[PDF] Latex Modified Concrete Bridge Deck Overlays eBook

Author : Delmo E. Koop
Publisher :
Page : 40 pages
File Size : 33,34 MB
Release : 1982
Category : Concrete
ISBN :

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Portland cement concrete overlay surfacings for bridge decks which will effectively resist de-icing salt solution penetration are a major concern. The report compares the relative effectiveness of latex modified concrete and high density concrete overlays.

Author : Osama Ahmed Abdulshafi
Publisher :
Page : 286 pages
File Size : 13,5 MB
Release : 1990
Category : Bridges
ISBN :

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This study is an investigation of the cause(s) of premature failure of latex modified concrete (LMC) bridge deck overlays in Ohio. Data and materials for 93 bridge decks overlaid with LMC were collected from five Ohio Department of Transportation Districts. Additional materials were collected and evaluations were conducted through monitoring the construction of seven LMC bridge deck overlays. Overall documentation and evaluation of the overlays and materials obtained are discussed; this includes field survey activities, construction monitoring and laboratory testing and analysis. Characteristics of the LMC mixtures and materials are evaluated and compared to acceptable standards. General findings were that most of the problems were due to the underlying old deck which was contaminated with chloride ions, previously undetected due to insufficient testing. Other conclusions are presented separately under construction monitoring, field surveys, and laboratory testing and analysis.

Author : Suvimol Sujjavanich
Publisher :
Page : 294 pages
File Size : 44,7 MB
Release : 1996
Category : Concrete
ISBN :

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Environmental factors and physical properties of latex modified concrete (LMC) are hypothesized to contribute to early age cracking in bridge deck overlays. Cracking permits the ingress of moisture and aggressive solutions into the substrate and may contribute to other subsequent distresses. Understanding the material properties and mechanisms involved is necessary to minimize these distresses. This research consisted of a two part study: first, the development of LMC strength and fracture properties at ages ranging from 5 hours to 28 days was studied, and secondly, the effects of the environment on LMC distresses were modelled. Environmental conditions: temperature, solar energy, and wind speed were determined from weather records. A fracture mechanics based model, the Fictitious Crack Model (FCM), incorporating finite element analyses and superposition techniques was employed with material properties from the first part of study on LMC performance. Different bilinear strain softening diagrams were used to predict fracture performance at different ages. The predictions agreed well with the test data. The impacts of temperature differentials on crack development were studied. The shrinkage effect was also indirectly incorporated through the temperature analysis. The material properties study indicated significant changes in strength, deformability and fracture properties, particularly during the early age. The developments differ slightly from conventional concrete. Test results indicated a significant improvement in reducing and bridging microcracks, especially in the prepeak-load region. Fracture toughness and deformability increased significantly with time. Fracture energy varied from 2.3 to 133.1 N/m, depending on age, and to some degree, on notch depth ratio. In the second stage, the FCM provided a reasonable prediction for crack initiation and propagation when only temperature effects are of concern. Age, surface conditions and structural restraint strongly affect crack resistance of the overlays. Only slight effects were observed from the overlay thickness in the study range (51-76 mm). Shallow preexisting cracks possibly reduce the crack resistance of the overlay about 30 percent. A prolonged moist cure for 48 hours after placing is suggested to reduce the risk of cracking. With available environmental information, it is possible to develop guidelines for appropriate environmental conditions for LMC bridge deck construction to minimize the risk of early age cracking.

Author : JM. Judy
Publisher :
Page : 6 pages
File Size : 39,58 MB
Release : 1977
Category : Bridge decks
ISBN :

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Premature failure of portland cement concrete bridge decks is of national concern, particularly in those areas where chloride residues accumulate in the concrete from winter deicing operations. West Virginia's research and field usage indicates that the application of a relatively thin (1 to 2-in.) overlay of portland cement concrete or mortar containing a latex modifier may result in a significant increase in the useful life of bridge decks. Eighteen structures, including both new construction and renovation of existing decks, have received the latex-modified concrete overlay. Results to date have been most encouraging.