I-69 Subgrade Stabilization Athar Khan, M.S., P.E., Director INDOT Geotechnical Services Division September 17 - 19, 2019 Midwest Geotechnical Conference
Outline • Background • Project Description • Pavement Cross Sections • Typical Subgrade Treatment • Instrumentation • Construction (QC/QA) • Conclusion
Background • Industry Involvement • Development of a Demo project • INDOT Current Practice
Subgrade Treatment Types 03-01-20 Type Subgrade Des escription I 24 in. of soil compacted in accordance with 203.23 IA [blank] IB 14 in. chemical soil modification Type ID subgrade treatment shall be constructed with 9 in. of coarse aggregate IC 12 in. coarse aggregate No. 53 in accordance with 301 No. 53 over 3 in. of coarse aggregate No. 5 or No. 8. Geotextile Type 2B in accordance with 918.02(c) shall be placed above and below the layer of No. 5 or No. 8 coarse aggregate. ID 12 in. coarse aggregate with Type 2B geotextile in accordance with 918.02(c) In areas where shallow utilities are encountered or chemical modification is not allowed, the Contractor may submit a request to the Engineer to substitute Type IC for II 6 in. coarse aggregate No. 53 in accordance with 301 Type IB. 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 geo eogrid in accordance e with 214 IVA 12 in. coarse aggregate with Geo eocell confining system in accordance e with 214 V 3 in. of subgrade ex excavated ed and replaced with 3 in. coarse aggregate No. 53
Typical Subgrade treatment • 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
Project Description • 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
General Site Plan
Typical Pavement Section
Soils encountered in Subgrade • Loam (A-4) • Sandy Loam (A-4) • Clay Loam (A-6) • Silty Clay Loam (A-7-6)
Traffic & Design Data TRAFFIC AND DESIGN DATA I-69 From 0.9 miles north of SR38 to SR9/109 I-69 From SR 9/109 to SR 67 I-69 From SR67 to 0.48 miles north of SR67 (Pertinent to Section 4 (Pertinent to Section (Pertinent to Section and 5) 4,5,&6) 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 5,000 psi 5,000 psi 5,000 psi Natural Subgrade (psi) Subgrade Treatment Type New Pavement - Type IB; New Pavement - Type New Pavement - Type Patching - Type IC IB; Patching - Type IC IB; Patching - Type IC Existing Pavement Full depth PCCP on outside northbound lane; SMA SMA over PCCP SMA over PCCP; PCCP over PCCP on inside northbound and southbound Under Bridges lanes 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
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 on 495 lbs/syd QC/QA‐HMA, 4, 64, Base, 25.0 mm on 495 lbs/syd QC/QA‐HMA, 4, 64, Base, 25.0 mm on Drainage 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
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