Question

From the stand point of concrete strength, which if the two opotion is undesirable and why?

5. Option A: Concrete cast at 5^oC and cured at 21^oC.
6. Option B: Concrete cast at 21^oC and cured at 5^oC.

Q3. From the stand point of concrete strength, which if the two opotion is undesirable and why? Option A: Concrete cast at 5°C and cured at 21°C. * Option B: Concrete cast at 21°C and cured at 5°C.

Answer 1

Solution:-

(a) Concrete cast at 5oC and cured at 21oC:-

Standard casting temperature is 10o C to 32o C(50o F to 90o F), if concrete casting temperature is below the 50o F so the setting time and setting actions is changed, and the setting action is very slow, so below the teperature 50o F for casting concrete is unsuitable. and 5o C concrete casting temperature is also undesirable.

Minimum casting temperature in cold conditions is 40o F (4.44o C), the concrete not set or setting actions take place in concete below the 4.44o C temperature , so this the minimum teperature to cast the concrete.

Standard curing temperature is 15o C to 27o C(60o F to79o F) , if curing temperaure is below the 15o C so the setting actions (hardenig and strength) is very slow so the concrete 28 day strength is less as compare to standard cured concrete 28 days strength. if the temperature is more than 27o C so the setting action is very fast so the strength of concrete is also less acompare to tandard cured concrete 28 days strength. So the curing temperaure 21o C is the good curing temperature.

(b)   Concrete cast at 21oC and cured at 5oC:-

Concrete casting temperature 21o C is good temperature for casting concrete, because the standard concrete casting temperature is 10o C to 32o C(50o F to 90o F) in this temperature range the concrete mixing and setting actions are very good.

Curing temperature 5o C is not good because the standard curing temperature is 15o C to 27o C(60o F to79o F) , if curing temperaure is below the 15o C so the setting actions (hardenig and strength) is very slow so the concrete 28 day strength is less as compare to standard cured concrete 28 days strength. if the temperature is more than 27o C so the setting action is very fast so the strength of concrete is also less acompare to tandard cured concrete 28 days strength.  

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