12-9.When you perform the flexural-strength tests for a mix design,how many samples should be brokenat 7 days?1.Five2.TWO3.Three4.Four12-10.If the beam sample is too roughfor a proper seat to be formedby the load surface, what actionshould be taken?1.Grind the surface2.Use another beam3.Cap the surface4.Shift the beam to achieveproper contact12-11.An average width and depth shouldbe obtained before performing theflexural-strength test.1.True2.FalseFigure 12AIN ANSWERING QUESTIONS 12-12 THROUGH12-14, REFER TO FIGURE 12A.12-12.What is the modulus of rupture forthe beam if P = 4,000 pounds,b = 6 inches, and the fractureoccurs at point B?1.61.6 psi2.123.5 psi3.172.8 psi4.379.6 psi12-13.What is the modulus of rupturefor the beam if P = 6,000 pounds,b = 4 inches, and the fractureoccurs at point C?1.250.0 psi2.277.8 psi3.388.9 psi4.583.3 psi12-14.If the beam ruptures at point Aunder a load of 5,000 pounds, thetest results should be computedby which, if any, of the followingformulas?12-15.The flexural strength of a testbeam is 625 pounds per squareinch. What is the approximatecompressive strength of theconcrete?1.3,700 psi2.3,800 psi3.3,900 psi4.4,000 psi12-16.The rebound method uses a hammerto test what strength of theconcrete?1.Compressive2.Shear3.Flexural4.Load bearing12-17.The pullout-test method iscorrelated with compressivestrength to determine whatinformation?1.In-place strength2.Flexural strength3.Load-bearing capacity4.Curing time83

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