Air Replaces Sand in "No-Fines" Concrete
Rudolph C. Valore, Jr. and William C. Green
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Concretes containing high-early strength cement, 20 to 30 percent entrained air in place of fine aggregate, siliceous pea gravel and a proprietary resin or detergent air-entraining agent, were made using ordinary rotating tilt-drum mixers. The maximum air contents in mixes having a compressive strength of 500 psi (28 days) were 25 percent (3.3 bag mix) and 29 percent (5.6 bag mix). The ratio of compressive to transverse and bond strengths was about 3. The saturation coeffcient and capillarity were much lower, the resistance to freezing and thawing generally higher, and the thermal conductivity (k) 30 to 40 percent lower than for nonaerated sand-gravel concrete. The drying shrinkage was about the same as for nonaerated concrete. The compressive strength of all mixes decreased about 100 psi for each percent increase in air content, which was difficult to control.