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The Phase I study, conducted prior to the work reported herein, developed the tools to design, mix, place, and cure concrete in cold weather made with various combinations of commercial admixtures. The admixtures helped to protect concrete and maintain productivity, even when the temperature of concrete falls to-5°C soon after mixing. Phase II addressed the effect of high doses of the chemical admixtures studied in Phase I. The primary finding from Phase I that led to this study was that admixtures, when used in moderate dosages, seemed to improve the freeze-thaw durability of concrete. Phase II found what appears to be a maximum dosage after which freeze-thaw durability becomes a concern. That is because cement hydration can only create a finite amount of space to absorb these chemicals. Thus, for freeze protection, admixture dosages should be designed according to water content as specified in Phase I, while, for freeze-thaw durability, admixture dosages should be dictated by cement content. When using both considerations, the freeze-protection limit for enhanced freeze-thaw durable concrete can be lower than the-5°C limit set in Phase I. DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents.

Abstract:A global database of in situ soil test measurements and associated attributes was compiled for use in developing California bearing ratio (CBR) prediction models. From a variety of potential data sources, a collection of U.S. Army and Air Force airfield pavement research and evaluation reports was selected for inclusion. The schema includes data fields for common geotechnical parameters related to airfield pavement strength and geomorphological features associated with soil formation. More than 4,500 records from 46 test sites, representing 10 countries and 4 continents, were gathered and more than 1,500 of these contain field CBR test values. The database includes a wide variety of Unified Soil Classification System (USCS) soil types from a diversity of natural environments. The distribution of the numeric parameters in the database fall within the range of published distributions for natural soils reported in the literature.