I-69 Subgrade Stabilization

Athar Khan, M.S., P.E., Director

INDOT Geotechnical Services Division

September 17 - 19, 2019

Midwest Geotechnical Conference

•Background

•Project Description

•Pavement Cross Sections

• Typical Subgrade Treatment

• Instrumentation

•Construction (QC/QA)

•Conclusion

Outline

• Industry Involvement

• Development of a Demo project

• INDOT Current Practice

Background

03-01-20

Type Subgrade Description

I 24 in. of soil compacted in accordance with 203.23

IA [blank]

IB 14 in. chemical soil modification

IC 12 in. coarse aggregate No. 53 in accordance with 301

ID 12 in. coarse aggregate with Type 2B geotextile in accordance with 918.02(c)

II 6 in. coarse aggregate No. 53 in accordance with 301

IIA 8 in. chemical soil modification

III In-place compaction in accordance with 203.23

IV 12 in. coarse aggregate No. 53 with Type IB geogrid in accordance with 214

IVA 12 in. coarse aggregate with Geocell confining system in accordance with 214

V 3 in. of subgrade excavated and replaced with 3 in. coarse aggregate No. 53

Type ID subgrade treatment shall be constructed with 9 in. of coarse aggregateNo. 53 over 3 in. of coarse aggregate No. 5 or No. 8. Geotextile Type 2B in accordancewith 918.02(c) shall be placed above and below the layer of No. 5 or No. 8 coarseaggregate.

In areas where shallow utilities are encountered or chemical modification is notallowed, the Contractor may submit a request to the Engineer to substitute Type IC forType IB.

Subgrade Treatment Types

• Subgrade is constructed with cement-soil modification with increase strength of 100 psi over natural soils as per section 215

• Usually 4% to 5% cement is used

• 14 in of subgrade is constructed

• LWD and/or Dynamic Cone Testing is performed

• Resilient Modulus of 8,000 to 9,000 psi is recommended for the pavement

Typical Subgrade treatment

• I-69 in Madison County Indiana

• Contract No: R-39093

• Contract Type: Design-Build

• Begins: Mile Marker 219

• Ends: Mile Marker 226

• Total Length: 14 miles (7 miles each bound)

• Existing lanes: 2 lanes in each direction

• Proposed improvement: Adding a lane in each direction plus intersection at SR 9 including ramps & bridges

Project Description

General Site Plan

Typical Pavement Section

• Loam (A-4)

• Sandy Loam (A-4)

• Clay Loam (A-6)

• Silty Clay Loam (A-7-6)

Soils encountered in Subgrade

TRAFFIC AND DESIGN DATA I-69 From 0.9 miles north of SR38 to SR9/109

(Pertinent to Section 4

and 5)

I-69 From SR 9/109 to SR 67

(Pertinent to Section

4,5,&6)

I-69 From SR67 to 0.48 miles north of SR67

(Pertinent to Section

6)

Functional Classification Freeway Freeway Freeway

Net Length for Project 6.77 miles 7.20 miles 0.48 miles

AADT 2018 (V.P.D) 53,490 41,680 37,840

AADTT 2018 (V.P.D) 11,437 11,221 12,041

Growth Factor 0.98% 1.11% 1.27%

Percent Trucks 21.38% 26.92% 31.82%

Design Speed (miles/hour) 70 70 70

Resilient Modulus of Prepared Subgrade (psi) 7,000 psi 7,000 psi 7,000 psi

Resilient Modulus of

Natural Subgrade (psi)

5,000 psi 5,000 psi 5,000 psi

Subgrade Treatment Type New Pavement - Type IB;

Patching - Type IC

New Pavement - Type

IB; Patching - Type IC

New Pavement - Type

IB; Patching - Type IC

Existing Pavement Full depth PCCP on outside northbound lane; SMA

over PCCP on inside northbound and southbound

lanes

SMA over PCCP SMA over PCCP; PCCP

Under Bridges

Number of Proposed Lanes 6 @ 12’ 6 @ 12’ 4 @ 12’

Proposed Shoulder Widths 10’ Outside, 10’ Inside 10’ Outside, 10’ Inside 10’ Outside, 4’ Inside

Traffic & Design Data

Proposed Subgrade

Cement Stabilized Subgrade shall be constructed as follows:

Subgrade Thickness Unconfined Strength over the natural soil

12 in 150 psi

12 in 400 psi

12 in 600 psi

Pavement Control Section

220 lbs/syd QC/QA‐HMA, 4, 76, Surface, 12.5 mm – SMA on 330 lbs/syd QC/QA‐HMA, 4, 76, Intermediate, 19.0 mm on495 lbs/syd QC/QA‐HMA, 4, 64, Base, 25.0 mm on495 lbs/syd QC/QA‐HMA, 4, 64, Base, 25.0 mm onDrainage Layer consisting of:

6” Aggregate Drainage Layer on Separation Layer consisting of: Geotextile for Pavement Type 1B on Subgrade Treatment Type IB

(cement only)

Various Pavement Test Sections

Pavement Section

• CEMENT STABILIZED SUBGRADE

• Description

• This work shall consist of the stabilizing soils to a depth of 12 in. by uniformly mixing Portland cement to achieve the desiredunconfined compressive strengths of 150 psi, 400 psi and 600 psi at seven days curing as shown on the plans to stabilize the subgrade. The subgrade shall be constructed in accordance with 105.03.

• Materials

• Materials shall be in accordance with 215.02 and the following:

• Portland cement, Type I....................901.01(b)

• Water 913.01

• Soils containing greater than 6% of organic material, or having a maximum dry density of less than 95 pcf or with a soluble sulfate content greater than 1,000 ppm shall not be used in the subgrade. The density shall be determined in accordance with AASHTO T 99, the organic content shall be determined in accordance with AASHTO T 267, and the sulfate content shall be determined in accordance with ITM 510.

• Construction Requirements Testing and Mix Design

• The Contractor shall be responsible for all tests required to determine the optimum cement content for producing stabilized subgrade with a minimum unconfined compressive strength of 150 psi, 400 psi, and 600 psi at seven days. One soil type encountered may notachieve this target for the 600 psi section. Cement content shall be targeted at 4%, 8% and 12% to achieve 150 psi, 400 psi and 600 psi design strengths respectively. The cement content may be adjusted if QC/QA testing results indicate issues with soils that wouldwarrant such changes but shall not exceed 12%. Laboratory testing, and mix design shall be performed by an approved geotechnicalconsultant in accordance with the Department’s Design Procedures for Soil Modification or Stabilization.

• Portland cement shall be from the Department’s list of approved sources. The test results and the geotechnical consultant recommendations shall be submitted to the Engineer and to the Office of Geotechnical Services for approval at least five business days prior to use. Soils cement stabilization shall produce subgrade sections with a minimum unconfined compressive strength of 150 psi, 400 psi, and 600 psi as specified for each section at seven days curing. The unconfined compressive strength test shall be performed in accordance with ASTM 39/39M-18. The Contractor’s quality control plan shall address all of the testing requirements for each individual section as specified. The documents shall be submitted to the Engineer along with the mix design.

• The one point proctor shall be performed on soils stockpiled from the 12 in excavation soils in accordance with ITM 512 and the quantity of cement may be adjusted for different soil types to produce tests sections with the minimum subgrade strength as specified. However, the source or type of cement shall not be changed during the progress of the work without approval. A change in source or type shall require a new mix design.

Storage and Handling

• The cement shall be stored and handled in accordance with the manufacturer’s recommendations.

• Weather Limitations

• The soil cement stabilization shall be performed when the soil has a minimum temperature of 45°F measured 4 in. below the surface, and with the air temperature rising. Cement shall not be mixed with frozen soils or with soil containing frost. The cement stabilized soil shall be limited to the area that can be covered by the pavement during the same construction season.

• Preparation of Soils

• The soils shall be prepared in accordance with 207.03. Aggregates larger than 3 in. shall be removed from subgrade whether encountered before or after mixing the soils and cement.

• 12 in. of the planned depth of original subgrade soil shall be removed and stored for reuse. After removal, the soil below the subgrade shall receive 14 in place chemical modification as a foundation improvement using a minimum of 3% cement or as directed.

• The Department will perform DCP acceptance testing of the treated layer in accordance with 215. Once accepted the original subgrade material shall be spread in its original location and treated to the unconfined compressive strength designed for the section as specified in the Final Pavement Design Report.

• In areas where high sulfate soils have been identified, the additional treatment shall include removal of 12 in. of soil below the subgrade elevation and replacement with compacted aggregate base, No. 53. The compacted aggregate base shall be placed and compacted in accordance with 207.

• Areas of high sulfate soil are known to be present at the following locations:

• Sta. 281+00 to Sta. 300+00 Line ‘C1’ RT

• Sta. 281+00 to Sta. 300+00 Line ‘C1’ LT

• Spreading of Cement

• The surface shall be scarified to the specified depth prior to distribution of the cement. One pulverization pass shall be performed prior to cement spreading. The cement shall be distributed uniformly by a cyclone, screw-type, or pressure manifold type distributor. Cement shall not be applied when conditions create problems in adjacent areas or create a hazard to traffic on any adjacent roadway. The spreading of the cement shall be limited to an amount which can be incorporated into the soil within two hours. If weather causes stoppage of work or exposes the cement to washing or blowing, additional cement may be spread when the work resumes.

Special Provisions

• Mixing

• The soil cement, and water when necessary, shall be thoroughly mixed by rotary speed mixers. The mixing shall continue until a homogenous layer of the required thickness has been obtained. One hundred percent of the material, exclusive of rock particles, shall pass a 1 in. sieve and at least 60% shall pass a No. 4 sieve. The mixing depth shall be 12 in. The standard Proctor for cement soils mixture shall be performed in accordance with AASHTO T 99. The Moisture content will be determined during soils cement mixing inaccordance with ITM 506. The moisture content of each mixture

• For 150 psi, a minimum of 2% above the optimum moisture content. For 400 psi, a minimum of 3% above the optimum moisture content. For 600 psi, a minimum of 4% above the optimum moisture content.

• Compaction

• Compaction of the mixture shall begin as soon as practical after mixing. Compaction efforts shall be in accordance with 203 or 207.03 as applicable. Compaction and testing shall be as follows:

• (a) For Portland cement stabilized soils, mixing shall be completed within 1 h of Portland cement placement and grading and final compaction shall be completed within 3 h after mixing.

• (b) Initial compaction equipment shall consist of vibratory padfoot roller with sufficient weight to achieve consistent strength.

• Acceptance Testing

• (a) Acceptance testing for compaction of cement stabilized soils will be performed on the finished grade with a LWD in accordance with 203.24(b). LWD tests will be 500 ft apart and each test consists of the average of three tests, performed at 2 ft from each edge of construction area and 1/2 of the width of the construction area. Test sections for 400 psi and 600 psi stabilized subgrade will be developed so that maximum allowable deflection can be used in accordance ITM 514. The acceptance test for the cement stabilized soils will begin seven days after compaction. Construction traffic or equipment shall not be allowed on the treated soils until the area has passed an LWD test with the exception of equipment with a maximum weight of 5 tons.

• (b) Moisture tests based on ITM 506 for soil cement mixtures will be performed at every 1000 ft during cement and soils mixing.

• (c) One gradation test will be performed at every 1000 lft of cement modified soil. Gradation tests will be performed in accordance with ITM 516.

• (d) Two unconfined compressive strength tests per AASHTO T 208 shall be performed from cores sampled by the Contractor at randomly selected locations from every 500 ft of full width lane and shall be obtained by the Contractor. The tests shall be performed by an approved geotechnical consultant. The test samples shall be cored by air, or dry coring method. Cores shall be a minimum diameter of 3 in. The unconfined compressive test verification shall be for the complete stabilized depth. Test results will be provided to the Engineer.

• (e) The two test specimens shall be prepared at 95% of the Standard Proctor and cured for seven days. Specimens shall be taken every 500 ft of length by lane width and shall be obtained by the Contractor. Unconfined compressive strength tests shall be performed in accordance with AASHTO T 208. Cement stabilized soils mixture shall be taken after pulverization. Test results will be provided to the Engineer.

• (f) The Contractor shall contact the Department Research Division for notification to schedule FWD testing one week before the top layers are placed to determine the subgrade resilient modulus.

• Department Research Division contact information:

• Indiana Department of Transportation

• Division of Research and Development

• P.O. Box 2279

• 1205 Montgomery Street

• West Lafayette, IN 47906

• Phone: (765) 463-1521

• (g) Cement spread rate shall be checked at every 1500 lft. Spread rate shall be in accordance with ITM 516.

• (h) The soil cement mixing depth shall be checked in accordance with ITM516 after mixing and prior to compaction.

• Sawcutting

• Stabilized subgrade areas at 600 psi shall be sawcut transversely as soon as the area has passed an LWD test but no later than the end of the seventh day of curing with a maximum spacing of 150 ft to control shrinkage cracking. The depth shall be 1/3 of the stabilized depth and width shall be 1/4 in. minimum. The Contractor shall accurately keep track of sawcut locations by station and submit this information to the Engineer.

• Curing

• Moisture content shall be maintained above the optimum for the first seven days after mixing with cement. Curing compound shall be applied to the surface and reapplied as applicable for the first seven days to aid in curing and prevent loss of moisture. Curing compound shall be in accordance with 504.04.

• Trimming

• Stabilized subgrade shall be prepped and adequate drainage shall be provided in accordance 207.03

• Proofrolling

• The entire stabilized subgrade shall be proofrolled in accordance with 203.26 and deflection or ruts greater 1/4 in. shall be corrected as directed.

Special Provisions

• Method of Measurement

• The Cement Stabilized Subgrade as specified in the Final Pavement Design will not be measured for payment. Cement used for soilsdrying with chemical modifiers will be measured in accordance with 217.10. Compacted Aggregate No. 53 used for additional foundation improvement will be measured in accordance with 301.09. Excavation required to remove, store and replace subgrade will not be measured for payment. Excavation required for placement of Aggregate No. 53 will not be measured for payment.

• Basis of Payment

• The work and materials necessary to construct the cement Stabilized Subgrade will be paid for under the lump sum item for Design/Build. Soils drying with chemical modifiers will be paid for in accordance with 104.03. Compacted Aggregate No. 53 used for foundation improvement will be paid for in accordance with 104.03.

• Payment will be made under:

• Pay Item Symbol Pay unit

• Design Build…………………………………………………………………………………………………………………………………………………LS

• The cost of performing mix designs by an approved geotechnical consultant, scarification of the subgrade, spreading and mixing of the cement and soil, compaction of the resultant mixture, shaping the subgrade, work required due to adjustments of proportioning, additional stabilization required due to weather conditions, correction of deficient areas, water required for the stabilization process, subgrade trimming, and all operations needed to meet the requirements of this specification shall be included in the cost of the pay items of this section.

• All work associated with soils drying with chemical or additional compacted aggregate for foundation improvement shall be included in the cost of items included in this section, including but not limited to excavation, storage of existing soils, pulverization, treatment, and replacement of existing subgrade.

Special Provisions

Instrumentation

• Testing and Mix Design

• Contractor shall submit Soil Management plan to the Engineer

• The mix design shall be performed by an approved geotechnical consultant in accordance with the Department’s Design Procedures for Soil Modification or Stabilization.

• The Contractor shall be responsible for producing stabilized subgrade with a minimum unconfined compressive strength of 150 psi, 400 psi, and 600 psi at seven days.

• Minimum strength shall be targeted not to exceed 20% over the minimum

Construction (QC/QA)

• Cement content shall be targeted at 4%, 8% and 12% to achieve 150 psi, 400 psi and 600 psi design strengths respectively.

• The cement content may be adjusted if QC/QA testing results indicate issues with soils that would warrant such changes but shall not exceed 12%.

• For 150 psi, a minimum of 2% above OMC

• For 400 psi, a minimum of 3% above OMC

• For 600 psi, a minimum of 4% above OMC

• Expect to perform 14” foundation improvement under 12” cement stabilized subgrade where needed (approximately on 30% area)

• Proofrolling of prepared subgrade shall be in accordance with sec. 203.26 before placing pavement

Construction (QC/QA)

Plan for Subgrade Testing Requirements 2019

•Compaction:

Compaction of the mixture shall begin as soon as practical after mixing.Compaction efforts shall be in accordance with 203 or 207.03 asapplicable. Compaction and testing shall be as follows:

• Soil – Cement mixing within 1 hour

• Compaction within 3 hours after mixing

Construction (QC/QA)

Quality Control (QC) Testing:

• Cement spread rate shall be checked at 1500 feet as per ITM-516

• Soil – Cement mixing depth shall be checked as per ITM-516 after mixing and prior to compaction

• One gradation test shall be performed at every 1000 feet as per ITM-516

• LWD test shall be performed as per 203.24(b)

• Moisture tests for soil cement mixtures shall be performed at every 1000 feet as per ITM-506

Construction (QC/QA)

• A minimum of one 4” core (full depth) shall be obtained by the contractor for qu testing at randomly selected location for every 2,000 feet as per AASHTO T-208 .

• Prepare 2 test specimens at 95% of Standard Proctor for every 2,000 feet and cure for 7 days for qu Test as per AASHTO T-208

• Construction traffic or equipment (>5 tons) shall not be allowed on the treated soils until the area has passed an LWD test

• All the above test results shall be provided to the Engineer.

Construction (QC/QA)

• Problems encountered during construction:

• Could not obtain 4” cores

• Could not verify qu strength in the field

• Could not pass proofrolling

• Could not pass LWD deflection criteria

Construction (QC/QA)

• Options explored:

• Consultations with experts such as Prof. Marshal Thomson (Illinois), Soheil Nazarian (Texas), Bill Vavrik (Illinois) etc.

• Validation by Clegg Hammer

• Validation by Seismic Modulus

• Try 8” core for qu testing

Construction (QC/QA)

Unconfined Strength and Resilient Modules of Soil-Cement - 2019

Batch Study Number Intended Testing Target Relative Density Unconfined Comp. Test (qu) Resilient Modules Test (Mr.)

1

UCS 95% 126.1

1 Mr 95% 13182

2

UCS 95% 173.1

Mr 95% 13673

3

UCS 95% 227.5

Mr 95% 12608

2

4

UCS 90% 122.5

Mr 90% 11739

5

UCS 100% 346.3

Mr 100% 15661

6

UCS 95% 243.6

Mr 95% 14607

7

UCS 95% 305.7

3 Mr 95% NA

8

UCS 95% 277

Mr 95% 14466

9

UCS 95% 230.3

Mr 95% 16648

10

UCS 90% 226.9

Mr 90% 13743

4

11

UCS 100% 267.7

Mr 100% 17537

12

UCS 95% 141.6

Mr 95% 14541

13

UCS 95% 117.3

5 Mr 95% 13656

14

UCS 95%

Mr 95% 18820

15

UCS 90% 375

Mr 90% 16130

6

16

UCS 95% 425

Mr 95% 15221

17

UCS 100% 600

Mr 100% 16796

18

UCS 95% 390

7 Mr 95% 12654

19

UCS 95% 475

Mr 95% 15435

SB 150 psi NB 400 psi NB 600 psi

Station Value Station Value Station Value

415+00 44.2 380+00 37 415+00 66.8

412+50 40.1 382+50 44.4 417+50 35.5

410+00 54.1 385+00 45.4 420+00 33.9

407+50 25.5 387+50 46.7 422+50 47.9

405+00 20.2 390+00 26.6 425+00 43.3

402+50 23.1 392+50 44.7 427+50 46.6

400+00 24.7 395+00 49.1 430+00 51.2

397+50 28.4 397+50 40.2 432+50 43.8

395+00 26.7 400+00 31 435+00 57

392+50 35.5 402+50 52.1 437+50 48.3

390+00 33.2 405+00 33.2 440+00 32.9

387+50 17.3 407+50 49.5 442+00 44.5

385+00 26.4 410+00 42.8 445+00 31.3

382+50 35.5 412+50 47.4 447+50 75.5

380+00 39 415+00 44.2 450+00 70.2

Clegg Hammer

I-69 Clegg Hammer Evaluation CriteriaSubgrade Strength Cleegg Hammer Number

150 psi 33.8

400 psi 58.6

600 psi 73.4

Seismic Modulus Testing

Seismic Modulus Data

Various Compaction Devices Testing DevicesMicrowave Oven Dynamic Cone Penetrometer Light Weight Deflectometer Clegg Hammer

Moisture Probe

Changes made:

• A minimum of one 8” core (full depth) by contractor for qu testing (as per ASTM C39/C39M – 18) at randomly selected location for every 2,000 feet.

• Provide 14” foundation improvement with cement throughout the project

• Prepare 2 test specimens at 95% of Standard Proctor for every 2,000 feet and cure for 7 days. qu Test as per AASHTO T-208

• Construction traffic or equipment (>5 tons) shall not be allowed on the treated soils until the area has passed an LWD test

• All the above test results shall be provided to the Engineer.

Construction (QC/QA)

Strength Test on 8” Core

• Clegg Hammer testing will be performed along with the LWD testing. This testing will be for information purposes.

• One gradation test will be performed at every 1000 feet as per ITM-516

• Moisture tests for soil cement mixtures will be performed at every 1000 feet as per ITM-506 to validate soil-cement mixture moisture at or above optimum

• The Engineer will contact the Division of Research to schedule FWD testing one week before the top layers are placed to determine the subgrade resilient modulus.

Construction (QC/QA)

• Quality Assurance (QA) Testing:

• Maximum allowable deflection for 150 psi, 400 psi and 600 psi subgrade will be provided by the Division of Research. The acceptance tests will begin seven days after compaction.

• Acceptance testing on the finished grade with LWD as per 203.24(b) . The tests will be 500 ft apart and each test consists of the average of three tests.

• 12” diameter LWD plate will be used for 150 and 400 psi sections whereas 6” plate in 600 psi section

Construction (QC/QA)

Target UCSLWD Loading Plate

Diameter (mm)

LWD Drop Weight

Mass (kg)

Maximum Average

Deflection (mm)

Maximum Individual

Deflection (mm)

150 psi 300 10 0.23 0.26

400 psi 300 10 0.19 0.22

600 psi 150 10 0.15 0.18

LWD Acceptance Criteria

TEST STRIP # 10

Contract R 39093 Road No,

Date 43411

Subgrade Treatment Type 1B - 150 PSI

Station Test Deflection (Sm) (mm) (1) (2) (3) Average

380+00 0.2 0.209 0.229 0.212666667

382+50 0.386 0.389 0.381 0.385333333

385+00 0.264 0.262 0.244 0.256666667

387+50 0.373 0.354 0.355 0.360666667

390+00 0.557 0.555 0.551 0.554333333

392+50 0.318 0.305 0.325 0.316

395+00 0.354 0.335 0.34 0.343

397+50 0.381 0.389 0.398 0.389333333

400+00 0.358 0.286 0.352 0.332

402+50 0.504 0.488 0.496 0.496

405+00 0.325 0.347 0.357 0.343

407+50 0.319 0.321 0.316 0.318666667

410+00 0.204 0.19 0.203 0.199

412+50 0.153 0.145 0.164 0.154

415+00 0.31 0.293 0.284 0.295666667

LWD Acceptance Test Data

TEST STRIP # 5 TEST STRIP # 6

Contract R 39093 Road No, Contract R 39093 Road No,

Date 43411 Date 43411

Subgrade Treatment Type 1B - 400 PSI Subgrade Treatment Type 1B - 600 PSI

Station

Test Deflection (Sm)

(mm) (1) (2) (3) Average Station

Test Deflection

(Sm) (mm) (1) (2) (3) Average

380+00 0.128 0.13 0.123 0.127 417+50 0.359 0.355 0.344 0.352666667

382+50 0.239 0.23 0.229 0.232666667 420+00 0.264 0.261 0.271 0.265333333

385+00 0.174 0.167 0.176 0.172333333 422+50 0.237 0.23 0.226 0.231

387+50 0.258 0.263 0.27 0.263666667 425+00 0.439 0.42 0.414 0.424333333

390+00 0.238 0.235 0.262 0.245 427+50 0.176 0.157 0.167 0.166666667

392+50 0.21 0.213 0.215 0.212666667 430+00 0.142 0.144 0.144 0.143333333

395+00 0.25 0.228 0.229 0.235666667 432+50 0.158 0.17 0.163 0.163666667

397+50 0.271 0.277 0.284 0.277333333 435+00 0.248 0.236 0.243 0.242333333

400+00 0.114 0.114 0.116 0.114666667 437+50 0.111 0.111 0.112 0.111333333

402+50 0.199 0.191 0.193 0.194333333 440+00 0.12 0.099 0.106 0.108333333

405+00 0.192 0.184 0.183 0.186333333 442+50 0.095 0.102 0.101 0.099333333

407+50 0.169 0.165 0.169 0.167666667 445+00 0.227 0.223 0.22 0.223333333

410+00 0.167 0.155 0.151 0.157666667 447+50 0.11 0.113 0.112 0.111666667

412+50 0.173 0.17 0.174 0.172333333 449+0 0

415+00 0.206 0.211 0.207 0.208 450+00 0.085 0.091 0.083 0.086333333

LWD Acceptance Test Data

• Strength validation of lab data is not possible during construction for A-6 or A-7 soils

• Resilient Modulus value of high strength subgrade is not as high as anticipated for fine grained soils

• Foundation treatment is very important to achieve stable subgrade

• Positive drainage is the key to complete construction of subgrade

• LWD is easy and most effective tool for compaction control

• After making changes, the entire subgrade construction was completed in two months without any problem

• Once the monitoring data are available, we will know more about the performance of high strength subgrade. We plan to monitor pavement performance for next two years

•

Conclusion

Construction Photos

Before Cement Stabilized Subgrade

Post construction Instrumentation

Post Construction Pictures

Post Construction Pictures

Post Construction Pictures

• Owner: INDOT

• INDOT Pavement Design Devision

• INDOT Geotechnical Division

• INDOT Division of Research

• INDOT Construction

• Designer: Michael Baker International

• Geotechnical Consultant: Earth Exploration

• Contractor: Reith Reilly & Walsh Construction

• Asphalt Pavement Association of Indiana (APAI)

Contract Team

47

Questions?