Tensar. TriAx Geogrid & New Advancements in Onsite Validation of Designs (APLT) Andrew W. Isenhour, PE Mid-Atlantic Regional Manager NC/SC/VA

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1 Tensar TriAx Geogrid & New Advancements in Onsite Validation of Designs (APLT) Andrew W. Isenhour, PE Mid-Atlantic Regional Manager NC/SC/VA

2 Who We Are

3 Tensar Group Overview Tensar Corporation is the parent company of several wholly-owned, market-leading subsidiaries including: Tensar International Corporation Geopier Foundation Company North American Green Subgrade Stabilization Pavement Optimization Pavement Interlayers Rail Section Reinforcement Foundation Improvement Pavement Drainage Layer Geopier Foundations Grade Separation Sierra System SierraScape System Mesa System ARES System Triton Marine Mattresses Waste Containment & Capping Erosion Control Blankets Turf Reinforcement Mats Hydro Seeding Sediment Control Geotextile Tubes Scour Protection Mats

4 Roadways System Overviews Rehabilitation Re-Construction New Construction

5 Agenda How Geogrid Works What is geogrid? Why TriAx? Case History TX Geogrid Applications Research Review Questions & Answers

6 Geogrids Different Types Tensar TX/BX Geogrids (PP) Tensar UX Geogrids (HDPE)

7 Tensar s Manufacturing Process

8 Aperture Size & Interlock

9 Development Objective: Better Geogrid Demonstration of Aggregate Confinement

10 Tension Membrane Effect Membrane tension Vertical Membrane support

11 Tension Membrane Effect Stiffness helps protect existing subgrade strength

12 Improved Bearing Capacity Reinforced Shear Surface Unreinforced Shear Surface

13 Lateral Restraint Lateral Shear Flow Lateral Restraint Due to Friction Figure 1. Lateral restraint reinforcement mechanism. Source: USACOE ETL Confinement of the aggregate base during loading Results in increase in STIFFNESS of the base material Improved/reduced vertical stress distribution applied to pavement subgrade

14 Research & Testing Research to Quantify Benefits KEEP IN MIND NO TWO GEOGRIDS PERFORM THE SAME!!

15 Research & Testing

16 Aggregate Rutting Profiles SS Unreinforced 3,000 axle passes Tensar BX Geogrid 10,000 axle passes Tensar TX Geogrid 10,000 axle passes

17 A Better Mousetrap - SS Unreinforced 3,000 axle passes Tensar BX Geogrid 10,000 axle passes Tensar TX Geogrid 10,000 axle passes

18 Roadway Applications: Definitions Used to provide a competent temporary road surface or a stable foundation layer for a permanent road when weak subgrade conditions are encountered. Subgrade Stabilization Enhanced performance or thickness reduction of a permanent road when constructed on a relatively firm foundation. Pavement Optimization

19 Design Method So What? How to Design with Geogrid? Subgrade Stabilzation Giroud-Han Design Method

20 Quantifying Subgrade Strength

21 Mechanical Subgrade Stabilization Unstabilized Mechanically stabilized with geogrid

22 Example of Potential Savings with TriAx Unstabilized 21 inches BX Type 1 15 inches BX Type 2 10 inches TriAx TX160 6 inches Given Information: Rut Depth = 1.5 in. Axle Load = 18 kips Tire Pressure = 80 psi No. of Passes = 1200 Sub base CBR = 20 (min.) Subgrade CBR = 1.6 (min.)

23 Geogrid Applications

24 Pavement Optimization Life Cycle Cost Savings Reduced Initial Cost

25 Flexible Pavement Design Research USACE Phase I Phase II Phase III Designed based on ASHTO methodologies: AASHTO 1993 AASHTO MEPDG Validation ARA APLT

26 Mechanically Stabilized Layers (MSLs) USACE Full Scale Studies Full-Scale testing 2 phases: Phase 1: CBR=3% Phase 2: CBR=6.5% Phase 3: Reconstruct Phase 2 Control vs. MSL Further develop design database AASHTO 93 design

27 Full-Scale Accelerated Pavement Tests Geogrid Stabilization of Thin Asphalt Pavements

28 Full-Scale Accelerated Pavement Tests Geogrid Stabilization of Thin Asphalt Pavements Significant procedures in place to reduce variability in testing (subgrade, base, asphalt, climatic impacts, ). APT testing is much more accurate than most field testing. Click above to go to:

29 Full-Scale Accelerated Pavement Tests Geogrid Stabilization of Thin Asphalt Pavements Stabilized Report Item 1 Report Item 4 Control Sections Report Item 5

30 Full-Scale Accelerated Pavement Tests Geogrid Stabilization of Thin Asphalt Pavements Heavy Vehicle Simulator (HVS-A). Capable of applying loads between 10,000 and 100,000 lbs. Uniformly distributed traffic load with typical wander introduced.

31 Full-Scale Accelerated Pavement Tests Geogrid Stabilization of Thin Asphalt Pavements Research Organization US Army Corps of Engineers Engineer Research and Development Center Sections Tested 2 inches (51 mm) HMA over 8 inches (203 mm) base (control) 3 inches (76 mm) HMA over 8 inches (203 mm) base (control) 2 inches (51 mm) HMA over 8 inches (203 mm) base over TX140 Testing Conducted Thickness Validation & Material Characterization Instrumentation of sections Pavement Characterization (post construction) HVS-A Traffic testing, FWD analysis Post trafficking forensics (in-field CBR, rutting of layers, ) Key Findings Control sections rutted quicker than the TX140 stabilized section. Pavement life of the TX140 stabilized section delivered over 18 times the traffic of the control section.

32 Full-Scale Accelerated Pavement Tests Geogrid Stabilization of Thin Asphalt Pavements Falling Weight Deflectometer Tests performed pre-traffic, during trafficking and post trafficking Impulse Stiffness Modulus (ISM) values were calculated to determine if the base was stress weakening or hardening.

33 Full-Scale Accelerated Pavement Tests Geogrid Stabilization of Thin Asphalt Pavements FWD Stiffness Values (ISM) FWD Stiffness Values of the Section As Trafficking Accumulated ESALs TX140 Control (2in) Control (3in) This is evidence that the geogrid reinforcement not only provided enhanced stiffness to the aggregate base during construction, it also maintained the stiffness of the aggregate base throughout trafficking to the levels tested in this study. --Corps of Engineers pg. 37

34 Full-Scale Accelerated Pavement Tests Geogrid Stabilization of Thin Asphalt Pavements Rutting Measured at 5 locations along each test item Control Measurements taken at selected trafficking intervals Rutting occurred quicker in the unstabilized sections. TX Stabilized

35 Full-Scale Accelerated Pavement Tests Geogrid Stabilization of Thin Asphalt Pavements Applied ESALs Rutting increases much slower Rut Depth (in.) Item 1 (TX 140) Item 4 (Control) Item 5 (3 in. AC) Rutting increases rapidly

36 Full-Scale Accelerated Pavement Tests Geogrid Stabilization of Thin Asphalt Pavements Applied ESALs Rut Depth (in.) Item 1 (TX 140) Item 4 (Control) Item 5 (3 in. AC)

37 Full-Scale Accelerated Pavement Tests Geogrid Stabilization of Thin Asphalt Pavements Summary of Testing Tensar TX stabilized base can significantly improve the performance of a pavement by maintaining stiffness of a pavement section and reducing rutting at the surface. At rutting levels of inches, sections stabilized with Tensar TX provided over 18 times that of the control, and over 7 times that of adding an extra inch of asphalt. 5,400 passes 12,640 passes 100,000+ passes

38 Mechanically Stabilized Layers (MSLs) ARA Berg Review/Validation Third-party review/validation of AASHTO 93 pavement design using Tensar TriAx geogrids

39 AASHTO 93 Optimization

40 Design Tools

41 Design Validation - APLT Mr Values Are Tested and Verified With Automated Plate Load Testing (APLT) The APLT system developed by Professor D. J. White, Ph.D., P.E. (Iowa State)

42 Automated Plate Load Testing (APLT) Field Response Summary

43 Automated Plate Load Testing Summary Hunt Highway, Arizona Research Organization Ingios Geotechics, Inc. Section Tested 6-inches of base over TX5 Testing Conducted Mr of the mechanically stabilized base course Mr of the subgrade Mr composite modulus Modulus of subgrade reaction (k) ev1 and ev2 strain modulus testing Resilient deflections (scaling exponent) 155,694 psi Mr (Ave) subgrade 16,144 psi Mr (Ave) composite 34,251 psi Ev2 (top of stabilized base) ksi Ev2/Ev1 Ratio 1.60 K-value (stabilized) 392 pci Tensar TX5 APLT Field Validation Layer Coefficient Mr (Ave) base % life extension 0.12 Unstabilized Value $118,000 in savings SP4 MSL Design Value Verified MSL Value

44 Automated Plate Load Testing Summary Hunt Highway, Arizona Actual Tested Values of the Stabilized Pavement Savings >$118,000 for both sections. Actual APLT results showed a layer coefficient of 0.31 providing 113% greater anticipated design life.

45 Geogrid Applications Paved Fire Access Lanes

46 Geogrid Applications Support Beneath Utilities

47 Geogrid Applications Support Beneath Utilities

48 Wesleyan Drive Tensar TX5 Reduced Undercut as VEP Reduced 8 of granular fill (undercut) and placed TX5 directly under 21A/21B 58

49 Commander Sheppard Severe pumping and rutting in subgrade Test sections were installed due to pumping 59

50 Commander Sheppard Tensar TX Fill Fill reduced where subgrade improved 60

51 Princess Anne Tensar TX5 Reduced Pavement Section as VEP Reduced 1 of 21A/21B & 2 of asphalt 61

52 Coal Ash Applications - Ash Pond Capping

53 Questions? Andrew W. Isenhour, PE Mid-Atlantic South Regional Manager NC SC VA - DC cell Aisenhour@tensarcorp.com