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The effect of fly ash content on the air entrainment, freeze-thaw durability, abrasion resistance, strength gain, shrinkage, and creep of concrete was studied. Two different fly ashes were used to replace 0, 20, and 35 percent of a portland cement by weight. A blended cement, containing 20 percent fly ash by weight, was also tested. Three different air entraining admixtures were used. It was found that the use of fly ash in concrete could reduce the effectiveness of air-entraining admixtures depending on properties of the fly ash, such as loss on ignition (LOI). However, concrete containing fly ash exhibited freeze-thaw resistance equal to or better than that of similar concrete containing portland cement only, provided both had similar entrained air contents. Similarly, concrete containing fly ash showed equal or better resistance to abrasion when compared to concrete of equal strength containing no fly ash. The strength gain characteristics of concrete containing fly ash are different from those of concrete containing no fly ash. The creep of concrete containing fly ash was found to be less than or equal to that of portland cement concrete when subjected to equal sustained loads, even though the 28 day compressive strength of the concrete containing fly ash was lower than that of concrete containing no fly ash. The shrinkage of concrete containing fly ash is highly dependent on the curing given to the concrete and on environmental conditions, such as temperature and relative humidity. Not only is the shrinkage of concrete containing fly ash affected by the previously mentioned conditions differently than that of concrete containing no fly ash, but concrete containing Class C fly ash is affected differently than concrete containing Class F fly ash.

Experimental studies on the resistance of concretes to freezing and thawing in a saturated sodium chloride solution are described. The concretes were made of various types of cement differing in content of blast furnace slag. They were cured in water for 1 to 48 days and subsequently stored in air with and without carbon dioxide. Also, the effect of curing, carbonation, and type of cement on the structure of hydrated cement pastes was studied by mercury intrusion porosimetry. The results indicated that for air-entrained portland cement concretes a comparatively short curing period is sufficient to obtain high durability. Prolonged storage in water may reduce durability. Carbonation may have a positive effect. For concretes made of blast furnace slag cements, the required curing time increases with increasing slag content. For cements with a high slag content, air entrainment did not result in improved resistance to freezing and thawing, and carbonation substantially reduced it. The observed behavior of concrete specimens can be interpreted in terms of microstructural changes of the hydrated cement pastes.

Paper presents the results of an experimental investigation on the freeze-thaw durability of polymer modified concrete (PMC). Basically, prism specimens were subjected to a maximum of 900 cycles of freezing and thawing, using ASTM C 666 Procedure A. Five sets of specimens with various amounts of polymer content were tested. The polymer consisted of a liquid epoxy resin and a curing agent (or hardener). Weight and fundamental transverse frequency were measured at various intervals of freeze-thaw cyclic loading. The results indicate that the freeze-thaw durability of PMC is better than that of non-air-entrained plain concrete. The PMC with polymer-cement ratio of 0.4 or higher can withstand 900 cycles of freezing and thawing.

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.

Describes a laboratory investigation of concrete to determine the effect of the various brands of Type 10 portland cement with and without interground limestone on the strength and freeze-thaw durability. Two classes of concrete and two combinations of aggregates were used in the investigations. A variation in the strength of concrete made with the various cements was found. The limestone addition increases the concrete strength. Concretes made with each of the cements had very good resistance to freezing and thawing in water. However, there was a considerable variation in the resistance to salt scaling.