Concrete Technology for Transportation Applications (2019) / Chapter Skim
Currently Skimming:
Pages 102-112
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 102... ...
102 Florida Department of Transportation: Temperature Control of Mass Concrete Criteria to Be Considered as Mass Concrete ACI 301, "Specifications for Structural Concrete for Buildings," states that a concrete placement should be designated as mass concrete when the maximum temperatures and temperature differences must be controlled due to factors including the content and type of cementitious materials, environment surrounding placement, and minimum dimension of placement. To put this statement in context, ACI 301 contends that, in general, a placement of structural concrete with a "minimum dimension equal to or greater than 4 feet should be considered mass concrete." ACI 301 also indicates that the minimum dimension could be reduced by concrete placements that produce higher rates of heat generation at early ages, such as those that contain Type III cement, accelerating admixtures, or have high contents of cementitious materials.
|
From page 103... ...
Case Examples of State Practices 103 6. Names and qualifications of all designees who will inspect the installation of and record the output of temperature measuring devices, and who will implement temperature control measures directed by the Specialty Engineer, 7.
|
From page 104... ...
104 Concrete Technology for Transportation Applications – All elements have the same insulation R value and active cooling measures (if used) , and – Ambient temperatures during concrete placement for all elements is within −10°F or +5°F of the ambient temperature during placement of the initial element.
|
From page 105... ...
Case Examples of State Practices 105 Illinois Department of Transportation: Reducing Concrete Shrinkage in Bridge Decks Introduction The Illinois DOT has for at least the last 20 years been working to mitigate the early age transverse cracking that is a typical problem on its bridge decks. A variety of high-performance concrete mix designs were tried in the late 1990s.
|
From page 106... ...
106 Concrete Technology for Transportation Applications humidity decreases during hydration or drying. Thus, by reducing moisture gradients within the concrete, internal curing can alleviate capillary stresses and associated shrinkage strains.
|
From page 107... ...
Case Examples of State Practices 107 • Working closely with the SRA manufacturer's technical representative is advisable. For example, if freeze-thaw deterioration is a concern, there are some SRAs that can make it more difficult to achieve a stable, satisfactory air void system.
|
From page 108... ...
108 Concrete Technology for Transportation Applications (3.65-m) lanes, 4-ft (1.22-m)
|
From page 109... ...
Case Examples of State Practices 109 Performance Within several months after construction, hairline horizontal cracks appeared in some panels. The thinking was that they were present since fabrication because shrinkage cracks had not opened enough to become visible until later.
|
From page 110... ...
110 Concrete Technology for Transportation Applications can be better controlled. SR is directly affected by water content, pozzolan content, and, to a lesser extent, by aggregate gradation.
|
From page 111... ...
Case Examples of State Practices 111 With the performance approach, the contractor/producer now assumes the responsibility of the production and performance of the concrete mixture. With this transfer of risk comes an increased material cost to the owner.
|
From page 112... ...
112 Concrete Technology for Transportation Applications DOT. One effective method that the Tennessee DOT has found to be useful in overcoming this resistance is by having a good working relationship with the individual industry liaison groups.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.