Control of Cracking in Bridge Decks

Control of Cracking in Bridge Decks
Author: D. Darwin
Publisher:
Total Pages: 7
Release: 2004
Genre: Bridge decks
ISBN:
GET BOOK

Crack surveys of bridge decks, performed over a 10-year period in northeast Kansas as part of three studies, provide strong guidance in identifying the parameters that control cracking in these structures. The surveys involve steel girder bridges--bridges that are generally agreed to exhibit the greatest amount of cracking in the concrete decks. The surveys include monolithic decks and decks with silica fume and conventional concrete overlays. The study demonstrates that crack density increases as a function of cement and water content, and concrete strength. In addition, crack density is higher in the end spans of decks that are integral with the abutments than decks with pin-ended supports. Most cracking occurs early in the life of a bridge deck, but continues to increase over time. This is true for bridges cast in both the 1980s and the 1990s. A key observation, however, is that bridge decks cast in the 1980s exhibit less cracking than those in the 1990s, even with the increase in crack density over time. Changes in materials, primarily cement fineness, and construction procedures over the past 20 years, are discussed in light of these observations. A major bright spot has been the positive effect of efforts to limit early evaporation, suggesting that the early initiation of curing procedures will help reduce cracking in bridge decks.

Cause and Control of Transverse Cracking in Concrete Bridge Decks

Cause and Control of Transverse Cracking in Concrete Bridge Decks
Author: M. Ala Saadeghvaziri
Publisher:
Total Pages: 206
Release: 2002
Genre: Concrete bridges
ISBN:
GET BOOK

Many concrete bridge decks develop transverse cracking and most of these cracks develop at early ages, some right after construction and some after the bridge has been opened to traffic for a period of time. Structural design factors have not been the subject of much research in the past and they were the main thrust of this research study. Using 2-D and 3-D linear and nonlinear finite element models many design factors such as girder stiffness, deck thickness, girder spacing, relative stiffness of deck to girder, amount of reinforcements, etc., were studied. The research study also included a comprehensive review of the existing literature as well as survey of 24 bridges in the state of New Jersey. Results of each research task are presented and discussed in detail. Furthermore, based on analytical results and literature review, the effect of various factors are quantified and specific recommendations for possible consideration in design are made.

Construction of Crack-free Bridge Decks

Construction of Crack-free Bridge Decks
Author: David Darwin
Publisher:
Total Pages: 135
Release: 2017
Genre:
ISBN:
GET BOOK

This serves as the final report on Transportation Pooled-Fund Program Project No. TPF-5(174), "Construction of Crack-Free Bridge Decks." The goal of the study was to implement the most cost-effective techniques for improving bridge deck life through the reduction of cracking. Work was performed both in the laboratory and in the field, resulting in the construction of 17 bridge decks in Kansas that were let under Low-Cracking High-Performance Concrete (LC-HPC) specifications. The report documents the performance of the decks based on crack surveys performed on the LC-HPC decks and matching control bridge decks. The specifications for LC-HPC bridge decks, which cover aggregates, concrete, and construction procedures, as well as procedures for performing crack surveys, are summarized. The first 13 LC-HPC bridge decks are compared to control decks in terms of crack density as a function of time. Survey results are also presented for three LC-HPC decks without control decks and one deck let under LC-HPC specifications on which the specifications were not enforced. The widths of measured cracks ranged from 0.006 to 0.025 inches (0.15 to 0.64 mm). The LC-HPC bridge decks exhibit less cracking than the matching control decks in the vast majority of cases. Only bridge decks LC-HPC-2 and LC-HPC-3 have higher overall crack densities than their control decks, the two best performing control decks in the program, and the differences are small. The majority of the cracks are transverse and run parallel to the top layer of the deck reinforcement. Relatively short cracks are present near the abutments and propagate perpendicular to the abutments (longitudinally). The study demonstrates the positive effects of reduced cementitious material and cement paste contents, improved early-age and long-term curing, concrete temperature control, limitations on or de-emphasis of maximum concrete compressive strength, limitations on maximum slump, and minimizing finishing operations on minimizing cracking in bridge decks.

Development and Layout of a Protocol for the Field Performance of Concrete Deck and Crack Sealants

Development and Layout of a Protocol for the Field Performance of Concrete Deck and Crack Sealants
Author: José Antonio Pincheira
Publisher:
Total Pages: 62
Release: 2009
Genre: Concrete bridges
ISBN:
GET BOOK

The main objective of this project was to develop and layout a protocol for the long-term monitoring and assessment of the performance of concrete deck and crack sealants in the field. To accomplish this goal, a total of six bridge decks were chosen for study. The decks have ages that vary from 4 to 30 years old, are all in good condition, though some presented a variety of longitudinal, transverse and diagonal cracking. In each deck, test segments were laid out along one lane in four of the six bridges. Drill powder samples were extracted in each segment in order to determine the in-situ, near-surface chloride ion content of the deck. Laboratory analyses of the samples showed that the chloride ion content varied between 3.2 lb/cy for the younger decks (3 years old) and 20.8 lb/cy for the older decks (28 years old). Based on the recommendations of a previous laboratory investigation, a pool of the best performing deck and crack sealants were selected to be applied in the decks. In two bridges, deck segments were sealed with four deck sealants while one segment was left unsealed to be used as a control segment. Additionally, the cracks in each of these segments were sealed with five crack sealants. While two other decks were also scheduled for sealing as part of this phase of the project, they were not done because the required curing time for some of the products was longer than deemed acceptable by DOT crews for these high traffic bridges. It is recommended, however, that every effort be made to have these decks be sealed in the near future. The remaining two bridges had been sealed at the time of construction. While no specific information could be secured about the product used in these decks, the low chloride ion content in these decks suggested that the applied product has helped reduce the ingress of chloride ions. Therefore, it is recommended that these decks continue to be monitored over time. Based on the inspections and the data collected in the field, a protocol and schedule for the continuing monitoring of sealant performance is presented.