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A concrete fish-breeding tank built near the north shore of Lake Superior failed during the first winter. The 250 mm thick concrete wall failed by cracking and delamination in the center of the concrete. The outside surfaces were generally unaffected. The concrete leaked water at such a rate that the tank became unusable. Spring-fed water inside the tank had been maintained at a constant temperature of 4.5 C. At this site, the mean daily temperature in December is -10 C; in January and February it is about -15 C. Minimum temperatures are commonly less than -30 C and may drop to -40 C. The concrete had been delivered by ready-mix trucks following a two-hour haul. Quality control on the site had been poor. The concrete in the failed areas was non-air-entrained and had a high water-cement ratio. Failure was attributed to formation of an ice lens within the permeable concrete.

Previous work demonstrated that carefully monitored length change measurements during the first freeze period of a concrete specimen containing the aggregate being evaluated show a "fingerprint" that can be successfully correlated with the durability factor that is obtained after many later cycles of freezing and thawing. Six different coarse aggregates were used in this study to further substantiate the conclusions of the previous work and to attempt to shorten the test evaluation procedure from 8 to 3 days. The slope of the cumulative length change versus temperature and the length change versus time curve of the first freeze cycle near the freezing point of water was used as the fingerprint. Although attempts to shorten the procedure by using a boiling water accelerated curing procedure were considered successful, it was recommended that other methods of accelerating early strengths be attempted. The tests indicated that the procedure was satisfactory for screening aggregates having a durability factor of less than 30 and greater than 50 percent.

A comprehensive review of the literature about durability (D-) cracking due to frost action in portland cement concrete pavements is developed. D-cracking is defined and described and the mechanisms causing the phenomenon are discussed. The idea that D-cracking is moisture oriented is established. It is affected by freezing temperatures that cause enough volumetric change in the moisture that exists in the cement-aggregate matrix and initiates a durability line crack in the concrete. Factors such as physical characteristics of aggregates and mortar, geographic location, maximum size of coarse aggregates, source of aggregates, and use of deicing agents are found to be among the main factors that affect the development of durability cracking. Tests to indicate frost resistance in aggregate are also reviewed. These tests are of two general types: weathering tests such as unconfined and confined freeze-thaw tests, and measurements of a physical property correlated with performance such as porosity, pore size, and absorption tests. The use of petrographic analysis is an absolute necessity to identify frost-susceptible aggregates. Other tests such as ASTM "Test for Resistance of Concrete to Rapid Freezing and Thawing" (C 666), ASTM "Test for Critical Dilation of Concrete Specimens Subjected to Freezing" (C 671), the PCA method, the Iowa Pore Index Test, and particularly ASTM "Evaluation of Frost Resistance of Coarse Aggregates in Air-entrained Concrete by Critical Dilation Procedures" (C 682) are also considered satisfactory methods to predict field durability performance of concrete aggregates. Researchers such as Axon and others, Iyer and others, and Thompson and Dempsey developed some pertinent tests that could be used in this area as well.

Permeability, a prime factor related to durability of concrete, was measured by water and gas flow in plain and reinforced concrete. The results are discussed in terms of porosity and pore size characteristics as determined by mix proportions and hydration parameters. 617-387 Development of impact-resonant vibration signature for inspection of concrete structures

An investigation was made to determine causes of abnormal expansion and heaving of portland cement-stabilized slag aggregate base material in an airfield runway. Field inspection, petrographic examinations, x-ray diffraction studies, and chemical analyses were made in this investigation. It was concluded that deterioration was due to reactions involving cement hydration products and sulfate derived from certain slag aggregate particles. Whether expansion developed depended on the nature of the sulfate-bearing components originally present in the slag. Recognition of potential for this type of problem appears to be lacking in the published literature and in current specifications.