• ♦Manual Notice 2021-2
• ►1. Introduction
  • ►1. Manual Overview
    • ♦1.1 Purpose
    • ♦1.2 Comprehensive Development Agreements
    • ♦1.3 Organization
  • ►2. Overview of Policy
    • ♦2.1 Summary
    • ♦Standard Operating Procedures for Responding to PIA Requests for PMIS and/or Skid Data
  • ►3. Training
    • ♦3.1 Overview
  • ►4. Contacts
    • ♦4.1 Contacts for Questions and Comments
• ►2. Pavement Design Process
  • ►1. Overview
    • ♦1.1 Introduction
    • ♦1.2 Preliminary Pavement Design
    • ♦1.3 Pavement Design Concept Conference
    • ♦1.4 Pavement Design Standard Operating Procedure
  • ►2. Pavement Design Standard Operating Procedure (SOP)
    • ♦2.1 Communication
    • ♦2.2 Conference Participants
    • ♦2.3 Discussion Items
    • ♦2.4 Final Authority for Pavement Design
  • ►3. District Pavement Engineer’s Role
    • ♦3.1 History
    • ♦3.2 Responsibilities
    • ♦3.3 District Pavement Engineer (DPE) Skills
  • ►4. Pavement Types
    • ♦4.1 Rigid and Flexible Pavement Characteristics
    • ♦4.2 Flexible Pavement
    • ♦4.3 Perpetual Pavement
    • ♦4.4 Rigid Pavement
    • ♦4.5 Continuously Reinforced Concrete Pavement
    • ♦4.6 Concrete Pavement Contraction Design (CPCD)
    • ♦4.7 Jointed Reinforced Concrete Pavement (JRCP)
    • ♦4.8 Post-tensioned Concrete Pavements
    • ♦4.9 Composite Pavement
  • ►5. Pavement Type Selection
    • ♦5.1 Introduction
    • ♦5.2 Principal Factors
    • ♦5.3 Secondary Factors
    • ♦5.4 Life-cycle Cost Analysis (LCCA)
  • ►6. Approved Pavement Design Methods
    • ♦6.1 Introduction
    • ♦6.2 Flexible Pavement Design System (FPS 21)
    • ♦6.3 Modified Texas Triaxial Design Method for Flexible Pavements
    • ♦6.4 TxCRCP-ME (for Continuously Reinforced Concrete Pavements)
    • ♦6.5 AASHTO 93 Design Procedure (for CPCD rigid pavement designs)
  • ►7. Pavement Design Categories
    • ♦7.1 Definitions
    • ♦7.2 Example of Conditions for Each Pavement Design’s Usage
    • ♦7.3 Federal Aid Eligibility for Preservation and 3R/4R Projects
  • ►8. Information Needed for Pavement Design
    • ♦8.1 Introduction
    • ♦8.2 Traffic Loads
    • ♦8.3 Serviceability Index
    • ♦8.4 Reliability (confidence level)
    • ♦8.5 Material Characterization
    • ♦8.6 Drainage Characteristics
    • ♦8.7 Evaluating Existing Pavement Condition
  • ►9. Pavement Design Reports
    • ♦9.1 Projects Requiring Pavement Design and Pavement Design Reports
    • ♦9.2 Pavement Design Report and Other Documentation
    • ♦9.3 Completing the Pavement Design Report
    • ♦9.4 Pavement Design Report Review and Archive
• ►3. Materials Investigation and Selection Information
  • ►1. Overview
    • ♦1.1 General
  • ►2. Geotechnical Investigation for Pavement Structures
    • ♦2.1 Introduction
    • ♦2.2 Preliminary Investigation
    • ♦2.3 Subsurface Exploration
    • ♦2.4 Treatment Guidelines
    • ♦2.5 Geotechnical Summary Report for Pavement Design Development
  • ►3. Flexible Base Selection
    • ♦3.1 Introduction
    • ♦3.2 Flexible Base Description
    • ♦3.3 Base Selection
  • ►4. Treated Subgrade and Base Courses
    • ♦4.1 General
    • ♦4.2 Cement, Lime and Fly Ash Treatments
    • ♦4.3 Asphalt Treatment (Plant-Mixed) Bases
    • ♦4.4 Emulsion and Foamed Asphalt Treatments
  • ►5. Performance Graded Binders (PG Binders)
    • ♦5.1 General
    • ♦5.2 Selecting a PG Binder
  • ►6. Hot-Mix Asphalt Pavement Mixtures
    • ♦6.1 General
    • ♦6.2 HMA Mix Design
    • ♦6.3 Guidelines for Selecting HMA Mixtures
    • ♦6.4 Selecting Surface Aggregates to Comply With the Wet Surface Crash Reduction Program (WSCRP)
  • ►7. Concrete Materials
    • ♦7.1 Hydraulic Cements
    • ♦7.2 Blended Cements
    • ♦7.3 Fly Ash
    • ♦7.4 Aggregates
    • ♦7.5 Water
    • ♦7.6 Chemical Admixtures
  • ♦8. Reinforcing Steel
  • ►9. Hydraulic Cement Concrete
    • ♦9.1 Primary Ingredients
    • ♦9.2 Determining Ingredient Proportions
    • ♦9.3 Creating Workability, Durability, and Adequate Strength
    • ♦9.4 Three Concrete Classes
  • ►10. Geosynthetics in Pavement Structures
    • ♦10.1 Introduction
    • ♦10.2 Description of Materials and Applications
    • ♦10.3 Geosynthetics for Surface Layer Reinforcement
    • ♦10.4 Geosynthetics for Geotechnical Reinforcement
    • ♦10.5 Geosynthetics for Drainage Applications
    • ♦10.6 Specifications and Testing
• ►4. Pavement Evaluation
  • ►1. Overview
    • ♦1.1 Introduction
    • ♦1.2 Visual Condition Surveys
    • ♦1.3 Non-destructive Testing (NDT)
    • ♦1.4 Destructive Testing
  • ►2. Visual Pavement Condition Surveys
    • ♦2.1 Overview
    • ♦2.2 Flexible Pavement Visual Survey Condition Categories
    • ♦2.3 Rigid Pavement Visual Survey Condition Categories
  • ►3. Non-Destructive Evaluation of Pavement Functional Properties
    • ♦3.1 Introduction
    • ♦3.2 Roughness
    • ♦3.3 Skid Resistance
  • ►4. Non-Destructive Evaluation of Pavement Structural Properties
    • ♦4.1 Introduction
    • ♦4.2 List of Non-Destructive Tools in Order of Availability
    • ♦4.3 Falling Weight Deflectometer (FWD)
    • ♦4.4 Dynamic Cone Penetrometer (DCP)
    • ♦4.5 Air-coupled Ground Penetrating Radar (GPR)
    • ♦4.6 Ground-coupled Penetrating Radar (GPR)
    • ♦4.7 Seismic Evaluation Tools
    • ♦4.8 Total Pavement Acceptance Device (TPAD)
  • ►5. Destructive Evaluation of Pavement Structural Properties
    • ♦5.1 Introduction
    • ♦5.2 Trenching Procedure
    • ♦5.3 Coring Procedure
    • ♦5.4 Augering
    • ♦5.5 Shelby Tube
  • ♦6. Geotechnical Investigation for Pavement Structures
• ▼5. Flexible Pavement Design
  • ♦1. Overview
  • ►2. Types of Flexible Pavements
    • ♦2.1 Definition of Flexible Pavement
    • ♦2.2 Types of Flexible Pavements
  • ►3. FPS 21 Design Parameters
    • ♦3.1 Introduction
    • ♦3.2 Program Tools
    • ♦3.3 Data Input Components
    • ♦3.4 General Input Descriptions
  • ►4. FPS21 Modulus Inputs and Backcalculation Methodology
    • ♦4.1 Overview of Modulus Inputs
    • ♦4.2 Virgin and Modified-in-Place Materials
    • ♦4.3 Modulus Values for Rehab and Reclamation-type Projects
    • ♦4.4 Backcalculation Methodology
  • ►5. Pavement Detours and Pavement Widening
    • ♦5.1 Pavement Detours
    • ♦5.2 Pavement Widening
  • ►6. Perpetual Pavement Design and Mechanistic Design Guidelines
    • ♦6.1 General
    • ♦6.2 Limiting Strain Criteria
    • ♦6.3 Foundation Design
    • ♦6.4 Designing a Perpetual Pavement Using FPS21
• ►6. Flexible Pavement Construction
  • ►1. Overview
    • ♦1.1 Acknowledgement
    • ♦1.2 Introduction
  • ►2. Base and Subgrade Preparation
    • ♦2.1 Introduction
    • ♦2.2 Intelligent Compaction
  • ►3. Pavement Surface Preparation
    • ♦3.1 Surface Condition
    • ♦3.2 Prime Coat - Flexible Pavements
    • ♦3.3 Underseals
    • ♦3.4 Seal Coats
    • ♦3.5 Existing Surface Preparation for Overlays
  • ►4. Special Considerations for the Construction of Perpetual Pavements
    • ♦4.1 Foundation
    • ♦4.2 Other Considerations
  • ►5. Plant Operations
    • ♦5.1 Batch Plants
    • ♦5.2 Drum Plants
  • ►6. Mix Transport
    • ♦6.1 Introduction
    • ♦6.2 Truck Types
    • ♦6.3 Operational Considerations
    • ♦6.4 Summary
  • ►7. Placement
    • ♦7.1 Introduction
    • ♦7.2 Placement Considerations
    • ♦7.3 Asphalt Paver
    • ♦7.4 The Spray Paver
    • ♦7.5 Thermal Profiling
    • ♦7.6 Material Transfer Vehicles (MTVs)
  • ►8. Compaction
    • ♦8.1 Introduction
    • ♦8.2 Compaction Measurement and Reporting
    • ♦8.3 Compaction Importance
    • ♦8.4 Factors Affecting Compaction
    • ♦8.5 Compaction Equipment
    • ♦8.6 Roller Variables
    • ♦8.7 Summary
• ►7. Flexible Pavement Rehabilitation
  • ►1. Overview
    • ♦1.1 Introduction
  • ►2. In-place Surface Recycling
    • ♦2.1 Hot In-place Recycling (HIR)
    • ♦2.2 Cold In-place Recycling (Bituminous Layers Only)
  • ►3. Geosynthetics
    • ♦3.1 Geosynthetics in Hot-Mix Asphalt (HMA) Applications
    • ♦3.2 Geosynthetics in Pavement Bases (non-HMA Applications)
  • ►4. Flexible Base Overlay and Flexible Base Thickening
    • ♦4.1 Flexible Base Overlay
    • ♦4.2 Flexible Base Thickening
  • ♦5. Full Depth Reclamation/Recycling (FDR)
  • ►6. HMA Overlays
    • ♦6.1 Structural Overlays
    • ♦6.2 Non-structural Overlays
  • ►7. Surface Treatments
    • ♦7.1 General
    • ♦7.2 Underseals
  • ♦8. Concrete Overlays
  • ►9. Reusing Rigid Pavements as Base
    • ♦9.1 Break and Seat
    • ♦9.2 Crack and Seat
    • ♦9.3 Rubblizing
    • ♦9.4 Multi-head Breaker (MHB)
  • ►10. Alternate Pavement Rehabilitation Options
    • ♦10.1 Alternate Options to Hot In-place Recycling
    • ♦10.2 Alternate Options to Thin Bonded Friction Course
    • ♦10.3 Alternate Options to Reflection Crack Relief Interlayer (RCRI)
• ►8. Rigid Pavement Design
  • ►1. Overview
    • ♦1.1 Rigid Pavement Types
    • ♦1.2 Selection of Rigid Pavement Type
    • ♦1.3 Performance Period
    • ♦1.4 Tied Concrete Shoulders
  • ►2. Approved Design Method
    • ♦2.1 Introduction
    • ♦2.2 TxCRCP-ME Design Program for CRCP
    • ♦2.3 AASHTO Rigid Pavement Design Procedure for CPCD
  • ►3. Rigid Pavement Design Process for CRCP
    • ♦3.1 TxCRCP-ME Design Program
    • ♦3.2 TxCRCP-ME Design Input Values
  • ►4. Rigid Pavement Design Process for CPCD
    • ♦4.1 Introduction
    • ►4.2 Input Values
  • ►5. Determining Concrete Pavement Thickness
    • ♦5.1 Introduction
  • ►6. Terminal Anchor Joint Selection for Concrete Pavement
    • ♦6.1 Terminal Joint Design Recommendation
  • ►7. Bonded and Unbonded Concrete Overlays
    • ♦7.1 Introduction
    • ►7.2 AASHTO Overlay Thickness Design for Bonded Overlays
    • ♦7.3 AASHTO Overlay Thickness Design for Unbonded Concrete Overlays
  • ►8. Thin Concrete Pavement Overlay (Thin Whitetopping)
    • ♦8.1 Introduction
    • ♦8.2 Guidelines for Thin Whitetopping (TWT)
• ►9. Rigid Pavement Construction
  • ►1. Overview
    • ♦1.1 Introduction
  • ►2. Concrete Mix Design
    • ♦2.1 Introduction
    • ♦2.2 Job Control Testing
    • ♦2.3 Opening to Traffic
    • ♦2.4 Maturity Method
  • ►3. Concrete Plant Operation
    • ♦3.1 Introduction
    • ♦3.2 Central-mixed Plants
    • ♦3.3 Shrink-mixed Concrete
    • ♦3.4 Truck-mixed Concrete
  • ►4. Delivery of Concrete
    • ♦4.1 Introduction
    • ♦4.2 Concrete Mixing Trucks
    • ♦4.3 Concrete Delivery Time
    • ♦4.4 Water Additions
    • ♦4.5 Wash Water
  • ►5. Reinforcing Steel Placement
    • ♦5.1 Introduction
    • ♦5.2 Reinforcing Steel
  • ►6. Paving Operations
    • ♦6.1 Introduction
    • ♦6.2 Fixed-form Paving
    • ♦6.3 Slip-form Paving
    • ♦6.4 Placing Concrete
    • ♦6.5 Finishing Operations
    • ♦6.6 Texturing Operations
    • ♦6.7 Curing the Concrete Pavement
  • ►7. Joints
    • ♦7.1 Introduction
    • ♦7.2 Contraction Joints
    • ♦7.3 Construction Joints
    • ♦7.4 Expansion Joints
    • ♦7.5 Joint Sealing
• ►10. Rigid Pavement Rehabilitation
  • ♦1. Overview
  • ►2. Full-Depth Repair
    • ♦2.1 Introduction
    • ♦2.2 Pavement Distress Types that Require Full-Depth Repair (FDR)
    • ♦2.3 Full-Depth Repair (FDR) Procedures
  • ►3. Concrete Pavement Repair
    • ♦3.1 Introduction
    • ♦3.2 Repair Procedures
  • ►4. Bonded Concrete Overlay
    • ♦4.1 Introduction
    • ♦4.2 Bonded Concrete Overlay (BCO) Procedures
  • ►5. Unbonded Concrete Overlay
    • ♦5.1 Introduction
    • ♦5.2 UBCO Procedures
  • ►6. Stitching
    • ♦6.1 Introduction
    • ♦6.2 Pavement Distresses that Require Stitching
    • ♦6.3 Types of Stitching
  • ►7. Dowel Bar Retrofit
    • ♦7.1 Introduction
    • ♦7.2 DBR Procedures
  • ►8. Joint Repair
    • ♦8.1 Introduction
    • ♦8.2 Pavement Distresses that Require Joint Repairs
    • ♦8.3 Load Transfer Devices
  • ►9. Diamond Grinding
    • ♦9.1 Introduction
    • ♦9.2 Pavement Distresses that Require Diamond Grinding (DG)
    • ♦9.3 Other Issues with DG
  • ►10. Thin HMA Overlays
    • ♦10.1 Introduction
    • ♦10.2 HMA Overlay on CRCP
    • ♦10.3 HMA Overlay on CPCD
  • ♦11. Retro-fitting Concrete Shoulders
• ►11. Ride Quality
  • ♦1. Overview
  • ►2. Ride Quality Measurement
    • ♦2.1 Introduction
    • ♦2.2 Equipment for Measuring Ride Quality
  • ♦3. Ride Requirements for Flexible Base
  • ♦4. Surface Test Type A for Concrete and Hot-Mix Asphalt Surfaces
  • ♦5. Surface Test Type B for Concrete and Hot-Mix Asphalt Surfaces
  • ♦6. Considerations for Improving Ride Quality
  • ♦7. Analysis of Ride Data
• ►12. Premature Distress Investigations
  • ►1. Overview
    • ♦1.1 Introduction
    • ♦1.2 Technical Assistance
  • ►2. Investigation Team
    • ♦2.1 Objectives
  • ►3. Investigation Process
    • ♦3.1 Overview
• ►13. Load Zoning and Super Heavy Load Analysis
  • ►1. Overview of Load Zoning
    • ♦1.1 Background
    • ♦1.2 Executive Orders
    • ♦1.3 What is in This Chapter?
  • ►2. Changing Load Zones on Roads
    • ♦2.1 Adding
    • ♦2.2 Removing
    • ♦2.3 Changing
  • ►3. Emergency Load Zones on Roads
    • ♦3.1 Setting Emergency Load Zones on Roads
  • ►4. Changing Load Zones on County Roads and Bridges
    • ♦4.1 Law Ruling
    • ♦4.2 Coordination Between County and District
    • ♦4.3 Required Information and Supporting Documentation
  • ♦5. Super Heavy Load Analysis Background
  • ♦6. Super Heavy Load Evaluation Process
  • ♦7. Damage from Super Heavy Load Moves
  • ♦8. Damage Claim Procedure

Chapter 5: Flexible Pavement Design

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Section 1: Overview

This chapter documents the policy for designing flexible pavements. The following topics are discussed:

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• types of flexible pavements,
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• design parameters used in FPS 21 (analytical flexible pavement design procedure),
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• FPS 21 modulus inputs and backcalculation methodology,
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• pavement detours and widening, and
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• design of perpetual pavements.