# Some solutions wet aggregates pour concrete early in

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. Some solutions Wet aggregates Pour concrete early in the morning (before sunrise) Wet forms Use Cool water Start early curing Cure with water Use retarders Cool concrete trucks by sprinkling water Use fog spraying 13. What is the modulus of rupture for a concrete with an f’ c = 4000 psi.? The modulus of rupture is given by psi 470 4000 5 . 7 f f 5 . 7 f r ' c r = = 14. Could the average of three consecutive concrete tests be below the specified concrete strength? Explain your answer. No. According to ACI 5.6.3.3 (a) every arithmetic average of any three consecutive strength tests shall equal or exceed f’ c . 15. The tests results for two cases with a specified f’c = 5000 psi are shown in the Table below. Determine if the concrete is acceptable in each case. Explain your answer. Case A Test # Cylinder #1 Cylinder #2 Test Average Average of 3 consecutive tests 1 5210 5240 5225 Not applicable 2 5430 5510 5470 Not applicable 3 4480 4870 4675 5123 4 5340 5460 5400 5182 5 4850 5010 4930 5002 Case B Test # Cylinder #1 Cylinder #2 Test Average Average of 3 consecutive tests 1 5310 5420 5365 Not applicable 2 5200 5350 5275 Not applicable 3 4480 4390 4435 5025 4 5420 5570 5495 5068 5 5850 5610 5730 5220

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Case A is satisfactory because it satisfies ACI 5.6.3.3 (a) and (b). Case B is not satisfactory because it does not satisfy ACI 5.6.3.3.(b)
• Spring '09
• bin-shafique
• ACI, sulfate resistance, strength reduction factors, massive concrete structures, early concrete strength

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