The Feasibility, The Feasibility, Constructability, and Constructability, and

Efficacy of Tire-Derived Efficacy of Tire-Derived Aggregate as a Component Aggregate as a Component

in Slurry Cutoff Wallsin Slurry Cutoff Walls

Slurry Cutoff WallsSlurry Cutoff Walls

A slurry cutoff wall is a form of seepage A slurry cutoff wall is a form of seepage barrier intended to stop the migration barrier intended to stop the migration of water through an impervious barrier.of water through an impervious barrier.

One of the methods used to construct a One of the methods used to construct a slurry cutoff wall is to excavate a trench slurry cutoff wall is to excavate a trench and then backfill it with a mixture of and then backfill it with a mixture of soil, cement, and bentonite clay (SCB) soil, cement, and bentonite clay (SCB)

Slurry Cutoff Walls in Slurry Cutoff Walls in Waterside ApplicationsWaterside Applications

In waterside applications, a cutoff wall is typically In waterside applications, a cutoff wall is typically constructed either at the toe of the levee or along constructed either at the toe of the levee or along the crown (top) of the levee. the crown (top) of the levee. The process is typically:The process is typically:

A trench that is excavated.A trench that is excavated. The trench is filled with hydrated bentonite clay slurry The trench is filled with hydrated bentonite clay slurry

to prevent the trench from caving in.to prevent the trench from caving in. The soil that was excavated is mixed with bentonite The soil that was excavated is mixed with bentonite

and cement and placed back into the trench.and cement and placed back into the trench. Samples are periodically taken to measure the Samples are periodically taken to measure the

permeability (ability of water to flow through the permeability (ability of water to flow through the backfill material).backfill material).

Slurry Cutoff Walls in Slurry Cutoff Walls in Waterside ApplicationsWaterside Applications

The Recycled Tire Slurry Cutoff The Recycled Tire Slurry Cutoff Wall Demonstration ProjectWall Demonstration Project

In 1998, a research grant was awarded to In 1998, a research grant was awarded to the CSU, Chico Research Foundation to the CSU, Chico Research Foundation to evaluate the feasibility of incorporating evaluate the feasibility of incorporating tires shreds into a levee slurry cutoff wall tires shreds into a levee slurry cutoff wall

The hypothesis for this project was that a The hypothesis for this project was that a large quantity of recycled tires could be large quantity of recycled tires could be incorporated into the backfill, alleviating incorporated into the backfill, alleviating the various piles of waste tires stockpiled the various piles of waste tires stockpiled in the State of California and providing an in the State of California and providing an effective barrier to water migration.effective barrier to water migration.

The Recycled Tire Slurry Cutoff The Recycled Tire Slurry Cutoff Wall Demonstration ProjectWall Demonstration Project

The Recycled Tire Slurry Cutoff Wall The Recycled Tire Slurry Cutoff Wall Demonstration Project was funded by the Demonstration Project was funded by the California Integrated Waste Management California Integrated Waste Management Board as a potential source for the reuse Board as a potential source for the reuse of waste tires. of waste tires. The project had four distinct stages:The project had four distinct stages:

Laboratory TestingLaboratory Testing Medium Scale TestingMedium Scale Testing Large Scale Field Testing - ImplementationLarge Scale Field Testing - Implementation Monitoring of ResultsMonitoring of Results

Preliminary Investigations

In 1998-1999, preliminary laboratory work began In 1998-1999, preliminary laboratory work began to determine if in fact, there was a method in to determine if in fact, there was a method in which the soil, cement, bentonite, and tire shreds which the soil, cement, bentonite, and tire shreds could be mixed resulting in a product that could be mixed resulting in a product that behaved similar to backfill materials being used behaved similar to backfill materials being used in traditional SCB cutoff walls in traditional SCB cutoff walls

The target used for measurement of performance The target used for measurement of performance was the USACOE specifications with three major was the USACOE specifications with three major criteria including:criteria including: Slump – 100–150 mm (4-6 inches) Permeability – Less than 5 x 10-7 cm/sec Compressive strength (fc) – Less than 100 psi

Preliminary InvestigationsContinued

The following Project obstacles were The following Project obstacles were quickly found as the preliminary quickly found as the preliminary investigations into the project began:investigations into the project began: Method of mixing materials in a large Method of mixing materials in a large

scale field testscale field test Method of testing permeabilityMethod of testing permeability Method of testing slumpMethod of testing slump Buoyancy of the tiresBuoyancy of the tires Variations of soil classification used in lab Variations of soil classification used in lab

tests from those actually found at the sitetests from those actually found at the site

Preliminary InvestigationsContinued

To address the obstacles of this project, the following ASTM To address the obstacles of this project, the following ASTM standard’s were researched and incorporated into the project:standard’s were researched and incorporated into the project:

ASTM C-143ASTM C-143: “Standard Test Methods for Slump of Hydraulic-Cement : “Standard Test Methods for Slump of Hydraulic-Cement ConcreteConcrete

ASTM D 5084ASTM D 5084: “Standard Test Methods for Measurement of Hydraulic : “Standard Test Methods for Measurement of Hydraulic Conductivity of Saturated Porous Conductivity of Saturated Porous

Materials Using a Flexible Materials Using a Flexible Wall Permeameter” Wall Permeameter” ASTM C-360ASTM C-360: “Test method for Ball Penetration in Freshly Mixed : “Test method for Ball Penetration in Freshly Mixed

Hydraulic Hydraulic Cement Concrete” Cement Concrete” ASTM C 150ASTM C 150: “Standard Specification for Portland Cement”: “Standard Specification for Portland Cement” ASTM D 422ASTM D 422: “Standard Test Method for Particle Size Analysis of Soils”: “Standard Test Method for Particle Size Analysis of Soils” ASTM D 2487ASTM D 2487: “Standard Classification of Soils for Engineering : “Standard Classification of Soils for Engineering

Purposes”Purposes” ASTM D 4318ASTM D 4318: “Standard Test Method for Liquid Limit, Plastic Limit, : “Standard Test Method for Liquid Limit, Plastic Limit,

and and Plasticity Index of Soils” Plasticity Index of Soils” ASTM D 698ASTM D 698: “Laboratory Compaction Characteristics”: “Laboratory Compaction Characteristics” ASTM D 1556ASTM D 1556: “Standard Test Method for Density and Unit Weight of : “Standard Test Method for Density and Unit Weight of

Soil in Soil in Place by the Sand-Cone Method” Place by the Sand-Cone Method” ASTM D 4832ASTM D 4832: “Preparation and Testing of Soil-Cement Slurry Test : “Preparation and Testing of Soil-Cement Slurry Test

Cylinders”Cylinders”

ASTM C-143ASTM C-143:: “Standard Test Methods for Slump of “Standard Test Methods for Slump of

Hydraulic-Cement Concrete”Hydraulic-Cement Concrete” This test method was used to provide the This test method was used to provide the

user with a procedure to determine slump user with a procedure to determine slump of plastic hydraulic-cement concretes.of plastic hydraulic-cement concretes.

The process uses freshly mixed concrete The process uses freshly mixed concrete and compacts it in a mold shaped liked and compacts it in a mold shaped liked cone and measures the displacement of cone and measures the displacement of the original and displaced center as the the original and displaced center as the slump in the concreteslump in the concrete

ASTM D 5084-00ASTM D 5084-00: “Standard Test : “Standard Test Methods for Measurement of Methods for Measurement of

Hydraulic Conductivity of Saturated Hydraulic Conductivity of Saturated Porous Materials Using a Flexible Porous Materials Using a Flexible

Wall PermeameterWall Permeameter”” This test methods covered laboratory This test methods covered laboratory

measurement of the hydraulic conductivity measurement of the hydraulic conductivity (also referred to as coefficient of (also referred to as coefficient of permeability) of water-saturated porous permeability) of water-saturated porous materials with flexible wall permeameter at materials with flexible wall permeameter at temperatures between 59 and 86 degrees temperatures between 59 and 86 degrees Fahrenheit.Fahrenheit.

This test methods may be utilized on all This test methods may be utilized on all specimen types (undisturbed, reconstituted, specimen types (undisturbed, reconstituted, remolded, compacted, ect.)remolded, compacted, ect.)

ASTM C-360ASTM C-360:: “Test method for Ball Penetration “Test method for Ball Penetration in Freshly Mixed Hydraulic Cement in Freshly Mixed Hydraulic Cement

Concrete”Concrete”

This test method utilized a 6” This test method utilized a 6” diameter, 30 pound Kelly Ball, diameter, 30 pound Kelly Ball, attached to a rod.attached to a rod.

A sample of slurry mix was prepared A sample of slurry mix was prepared and then struck with the Kelly ball. and then struck with the Kelly ball.

The depth of penetration was The depth of penetration was measured and then correlated to the measured and then correlated to the slump slump

ASTM C 150ASTM C 150:: “Standard Specification for “Standard Specification for

“Portland Cement”“Portland Cement”

The Portland Cement standard specifications The Portland Cement standard specifications cover:cover: Concrete additionsConcrete additions Chemical CompositionChemical Composition Physical PropertiesPhysical Properties SamplingSampling Test MethodsTest Methods Rejection CriteriaRejection Criteria Concrete StorageConcrete Storage

ASTM D 422ASTM D 422:: “Standard Test Method for Particle “Standard Test Method for Particle

Size Analysis of Soils”Size Analysis of Soils”

This test method covered the This test method covered the quantitative determination of particle quantitative determination of particle sizes in soils as follows:sizes in soils as follows: Particles larger than 75um (retained on Particles larger than 75um (retained on

the No. 200 seive) are determined by the No. 200 seive) are determined by sievingsieving

Particles smaller than 75um are Particles smaller than 75um are determined by a sedimentation process, determined by a sedimentation process, using a hydrometerusing a hydrometer

ASTM D 2487ASTM D 2487: : “Standard Classification of “Standard Classification of

Soils for Engineering Purposes”Soils for Engineering Purposes”

This standard used a system for This standard used a system for classifying mineral and organo-classifying mineral and organo-mineral soils for engineering mineral soils for engineering purposes based on laboratory purposes based on laboratory determination of particle-size determination of particle-size characteristics, liquid limit, and characteristics, liquid limit, and plasticity indexplasticity index

ASTM D 4318:ASTM D 4318: “Standard Test Method for Liquid “Standard Test Method for Liquid Limit, Plastic Limit, and Plasticity Limit, Plastic Limit, and Plasticity

Index Index of Soils”of Soils”

This test method covered the This test method covered the determination of a soils liquid limit, determination of a soils liquid limit, plastic limit, and plasticity index.plastic limit, and plasticity index.

The results of these tests distinguish The results of these tests distinguish the boundaries of a plastic soils state the boundaries of a plastic soils state of consistency.of consistency.

ASTM D 698: ASTM D 698: “Laboratory Compaction “Laboratory Compaction

Characteristics”Characteristics”

This test method covered laboratory This test method covered laboratory compaction methods used to compaction methods used to determine the relationship between determine the relationship between water content and dry unit weight of water content and dry unit weight of soilssoils

ASTM D 1556:ASTM D 1556: “Standard Test Method for Density “Standard Test Method for Density and Unit Weight of Soil in Place by and Unit Weight of Soil in Place by

the Sand-Cone Method”the Sand-Cone Method” This test was used to determine the This test was used to determine the

in-place density and unit weight of in-place density and unit weight of soils using a sand cone apparatussoils using a sand cone apparatus

The test is applicable for soils The test is applicable for soils without appreciable amounts of rock without appreciable amounts of rock or coarse materials in excess of 1 ½ or coarse materials in excess of 1 ½ in (38mm) diameter in (38mm) diameter

ASTM D 4832ASTM D 4832: : “Preparation and Testing of “Preparation and Testing of

Soil-Cement Slurry Test Soil-Cement Slurry Test Cylinders”Cylinders”

This test method covered procedures This test method covered procedures for the preparation, curing, for the preparation, curing, transporting and testing of controlled transporting and testing of controlled low strength material (CLMS)low strength material (CLMS)

Laboratory Work

Upon completion of the preliminary investigations Upon completion of the preliminary investigations and discussions with the experts in the field of and discussions with the experts in the field of slurry cutoff walls, the project was deemed slurry cutoff walls, the project was deemed feasible and initial mix design testing beganfeasible and initial mix design testing began

More than 500 pounds of shredded tires were More than 500 pounds of shredded tires were supplied to the CSU, Chico Research Foundation supplied to the CSU, Chico Research Foundation varying in size ranges from 2” x 2” up to 8” x 8”. varying in size ranges from 2” x 2” up to 8” x 8”.

Using these tire shreds, preliminary tests were Using these tire shreds, preliminary tests were conducted using soil from the surface of the conducted using soil from the surface of the proposed construction site and it became proposed construction site and it became apparent that 2” minus tire chips would provide apparent that 2” minus tire chips would provide the best workability and efficiencythe best workability and efficiency

Mix DesignMix Design

In the mix design, it was found that twenty four hours fully assured full In the mix design, it was found that twenty four hours fully assured full hydration of the bentonite and provided an effective slurry for testing hydration of the bentonite and provided an effective slurry for testing

Mixes were tested using a three cubic foot electric concrete mixer and Mixes were tested using a three cubic foot electric concrete mixer and each test mix was tested for slump and compressive strength each test mix was tested for slump and compressive strength

When a mix met both of these requirements it was sent to a Independent When a mix met both of these requirements it was sent to a Independent lab for permeability testing lab for permeability testing

The permeability testing had to be specially conducted at a second lab The permeability testing had to be specially conducted at a second lab due to the size of the tire chips.due to the size of the tire chips.

Special test cylinders were constructed that had twelve inch diameter Special test cylinders were constructed that had twelve inch diameter plastic pipe with a plywood bottom plastic pipe with a plywood bottom

The test procedure ASTM D-5084 was used to accommodate the USACOE The test procedure ASTM D-5084 was used to accommodate the USACOE requirements that hydraulic conductivity was not to exceed 5 x 10-7 requirements that hydraulic conductivity was not to exceed 5 x 10-7 cm/sec cm/sec

After approximately two months, a proposed mix design was achieved. After approximately two months, a proposed mix design was achieved. The achieved mix design, due to the viscosity of the mix, found that it The achieved mix design, due to the viscosity of the mix, found that it

appeared the separation of the tires from the slurry was unlikely thus appeared the separation of the tires from the slurry was unlikely thus alleviating most of the concern about the tires floating in the bentonite. alleviating most of the concern about the tires floating in the bentonite.

Mix Design and Parameters

proposed mix design:proposed mix design:

Slurry Mix Item Slurry Mix Item Percent by WeightPercent by Weight

Soil Soil 67%67%

Bentonite Clay Bentonite Clay 3%3%

CementCement 5%5%

Tire ChipsTire Chips 25%25%

Mix Design

Medium Scale TestingMedium Scale Testing

In spring of 1999, After a design mix was In spring of 1999, After a design mix was established, a second larger round of tests established, a second larger round of tests began at a independent testing labbegan at a independent testing lab

At this lab, two medium scale mixes were At this lab, two medium scale mixes were prepared, using soil obtained from the site in prepared, using soil obtained from the site in a ready-mix concrete trucka ready-mix concrete truck

Both of these mixes were tested for both Both of these mixes were tested for both permeability as well as compressive permeability as well as compressive strength strength

From the results of this test, it was deemed From the results of this test, it was deemed the mix was adequate to proceed with the mix was adequate to proceed with construction of large scale project.construction of large scale project.

Large Scale Field Test Excavation of the cutoff wall commenced on June 17, 1999. Excavation of the cutoff wall commenced on June 17, 1999. The equipment utilized included:The equipment utilized included:

2 Caterpillar excavators – One at each end of the trench. The 2 Caterpillar excavators – One at each end of the trench. The lead excavator was digging the trench and the second excavator lead excavator was digging the trench and the second excavator was mixing and placing the Soil-Cement-Bentonite-Tire mix for was mixing and placing the Soil-Cement-Bentonite-Tire mix for backfill.backfill.

1 Caterpillar Integrated Tool Carrier (ITC) – This piece of 1 Caterpillar Integrated Tool Carrier (ITC) – This piece of equipment served many purposes. With it interchangeable equipment served many purposes. With it interchangeable components, it can serve as a forklift to offload cement and components, it can serve as a forklift to offload cement and bentonite from the delivery trucks. The ITC can also attach a bentonite from the delivery trucks. The ITC can also attach a front end bucket to serve as a loader, and a boom which allowed front end bucket to serve as a loader, and a boom which allowed carrying heavy loads. The primary function of the ITC was to carrying heavy loads. The primary function of the ITC was to deliver cement to the mixing bin.deliver cement to the mixing bin.

1 Caterpillar 953 Track Loader – The track loader is similar to a 1 Caterpillar 953 Track Loader – The track loader is similar to a rubber tired front end loader only it is mounted on tracks for rubber tired front end loader only it is mounted on tracks for traction and flotation. The track loader was used to load soil and traction and flotation. The track loader was used to load soil and tire chips into the mixing bin. Once all materials were measured tire chips into the mixing bin. Once all materials were measured and placed into the mixing bin, the front end loader would and placed into the mixing bin, the front end loader would agitate the materials to mix them prior to placement.agitate the materials to mix them prior to placement.

1 – 6” contractors pump – the pump was used to supply water to 1 – 6” contractors pump – the pump was used to supply water to the bentonite hydration and mixing tanks. The water was the bentonite hydration and mixing tanks. The water was supplied from the canal which is fed from the Feather River.supplied from the canal which is fed from the Feather River.

Large Scale Field Test: Equipment

Large Scale Field Test: Equipment

Large Scale Field Test

The project consisted of a 30 foot The project consisted of a 30 foot deep, 1,400 lineal feet long, cutoff wall deep, 1,400 lineal feet long, cutoff wall on a DWR levee in Gridley, CA and on a DWR levee in Gridley, CA and utilized 475 tons of recycled tires. utilized 475 tons of recycled tires.

This location was selected because the This location was selected because the canal adjacent to the levee is drained canal adjacent to the levee is drained and filled annually thus providing a and filled annually thus providing a good opportunity for monitoring good opportunity for monitoring

DWR levee

QA/QCQA/QC

During construction, due to Quality During construction, due to Quality Assurance and Quality Control, slump Assurance and Quality Control, slump measurements were conducted on a measurements were conducted on a regular basis, as well as, permeability regular basis, as well as, permeability and Compressive strength testsand Compressive strength tests

The process of Quality Assurance and The process of Quality Assurance and Quality Control was conducted by the Quality Control was conducted by the USACOE specifications USACOE specifications

Monitoring of Results

After the project was constructed, nine-four After the project was constructed, nine-four inch diameter monitoring wells were installed inch diameter monitoring wells were installed

The monitoring wells provide an opportunity The monitoring wells provide an opportunity to measure the depth of the ground water to to measure the depth of the ground water to determine if water was migrating from the determine if water was migrating from the canal, through (or around) the cutoff wall. canal, through (or around) the cutoff wall.

Weekly groundwater measurements were Weekly groundwater measurements were taken over the course of two years which taken over the course of two years which determined that the water appeared to be determined that the water appeared to be migrating through the levee at both ends of migrating through the levee at both ends of the cutoff wall (not through the wall). the cutoff wall (not through the wall).

Groundwater MeasurementsGroundwater Measurements

6 HOURS AFTER FILLING CANAL

0

0.25

0.5

0.75

1

1.25

1.5

1.75

2

W-1 W-2 W-3 W-4 W-5 W-6 W-7 W-8 W-9

WELL

WA

TE

R E

LE

VA

TIO

N IN

CR

EA

SE

(F

T)

Groundwater MeasurementsGroundwater Measurements

12 HOURS AFTER FILLING CANAL

0

0.25

0.5

0.75

1

1.25

1.5

1.75

2

W-1 W-2 W-3 W-4 W-5 W-6 W-7 W-8 W-9

WELL NUMBER

WA

TE

R E

LE

VA

TIO

N IN

CR

EA

SE

(F

T)

Groundwater MeasurementsGroundwater Measurements

24 HOURS AFTER FILLING CANAL

0

0.25

0.5

0.75

1

1.25

1.5

1.75

2

W-1 W-2 W-3 W-4 W-5 W-6 W-7 W-8 W-9

WELL NUMBER

WA

TE

R E

LE

VA

TIO

N I

NC

RE

AS

E (

FT

)

Monitoring of Results

GROUNDWATER ELEVATION - WELL NO. 1

74

75

76

77

78

79

80

81

82

83

84

12/11/2003

12/25/2003

1/8/2004

1/22/2004

2/5/2004

2/19/2004

3/4/2004

3/18/2004

4/1/2004

4/15/2004

4/29/2004

5/13/2004

5/27/2004

6/10/2004

6/24/2004

7/8/2004

7/22/2004

8/5/2004

8/19/2004

9/2/2004

9/16/2004

9/30/2004

10/14/2004

10/28/2004

11/11/2004

11/25/2004

12/9/2004

12/23/2004

1/6/2005

1/20/2005

2/3/2005

2/17/2005

3/3/2005

3/17/2005

3/31/2005

4/14/2005

DATE

EL

EV

AT

ION

(F

T)

CANAL DRAINED CANAL FULL CANAL DRAINED

Secondary Monitoring Secondary Monitoring

To answer the question of how the water was To answer the question of how the water was migrating from the canal to the adjacent field, a migrating from the canal to the adjacent field, a water level data logger was installed in each water level data logger was installed in each well prior to the canal being filled in April, 2005 well prior to the canal being filled in April, 2005

The water level data logger took elevation The water level data logger took elevation readings every 15 minutes a 2 week periodreadings every 15 minutes a 2 week period

Following the 2 week period it was determined Following the 2 week period it was determined there was sufficient data to opine that the water there was sufficient data to opine that the water was migrating around or under the cutoff wall was migrating around or under the cutoff wall and the project was successful.and the project was successful.

Ending Results of using Tire-Derived Aggregate as a Component in Slurry

Cutoff Walls The project successfully showed that the cutoff The project successfully showed that the cutoff

wall construction process was not affected by the wall construction process was not affected by the incorporation of recycled tires incorporation of recycled tires

Furthermore, the following was discovered Furthermore, the following was discovered through the project:through the project: Using Tire-Derived aggregate increased the per square

foot cost of the project by $0.51 but also had the added result of recycling 475 tons of disposed tires

Future projects could implement this technology and possibly recycle up to 63,980 tons of tire material per year in similar projects

This would equate to approximately 6.4 million tires recycled each year.