Most authoritative works that discuss the issue of whether or not calcium chloride should be used as an accelerating admixture in concrete made with Type V sulfate-resisting cement warn against its use. The origin of this warning is reviewed, and the conclusion is reached that it is probably not harmful to obtaining the desired level of sulfate resistance (for which the use of Type V cement was specified) to use calcium chloride in normally acceptable amounts as an accelerating admixture in such concrete to mitigate the effects of cold weather.

Corrosion of reinforcing steel is now recognized as the most critical limit state affecting the durability and long-term stability of concrete structures. Although concrete is inherently alkaline and provides a natural protection to any embedded steel in it, thereby insuring its chemical passivity, concrete structures deteriorate for a variety of reasons. Steel corrosion is the most insidious and destructive form of damage, and once it starts, it is almost impossible to stop the process (unless such remedial measures as cathodic protection systems are applied), until eventually the safety, stability, and design life of the structure are all drastically reduced in time. The primary causes of steel corrosion are inadequate cover to steel, carbonation, neutralization due to atmospheric pollutants, and/or chloride penetration. The quality of concrete, its pore structure, and permeability characteristics are thus major factors controlling steel corrosion. However, it is inherent in the nature of concrete construction that there is no single method of corrosion protection that may be presumed to insure satisfactory serviceability throughout the life of a structure. This paper briefly reviews the factors that influence concrete deterioration and loss of alkalinity. It is shown that long-term durability of concrete structures can only be insured by a dual approach--developing a durable concrete, and providing a protective coating to the steel. Such methods of steel protection as cement-slurry coating, epoxy coating, and galvanizing are discussed. Extensive test results are presented on the corrosion resistance of plain, epoxy-coated, and galvanized bars when exposed to a marine environment, and chloride intrusion in cracked members. Cracking, cover, and concrete quality are identified as the major parameters influencing steel corrosion, but cover to steel is the most critical factor in preserving the electrochemical stability of steel. The paper shows that both epoxy-coated reinforcing bars and galvanized reinforcing bars can provide excellent resistance to chloride-induced corrosion.

One of the major problems with rehabilitation of frost damage in old non-air-entrained hydraulic structures is prevention of failure of the repaired surface at the new/old concrete interface or in the old substrate concrete below the repair due to trapped moisture and subsequent freezing of the critically saturated substrate. A survey of several 40- to 75-year-old, non-air-entrained concrete dams indicated that in many cases the concrete at the water line was not damaged due to freezing and thawing. This would appear to contradict conventional wisdom based on ASTM C 666 testing of non-air-entrained concrete. Instead, most of the deterioration had taken place on the inclined downstream faces of the gravity sections, away from direct exposure to water, but subject to many cycles of freezing in air. In some cases, water leaked through joints in the concrete and initiated progressive raveling. However, in other cases, it appeared that moisture was drawn to the exposed surfaces by capillary suction. As a result of these observations, it was decided to develop a one-sided freezing test, with the unfrozen side exposed to water and the freezing side exposed to air, to better simulate field exposure. The cylindrical concrete specimens are monitored with temperature, relative humidity, and moisture probes at various depths during testing. This should allow evaluation of non-air-entrained concrete and various repair materials on the freezing surface to observe whether moisture is building up to critically saturated levels that would result in deterioration. While the equipment for this test has been designed and built, testing is at a preliminary stage. Describes the nature of frost damage in hydraulic structures and then describes the new test procedure in detail.

As the sole domestic building material in Iceland, concrete is widely used for house construction as well as for other construction, such as dams, bridges, and harbors. In Iceland, conditions are in many ways extreme: the climatic conditions are harsh, the cement is high in alkalies, aggregates are of varying quality (some being reactive), and codes and standards have been sparse. Field surveys have shown that alkali-aggregate reaction (AAR) damage occurs where no preventive measures were taken and other conditions were unfavorable. Preventive measures taken in dam and bridge construction have proven to be effective. No AAR damage has been found in constructions erected after 1979, when several preventive measures were taken. The most important one is 5 to 7+ percent replacement of cement with silica fume Stricter criteria have been enforced to secure freeze-thaw durability, and durability design is improving. Research in repair and maintenance methods has had considerable influence on the construction industry.

The principal mechanism for the deterioration of concrete is transport of fluids either into or out of the pore structure of hardened body. The fluid transport occurs via a complex network of interconnected porosity incorporating both the cementitious matrix and matrix/aggregate interfacial regions. Paper describes the development of an experimental method and a mathematical background for a rapid water-permeability measurement method and a mathematical model relating porosity, described in terms of a log-normal distribution, to permeability.