ash to be used as a lightweight fill material. The specification requires that material property test results and laboratory analyses, including EPA extraction procedure toxicity test results for the ash leachate, shall be submitted for approval prior to construction. Construction employs standard equipment and is not overly complicated. Placement methods, equipment, lift thickness, minimum relative density, and required technique are specified. The contractor should use the appropriate number of passes to achieve a minimum relative compaction of 95% as compared to standard proctor. Requirements for compacted moisture content could be better clarified. After compaction, lifts are tested to verify in-place densities and moisture contents. Methods for determining the moisture content are not specified. Also, the frequency of testing is left up to the Engineer. The potential use of a test strip is included in the specification but detailed requirements are not provided. For the most part, risk is fairly allocated between the contractor and owner. However, the specification places some responsibilities on the Owner’s Engineer that could be fairly transferred to the Contractor (e.g., the responsibility of selecting drain pipe locations to prevent ponding could be transferred from the Engineer to the Contractor). The allowance of 10 working days for the Engineer to review the final grades seems excessive and could potentially delay Contractor operations.

This specification is to be used in conjunction with the latest versions of Delaware DOT Standard Specifications, which are available online at:

www.deldot.gov/information/pubs_forms/manuals/standard_specifications/index.shtml

-Wood Fiber-


The specification Wood Fiber - Washington DOT would require significant improvement in order to develop a method approach guide specification for wood fiber. This specification lacks sections on QC/QA and acceptance criteria, and it provides very little detail. The relevant lightweight fill QC/QA requirements that should be included are material testing, surveying methods, test sections, and construction monitoring.


Only one wood fiber lightweight fill specification was reviewed as part of this assessment. This specification should be modified based on project specific parameters and in accordance with the recommended Design Guidance and QC/QA Procedures for lightweight fill.

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SPECIFICATIONS Specification Name/Number: Wood Fiber - Washington DOT Reference(s):


This specification is only applicable to wood fiber to be used as lightweight fill material. Material requirements include composition and maximum dimension. Construction requirements are simple and straightforward, with placement, equipment, lift thickness, and number of passes well-defined. This specification could be improved by clarifying ambiguous language and including clearly explained QC/QA requirements and acceptance criteria. Some examples of ambiguous language are the interchanged use of the terms “wood fiber” and “sawdust” and the requirement for “uniformly dense fill.”

-Shredded Tire-


The Shredded Tire – Model Specification and Tire Derived Aggregate (TDA) specification are both high quality method approach specifications. The Shredded Tire – Model Specification is provided in a general format that is not specific to a particular project or state. The Tire Derived Aggregate (TDA) specification is project and state-specific. If a method approach guide specification is developed, the Shredded Tire – Model Specification could be combined with the definitions, material requirements, and requirements for the geotextile enclosure layer from the Tire Derived Aggregate (TDA) specification. In addition, it may be useful to include some of the information on geotextile requirements from the Ontario Provincial Standard Specifications in the guide specification. Both the Shredded Tire – Model Specification and Tire Derived Aggregate (TDA) specification contain all relevant QC/QA requirements and acceptance criteria.


In the following section, two shredded tire lightweight fill specifications are provided. These specifications should be modified based on project specific parameters and in accordance with the recommended Design Guidance and QC/QA Procedures for lightweight fill.

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SPECIFICATIONS Specification Name/Number: Shredded Tire - Model Specification Reference(s):


This specification is only applicable for tire shreds made from scrap tires. Material requirements include cleanness, gradation, and maximum dimension of the tire shreds. Requirements for the survivability of the geotextile enclosure layer are mentioned, but the details need to be inserted by the user in this guide specification. Construction requirements are simple and straightforward, with placement, equipment, lift thickness, and number of passes well defined. QC/QA includes random sampling of tire shred during production to verify conformance with material requirements. This specification is provided in a general, non-project or state specific format and is easily adaptable.

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SPECIFICATIONS Specification Name/Number: Tire Derived Aggregate (TDA) Source(s):

Ontario Ministry of Transportation

This specification is only applicable for tire shreds made from scrap tires. Material requirements include cleanness, gradation, and maximum dimension of the tire shreds. Construction requirements are simple and straightforward, with placement, equipment, lift thickness, and number of passes well defined. QC/QA includes sampling of tire shred lots to verify conformance with specification material requirements.

This specification should be used in conjunction with Ontario Provincial Standard Specifications available online at:

https://www.raqsb.mto.gov.on.ca/techpubs/ops.nsf/OPSHomepage

-Cellular Concrete-


In total, nine specifications were reviewed for cellular concrete. Many of the assessed specifications contained ambiguous language and lacked detailed requirements. The specification Lightweight Concrete Fill (Type A & B) is the most well-suited for use in developing a combined performance/method approach guide specification. Mixing equipment requirements, tolerance and surface grading requirements, and additional material properties from the other specifications should be combined with the Lightweight Concrete Fill (Type A & B) specification during development of the guide specification. In the guide specification, it would be helpful to clarify the foaming agent approval process and requirements. In addition, the specification should be modified so that risk is fairly allocated between the Contractor and Owner. Unnecessary risk could be removed from the Owner by removing the Engineer from a supervisory role during placement and mixing operations, and by providing clear requirements to be met by the Contractor instead. All relevant QC/QA requirements for lightweight fill are included in the specification.


In the following section, an example of a typical cellular concrete lightweight fill specification is provided. This specification should be modified based on project specific parameters and in accordance with the recommendations found in the Design Guidance and QC/QA Procedures documents for lightweight fill.

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SPECIFICATIONS Specification Name/Number: Lightweight Concrete Fill (Type A & B) Source(s):

New York State DOT

This specification is applicable for cast-in-place cellular concrete produced from a mixture of Type I, II, or III Portland cement, water, foaming agent, and admixtures. Material requirements include density and compressive strength. In addition, there is reference to an approval process associated with the particular foaming agent that is unclear but appears to qualify materials based on compressive strength, air-dry density, freeze-thaw, and water absorption characteristics. Construction requirements include pour requirements, lift thickness, and waiting periods between lifts. Tolerances, surface grading, and mixing requirements are not included in this specification, but the cellular concrete is placed under the supervision of the Engineer. This may not be desirable for all projects as it allocates substantial risk to the Owner's Engineer. Instead, it is recommended that these requirements be clearly stated in the specification and the Engineer should only provide verification of Contractor compliance. QC/QA requirements in this specification include testing to verify cast density and compressive strength.

This specification is to be used in conjunction with NYDOT 2006 Standard Specifications (Metric). The NYDOT Standard Specifications are available online at:

www.nysdot.gov/main/business-center/engineering/specifications/

-Geofoam -


A total of ten specifications for both geofoam and/or geomembrane linings were assessed. Eight of the specifications pertain to geofoam fill material and two of the specifications pertain to geomembrane linings used to protect the geofoam fill material.

The geofoam specification EI 08-014: Revised Special Specification for Expanded Polystyrene Fill is well suited for use in developing a method approach guide specification for geofoam. This specification is fairly complete but should be combined with block fitting and final grade tolerance requirements from the other assessed specifications. Depending on the project, it may also be helpful to include sections on gripper plates and Manufacturer Quality Control/Manufacturer Quality Assurance (MQC/MQA). These topics are thoroughly discussed in the specification Geofoam Fill Material – Massachusetts DPW (Central Artery Project) (not included in this document). The specification EI 08-014: Revised Special Specification for Expanded Polystyrene Fill contains all relevant lightweight fill QC/QA procedures.

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SPECIFICATIONSThe geomembrane specification Special Provision for Geomembrane could be used to develop a method approach geomembrane guide specification. This specification should be improved by:

Allowing other geomembrane materials.

Refining properties listed and property values to allow other products.

Clarifying ambiguous language.

Adding some further detail.

In addition, it may be desirable to either remove or provide additional clarification for the final page of the specification related to drainage system waterproofing. This specification contains all relevant QC/QA procedures.

Geomembrane materials are not routinely used by transportation agencies or by highway works contractors. Therefore, agencies may prefer to use specific materials that they are familiar with. Additionally, agencies may want to include a contractor experience requirement in the specification to encourage/ensure that the prime contractor utilizes an experienced geomembrane subcontractor. Three primary items should be considered for a geomembrane specification: functionality (i.e., design), constructability, and durability. For geomembrane coverage of EPS lightweight fill:

Design items include barrier function and interface friction strength with adjacent materials (EPS and soil).

Constructability items include seaming (field and factory), seam integrity, geomembrane and seam strength, puncture resistance, and flexibility (conform to required shape).

Durability items include high resistance to gasoline and to diesel fuel.


In the following section, two examples specifications are provided. The first specification pertains to the geofoam fill material and the second pertains to the geomembrane linings used to protect the geofoam fill material. These specifications should be modified based on project specific parameters and in accordance with the recommendations found in the Design Guidance and QC/QA Procedures documents for lightweight fill.

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SPECIFICATIONS Specification Name/Number: EI 08-014: Revised Special Specification For Expanded

Polystyrene Fill Source(s):

New York State DOT

This specification is applicable to geofoam fill material. Material requirements include density, compressive strength, flexural strength, and flammability based on the oxygen index. Construction requirements include site preparation, field cutting requirements, layout, and protection of geofoam blocks. Tolerances for block fitting and final grades are not provided. QC/QA includes testing of block specimens prior to placement to evaluate conformance with material requirements.

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SPECIFICATIONS Specification Name/Number: Special Provision for Geomembrane Source(s):

Virginia DOT

This specification is applicable to geomembrane lining used to protect the geofoam fill material. Numerous material requirements are listed including, but not limited to, weight, puncture and tear resistance, tensile strength, elongation at yield, water absorption, abrasion resistance, permeability, and chemical resistance. A single, specific material type is listed (and presumably the properties and specified values are single, material-specific), and thus limits other material types which could be utilized. Specific property values may limit other products manufactured of the same material. Construction requirements include site preparation, placement, field seaming, and patching. QC/QA includes visual inspection and verification of seam continuity. This specification contains some ambiguous language (e.g., the section about placing the lining in a manner to assure minimum handling) and lacks sufficient detail (e.g., methods for sealing the lining around projections are not specified).

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References

Elias, V., Welsh, J., Warren, J., Lukas, R., Collin, J. G., and Berg, R. R. (2006). Ground Improvement Methods - Volume I. Federal Highway Administration, NHI-06-020.

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Documents

LIGHTWEIGHT FILL SPECIFICATIONS - GeoTech · PDF filelightweight fill november 2012 page 1 of 54 r02 geotechnical solutions for soil improvement, rapid embankment construction, and