Integrating Construction Practices and Weather Into Freeze Thaw Specifications

It has been suggested that the freeze-thaw behavior of concrete can be related to the rate at which the concrete absorbs water and reaches a critical degree of saturation. After the critical degree of saturation is reached and frozen the sample begins to crack and the stiffness degrades rapidly. This mechanism was suggested by Fagerlund and then expanded by research completed under pooled fund - TPF-5-297. Despite these advancements, there is still more work that is needed. Current design practices for freeze thaw durability are not based on actual weather conditions and are instead based on artificial conditions created in ASTM C 666 testing of concrete. While these conditions seem to have been conservative, a better answer could be obtained if there was more information about how concrete wetted and dried in different environments. This research will use a novel way to measure this by combining low-cost data loggers to measure the moisture and temperature changes in a concrete sent to a number of different environments. This information will be combined with new models that account for the rate that concrete reaches a critical degree of saturation. This work will create specifications that are tailored for different weather conditions and also create a useful forensic tool that could be used to determine the loss in the life of a structure if a substandard concrete is placed. Freeze thaw damage can be suppressed by casting a small and well distributed bubble system in the concrete. The Super Air Meter (SAM) is a new method to measure the size and spacing of these bubbles while the concrete is still fresh by using sequential pressures. Under pooled fund TPF-5-297 the validity of the SAM was established in the lab and the field as well as several new tools were developed to improve the accuracy of the method. Testing was then done to investigate how different construction methods impact the air void system such as pumping. This work will aim to continue to develop the SAM and how different construction practices impact the air void system in fresh concrete. The ultimate goal of this work is to build on previous research efforts to produce improved specifications and advance existing test methods; while, improve the underlying understanding of freeze thaw damage. This work will specifically focus on construction practices and the impact of weather.

Language

  • English

Project

Subject/Index Terms

Filing Info

  • Accession Number: 01731884
  • Record Type: Research project
  • Source Agency: Federal Highway Administration
  • Contract Numbers: TPF-5(448)
  • Files: RiP, USDOT, STATEDOT
  • Created Date: Feb 25 2020 3:11PM