EXHIBIT_K_-_TXDOT_Concrete_Repair_Manual_crm.pdf

EXHIBIT K - TXDOT Concrete Repair Manual crm Concrete Repair Manual January 2017

© 2017 by Texas Department of Transportation

(512) 463-8630 all rights reserved

Manual Notice 2017-1

From: Gregg A. Freeby, P.E. / Director, Bridge Division

Manual: Concrete Repair Manual

Effective Date: January 01, 2017

Purpose

This manual includes step-by-step repair procedures for use on new and existing concrete members cast for the Texas Department of Transportation (TxDOT).

Changes

Revision to this manual include the addition of a manual revision history to Chapter 1; revision breaking Chapter 1 into seven sections with no changes to content; revision adding Section 8, dis-cussing rail damage due to vehicular impact, to Chapter 2; revisions for consistency with current DMS-4655; revised maximum application for neat product to 2"; various revisions to Chapter 3, Section 4, “Bridge Deck Repair” and Section 6, “Crack Repair – Gravity-Fed Epoxy” for improved performance of repairs; and minor formatting and editorial revisions in various sections.

Contact

Please contact the Bridge Division with comments or questions.

Archives

Past Manual Notices are available in a PDF archive.

crm_mn_archive.pdf

Table of Contents

Chapter 1 — Introduction

Section 1 — Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

Section 2 — Using the Concrete Repair Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

Section 3 — Standard Specification References to the Concrete Repair Manual . . . . . . . . . 1-4

Section 4 — Repairs and Repair Manual. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5

Section 5 — Repair Procedure Submission and Approval . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6

Section 6 — Quality Control/Quality Assurance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7

Section 7 — Definitions and Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9

Chapter 2 — Damage Assessment and Repair Types

Section 1 — Defining Concrete Spalls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 Spall Categories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 Selecting an Appropriate Repair Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

Section 2 — Voids Due to Honeycombing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5 Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5 Investigating Honeycombed Regions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5 Repairing Honeycombed Regions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

Section 3 — Damage over Traffic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6 Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6

Section 4 — Prestressed Concrete Piling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7 Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7 Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7 Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7 Assessing Damage Prior to Driving (e.g. in the Fabrication Yard). . . . . . . . . . . . . . . . . . . 2-7 Assessing Damage During Driving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8

Section 5 — Taking, Marking, and Patching Cores . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9 Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9 Selection Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9 Taking Cores to Check Compressive Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9 Taking Cores to Investigate Potential Concrete Material Problems . . . . . . . . . . . . . . . . . . 2-9 Taking Cores to Investigate Specific Defects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10 Marking Cores . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10 Patching Cores . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10

Section 6 — Trimming or Cutting Prestressed Concrete Girder Ends . . . . . . . . . . . . . . . . 2-11 Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11 Concrete Repair Manual i TxDOT 1/2017

Provisions for Acceptance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11 Repair Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12

Section 7 — Recessing Prestressed Strands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13 Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13 Repair Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13

Section 8 — Rail Damage Due to Vehicular Impact. . . . . . . . . . . . . . . . . . . 2-14 Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-14 Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-14 Repair Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-14

Chapter 3 — Repair Materials and Procedures

Section 1 — Minor Spall Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2 Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2 Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2 Repair Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3 Commentary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5

Section 2 — Intermediate Spall Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6 Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6 Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6 Repair Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7 Commentary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12

Section 3 — Major Spall Repair and Concrete Replacement . . . . . . . . . . . . . . . . . . . . . . . 3-13 Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13 Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13 Repair Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13 Commentary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-17

Section 4 — Bridge Deck Repair. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-18 Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-18 Selecting an Appropriate Repair Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-19 Repair Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-20 Commentary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-22

Section 5 — Crack Repair – Pressure-Injected Epoxy . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-24 Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-24 Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-24 Repair Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-24 Commentary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-26

Section 6 — Crack Repair – Gravity-Fed Epoxy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-27 Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-27 Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-27 Concrete Repair Manual ii TxDOT 1/2017

Repair Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-27 Commentary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-28

Section 7 — Crack Repair – Surface Sealing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-29 Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-29 Method 1: Rout-and-Seal Cracks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-29 Method 2: Surface Sealing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-29 Concrete Repair Manual iii TxDOT 1/2017

Chapter 1 — Introduction

Contents:

Section 1 — Overview

Section 2 — Using the Concrete Repair Manual

Section 3 — Standard Specification References to the Concrete Repair Manual

Section 4 — Repairs and Repair Manual

Section 5 — Repair Procedure Submission and Approval

Section 6 — Quality Control/Quality Assurance

Section 7 — Definitions and Abbreviations Concrete Repair Manual 1-1 TxDOT 01/2017

Chapter 1 — Introduction Section 1 — Overview Section 1 — Overview

This manual includes step-by-step repair procedures for use on new and existing concrete members cast for the Texas Department of Transportation (TxDOT). It includes a comprehensive list of com-mon concrete distress and repair methods. The methods adhere to industry standards and the provisions from applicable documents by the American Concrete Institute and American Society for Testing and Materials. This manual was developed in collaboration with various repair material manufacturers to ensure that the procedures meet common proprietary requirements.

In general, repairs to TxDOT concrete structures should be implemented in accordance with the methods outlined in this manual. However, unusual circumstances occasionally arise. Engineers may determine that methods differing from those outlined here are more appropriate in some circumstances.

Updates to the manual are summarized in the following table.

Table 1-1: Manual Revision History

Version Publication Date Summary of Changes

2015-1 April 2015 New manual.

2017-1 January 2017 Revision adding manual revision history to Chapter 1; revision breaking Chapter 1 into seven sec-tions with no changes to content;

revision adding Section 8, discuss-ing rail damage due to vehicular impact, to Chapter 2; revisions for consistency with current DMS-4655;

revised maximum application for neat product to 2"; various revi-sions to Chapter 3, Section 4, “Bridge Deck Repair” and Section 6, “Crack Repair – Gravity-Fed Epoxy” for improved performance of repairs; minor formatting and edi-torial revisions in various sections.

Concrete Repair Manual 1-2 TxDOT 01/2017

Chapter 1 — Introduction Section 2 — Using the Concrete Repair Manual Section 2 — Using the Concrete Repair Manual

When developing repair or rehabilitation plans, the Engineer should specifically include which sec-tions of this manual will be enforced. Chapter 2 includes information on assessing damage, distress limits, and common types of concrete repair. Chapter 3 includes information on various repair materials and procedures for implementation.

Typically concrete repair work will include categorizing the type of distress as outlined in Chapter 2 and selecting a type of repair material from Chapter 3. In some cases, the material section includes enough information that choosing a corresponding type of repair is not necessary. For instance, the sections on crack repair do not require that corresponding repair types be selected

Each section in this manual is written as a stand-alone document, and individual sections contain all necessary information on material selection and application. It is not necessary to read the manual from start to finish. Rather, the intention is that Inspectors and Contractors will need only to refer-ence the applicable section or sections. The sections are kept as concise as possible since they are intended for field use.

This manual does not address post-tension strand, duct, or anchorage repairs. Repairs or defects associated with post-tension work should be addressed by the Bridge Division Construction & Maintenance Group on a case-by-case basis.

Concrete Repair Manual 1-3 TxDOT 01/2017

Chapter 1 — Introduction Section 3 — Standard Specification References to the Concrete Repair Manual Section 3 — Standard Specification References to the Concrete Repair Manual

The Concrete Repair Manual is referenced in several 2014 Standard Specification Items. This sec-tion includes a list of each of those references, along with the corresponding Section to reference within this Manual.

Standard Specification References

Spec Item Item Title Spec Reference Repair Manual Reference

409 Prestressed Concrete Piling

3.1 (Defects and Breakage)

Refer to Section 2.4 for limits and repair procedures when assessing damage to pre-stressed concrete piling.

420 Concrete Substructures 4.13 (Ordinary Surface Finish)

Spalls are defined per Section 2.1, and repaired (based on severity) per Section 3.1, 3.2, or 3.3. Most spalls in this category will be defined as minor and repaired per Section 3.1.

424 Precast Concrete Struc-tural Members (Fabrication)

4.3 (Workmanship) Recess prestressed strands per Section 2.7.

4.3.1 (Defects and Breakage)

This item covers damage or surface defects that occur during fabrication, handling, storage, hauling, or erection of precast con-crete members. Any of the sections in this manual could apply depending on the situation.

429 Concrete Structure Repair

2 (Materials)

3 (Construction Methods)

Severity of the unsound, delaminated, or spalled concrete is defined per Section 2.1.

After defining, select materials and imple-ment repair per Section 3.1 (Minor), 3.2 (Intermediate), or 3.3 (Major).

780 Concrete Crack Repair 2 (Materials)

3 (Construction Methods)

Select materials and perform repair work in accordance with the applicable section in this manual. Section 3.5 covers pressure-injected epoxy, 3.6 covers gravity-fed epoxy, and 3.7 covers both routing and sealing and surface sealing.

788 Concrete Beam Repair 2 (Work Methods) Concrete Beam Repair is a plan-specific item. Provide materials and perform work in accordance with the applicable sections of this Manual and as defined in the project plans.

Concrete Repair Manual 1-4 TxDOT 01/2017

Chapter 1 — Introduction Section 4 — Repairs and Repair Manual Section 4 — Repairs and Repair Manual

It is critical that repair crews use appropriate repair materials and installation methods. Even the best materials will not work effectively unless each aspect of the repair work is considered. Proper proportioning, mixing, surface preparation, application, and curing are all vital to the long-term success of a repair.

TxDOT maintains Departmental Material Specifications and corresponding preapproved Material Producer Lists for most of the materials outlined in the manual. It is vital that Engineers, Inspec-tors, and Contractors select and use only preapproved materials when applicable. The Engineer may select or Contractors may propose to use material not included on an MPL if it will provide for the best repair in a specific application. The Engineer will review such requests from the Contractor on a case-by-case basis, but in almost all cases a preapproved material should be selected.

Notify the Engineer before proceeding with the repairs if there are discrepancies between TxDOT’s requirements and industry standards or manufacturers’ instructions. Maintain up to date copies of the manufacturers’ technical literature to ensure the proper procedures are followed.

Concrete Repair Manual 1-5 TxDOT 01/2017

Chapter 1 — Introduction Section 5 — Repair Procedure Submission and Approval Section 5 — Repair Procedure Submission and Approval

When the Engineer prepares repair or rehabilitation plans that include reference to this manual, the Contractor must prepare and submit formal procedures outlining repair plans and which proprietary materials they plan to utilize. Submit the package a minimum of two weeks prior to implementation so the Engineer has sufficient time to review. The Engineer must approve in writing any procedures that differ from those in this manual or materials that are not included in one of TxDOT’s MPLs.

For damage that occurs in precast concrete fabrication yards or on construction sites in which Con-tractor is required to prepare a Nonconformance Report or Request for Information, the Contractor should propose repair methods and materials outlined in this manual. Contractors may also propose to use a procedure that differs from those outlined in this manual, in which case TxDOT will con-sider on a case-by-case basis.

For cases in which the Engineer is not preparing repair documents and the Contractor is not issuing a Nonconformance Report or Request for Information, the Contractor and Inspectors should work collaboratively to determine an appropriate repair solution and then follow the applicable sections from this manual.

Concrete Repair Manual 1-6 TxDOT 01/2017

Chapter 1 — Introduction Section 6 — Quality Control/Quality Assurance Section 6 — Quality Control/Quality Assurance

In addition to providing step-by-step procedures for Contractors and Fabricators, this manual is also meant to provide Quality Control (Contractor) and Quality Assurance (Owner) inspectors with the knowledge needed to ensure that appropriate repair solutions are selected and implemented.

Each procedure in Chapter 3 of this manual includes detailed instructions on each individual facet of the repair.

Proper attention to and implementation of each step in the repair process is critical to successful application. The first step is ensuring that the contractor is using approved materials. Correct pro-portioning and mixing is also critical. A common mistake is for Contractors to “eyeball” or guess at proper proportions when using multi-part mixes. Inspectors should verify that Contractors are mea-suring, either by volume or weight, all individual components prior to mixing. In almost all cases the Contractor should utilize an acceptable form of mechanical mixing; hand mixing is not accept-able. It is not possible to put a sufficient amount of energy into mixing when doing so usinga shovel, trowel, or by hand. In small applications a small “jiffy” type paddle and mixer are often suf-ficient. When using larger quantities of cementitious repair material a mortar or volumetric mixer is more appropriate.

Application varies significantly with repair type and material. Refer to the applicable section in Chapter 3.

Another frequent problem leading to premature failure of repairs, especially cementitious materi-als, is inadequate curing. Improper curing often leads to cracking very early in the life of the repair.

The best (and easiest) curing method is to leave the forms in place when using form-and-pour applications. In those cases only a small amount of moist curing is required in the small areas used to place the concrete. Ponding is also an excellent method of curing but is typically impractical in most repair scenarios. Many manufacturers include instructions for application of curing mem-branes. However, continuous moist curing is typically preferable to curing membranes. When using wet mats it is imperative that the mats be kept moist during the entire curing interval. In cases where membrane curing is approved, the Contractor must use material that is preapproved by TxDOT and is acceptable to the repair material supplier.

Since curing requirements vary significantly depending on the type of material and the manufac-turer, it is important that curing methods adhere to the technical product literature for the specific material being utilized. As noted above, moist curing is the preferred method for most cementitious patch materials. However, moist curing can actually harm some patch materials, such as those that contain magnesium phosphate. Again, the Contractor must adhere to the requirements for the spe-cific material being applied.

Contractor’s Responsibilities (QC):

Concrete Repair Manual 1-7 TxDOT 01/2017

Chapter 1 — Introduction Section 6 — Quality Control/Quality Assurance It is the Contractor’s responsibility to use repair materials specified in the Contract Documents and this manual. For materials in which there are lists of materials available through TxDOT’s DMS and MPL process, the Contractor should only use products that have been preapproved.

Any deviation from the originally proposed and approved materials must be approved by the Engineer in writing. When in doubt, contact the Bridge Division or Construction Division for guidance on whether a proposed material is acceptable.

Store materials on jobsite according to material supplier’s requirements, preventing direct exposure to sunlight and moisture. Materials exceeding their shelf lives may not be used.

When required by the Contract, perform a trial repair or mockup to demonstrate acceptable performance and installation methods.

Ultimately, quality is the Contractor’s responsibility. If the Contractor feels that any of the pro-cedures outlined in this manual or in the contract plans could lead to unacceptable performance, they must inform the Engineer of those concerns in writing prior to commencing work. In such cases, the Engineer will work collaboratively with the Contractor to come to an agreeable solution.

Owner’s Responsibilities (QA):

Check materials to ensure that they are appropriate for the given application. Material should either be on one of TxDOT’s preapproved lists or approved by the Engineer prior to use.

Ensure that the Contractor is following the procedures outlined in this manual and as shown on the plans for material selection, preparation, implementation, curing, and any other steps cru-cial to the performance of the concrete repair. Procedures may need to be altered for varying weather conditions (excessive heat or cold, rain, high wind, etc.).

Verify that all damaged material has been removed and that the remaining surface is clean and sound before the Contractor proceeds with repair material installation.

Confirm that repair material performance is acceptable through visual observations and nonde-structive testing. Patch material should not exhibit cracking. One of the easiest and most effective tests is to sound the repair material using firm (but not destructive) blows with a ham-mer. When repair material has debonded from the substrate there is generally a distinctive hollow sound when the material is struck. Defective repair material must be removed and replaced.

In some cases, the Contractor may opt to perform nondestructive or destructive testing when there is a question about whether a repair is performing adequately. Often such testing will involve taking cores for petrographic analysis. Though a Contactor may use an independent consultant or lab for performing forensic or petrographic investigations, ultimately TxDOT will decide whether a repair is acceptable.

Concrete Repair Manual 1-8 TxDOT 01/2017

Chapter 1 — Introduction Section 7 — Definitions and Abbreviations Section 7 — Definitions and Abbreviations

The terms “Engineer,” “Inspector,” “Contractor,” and “Fabricator” are used regularly throughout this manual. “Engineer” typically refers to the Engineer of Record that signed and sealed the repair plans, the Area Engineer or the Area Engineer’s authorized representative where the work is being performed, or in the case of precast fabrication one of the licensed Professional Engineers at TxDOT Construction Headquarters in Austin. “Inspector” refers to the person, usually a Depart-ment employee, assigned by the Engineer to check compliance with the Contract. “Contractor” refers to the entity responsible for implementing the repair work. “Fabricator” refers to a manufac-turer that produces precast concrete structures for TxDOT. When not specifically stated, requirements for Contractors also apply to Fabricators.

The following abbreviations are used in the manual:

CFRP: Carbon Fiber Reinforced Polymer

CST: TxDOT Construction Division

DMS: Departmental Material Specification

MPL: Material Producer List

NCR: Nonconformance Report (typically prepared by Precast Fabricators)

QA: Quality Assurance

QC: Quality Control

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SSD: Saturated Surface-Dry Concrete Repair Manual 1-9 TxDOT 01/2017

Chapter 2 — Damage Assessment and Repair Types

Section 1 — Defining Concrete Spalls

Section 2 — Voids Due to Honeycombing

Section 3 — Damage over Traffic

Section 4 — Prestressed Concrete Piling

Section 5 — Taking, Marking, and Patching Cores

Section 6 — Trimming or Cutting Prestressed Concrete Girder Ends

Section 7 — Recessing Prestressed Strands

Section 8 — Rail Damage Due to Vehicular Impact Concrete Repair Manual 2-1 TxDOT 01/2017

Chapter 2 — Damage Assessment and Repair Types Section 1 — Defining Concrete Spalls Section 1 — Defining Concrete Spalls

Description

Spalls are categorized based on severity of damage per the definitions in this Section. Once a spall has been categorized, then an appropriate repair material and installation procedure can be selected.

Reference: Standard Specification Item 429, “Concrete Structure Repair.”

Notes

Based on severity, spalls can be categorized as minor, intermediate, or major. Appropriate repair materials and methods differ significantly depending on the spall depth, size (area), and configura-tion (horizontal, vertical, or overhead). The guidelines in this section help define various spall types. These are general definitions; depending on the circumstances, an Engineer may define spall severity differently than these definitions, on a case-by-case basis.

This section does not apply to spalls in the riding surfaces of bridge decks. Refer to the Chapter 3 sections on Bridge Deck Repair when addressing such damage.

Spall Categories

Minor Spall:

Damage is less than 1 inch deep and it covers an area less than 12 square inches. However, if the majority (more than 50%) of a reinforcing bar circumference or strand is exposed due to inadequate cover then the spall would be classified as Intermediate even if it is less than 1" deep.

The Inspector may elect to designate patches that cover areas larger than 12 square inches as minor depending on the location and extent of the damage.

A deeper spall (2" maximum) can be categorized as minor as long as it does not progress beyond the outer layer of reinforcement.

Intermediate Spall:

The damage exposes a majority (more than 50%) of the outer cage of reinforcing steel or strand circumference, or the damage is greater than 2" deep.

The maximum depth of an intermediate spall is 6 inches.

No significant stresses are likely to develop due to service loads.

Major Spall:

Damage extends well beyond the outer cage of reinforcement.

Concrete Repair Manual 2-2 TxDOT 01/2017 ftp://ftp.dot.state.tx.us/pub/txdot-info/des/spec-book-1114.pdf

Significant stresses are likely to develop in or immediately around the patch material due to service loads.

Selecting an Appropriate Repair Procedure

Minor Spall:

Regardless of configuration (vertical, overhead, or horizontal), the best repair method for minor spalls is typically neat epoxy or epoxy mortar. Epoxy that is formulated for concrete repair has very tenacious bond and performs well in thin applications.

Excavating the concrete to expose all corroded sections of the bar is the only way to stop corrosion, but that typically requires the removal of sound material. Such measures are usually unnecessary unless the minor spalling is occurring over a large area.

Applying epoxy over thin spalls in which a small amount of steel is exposed will not typi-cally stop corrosion. However, it provides an excellent waterproof barrier and can significantly slow down the rate of corrosion if properly applied.

Building up thin spalls with epoxy mortar is generally an aesthetic decision. Mortar should not be applied if the damage will occur over vehicular or pedestrian traffic. In those cases only neat epoxy should be applied.

Intermediate Spall:

Proprietary, bagged concrete repair materials are typically used to patch intermediate spalls. Use only preapproved materials meeting the requirements of DMS 4655, “Concrete Repair Materials.”

A common mistake when choosing bagged concrete repair materials is to select those with compressive strengths far higher than needed. Materials with lower compressive strengths typically perform better since they also have a lower Modulus of Elasticity, and therefore greater ductility. For intermediate spalls it is typically desirable not to redistribute loads into the patch material. Limiting compressive strength and Modulus of Elasticity are the best ways of achieving that.

Vertical and Overhead Repairs:

In most cases a Contractor will opt to use a trowel-applied repair material in vertical and overhead applications. The maximum lift thickness of trowel-applied materials is 2 inches or the maximum permitted by the repair material supplier, whichever is less.

In deeper applications the Contractor may propose to patch using pneumatically applied cementitious material, in which case they should follow the provisions set forth in Item 431. Pneumatically placed concrete is not addressed in this manual. The Engineer must approve use of pneumatically placed concrete in lieu of the repair methods outlined in this manual.

The Contractor may opt to use form-and-poured bagged material or batched concrete, which is often a better option since it can be extended with coarse aggregate. Most Concrete Repair Manual 2-3 TxDOT 01/2017 ftp://ftp.dot.state.tx.us/pub/txdot-info/cst/DMS/4000_series/pdfs/4655.pdf trowel-applied materials do not include coarse aggregate, which can lead to shrinkage cracking if not applied or cured properly.

Horizontal Repairs: Form-and-pour materials are typically the best option in horizontal appli-cations because they can be extended with coarse aggregate, which significantly reduces the potential for shrinkage cracking.

Precast Concrete Production Yards: Batched concrete is readily available in precast concrete plants. Therefore, fabricators should typically use batched concrete (same mix design) as that used to fabricate the damaged member, even when the spall is classified as intermediate.

Major Spall:

Major spalls typically involve deep repairs to members in which capacity has been reduced as a result of the damage. The repair is meant to restore capacity of the damaged member. The best option in such applications is to use batched concrete with properties similar to the parent material.

When the mix design is unknown, the Engineer and Contractor should select an approved concrete mix that meets the requirements of the anticipated service loads.

In smaller applications it is often not practical to specify batched concrete when rehabili-tating or repairing existing structures. The Engineer should determine when a preapproved bagged material is more appropriate and offer that as an alternative to batched concrete.

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Chapter 2 — Damage Assessment and Repair Types Section 2 — Voids Due to Honeycombing Section 2 — Voids Due to Honeycombing

Description

Honeycombing in concrete members can result from either of the following:

Forms not being sufficiently secure or tight, allowing mortar to leak out during casting opera-tions. The grout leakage can lead to pockets of air voids between coarse aggregate.

Lack of consolidation due to unworkable concrete mixes or inadequate vibration.

Investigating Honeycombed Regions

The biggest cause for concern when voids occur on the exterior portions of members is that addi-tional, unseen defects could exist on the interior portions. Honeycombing due to lack of proper consolidation is of particular concern, especially in the portions of precast concrete members that are highly congested with prestressing strands and mild reinforcement.

Prior to considering repair options, explore the voids to check for additional damage. The areas around the voids should be chipped to sound, undamaged concrete. However, do not chip out con-crete around prestressed strands before discussing with the Engineer.

Occasionally Contractors ask to use Nondestructive Evaluation (NDE) to investigate the severity of honeycombing when it appears to be severe and the Engineer is considering rejection. Most of the available technology (e.g. Impact Echo and Pulse Velocity) cannot effectively show whether small voids exist along congested prestressing strands or mild reinforcement. Although the Contractor may propose to use NDE, it is up to the Engineer to determine whether it is acceptable. Generally NDE requires destructive verification testing, which is oftentimes not an option in highly congested concrete, such as the bottom flanges of prestressed girders.

Repairing Honeycombed Regions

After the honeycombed regions have been removed, the damaged area should be evaluated and defined per Section 1 of Chapter 2 unless the damage is too severe to consider acceptance of the member. An appropriate repair material and method can be selected once the damage is cate-gorized as minor, intermediate, or major.

At a minimum, remove defective material, patch, and finish as required in Section 420.4.13 of the Standard Specifications for Ordinary Surface Finish.

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Chapter 2 — Damage Assessment and Repair Types Section 3 — Damage over Traffic Section 3 — Damage over Traffic

Description

This section applies to damage that occurs or could occur over vehicular or pedestrian traffic. Dam-age consists of any spall, delamination, honeycombing, or other unintentional void. The Engineer will typically require additional measures to help ensure the repair material will not fall into traffic in the case of a patch failure.

The most frequent damage that occurs over roadways is overhead vehicular impact. In addition to whatever structural and waterproofing repairs are necessary, the Engineer should typically also require confinement or other acceptable means to prevent spalling or to catch portions of the repair material that become detached. Wire netting often works as a temporary solution. More permanent solutions should be included when the member or members are repaired. In almost all cases the best option for preventing damaged concrete from falling onto traffic is to confine the patch material with Carbon Fiber Reinforced Polymer wraps. Perform the CFRP work in accordance with Item 786.

In the case of precast concrete fabrication, damage that will occur over traffic may not be patched unless approved by the Engineer. When feasible, members should be reassigned or rotated to move the damage to an area where damage will not occur over traffic in its final configuration. Minor damage may be coated with neat Type VIII epoxy but should not be built up with repair mortar.

When the Engineer does permit more extensive repair, the patch material must be confined using CFRP or other approved method.

There is no standard repair procedure for patching damage over traffic. Do not proceed with such repairs without authorization from the Engineer.

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Chapter 2 — Damage Assessment and Repair Types Section 4 — Prestressed Concrete Piling Section 4 — Prestressed Concrete Piling

Description

This section includes limits and repair procedures when assessing damage to prestressed concrete piling.

Reference

Standard Specification Item 409, “Prestressed Concrete Piling.”

Notes

Assessing piling damage is divided into two categories: (1) damage that occurs prior to driving (during fabrication, handling, storing, or hauling), and (2) damage that occurs during driving oper-ations (lifting or driving). When assessing damage to exposed portions of prestressed piling in an existing structure, treat it as a typical concrete substructure element. No special limits apply.

The acceptance and rejection criteria for prestressed piling are more severe than with most other structural elements because the consequences of a failure are also very severe. Foundation distress is typically very difficult to remedy and can lead to shortened service life of an entire bridge. There-fore, damage that could potentially hinder performance or reduce durability will typically lead to rejection of the piling.

Assessing Damage Prior to Driving (e.g. in the Fabrication Yard)

Minor damage.

Only thin spalls may be repaired. The Engineer will determine what constitutes an accept-able spall, but in general the limits are 1-inch in depth and 6 square inches in area. If either of those limits is exceeded, or if the damage exposes any reinforcing steel or prestressing strand, the damage will render the piling unacceptable unless specifically deemed other-wise by the Engineer.

Smooth out the perimeter of the damaged area to eliminate jagged edges.

Minor spalls deemed acceptable for repair should be cleaned and coated with neat epoxy in accordance with Section 1 of Chapter 3 of this manual.

Do not build up the spalled areas with repair material other than neat epoxy since it is likely to debond during driving operations.

The Engineer may allow for repair when damage is deeper than 1 inch but does not prog-ress beyond the outer layer of steel reinforcement. In those cases the damaged areas Concrete Repair Manual 2-7 TxDOT 01/2017

Chapter 2 — Damage Assessment and Repair Types Section 4 — Prestressed Concrete Piling should be built up with epoxy mortar and completely confined by CFRP wrapped com-pletely around the piling.

Damage to one end.

If one end of a piling is damaged beyond the limits outlined above, but the damage extends less than 6 inches from the end, then the fabricator or contractor may remove (cut) up to 6 inches from the end to eliminate the damaged portion.

Clearly mark the altered side as the “Tip End.”

After cutting, recess the prestressing strands 3/8-inch minimum and fill the voids with epoxy mortar (typical strand end treatment).

Re-form the chamfers after completing the cutting and patching operations.

Damage to both ends.

There are no standard criteria for acceptance or rejection when both ends of a piling are damaged, but generally the member will be rejected since it would not be possible to avoid hammering a damaged end.

Engineer must approve any repairs when damage occurs on both ends of a piling.

Assessing Damage During Driving

Horizontal cracks (transverse to longitudinal reinforcement or strand) greater than 1/16 inches wide.

Piling will be rejected if crack occurs in a portion that will be below ground or water level after driving.

If crack will occur above grade or water level, the Contractor may opt to cut back beyond the crack and rebuilt to finished grade.

Horizontal cracks less than 1/16 inches wide.

Inject the cracks with epoxy in accordance with Section 3.7 of this manual.

If cracks develop that will be inaccessible in final configuration, cease driving operations and repair cracks before continuing.

Vertical or diagonal cracks.

In most cases a piling member will be rejected if vertical or diagonal cracks form during driving operations.

If the Engineer approves repair of vertical or horizontal cracks, inject with epoxy in accor-dance with Section 3.7 of this manual.

Fine hairline cracks (less than 0.006 inches) or surface checks that do not extend to the plane of the nearest reinforcing steel will not require repair and will not be cause for rejection.

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Chapter 2 — Damage Assessment and Repair Types Section 5 — Taking, Marking, and Patching Cores Section 5 — Taking, Marking, and Patching Cores

Description

Cores may be taken from concrete members for a variety of reasons, including verification of com-pressive strength, investigation of potential concrete material problems (e.g. segregation or bleeding), or examination of specific defects (e.g. cracks or cold joints). This section covers proper taking and marking of cores, and patching of the core holes.

Selection Criteria

Select core locations and have them approved by the Engineer. Check fabrication sheets so, if pos-sible, cores are taken with minimum impact to mild reinforcement. Check design sheets or shop drawings so do not take cores through prestressing strands unless specifically approved by the Engineer.

Take four-inch outside diameter cores when feasible. When approved by the Engineer, take smaller cores in highly congested areas to avoid impact to mild reinforcement or prestressed strands.

When possible, take cores through the entire width of the concrete section.

Taking Cores to Check Compressive Strength

Take at least two cores from a member if design cylinders reveal a potential deficiency in the required 28-day compressive strength.

Evenly space the cores along the member(s) in question. Typically, take the cores through the webs or sidewalls of prestressed concrete girders.

Ensure cores taken for testing compressive strength have lengths at least twice their diameter.

There can be no mild reinforcement or prestressed strands in the cores if they will be used for testing compressive strength.

Taking Cores to Investigate Potential Concrete Material Problems

To check questionable batches of concrete, take the cores through the worst section or sections.

Also take a control core from the same member where the concrete was placed from a different batch and there are no apparent problems.

If checking for bleeding or segregation, take one core through the problem area and another core through the top of the member directly above the first one. Again, take a control core from an unaffected section of the member.

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Chapter 2 — Damage Assessment and Repair Types Section 5 — Taking, Marking, and Patching Cores Taking Cores to Investigate Specific Defects

Take cores directly through the problem areas when investigating specific damage or defects. It typically will not be necessary to take control cores in these types of situations.

If investigating a cold joint, take the sample such that approximately half the core is above the joint and half is below the joint.

Marking Cores

Draw two arrows on the core locations BEFORE a core is taken. Point both arrows straight up, and drawn them on each side (left and right) of the core. In most cases the petrographer will need to cut in the vertical orientation, so it is important that the core be marked such that both sides will indi-cate the “up” direction after cutting.

After a core has been taken, write additional information on each side (left and right) of the sample.

Include the following information:

Structure No. (existing structure) or CSJ (new construction).

For new construction, name of Prime Contractor if at jobsite or Fabricator if in Precast Con-crete Plant.

Member ID and location.

Core number. Also, take photographs and notes indicating from where in the member the core was taken and why.

Again, most cores are cut vertically. Write all of the above information on both sides of the core so each part of the sample can be properly identified if it is cut.

Include a standard TxDOT Form 202 for each set of cores taken from a member. Request that the TxDOT Inspectors fill out Form 202 as needed so hard copies of the completed forms can be sent directly with the samples. Also send copies of applicable concrete mix design worksheets and batch tickets with the cores when they are available.

Patching Cores

As with all large patches, utilize preapproved bagged cementitious repair material or batched con-crete to patch core holes when feasible. Follow the requirements set forth in the section on Intermediate Spall Repair for implementing the work.

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Chapter 2 — Damage Assessment and Repair Types Section 6 — Trimming or Cutting Prestressed Concrete Girder Ends Section 6 — Trimming or Cutting Prestressed Concrete Girder Ends

Description

This section includes allowances and repair procedures for trimming or cutting the ends of pre-stressed concrete I-beams.

Removal of more than 1 inch of a beam end is considered cutting.

Removal of 1 inch or less from a beam end is considered trimming.

Cutting beam ends requires preparation of an NCR from the Fabricator. The TxDOT Inspector determines whether an NCR is required when a beam end will be trimmed.

NOTE: Standard provisions for cutting beam ends apply to Tx Girders (bulb tees) only. Cutting the ends of prestressed members other than Tx Girders requires a detailed analysis by a Pro-fessional Engineer and authorization from TxDOT CST Headquarters or the Bridge Division. There is no standard repair for such alterations; proposals will be considered on a case-by-case basis.

Provisions for Acceptance

No more than 12 inches may be removed from either girder end.

If more than 6 inches is removed from a girder end, include in the modification proposal stamped calculations from a Professional Engineer indicating the viability of the proposed modification.

Calculations must include:

Required moment and shear capacity.

Actual moment capacity of the modified member, obtained using PGSuper or another accept-able analysis program.

Actual shear capacity.

In most cases equal amounts should be removed from each end if the total length to be cut exceeds 6 inches. However, that would not be a viable solution if a beam end is being cut in order to elimi-nate damage or when a beam end contains an anchor slot.

The Area Engineer and CST Engineer must approve modifications. All parties, including the Fabri-cator, Contractor, and Engineer, must agree that trimming will not result in any unacceptable issues related to deck forming, slab or haunch thickness, camber, or plan profile deck geometry.

The girder must be modified as required for use in its new configuration, including but not limited to blockouts, inserts, hangers, and bevels.

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Chapter 2 — Damage Assessment and Repair Types Section 6 — Trimming or Cutting Prestressed Concrete Girder Ends When the strand pattern differs from the destination design, or if more than 6" is cut off one or both beam ends, a replacement shop plan for the permanent record must be provided that indicates all characteristics of the candidate girder that differ from the originally specified girder.

Include dual girder identification by permanently marking the inside face of the girder, clearly indi-cating which is the previous girder I.D. and which is the current I.D. Fabricator or Contractor must send written notification to the Area Engineer informing them of the circumstances of the dual marked girder for their information and records.

Repair Procedure

After the beam has been trimmed or cut, re-measure the member (length, skew, and batter) to ensure that the altered dimensions are acceptable.

Once the dimensions have been checked and found to be acceptable, remove all vertical reinforce-ment that has less than 3/4-inch concrete cover. Recess longitudinal reinforcing steel and prestressing strands approximately 3/8-inch.

Locate the steel using shop drawings, exploratory drilling, and whatever other means is neces-sary to ensure that all reinforcement with inadequate concrete cover is identified.

Remove the steel using a torch or other approved method. Do not overheat or damage the sur-rounding concrete and steel that will remain in place.

If steel is removed using a torch, abrade the steel and concrete surfaces with a needle…