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NCHRP Web-Only Document 269: Guide Specification for Service Life Design of Highway Bridges A-1 A P P E N D I X A Literature Review of Transportation Agency Supported Research Introduction This section summarizes research reports, technical and synthesis documents that were identified as part of the literature review effort. Particularly, documents related to State DOT sponsored research and that are relevant to the service life design of bridges are included. For organizational purposes, the effort of the literature review for this project was first categorized into either supporting research/guidance or direct guidance. Supporting research/guidance was defined as a study that provided information related to service life performance (and potential interventions), but did not provide design guidance directly. Direct guidance documents are presented and discussed in Chapter 2, Literature Review Synthesis. DOT-related supporting studies are presented here. Sources are grouped in three loosely defined topics: 1) identification and modeling of deterioration mechanisms; 2) Research on Bridge Maintenance, Preservation, and Retrofit; and 3) Service Life Design guidance. Each identified source is presented in a summary that includes (a) the purpose and/or objectives of the study/document, (b) a description of the methodology employed to achieve the stated objectives, and (c) a summary of the relevant conclusions. Associated references are included in the References list. Identification and Modeling of Deterioration Mechanisms Assessing and Enhancing the Durability and Longevity Performance of Highway Bridges (Ramey and Wright 1994) This paper is the final report on Highway Research Center Project 2-13506. The overall objective of this report was to achieve enhanced durability performances of new and rehabilitated highway bridges. To achieve this, it assesses the long-term durability performance issues of steel, reinforced concrete, and pre- stressed concrete multi-girder bridges using findings drawn from historical data of a population of Alabama DOT bridges, literature review and DOT/consultant surveys. The paper presents the primary factors that affect the long-term durability performance of a structure and identifies multidisciplinary actions that should be taken to enhance durability performance. The literature review (Chapter 2) touches on mechanisms of deterioration and bridge failure, material durability, and code spec requirements for durability for bridge decks, bridge systems, and other components that drive overall bridge deterioration. Chapter 3 defines categories of bridge system, subsystem, and components as well as deterioration and failure classifications of the systems and components. Chapter 4 presents the results of the survey sent to Alabama bridge owners that included questions of durability performance and how it relates to the phases of a bridges service life: planning, design, construction, and long-term maintenance. Chapter 5 presents the results of a study on a subset of Alabama DOT Bridge records. The durability performance of bridge systems, subsystems, and components is summarized along with the modes of deterioration and failure for these systems and components. The study found that the worst structurally deficient components were the
NCHRP Web-Only Document 269: Guide Specification for Service Life Design of Highway Bridges A-2 deck and substructure. The worst subcomponents were reinforcement/deck structure, curbs, sidewalks, expansion joints, paint, live load deflection, and abutment walls. A comparison of overall performance as well as performance between concrete versus steel, and simple span versus continuous is given. The study found that simple span was âfar superiorâ to continuous span and that short spans saw less deterioration than longer spans. Chapter 6 presents the results of interviews and site visits with Alabama DOT officials. Chapter 7 presents a list of 57 factors that affect highway bridge durability performance. Some factors are based on findings from the literature review, survey, paper study, and interviews, others are recommendations based on these findings. Chapter 8 summarizes conclusions and provides recommendations based on the 57 factors presented in Chapter 7 and the critical phases that affect a bridges service life (planning, design, construction, and long-term maintenance). MinnDOT Deterioration Rates of Minnesota Bridge Decks (Nelson 2014) The purpose of the research was to investigate the rate in which MinnDOT concrete bridge decks deteriorate and the factors that affect the rate of deterioration. The report discusses the findings of this research including the time, on average, that a deck remains at different National Bridge Inventory (NBI) ratings, and the factors that cause a bridge deck to transition from one rating to another. These factors included or were related to: reinforcement, overlay, ADT, concrete cover, materials, and bridge location. The research used a data mining approach to draw conclusions based on rating data form the NBI database. The study found that type of deck reinforcement and bridge location were the biggest factors affecting the time a bridge occupies a specific NBI rating. It was found that bridges with epoxy coated bars had better performance. It recommends that deck deterioration tables should be maintained on at least a four year cycle in order to have sufficient data to warrant presentation. Assessment of Bridge Joint Performance in NE U.S. (Quinn and Civjan 2016) The purpose of this report and underlying research was to determine and conclude on the best practices for bridge expansion joints and headers based on research of bridges in the NE United States. A technical review was conducted that included findings collected from communication with MassDOT personnel as well as a survey of bridge owners from nine states in the NE United States. The performance, installation and maintenance practices of different joint and header types was evaluated. The conclusions recommended in this survey may provide deemed-to-satisfy or avoidance criteria for joints and headers. Bridge Deck Service Life Prediction and Costs (Williamson et al. 2007) Thirty-seven bridge decks were surveyed. This survey consisted of visual inspection, pachometer testing to determine depth of cover, chain dragging, and coring. The cores were analyzed to determine the chloride concentrations at varying depths. The gathered measurements were used to generate distribution models of parameters to which service life calculations are sensitive. The parameters are as follows: 1. Diffusion Coefficient; 2. Surface Chloride Concentration; and 3. Cover Depth. The parameter distributions were input into a Bridge Corrosion Analysis computer program, which performed a Monte Carlo analysis. The analysis was run to predict the end of service life, which was defined as the point in time for which 12% of the bridge deck by area exhibits damage. Analysis showed that bridges built according to current specifications are predicted to have service lives well exceeding 100 years. However, the authors also admit that the model is not capable of accurately predicting the service life of an individual bridge, due to the variability (spatially) of the input data. The
NCHRP Web-Only Document 269: Guide Specification for Service Life Design of Highway Bridges A-3 authors suggest the same procedure be carried out to estimate the service life of a chosen population of bridge decks. The authors recommend the following time to deterioration stages: ⢠6 years to cracking in the cover (for bare steel) ⢠16 years for propagation from 2% to 12% damage (for bare steel) However, it seems like the deterioration rates calculated are based on few temporal data points, and therefore should be considered suspect until independently verified. The addition of fly ash or slag to the deck concrete mixture was found to dramatically reduce the diffusion rate of chlorides into concrete and have equivalent long-term corrosion protection effects. A Life Cycle Cost Analysis was performed for two bridge âmaintenanceâ alternatives: polymer overlay, and concrete overlay. It was found that the life cycle cost depended heavily on bridge/site specific parameters, and therefore neither maintenance options could be categorically recommended. Corrosion Forecasting for 75-Year Durability Design of Reinforced Concrete (Sagues et al. 2001) Objective of this study is to improve forecasting ability by updating information on the rate of chloride- ion penetration, with special attention to the effect of cracks, in the substructure of FDOT marine bridges constructed with the most promising concrete formulations. Field surveys conducted on existing bridges, predictive methods of corrosion initiation and propagation, evaluation of electrochemical corrosion prevention. Calculations of the penetration of chloride in sound concrete revealed that the rebar acts as an obstruction to the diffusional chloride flow, causing a local increase in concentration. That increase shortens the projected time for corrosion initiation compared to that evaluated assuming unrestricted diffusion. The effect can be strong (reductions by as much as 40%) depending on the concrete cover, rebar diameter, and chloride threshold value. Derating factors to account for this effect were computed and proposed for use in durability estimates. An integrated corrosion initiation model for sound concrete was created that considers the concrete mixture proportions, rebar cover and size, and system geometry (flat wall, 2- and 3- way corners, or cylindrical columns). Rebar itself can act as an obstruction to the diffusional chloride flow, causing a local increase in concentration and considerable relative reduction in the projected time to corrosion initiation when the rebar cover is low or the critical chloride concentration high. Results of this investigation can be summarized in terms of a derating factor Tf < 1 that can be used to estimate the reduction in time to initiation of corrosion due the presence of rebar. Experiments revealed that the amount of critical corrosion penetration needed to cause cover cracking was greater when corrosion was localized (as it may happen in an area of preferential chloride penetration) than when corrosion was more uniform (as in sound concrete). A quantitative relationship between critical corrosion penetration, rebar cover and diameter, and length of the corroding region was established.
NCHRP Web-Only Document 269: Guide Specification for Service Life Design of Highway Bridges A-4 NCHRP Report 558 - Manual on Service Life of Corrosion-Damaged Reinforced Concrete Bridge Superstructure Elements (Sohanghpurwala 2006) The primary objective of this research is to provide procedures for the following: 1. Assessing the condition of reinforced concrete bridge superstructure elements subjected to corrosion- induced deterioration. 2. Predicting the remaining service life of such elements. 3. Quantifying the service life extension for such elements expected from alternative maintenance and repair options. The scope of work for this project was limited to bridge superstructure elements reinforced with black reinforcing steel and, to some extent, epoxy coated reinforcing steel. It did not include pre-stressed concrete elements and other modified steels. This manual is targeted toward engineers and maintenance personnel charged with maintaining the bridge structures. This manual can be used by state and other highway agencies and adopted with or without modifications as guidelines for use within the organization. This report proposes a measurement, the Susceptibility Index (SI), for service life assessment. SI is the measure of the average distribution of chloride ions with respect to an established threshold. Models for chloride diffusion and corrosion damage. Models calculate SI based on distribution of chloride ions in areas not presently damaged (Equation 11). SI is scaled to 10, where larger values reflect less chloride ions at the steel depth. A negative SI would signify that corrosion has initiated at most locations and corrosion-induced damage can be expected soon in sound areas (beyond threshold). Optimal mitigation solutions are selected based on the calculated SI value (Figure 3). Corrosion control strategies that might be considered for rehabilitating a reinforced concrete structure experiencing deterioration due to chloride-induced corrosion. SI was also developed to minimize cost and perform the In-Depth Inspection only when necessary. Recommendations and minimum sample size requirements for evaluation methods were given. Selection of corrosion control systems and service life extension was also based on SI values. Research on Bridge Maintenance, Preservation and Retrofit NCHRP Report 668 - Framework for a National Database System for Maintenance Actions on Highway Bridges (Hearn et al. 2010) This report encourages bridge owners to implement a proposed uniform system for reporting bridge maintenance actions and their performance. Called the National Bridge Maintenance Database (NBMD), the data base promotes sharing of data on bridge maintenance allowing owners to evaluate the cost and performance (or benefit) of certain actions. There is a variety of preservative maintenance actions available to bridge owners, however, each owner may have different practices for employing and reporting on the cost and performance of these actions. This lack of knowledge transfer may delay the progression of successful bridge preventative maintenance programs. The report summarizes current practice in bridge maintenance, and data reporting and proposes a new framework to provide bridge owners with a means of effectively maintaining their resources which includes the evaluation and selection of an appropriate maintenance and preservation strategy. Chapter 1 defines the scope of bridge maintenance and maintenance related activities and discusses the current maintenance practices of several state DOTs. Chapter 2 introduces the National Bridge Maintenance Database (NBMD) framework for uniform reporting. Chapter 3 details the NBMD ready software applications that are currently available. Chapter 4 explains the sources of data for the NBMD. Chapter 5 discusses how the element level costs of maintenance actions are
NCHRP Web-Only Document 269: Guide Specification for Service Life Design of Highway Bridges A-5 determined, a feature of the NBMD system and software applications. Chapter 6 provides a glossary of terms related to Highway Bridge Maintenance. The NBMD system does not directly relate to the objectives of this project but the discussion of the bridge maintenance practices of several state DOTs does provide some insight on the current state of practice. Nonetheless, encouragement of the uniform reporting of the cost and performance of different bridge maintenance actions may be beneficial and could be considered in Deemed-to-Satisfy Provisions. Investigation of Integrity and Effectiveness of RC Bridge Deck Rehabilitation with CFRP Composites (Lee et al. 2004) This Caltrans report develops methodologies to evaluate the integrity and effectiveness of external bonding of carbon fiber reinforced polymer (CFRP) composites to the bridge deck soffit of Spans 8 and 9 of the eastbound structure of the Watson Wash Bridge. Wet lay-up and pultruded CFRP composites are applied to the deteriorated decks of the Watson Wash Bridge. A global vibration-based nondestructive evaluation procedure measuring changes in modal strain energy is used to determine stiffness changes in the bridge structure before and after application of CFRP composites. The effect of CFRP composite material variation and degradation are incorporated into a measure of the reliability index, which is related the probability of failure; failure is defined as the yield of steel reinforcement. The reliability index provides the means to combine the effects of material variation, CFRP composite degradation, and measured stiffness changes from the field to assess the service life of a FRP rehabilitated structure as shown from a series of progressive damage tests. Based upon the results of the measured system changes, effects of material variation, and effect of CFRP composite degradation, CFRP rehabilitation designs are recommended for the parallel westbound Watson Wash Bridge structure. Recommended CFRP rehabilitation designs are intended to prevent the occurrence of punching shear failure, and sustain HS20 and Permit Load demands in the longitudinal and transverse slab directions for a period greater than 25 years at a reliability level of 3.5, failure probability of 0.02%. A cost comparison between recommended CFRP rehabilitation and new bridge construction costs shows a savings of 75 to 80% with CFRP rehabilitation of the entire bridge deck area of the existing westbound Watson Wash Bridge. Standard Practice for Washing and Cleaning Concrete Bridge Deck (Burgdorfer et al. 2013) The purpose of this report to WSDOT was to evaluate the cost and benefit of routine washing of concrete bridge decks. A technical review was conducted that included a literature review, and nationwide survey of several state bridge DOTs. The technical review focused on the washing practices of decks, joints, and bearings. A summary of common washing practices and the cost/benefit of each is reported. These practices may be relevant for deemed-to-satisfy provisions in bridge maintenance. MWBPP Bridge Preservation Research Survey Results (Washer et al. 2012) This report presents the results of a survey sent to states in the Midwest Bridge Preservation Partnership. The purpose of the 2012 survey was to gather information on bridge preservation research being conducted by the Midwest states. States reported on research related to preventative (or condition driven) maintenance actions or strategies that "prevent, delay, or reduce deterioration" of bridges/bridge elements. Much of the research reported focused on concrete, concrete decks, and mix design.
NCHRP Web-Only Document 269: Guide Specification for Service Life Design of Highway Bridges A-6 FHWA Bridge Preservation Guide (FHWA 2011) In order to have a successful bridge program, bridge owners need to adopt and implement more systematic processes for bridge preservation with a balanced approach to preservation and replacement. Without such an approach, bridge programs can become inefficient and cost-prohibitive. The FHWA Bridge Preservation Guide is intended to provide Federal, State, and local bridge engineers, owners, and practitioners with a framework for a systematic approach to preventative maintenance. This guide first provides definitions and corresponding commentaries related to bridge maintenance and preservation. These activities include: preservation, general preventative maintenance activities, cyclical preventative maintenance activities, condition based preventative maintenance activities, rehabilitation, and replacement. It defines a good bridge preservation program as one that employs cost-effective strategies and actions to maximize the service life of the bridge, which includes applying the proper action at the appropriate time to extend service life at a lower cost. These strategies and actions are discussed. The guide proceeds to give definitions on the evaluation/classification of a bridge or bridge component used when deciding on one of these bridge program activities. The remainder of the guide serves to define and outline a systematic preventative maintenance (SPM) program. Discussed within this SPM program are objectives and strategies for the assessment of a bridge and the application of several bridge preservation activities that may extend the life of bridges. NCHRP Project 14-23 Report: Practical Bridge Preservation Actions and Investment Strategies (Johnston et al. 2014) Although many DOTs have significant experience with bridge preservation actions and their effectiveness to extend the service life of a bridge based on prior experience, however there exists little quantitative data available to measure, evaluate, and document the performance of specific bridge preservation actions. Absence of a creditable, quantitative basis for measuring effectiveness of various bridge preservation activities leads to inadequate funding of well-planned bridge preservation programs. This report aimed to catalog and evaluate bridge preservation actions, provide decision making strategy for alternative methods, and to develop a method for determining the appropriation of funding. Due to the various systems used by DOTs to collect/assess practical bridge preservation actions, as well as the variation of data on the element level and the conversion of data collection to the new system based on the 2013 AASHTO Manual for Bridge Element Evaluation, data is incomplete or inconsistent, limiting the outcomes of the research objectives, however progress was made toward developing a system for assessing bridge preservation actions and investment strategies. Properly and uniformly defining the condition of a bridge element is critical in the decision-making process, as is understanding the effectiveness of a certain bridge preservation action for that particular bridge element. This report gives several methods for determining the condition state of an element and discusses the effectiveness of preservation actions needed at different condition states. The report catalogs bridge element preservation actions and the impacts of those actions on Bridge Service Life. It identifies âbest practice agenciesâ that have successful bridge preservation programs and long-term strategies to track progress toward agency goals. A methodology to prioritize bridge preservation actions on an element level basis and to determine the appropriate levels of funding is proposed based on LCCA at the element level. It draws conclusions and gives recommendations for bridge agencies to consider when developing and implementing an effective bridge preservation program. It is apparent that the research is still lacking the data needed to provide a comprehensive methodology for decision making in a bridge preservation program. Note that the project was discontinued after Phase II and related work was performed under NCHRP Project 14-36.
NCHRP Web-Only Document 269: Guide Specification for Service Life Design of Highway Bridges A-7 Guidelines for Selection of Bridge Deck Overlays, Sealers and Treatments (Krauss et al. 2009) The purpose of this research/report is to present the appropriate factors to consider to make decision making easier. It defines factors for characterizing the condition of the deck (Percent deterioration, NBI ratings, estimated time to corrosion, deck surface condition, concrete quality) and primary repair decisions (Do nothing, Maintenance, Protective overlay, rehab/retrofit). It provides a methodology for selecting bridge deck treatments for different bridge deck conditions and materials in order to promote more consistent and universal procedures for decision making. A technical review was conducted and the findings were reported based on a survey sent to U.S. and Canadian DOTs, as well as a lit review. Guidance is given on the best practice for estimating bridge deck condition, and selection of bridge deck overlays/sealers/treatments. This guidance may be used for deemed-to-satisfy or avoidance rules for concrete bridge design and maintenance. FHWA Seismic Retrofitting Manual for Highway Bridges (FHWA 2006) This manual provides the most current state of practice in assessing vulnerability to the effects of earthquakes, and implementing retrofit measures to improve performance for highway structures including highway superstructure (bridges) and substructure (retaining walls, engineered slopes, etc.). This report is a major revision the previous Seismic Retrofitting Manual for Highway Bridges. It includes current advances in earthquake engineering, field experiences with seismic retrofitting, and the performance of bridges in recent earthquakes based on findings of several years of research with multidisciplinary contributions. A performance based retrofit philosophy is introduced for two different ground motions with return periods of 100 and 1000 years, where a higher level of performance is required for the shorter return period. Retrofit criteria is recommended according to bridge importance and recommended service life. Higher performance is expected for newer bridges. The manual characterizes the seismic and geotechnical hazards a highway structure may experience and provides a methodology for screening and prioritizing bridges based on importance. Evaluation methods for the assessment of demand and capacity are given, using either a component level or system level approach. Guidance is provided as to which, if any retrofitting measure should be taken based on the screening/characterization and evaluations procedures. Retrofitting measures are given for the following components: bearings, seats, columns, piers, cap beams, joints, abutments, and foundations. This document encompasses risk mitigation for seismic events. The recommendations in this manual may be considered for superstructure and substructure design. Specifically, the proposed methodology for assessment and retrofit may be included as deemed-to-satisfy or avoidance of deterioration provisions. Leo Frigo Bridge Investigation (Michael Baker Jr., Inc. 2015) This report presents the findings for the investigation to repair the I-43 Leo Frigo Memorial Bridge, as well as to mitigate potential damage caused by a sag in the bridge deck in and about Pier 22 that occurred on September 25, 2013. Michael Baker Jr Inc. in conjunction with WisDOT, FHWA, and other consulting firms performed an investigation which included visual inspection, NDE, and DE (Cores) after the 2â vertical support movement that occurred on September 25, 2013. This report presents the findings from this investigation. Severe environment conditions of the soil lead to rapid corrosion of sections of the steel piles. Once sufficient material was lost from enough piles, the remaining piling became unstable. Visual examination indicated that crushing/buckling of the most heavily deteriorated sections was the most common mode of failure. The investigation lead to proposed repairs. These repairs are reported in this document and they provided corrosion protection measures that offered 75 years of service life (fiberglass- reinforced polymer sleeves were placed around the new piles for added corrosion protection). An interesting
NCHRP Web-Only Document 269: Guide Specification for Service Life Design of Highway Bridges A-8 conclusion about drainage was made in the report. Specifically, care should be taken as to where drainage of chloride containing water is sent. In this case, the scuppers of the bridge drained deicing chemicals off the bridge directly over pier locations. Although minimal consequence was observed in this case, it is important to consider in other cases. NCHRP Synthesis 425: Waterproofing Membranes for Concrete Bridge Decks (Russel 2012) The waterproofing membranes available are all proprietary products. They are used on new bridge decks and as a retrofit on existing decks as an attempt to extend the service life of the deck. Most of the states and provinces that do not use waterproofing membranes cite reasons such as the nonuse of deicing salts, poor performance of membranes in the past, the use of alternative deck protection strategies, and the preference for having an exposed concrete deck to observe any deterioration. The state agencies that permit the use of membranes specify that they adhere to ASTM standards, which address the properties of the membranes themselves, but little guidance is provided as to the type of membrane to install. There is little unbiased information available, comparing different products. The membranes are installed according the vendorâs specifications, although some states provide general installation guidelines. Quality control of the application is important as the adhesion of the membrane to the concrete deck and asphalt wearing surface is important for good performance. A minimum wearing surface of 4 inches is recommended to avoid damage of the membrane during resurfacing. There are no methods to assess the quality and performance of installed waterproofing membranes. There remains a need to develop testing methods of the many membrane products so they may be compared. Furthermore, research is needed to determine their efficacy at improving bridge deck durability. It should also be noted that NDE methods cannot currently assess the condition of the deck when a membrane and wearing surface is installed. NCHRP Report 810: Consideration of Preservation in Pavement Design and Analysis Procedures (Applied Pavement Technology 2015) The objective of this work is to identify and develop pavement preservation treatments that may be incorporated into the Mechanistic-Empirical Pavement Design Guide Manual of Practice (MEPDG). This work was performed though interviews with subject matter experts as well as a literature survey of existing data on the efficacy of treatments. The intention of this report was to serve as a reference for further modifications to the design codes including the introduction maintenance and preservation considerations. Three methodologies for the inclusion and calibration of the data from the meta-survey into the MEPDG were presented. These methodologies are limited due to the original design models not accounting for maintenance or environmental effects on pavement performance. Despite the quantity of information gathered for this project, further research is needed to fully develop and validate the different calibration approaches. Further, the inability to accurately quantify both initial and long-term effects of preservation treatments on performance makes their inclusion in pavement design and analysis procedures difficult. Bridge Deck Cracking: Effects on In-Service Performance, Prevention and Remediation (Hopper et al. 2015) The main objectives of this project were: (a) to identify the causes of early-age cracking in concrete bridge decks, (b) to provide recommendations for effective mitigation of early-age cracking, (c) to assess the effect of cracks on the long-term durability and performance of concrete bridge decks, and (d) to identify
NCHRP Web-Only Document 269: Guide Specification for Service Life Design of Highway Bridges A-9 the best and most cost-effective (on a life cycle cost basis) remediation practices and optimum time to remediate to extend the life of bridge decks. The project was completed in six tasks and this document reports details of the methods of data collection, analysis, and conclusions for each task. The research team found the following list of structural design factors that are likely to reduce the risk of early-age deck cracking: ⢠Increased cover thickness to 2.5 or 3â. ⢠Prohibit the use of bar sizes greater than #5; increase deck thickness if required. ⢠Ensure the top main bar spacing is 6â or less. ⢠Place longitudinal bars outside (on top) of the transverse bars. ⢠Stagger shear studs and deck slab bars to prevent weak plane. ⢠Use pre-stressed (P/S) girders for integral abutments. ⢠Decks on steel girders (due to higher stiffness, higher thermal conductivity) have shown more cracking than decks constructed on concrete girders. Simply supported decks crack least and integral abutment crack most. NCHRP Project 12-100: Guidelines for Maintaining Small Movement Bridge Expansion Joints (Shenton et al. 2016) This project developed guidelines for maintenance and repair of small movement expansion joints (SMEJ), with the objective of the guidelines being adopted by AASHTO. The main aspects of the project included a literature review, survey of stakeholders, and the development of SMEJ replacement, repair, and maintenance procedures and associated guidelines. The guidelines developed focused on modes of failure, sizing joints, selection of replacement joints, and procedures for maintenance and repair. NCHRP Report 848: Condition Assessment of Bridge Post-Tensioning and Stay Cable Systems Using NDE Methods (Hurlebaus et al. 2016) In this project, various NDE technologies were evaluated using a full-scale post-tensioned girder specimen and four large-scale cable specimens. Strand and grout defects were purposefully created within the specimens for the NDE methods to evaluate. Metrics were developed to evaluate the performance of the various NDE methods. The NDE methods were scored using the metrics, and subsequently ranked. Guidance was created to help users identify the appropriate NDE method(s) for evaluating a particular type of defect. NCHRP Project 14-30: Spot Painting to Extend Highway Bridge Coating Life (Hopwood et al. 2018a, 2018b) These two reports offer guidance on spot painting of steel highway bridges. The goal of the research was to provide a resource for maintenance personnel on proper spot painting utilization. The research focused on assessment of existing coatings to determine the appropriate painting action, selection of coating type, preparation and application, and coating inspection.
NCHRP Web-Only Document 269: Guide Specification for Service Life Design of Highway Bridges A-10 Maintenance Actions to Address Fatigue Cracking on Steel Bridge Structures (Connor and Lloyd 2017) This research was performed under NCHRP Project 20-07, Task 387. The results of the research were a set of guidelines for maintenance of steel bridges with fatigue cracking and constraint-induced fracture (CIF) prone details. The guidelines drew from project reports, research reports, ongoing research projects, and a survey of industry professionals. The document provides information on the causes of fatigue cracking and CIF, as well as repair and retrofit options. Case studies are also provided to illustrate solutions to fatigue and CIF problems. Service Life Design Guidance NCHRP Synthesis 474 - Service Life of Culverts (Maher et al. 2015) The report updates previous NCHRP research, the 1998 Synthesis 254: Service Life of Drainage Pipe, which was an update of the 1978 NCHRP Synthesis 50: Durability of Drainage Pipe. Itâs objective is to document the state of current practices, degradation mechanisms, materials, repair, protection, rehabilitation and replacement procedures, and inspections requirements. The information was obtained through a survey to state agencies and a literature review to determine the state of practice and their performance. Chapter 1 presents the objectives and background of previous studies concerning culverts service life. The scope, methodology and the study approach are also defined. Chapter 1 mentions that currently there is no consensus among state DOTs about culverts service life, and estimating models are usually associated with specific geographic areas and environments. Design services could range from 15 to 100 years, depending on the average daily traffic or functional classification of roadway. Chapter 2 presents a summary with the results of the survey to state agencies. Regarding the criteria used to set culverts design service life, considerations cover a wide range among states. The most common are functional classification of roadway, risk of premature failure, average daily traffic (usage), and financial cost of future rehabilitation or repair. Almost half of the states have âothersâ responses as design criteria, showing the discrepancy of the criteria used between states, and that some agencies are not using the concepts of design and material service lives to evaluate and select culverts. Generally design service life requirements range from 25 to 100 years, having 50 or 75 years as the highest DSL required at many agencies. Respecting material service life, most common factor to consider were corrosion and abrasion, followed by settlement and stress cracking. Chapter 3 gives a summary of the degradations mechanisms that deteriorates the service of culvert pipes. Florida DOT and several other select agencies have sponsored significant research in the area of pipe degradation, and this research can form the basis for better service life prediction models in the future. Polyethylene coating for composite steel spiral rib pipe was the only steel coating studied by DeCou and Daviesâ (2007) that could provide a 50-year service life. In 2013, Caltrans concluded that to provide a 50-year service life for that application with abrasion level 5, steel plate would have been required. Other factors that could impact culvert service life are summarized, such as, freeze/thaw, high humidity conditions, time-dependent mechanical properties (HDPE and PVC), slow crack growth, ultraviolet radiation, seismically induced degradation, access/construction equipment, fire damage, scour at outlet and channel degradation, and pipeâheadwall connection problems. Chapter 4 documents the definitions, key topics, and design methods used to evaluate the service life of culvert materials. Typically, the service life of concrete pipe ranges from 75 to 100 years, although it depends greatly on the class of pipe and type of environment. A measure to respond against sulfate damage is using special mix concrete designs with SCMs such as fly ashes or silica fume, that provide resistance to sulfate attack. Typically, the expected service life in metal culverts is 50 years. Given that corrosion is the mayor factor that affects the service life of metal culvert, a number of factor-applied coatings offer protections to
NCHRP Web-Only Document 269: Guide Specification for Service Life Design of Highway Bridges A-11 the metal improving its actual service life. Coatings such as bituminous and asphalt-based, fiber-bonded bituminous, asphalt mastic, polymerized asphalt, and polymeric sheet coating have shown great performance in metal culvert against corrosion. Other materials such as thermoplastic pipe, PVC, vitrified clay pipe, ductile iron pipe, or HDPE, use a design service life that range from 50 to 100 years. Chapter 5 summarizes the most common available protection methods and materials, used in rehabilitation, repair, and replacement procedures available to extend or reestablish culvert service life. Chapter 6 shows the specifications and procedures that need to be performed for culvert inspections, during, and after construction. Chapter 7 addresses LCCA procedures in infrastructure design that helps to identify the most effective long-term alternative to facility owner. The Perrin and Jhaveri developed a methodology that calculates the total cost of installing a culvert given design life of 100 years (usually), taking the total cost as the sum of installation or replacement cost and user-delay cost. A variety of failure culvert cases were evaluated to illustrate various cost and demonstrate how longer service life would result in cost savings in the long term. NCHRP Synthesis 441 - High Performance Concrete Specifications and Practices for Bridges (Russel 2013) This report documents the types of specifications and practices used by state agencies to produce High Performance Concrete and to find what specifications and practices have been reported an improvement in bridge performance and what activities that have not. Information was collected through a literature review, evaluation of the specifications used by different state agencies and a survey to highway agencies through the AASHTO Highway Subcommittee on Bridges and Structures. A total of 42 agencies participated in the survey. Once concluded the survey, six agencies were selected to collect deeper information about their specifications and performs. The report is intended to help bridge owners, designers, contractors, and material suppliers determine the appropriate requirements for the use of High Performance Concrete in bridges using the information of existing practices. Chapter 1 presents a background of previous cases of study of HPC, including a program of FHWA in 1993 that included the construction of 19 bridges. After been in service for several years the inspection indicated that cracking in bridge decks ranged from none to more than expected. Other observations suggest that usage of HPC resulted in more cracking of concrete bridge decks. Chapter 2 addresses the evolution of HPC for bridges beginning with the first strategic Highway Research Program in the 1980s product of the interest developed in the potential use of HPC to extend the service life of bridges. It describes the various initiatives undertaken by FHWA and AASHTO to promote the use of HPC with the state agencies. In 1993, the FHWA started a national program to implement the use of HPC in bridges. After been in service for 5 to 10 years, field surveys found that in general, the HPC performed well with no indications of significant deterioration as a result of material conditions. Also, they observed no significant signs of spalling or delamination. As well of no indications of ASR, sulfate attack, or other harmful reactions. The results also showed that in some cases that the use of HPC reduced bridge deck cracking. The most general definition of HPC obtained from the state survey was: âConcrete with a life cycle of 75 years or more based on durabilityâ. Chapter 3 addresses how states are currently incorporating HPC in their specifications and in their construction of cast-in-place concrete. Chapter 4 presents states are incorporating HPC in their specifications and construction practices for precast concrete. Chapter 5 gives more detailed information about the usage of HPC in six states (Kansas, Louisiana, New York, Virginia, Washington, and Wisconsin). The NYSDOT stated that a combination of high strength HPC and corrosion inhibitor will provide a service life of 75 to 100 years. This agency also stated that the used of HPC resulted in better performance compared with conventional concrete, including for cast-in-place and precast concrete decks. According to the information gather from the state's agencies the performance of HPC is better that of conventional concrete, although they still have concern respecting the amount of cracking in concrete bridge decks. Nowadays, all states allow the use of SCMs which reduce
NCHRP Web-Only Document 269: Guide Specification for Service Life Design of Highway Bridges A-12 the permeability of water and deicing salts, reducing the probability of deterioration of bridge girders and decks as a consequence of freeze-thaw damage and reinforcement corrosion. NCHRP Synthesis 423 - Long-Term Performance of Polymer Concrete for Bridges Decks (Fowler and Whitney 2011) This report documents the use of thin polymer overlays in concrete bridge decks collecting information from previous research programs and practices. It presents specifications, materials used, quality control, failures, service life, warranties and relative cost from previous research programs. Identifies practices that have been found useful and summarize the important preservation methods that have produced long-lasting and durable Thin polymer overlays (TPOs). The information was obtained from states agencies and Canadian provinces, a survey to vendors, selected interviews and a literature review. TPOs can provide many advantages in wearing surfaces, such as little dead load, fast cure times, ability to transition from overlaid lane to non-overlaid lane during construction, low permeability, and good frictional resistance. In Chapter 2, a literature review is provided, including practices from the late 1980s to early 2000s. It mentions useful information about materials used, installation and test methods, field sections, service life, cost, failures, warranties, and special applications. Moreover, construction specifications and issues were found from the literature review. Chapter 3 presents the performance in the field of TPO activities, according to the information collected from agencies, contractors, and material suppliers. A total of 40 states and seven Canadian provinces participated in the survey. It was discovered that more than 2,400 TPOs have been completed in the United States and Canada. Seven states and three provinces have not used TPOs. Causes of failures were also mentioned. From the selected interviews was obtained a variety of repair procedures, installation procedures, problems encountered and construction recommendations. The material suppliers provided opinions on problems encountered and recommendations for improvement of materials applications. According to the literature and surveys, the main factors that influence the performance of thin polymer overlay are the soundness of the substrate, surface preparation, compatibility of the overlay and substrate, aggregates, overlay thickness, bridge girder flexibility, environment, and constructability and workmanship. Agencies have replaced delaminated TPOs with similar materials or with hydraulic cement concrete. Chapter 4 covers overlay types, materials, qualification of the substrate, installation methods, construction test methods, special applications, and warranties, that have been encounter in proven practices. Chapter 5 presents the procedure to be applied for thin polymer overlay repairs. TPOs have become an accepted construction method for bridge deck preservation, restoring surface friction and extending the lives of decks. The three most common overlay types, multi-layer, slurry, and premixed, are used throughout the United States and Canada. When constructed properly on sound decks, TPOs could provide a service life of 20 or 25 years. Design and Construction of Segmental Concrete Bridges for Service Life of 100 to 150 Years (Rostam 2005) Adoption of more complex and high performance materials raises the demand for high quality workmanship and execution competence. This is not always recognized or respected by owners/designers/supervision teams, leading to low performance structures. The complex requirements of designing well performing concrete structures with a long service life is discussed, highlighting the multidisciplinary considerations that must be taken. The paper highlights the fact that high performance materials, although proven durable, are not of much concern as these aren't the challenge. Rather, a high performance system as a whole is the greater challenge. It also discusses a possible flaw in the "one sided approach" to increasing service life through concrete refinement or corrosion protection of reinforcement. A new approach to design and execution is proposed that incorporates an understanding of this interaction in all aspects of design, material selection, and construction. Several different service life design strategies
NCHRP Web-Only Document 269: Guide Specification for Service Life Design of Highway Bridges A-13 are discussed, specifically avoidance of deterioration, deemed-to-satisfy, and probabilistic performance based design. Several materials are presented and their performance is evaluated. The paper proceeds to discuss the importance of construction and the interaction of design and execution throughout the entire process. It identifies two points critical to overcoming these challenges: (1) the owner must define the performance requirements of a structure in a format that can be translated into a quantified design basis that takes into account not only economical but technical concerns of the long-term performance of a design including the need for maintenance, and (2) a multidisciplinary approach between designer and contractor must be adopted to combine the readily available knowledge from design, construction, materials, and deterioration to develop a solution that is adapted for the individual structure in its particular environment. Concrete Mix Proportioning to Meet Durability Concerns for Confederation Bridge (Langley 1999) To showcase the features of a bridge in Canada that was designed to resist the corrosive forces presented by the freezing, marine environment. Concrete mix proportions are chiefly discussed. This paper presented nothing new, nor did it illustrate the effectivity of the design/construction decisions. However, it provides an organized and concise example of what factors to consider when designing and building new construction in an environment where corrosion is a concern. SHRP S-360 - Concrete Bridge Protection Manual (Weyers et al. 1993) The purpose of this manual is to serve as a guide for bridge owners for cost-effective-protection, repair, and rehab of reinforced concrete bridges exposed to chloride-ion-bearing environments. The manual focuses on one form of deterioration: chloride-ion-induced corrosion of reinforcing steel in reinforced concrete. Chapter 2 discusses process of chloride-ion-induced corrosion as a primer for subsequent chapters on the protection, repair, and rehab of concrete structures exposed to such deterioration. Short-term and long-term methods/procedures are provided in this manual. Also discussed in chapter 2 are models for determining the effects of this deterioration and for estimating time to rehabilitation. Additionally, a framework for selecting cost-effective methods for maintenance is presented. Repair and rehab are defined separately. Repair is a short-term fix that does not address the mechanism of deterioration. Rehab specifically addresses the deterioration in an effort to prevent it from happening in the future. Several mathematical models are presented for diffusion, cracking, and deterioration, and examples are given. Chapters 3 and 4 present standard and experimental methods for protection, repair, and rehab. The cost and performance of the resented methods is evaluated. The mathematical models for determining the effects of deterioration, estimating the time until and cost of rehabilitation may be of some interest to this project. NCHRP Synthesis 333: Concrete Bridge Deck Performance (Russel 2004) The most important structural design practice to reduce corrosion of reinforcement in uncracked concrete bridge decks is to provide a minimum cover to the top layer of reinforcement of 64 mm (2.5 in.). The most important construction practices to achieve a low permeability, uncracked bridge deck with adequate freeze-thaw resistance is to initiate wet curing of the concrete immediately after finishing any portion of the concrete surface and maintaining wet curing for a minimum of 7 days. Other practices that are beneficial include moderate concrete temperatures at time of placement, and minimum finishing operations consistent with achieving the desired concrete surface.
NCHRP Web-Only Document 269: Guide Specification for Service Life Design of Highway Bridges A-14 NCHRP Report 566: Guidelines for Concrete Mixtures (Lawler et al. 2007) This report presents guidelines that facilitate the use of SCMs by highway agencies improving the durability of concrete in highway constructions, especially bridge decks. Is intended to state engineers and other professionals involved in the design and construction of concrete bridge decks as well other structures that integrate SCMs. The report used a statistically based experimental methodology to identify the optimum concrete mixture proportions for a set of specific conditions. The methodology centers on the durability and the performance requirements of concrete for precise environment conditions. Step 1 defines the concrete performance requirements, given guidance on concrete design requirements and the appropriate test methods used. A flowchart is given to select concrete service environment and properties. It also summarizes typical SCM and the range of use for each concrete property. It presents the effects of SCM on compressive strength such as, fly ash, silica fume and class N pozzolans and their interaction with cement. Other design requirements such as, freezing and thawing environments, corrosion, abrasive environments, alkali-silica potential reactions and cracking resistance considerations are also addressed. Step 2 describes the raw materials selection process. A careful review of the raw material selection is an important part in the optimization process of concrete performance, so it can minimize the risk of harmful mechanisms that might affect the bridge concrete deck. It discusses the selection of SCMs, giving material specifications and hydration considerations. Requirements for the selections of aggregates are followed according to AASHTO M 6/80 specifications. Presents specification to consider for air entraining and chemical admixtures. For each type of admixtures are presented the requirements regarding the performance of concrete. An example is presented from hypothetical case of study. The selection process of durable raw materials is presented in a flowchart in figure S2.1. Step 3 describes the generation the experimental design matrix using the orthogonal design method. Describes the experiment details, selection the number of mixtures and selection of the design matrix. In Step 4 the objective is the generation of performance data to be use from the previous selected combinations of materials exposed in the experimental design matrix. Thus, the concrete is prepared and evaluated. In Step 5 all tested mixtures are compared using the framework of desirability functions previously established in step 1. For each individual test method is modeled the response versus the factors tested. Test results are analyzed to find the best tested concrete (BTC) and the best predicted concrete (BPC). The BTC best meets the performance criteria as is designated by the desirability functions. The BPC may not be in the design matrix and have not been tested, nonetheless is expected to perform better than the BTC according to the statistical model. In Step 6 the objective is to define and select the best concrete (BC). Testing and analysis are intended to give confirmation that the development of the mixture is better than the BTC. Further data analysis of the test result is performed. The final selection of the BC is accomplished. NCHRP Synthesis 209: Sealers for Portland Cement Concrete Highway Facilities (Cady 1994) This synthesis contains detailed information on concrete sealing material, describing the various classes of sealers, their chemical characteristics, application to specific needs, and practice and performance characteristics. Three levels of service severity, in terms of the locations of sealer applications on highway structures: "Severe" service refers to surfaces subject to traffic wear as well as direct application of deicing chemicals. "Moderately severe" service pertains to members subject to splashing or spraying of brine by traffic, or drainage of deicer melt water through open deck joints. "Moderate" service relates to areas generally protected from direct deicer application or generally out of the range of direct traffic splash, but occasionally subject to runoff and/or aerosols containing deicing salts (Table 10). The service life of a concrete sealer relative to chloride ingress is a function of three categories of factors:
NCHRP Web-Only Document 269: Guide Specification for Service Life Design of Highway Bridges A-15 1. Sealer material properties; 2. Service conditions related to sealer durability, and; 3. Chloride diffusion related factors (Table 12). Service life data compiled literature search is also presented (Table 14). Recommendations were made for the application of sealers based on a survey questionnaire given to sealer manufacturers. Interim Conclusions, Recommendations and Design Guidelines for Durability of Post- Tensioned Bridge Substructures (Schokker et al. 1999) Purpose of this report is to evaluate the effectiveness of corrosion protection measures for post-tensioned concrete substructures. Laboratory testing of ârepresentativeâ specimens and a literature review were utilized. Recommendations from this report include: Grout with a lower w/c-ratio and the addition of fly ash both help to reduce corrosion. Anti-bleed admixture may also reduce corrosion; Post-tensioning increased durability; Plastic should be used for irrigation ducts. State of the Art Report About Durability of Post-Tensioned Bridge Superstructures (West et al. 1999) The objectives of this report were to: 1. Survey the condition of bridge substructures in Texas, 2. Provide background material on bridge substructure durability, and 3. Review durability research and field experience for post-tensioned bridges. The overall research objectives for Project 0-1405 were as followed: 1. To examine the use of post-tensioning in bridge substructures, 2. To identify durability concerns for bridge substructures in Texas, 3. To identify existing technology to ensure durability or improve durability, 4. To develop experimental testing programs to evaluate protection measures for improving the durability of post-tensioned bridge substructures, and 5. To develop durability design guidelines and recommendations for post-tensioned bridge substructures. This report included a great deal of information on methods to improve post-tensioned bridge service life and durability. Recommendations were given for substructure drainage, deck joints, splashing, and geometry. Also included were recommendations to prevent freeze-thaw and AARs that shorten service life spans. The field performance of existing post-tensioned concrete bridges was found to be acceptable albeit cases with poor design, construction practice, and regular maintenance. Post-tension systems were recommended for grouting, anchorage protection, and ducting methods to prevent corrosion penetration and prolong serviceability. FHWA Technical Advisory: Uncoated Weathering Steel in Structures (FHWA 1989) This technical advisory purpose is to provide engineers with suggested guidelines for proper application of uncoated (unpainted) weathering grade steels in highway structures and recommendations for maintenance to ensure continued successful performance of the steel. The report is based on the information gather from the Weathering Steel Forum in July of 1988 sponsored by FHWA. Uncoated weathering grade steels have been available for the bridge industry for many years. Its additional cost is compensated by the
NCHRP Web-Only Document 269: Guide Specification for Service Life Design of Highway Bridges A-16 elimination of steel painting of the structure. There are also environmental benefits for the use of this material. The reduction in initial painting decreases the number of volatile organic compounds (VOC) emissions when are used oil based coatings. The elimination of removal of the coating and disposal of contaminated blast cleaning debris. In addition, there are cases where the cost of the collection and disposal of materials from the painting project were so high that it was either abandoned or replace with a new bridge. In general, in steel highway bridges and other steel structures the control of corrosion and the mitigation of its related damaged is a major issue. A special aspect of the problem is to ensure the used of uncoated (AASHTO M270 Weathering Grade) steels in an environment, and appropriate details, that will guarantee cost-effective performance over the expected service life of the structure. Guidelines for the type of environments, locations, maintenance actions, and design details are addressed and detailed. NCHRP Report 733 - High Performance High Strength Lightweight Concrete for Bridge Girders and Deck (Cousins et al. 2013) The purpose of this project was to develop recommendations for the inclusion of high-performance/high strength lightweight concrete in the AASHTO LRFD Bridge Design Specifications and AASHTO LRFD Bridge Construction Specifications. A full probabilistic approach was used to review current design standards and apply the results of experimental investigation to develop the guidelines. Experiments were used to identify differences between lightweight and normal concrete in material properties, shear strength, reinforcing steel behavior, pre-stress losses, and camber. The modified modulus of rupture for sand- lightweight concrete (SLC) was proposed to be between 0.26âfâc and 0.31âfâc. Further it was recommended that the lower bound of the modulus of rupture be used when considering service load cracking. NCHRP Report 679 - Design of Concrete Structures Using High Strength Steel Reinforcement (Shahrooz et al. 2011) The purpose of this report was to evaluate the specifications for high strength reinforcing steel found in the AASHTO LRFD Specifications. A full probabilistic approach was utilized and based on both analytical and experimental methods. The application of A1035 reinforcing steel on bridge decks was investigated as a one-to-one replacement for A615 steel. The study found that under service loads A1035 provides no significant increase in contribution in terms of flexural strength or reduction in crack width, and the primary advantage to the use of A1035 over A615 to be less corrosion. Further, the use of high strength steel to reduce the total area of reinforcing steel is limited due to reinforcing steel spacing requirements. NCHRP Synthesis 517: Corrosion Prevention for Extending the Service Life of Steel Bridges (Ault and Dolph, 2018) The goal of this work was to help owners and designers select proper materials and coatings for steel bridges, as well as to develop effective maintenance plans for both new and in-service bridges. The synthesis focuses on the current practice of corrosion prevention of atmospherically exposed bridge superstructure steel. The document does not specifically address other steel bridge elements, such as buried components, reinforcing steel, or bearings.
