SP100 "Concrete Durability" has been designed to examine the effects of various concreting materials and construction techniques on the ability of hydraulic cement concretes to remain durable under various aggressive exposure conditions found in today’s environment. "Concrete Durability," a symposium volume comprised of 111 papers from around the world, examines the present state of knowledge, identifies and discusses problems and known solutions, and determines what improvements in practice are needed and how they may be achieved. Published in two volumes, and divided by subject matter (sulfate attack, alkali-aggregate reaction, abrasion, corrosion, and others) topics covered include: durability of high-strength concrete, why we have concrete durability problems, concrete durability in bridges, evaluation of the effectiveness of curing concrete structures, frost susceptibility of high-strength concrete, fly ash, and concrete durability, deterioration of aggregates -- the underlying causes and much more.

The oxygen flux through concrete saturated with water has been calculated by means of the theoretically determined diffusion constant. Presuming oxygen diffusion to be the rate-controlling step, it is concluded, based on this flux, that the corrosion of reinforcement in the underwater zone is negligible. This holds also if the chloride concentration at the surface of the embedded steel exceeds the 0.4 percent by weight of cement level. The calculations are confirmed by analyses carried out on a 35-year-old concrete sea structure that is, until now, the most extensively examined one. In the splash zone of the structure, the chloride concentrations at the surfaces of the reinforcements far exceed the 0.4 percent level. In this zone there is corrosion only in places where depth of cover or quality of concrete are inadequate. Calculation of the oxygen fluxes with the help of diffusion coefficients, taken from the literature, shows that the corrosive attack would be too severe even at a relative humidity of 90 percent. This indicates that the durability of offshore concretes in the splash zone iscontrolled by a thin layer of material saturated with water.

Presents results of accelerated freezing and thawing tests on non-air-entrained concretes containing chloride when tested in water and seawater, in accordance with ASTM C 666, Procedure A. A total of 25 concrete mixes were made. The water-cement ratio of the mixes was 0.55, and the percentage of chloride content as NaCl were 0, 0.1, 0.3, 0.5, 1.0, 3.0, 5.0, and 7.0 percent of the oven-dry sand by weight. Mixing water was replaced by the seawater to add NaCl to each concrete mix. A number of test cylinders were made for testing in compression at various ages, and the test prisms were cast for determining their freezing and thawing resistance. The fundamental transverse resonant frequency, the weight, and the length change of the test prisms were measured during the freezing and thawing test. The air-void parameters of the hardened concrete were determined for using sawn sections of the test prisms. The pore-size distributions of the hardened concrete were measured by a mercury porosimeter. The test results indicated that the freezing and thawing resistance decreased with increasing chloride content in both water and seawater. The air-entrained concrete containing less than 0.3 percent NaCl showed a good freezing and thawing resistance. The air-entrained concrete containing more than 0.5 percent NaCl did not perform satisfactorily in freezing and thawing tests conducted in water and seawater.

Results of a wide-ranging study undertaken to examine the effect of a superplasticizing admixture on the durability of normal-workability concretes are reported. The investigation was based on cement-reduced concrete mixes covering a range of 28-day strength from 20 to 65 MPa, with water-reduced concretes included to increase the data base. Corresponding normal concretes were used for comparison. The experimental program covered included measurements of air and water permeability to assess the overall durability potential; the rates of carbonation and chloride ion diffusion to assess the possible risk of steel reinforcement corrosion in concrete; and the deterioration under alternate freezing and thawing and wetting and drying to assess the resistance of concrete to frost attack and weathering. The results showed that, for a given workability and design strength, the use of a superplasticizing admixture can be expected to effect improvement in the durability of concrete.

Research since 1979 on sealers, coatings, and concrete containing admixtures is summarized. A test procedure developed during a National Cooperative Highway Research Program project, "Concrete Sealers for Protection of Bridge Structures," was used. This test method uses 10 cm cube specimens, and water absorption and chloride ion penetration is determined after 21 days of exposure to 15 percent NaCl solution. The study focuses on the minimization of the ingress of chloride-laden water into concrete, the influence of water-cement ratio, the relationship between water absorption and chloride ion content in concrete, and the comparison of the chloride distribution profiles through the conventional portland cement concrete and concrete containing various admixtures (superplasticizers, polymer emulsions, condensed silica fume).