EFFECTS ON HIGH CONCRETE TEMPERATURES
Mixing Water Requirements
Because high temperatures accelerate hardening, a particular concrete consistency generally requires more mixing
water than normal. Figure 4-13 shows a linear relationship between an increase in concrete temperature and the
increase in mixing water required to maintain the same slump. However, increasing water content without
increasing cement content results in a higher w/c ratio, which has a harmful effect on the strength and other
desirable properties of hardened concrete.
Figure 4-13. Relationship between concrete temperature and mixing water.
Compressive Strength of Concrete
Figure 4-14 on page 4-24 demonstrates the effects of high concrete temperatures on compressive strength. Tests
using identical concretes having the same w/c ratio show that while higher concrete temperatures increase early
strength, the reverse happens at later ages. If water content is increased to maintain the same slump (without
changing the cement content), the reduction in compressive strength is even greater than that shown in Figure
4-14.
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