NaNO2-NaSO4 Combined Additive in Cold Concrete.
COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH
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Experiments were conducted in which NaNO2, Na2SO4 and NC2H4OH3 were added to cold concrete to prevent freezing and promote strengthening. NaNO2 was added in an amount equal to 13.3 of the water content of the concrete, and Na2SO4 and NC2H4OH3 in amounts equal to 3 and 0.03, respectively, of the cement content. The concrete was kept from freezing at -10 C and the strength increased to over 60 of the design strength after 28 days and 80-90 of the design strength after three months. If this type of additive is used under positive temperature conditions 10 to 15 C, it results in an early strengthening effect, good concrete density, resistance to infiltration of up to 28-30 kgsq cm, strength in the later stages 5 to 10 greater than that of ordinary concrete and physical properties superior to those of ordinary concrete. Because of the rust-preventing action of NaNO2, the cold concrete additives do not have any rusting or corroding effects on the steel bars. The facts that cold concrete is convenient to work with, that the additives can be obtained easily and that the costs are comparatively low make this a method that is well worth adopting and using widely in carrying out construction during winter. Author
- Ceramics, Refractories and Glass