introduction to cellular geosynthetics (geofoams and geocombs) a manhattan college center for...

Introduction to Cellular Introduction to Cellular GeosyntheticsGeosynthetics

(Geofoams and Geocombs)(Geofoams and Geocombs)

A Manhattan College Center for GeotechnologyTechnology Transfer through Distance Learning Program

Educational Product

Presentation prepared by

John S. Horvath, Ph.D., P.E.Professor of Civil Engineering

Director/Center for Geotechnology

Manhattan CollegeSchool of Engineering

Bronx, New York, U.S.A.

Manhattan College · School of Engineering · Center for Geotechnology

Construction Material Changes

• improvements to traditional materials (steel and PCC)

• development of new functions (roles) and applicationsfor existing materials

• development of new materials

• use of recycled waste materials

Construction Material Changes

• improvements to traditional materials (steel and PCC)

• development of new functions (roles) and applicationsfor existing materials <<< geocombs and some geofoams

• development of new materials <<< some geofoams

• use of recycled waste materials <<< some geofoams

Geofoam ...

Generic term for any closed-cell foam used in a geotechnical application that is manufactured either in a fixed plant or in-situ from an expansion process using a blowing agent:

• polymeric (plastic)– polyethylene (PE)– expanded polystyrene (EPS) <<< predominant– extruded polystyrene (XPS)– polyurethane (PUR)

• glass (cellular glass)

• cementitious

EPS block in temporary storage after molding.The entire block weighs less than the person handling it!

Example of one of at least three different designs ofEPS-shape geofoam "anti-buoyancy" blocks

developed in Japan (dimensions in millimetres).

Geocomb ...

… the newest "geo" material (geosynthetic), formerly referred to as "structures alveolaires ultra légères" (SAUL) or "ultra light cellular structures" (ULCS) in France where it was developed and has been used since the 1980s.

… defined as an open-cell (honeycomb shaped in cross-section) polymeric (PP, PVC) material created by an extrusion process. Typically supplied as a panel- or block-shaped final product.

PP (left) and PVC (right) geocombs.

typical tube (~ 25 mm/1 in)

Benefits of Using Geofoams and Geocombs

• efficient use of solid material • work with the forces of nature, not against them

• can be useful for both new construction and with existing structures, permanent and temporary, all climates/weather, "good" and "poor" ground

• provide unique geosynthetic functions

• can be multifunctional in many applications

• compatible and synergistic with other types of geosynthetics

Overview of Design Process

• design by function to identify desired properties

• define parameters for desired analyses and obtain relevant technical information for these parameters

• generally treat as an equivalent earth material and use conventional geotechnical analytical methods

• economic assessment (construction + O&M)

• relevant standards and specifications

Geosynthetic Functions

• thermal insulation (1960s) >>> geofoams only

• lightweight fill (1970s) >>> geofoams & geocombs

• drainage (1970s) >>> geofoams & geocombs

• noise/vibration damping (1980s) >>> geofoams only

• compressible inclusion (1980s) >>> geofoams only

• structural (1990s) >>> geofoams only11

Important Aspects of Material Behavior andOther Technical Issues for Design

• index properties

• mechanical (stress-strain-time) behavior

• thermal properties

• constructability and safety

• durability

• environmental impact

Factors to Consider in an Economic Assessment

• design aspects of initial construction

• constructability aspects of initial construction

• reduced costs of operation and maintenance

Manhattan College · School of Engineering · Center for GeotechnologyManhattan College · School of Engineering · Center for Geotechnology

Standards and Specifications

• standards constitute technology documentation and are the foundation of any technology

• specifications are the project-specific application of relevant standards to define the minimum acceptable results in a given application

Thermal Insulation Benefits

• life-cycle energy cost savings

• construction cost savings

• improved geotechnical/structural performance

Thermal Insulation Applications

• buildings and storage tanks (all climates)

• landfill liners (all climates)

• shallow buried structures (all climates)

• earth retaining structures (cold climates)

• pavements and railways (cold climates)

• underground conduits (cold climates)

• shallow foundations (cold climates)16

Test of landfill-liner thermal insulation alternatives in the U.S.A.17

Use of geofoam behind an earth retaining structure to prevent seasonal freezing of the wall drainage system

and retained soil.Note that the drainage system could be incorporated into the geofoam product for overall increased efficiency and

reduced cost.

drainage layer

geofoam

Rebuilding an existing road in Norway with geofoam insulation.19

Rebuilding an existing railway in Norway with geofoam insulation.20

Use of geofoam above an underground conduit to locally modify the depth of seasonal freezing to allow shallower conduit embedment. Note that the geofoam could also be

designed to act as a compressible inclusion to reduce forces acting on the conduit.

geofoam

normal conduit depth

depth of seasonalfreezing

Typical Frost Protected Shallow Foundation concept application.

geofoam

depth ofseasonalfreezing

footing depthwithout insulation

Lightweight Fill Applications

• embankments and fills: transportation water resources foundation support architecture and landscaping

• earth retaining structure backfill and fills

Rebuilding a failed road embankment in the U.S.A.in the winter using EPS-block geofoam.

Spraying a PCC facing on a "geofoam wall" type road fillin the mountains of Japan.

Constructing an EPS-block geofoam road embankment in Norwayfor a combined bridge approach fill and bridge abutment foundation.

Note the wooden formwork for the abutment footing.26

Using EPS-block geofoam to construct an abutment backfillfor a new road bridge in Chile.

Completed approach embankment and abutment backfillusing EPS-block geofoam for a new road bridge in Canada.

Constructing an approach embankment and abutment backfillusing geocomb blocks for a road bridge in France.

Rehabilitating and raising a levee in the U.S.A. using EPS-block geofoam.30

Building basement wall in the U.S.A. backfilled using EPS-block geofoam.31

Anchored bulkhead in Japan partially backfilledusing EPS-block geofoam.

Barbed connector plates used between blocks of EPS geofoamin Japan (dimensions are in millimetres, 25 mm = 1 in).

100 mm (4 in) square barbed connector plateused between blocks of EPS geofoam in the U.S.A.

Drainage Applications

• fluid transmission using geofoams: ground water around below-grade structures ground water behind earth retaining structures leachate collection systems in landfills ground-borne gases around below-grade structures

• fluid transmission and storage using geocombs

EPS-shape geofoam product developed in the U.K. specifically for collecting and draining ground-borne gases

such as methane and radon. Note that it also provides thermal insulation for the structure. 36

Geofoam drainage geocomposite available in Asia, Europe and theU.S.A. that uses a glued polystyrene porous block core.

glued polystyrene porous blockhigh-permeability core

Geofoam sheet-drain product composed of pieces ofrecycled PE that was developed in The Netherlands.

Drainage (fluid transmission and storage) applicationsusing geocomb panels and blocks developed in France.

Noise and Vibration Damping Applications

• attenuation of small-amplitude, ground-borne vibrations from:

motor vehicles trains

• attenuation of noise from trains

EPS-block geofoam used to dampen noise and vibrations from a railway in Germany . The EPS blocks directly

beneath the tracks are also acting as a lightweight fill for the clay ("Ton") subgrade.

PCC slabEPS-block geofoam

EPS-block geofoam

EPS-block geofoam used to dampen noise and vibrationsfrom light-rail vehicles (trams/trolleys) in France and Germany.

EPS-block geofoam

PCC layers

PCC ties (sleepers)

Compressible Inclusion Applications

• lateral earth pressure and settlement reduction:

shear-strength mobilization of "normal" soils volume change of expansive/freezing soil/rock structure movement

• vertical stress reduction from expansive soil/rock

• vertical arching above underground conduits

tensile reinforcement(optional)

geofoam

Use of geofoam compressible inclusion behind a rigid/non-yielding earth retaining structure to reduce

lateral earth pressures(optional use of geosynthetic tensile reinforcement also

shown).

soil movement

Use of a resilient-EPS geofoam geocomposite in the U.S.A. to act as acompressible inclusion to accommodate integral-abutment bridge

movement. Drainage is also provided by the same product.

Use of a geofoam compressible inclusion aroundfoundation elements of a structure to

reduce stresses in expansive ground (soil or rock) conditions.

geofoam

ground movement

ground movementground movement

EPS-block geofoam used as a compressible inclusion around areinforced-PCC grade beam in expansive soil in the U.K.(geofoam also served as formwork during construction).

EPS-block geofoam used as a compressible inclusion beneath a deep-foundation supported tunnel base slab in

expansive ground in the U.K. 48

EPS-block geofoam product used as a compressible inclusion beneatha deep-foundation supported base slab of a building in Canada

(similar product also developed in U.K.).

Use of a geofoam compressible inclusion above anunderground conduit to reduce vertical stresses acting on

theconduit by inducing vertical arching within the overlying

ground movement

geofoam

ground movement

Multifunctional use of a geofoam geocomposite only ~ 150 mm (6 in)thick simultaneously providing compressible inclusion, drainage and

thermal insulation behind a building basement wall in the U.S.A.

Structural/Miscellaneous Applications

• forms for PCC walls • MSEW facing panels

• void formers for PCC slabs

• crash barriers for motor vehicles and aircraft

• impact cushioning for rock sheds

• void filling and foundation remediation

Panels cut from block-molded EPS used as formwork for a reinforced-PCC basement wall in the U.S.A. The EPS also

provides post-construction thermal insulation for the life of the structure. 53

MSEW system developed in the U.K. with geogrid reinforcementand facing panels cut from block-molded EPS.

Generic components of EIFS technology used over EPS and XPSto create a wide variety of durable architectural finishes.

mesh reinforcementunderlayment

two-part stucco-likefinish

Block-molded EPS used as a lightweight void former for apile-supported structural slab constructed over a soft

subgradein the U.S.A.

EPS blocks used as crash-cushioning barriers around an auto-racing track in the U.S.A. Note evidence of extensive

prior collision damage.

Credit: Paul Arch Racing Photos

EPS blocks

EPS blocks used as protection for PCC rock sheds inmountainous areas in Europe and Japan.

EPS blocks

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