DESIGN AND CONSTRUCTION GUIDELINES FOR THERMALLY INSULATED CONCRETE PAVEMENTS TPF-5(149) MnDOT Contract No. 89261 Task 5 Prepared by: Priyam Saxena Lev Khazanovich June 2011 2 TABLE OF CONTENTS TABLE OF CONTENTS............................................................................................................... 2 LIST OF FIGURES ....................................................................................................................... 4 LIST OF TABLES ......................................................................................................................... 6 PART 1: INTRODUCTION ....................................................................................................... 7 PART 2: BACKGROUND ........................................................................................................... 9 Components of Stress under Temperature Curling ............................................................... 9 MEPDG Rapid Solutions for Predicting Critical PCC Bottom Surface Stresses........... 11 Slab Equivalency Concept ........................................................................................................................ 11 MEPDG Neural Networks for Computing PCC Stresses ............................................................... 15 Adoption of the Fatigue Cracking Model for Composite Pavements in MEPDG ........ 19 Asphalt Characterization .............................................................................................................. 20 Viscoelastic Behavior of Asphalt Concrete ....................................................................................... 20 Characterization of Asphalt in the MEPDG ....................................................................................... 21 Limitations of the Structural Modeling of Composite Pavements in the MEPDG ..... 23 Use of a Single Dynamic Modulus of Asphalt ................................................................................... 23 Assumption that the AC Modulus Changes on a Monthly Basis ............................................... 23 PART 3: Finite element Analysis of Composite pavement InCORPORATING A Viscoelastic LAYER ................................................................................................................ 25 Viscoelastic Material Representation of Asphalt Concrete .............................................. 25 Development of Finite Element Model for the Analysis of Viscoelastic Slab-on- Grade .................................................................................................................................................... 30 Formulation of the Finite Element Model ......................................................................................... 31 Thermal Loading ......................................................................................................................................... 35 Viscoelastic Analysis .................................................................................................................................. 35 FE Formulation of the Winkler Foundation ..................................................................................... 38 Extension of the FE Model to Multi-Layered Composite Pavements ............................. 41 Equivalent Single Layer Slab .................................................................................................................. 42 Equivalent Linear Temperature Gradient in the Equivalent Single Layer Slab ................ 43 Equivalent Linear Creep Strain Gradient in the Equivalent Single Layer Slab .................. 43 Additional Stresses in the Composite Pavements Due to Non-linear-strain-causing Temperature and Non-linear-strain-causing Creep Strains Components ........................... 44 Step-by-Step Procedure for Computing the Stresses in the Composite Pavement .. 46 Validation of the Finite Element Model ................................................................................... 47 Viscoelastic Plate on Viscoelastic Winkler Foundation ............................................................... 48 Viscoelastic Plate with Simply Supported Corners ....................................................................... 52 Verification of the Formation for Multi-Layered Slabs ................................................................ 54 Sensitivity of the Viscoelastic FE Model to Internal Parameters ............................................. 59 Summary ............................................................................................................................................. 66 PART 4: Stress Solutions Using the 2-Moduli Approach ......................................... 68 AC Moduli under Traffic Loads and Temperature Gradients .......................................... 68 The 2-Moduli Approach ................................................................................................................. 70 Stress Computation Procedure using the 2-Moduli Approach ........................................ 70 The First Elastic Problem ......................................................................................................................... 71 The Second Elastic Problem ................................................................................................................... 72 3 The Third Elastic Problem ....................................................................................................................... 73 Combined Stress .......................................................................................................................................... 74 Brief Formulation for the FE Model Based on the 2-Moduli Approach ........................ 75 Step-by-Step Procedure for Computing the Combined Stresses ..................................... 76 Verification of the Combined Stress Obtained Using the 2-Moduli Approach ........... 79 Comparison with the Viscoelastic FE Model – Example 1 .......................................................... 79 Comparison with the Viscoelastic FE Model – Example 2 .......................................................... 81 Comparison with Simple Addition of the Stresses ........................................................................ 82 Comparison of the Stress Solution using the 2-Moduli Approach with the Stress Solution using the MEPDG Process ............................................................................................ 84 Summary ............................................................................................................................................. 86 Part 5: Development of a Framework for Implementation of the 2-Moduli Approach into MEPDG .......................................................................................................... 88 Simplification of the Structural System ................................................................................... 88 Equivalency Techniques for Multi-Layered Pavements .................................................... 93 Summary ............................................................................................................................................. 97 PART 6: Conclusions ............................................................................................................ 98 Research Findings ........................................................................................................................... 98 Recommendations for the Future Research .......................................................................... 98 References .............................................................................................................................. 100 APPENDIX A ........................................................................................................................... 106 Unbonded AC-PCC and Unbonded PCC-Base Interfaces ................................................... 107 Bonded AC-PCC and Bonded PCC-Base Interfaces ............................................................. 111 Unbonded AC-PCC and Bonded PCC-Base Interfaces ........................................................ 115 Bonded AC-PCC and Unbonded PCC-Base Interfaces ........................................................ 118 4 LIST OF FIGURES Figure 1 Structure of (a) rigid pavement, (b) flexible pavement, and (c) composite pavement (adopted from AASHTO 2008). .................................................................. 8 Figure 2 Schematics for (a) original multi-layered system, (b) single slab system A, and (c) two-slab system B................................................................................................ 16 Figure 3 Structural model for (a) NNA1 (corresponding to single axle load) and (b) NNA2 (corresponding to tandem axle load). ............................................................ 17 Figure 4 Structural model for (a) NNB1 (corresponding to single axle single wheel load) and (b) NNB2 (corresponding to single wheel load). ............................................... 18 Figure 5 Conversion of a composite pavement to an equivalent PCC structure. ............. 19 Figure 6 (a) Effective length and (b) effective depth for single axle in a conventional flexible pavement. ..................................................................................................... 22 Figure 7 Stress-strain responses under different