ACI Concrete Strength Technician – ASTM C617, C78, and C1231 Exam Questions with Answers

Description: This file provides exam questions and answers for ACI Strength Technician certification, focusing on ASTM test standards. It covers unbonded capping (C1231), compressive strength testing (C617), and flexural strength testing (C78). The material explains specimen preparation, modulus of rupture formulas, fracture measurement, and capping procedures. What is ASTM C1231? - answerStandard Practice for use of Unbonded Caps in determination of compressive strength of hardened cylindrical concrete specimens (C1231) The height (cavity) of the metal retaining ring must be - answer(25 +/- 3mm) (C1231) If the retaining ring is greater than 4in (100mm) it must be at least __ thick. If it is less than 4in, it must be at least __ thick. - answer.47 in (12mm) and .35in (9mm) (C1231) Bearing surfaces of the retaining ring must not have gauges greater than - answer.01 inches (.25mm) deep or .05in (32mm) surface area (C1231) For specimen ends, depressions under a straightedge must not exceed - answer.2 inches (5mm) measured across any diameter using a round wire Page1 edge (C1231) Depressions on ends of specimens that exceed ___ must be corrected by sawing or grinding - answer.2in (5mm) Procedures for capping enable concrete cylinders and cores to meet C617's practice requirements for___ and___. - answerperpendicularity and planeness Capping plates can be made of what material? (C617) - answerglass, machined metal, polished granite, or diabase (c1231) The inside diameter of the retaining rings shall not be less than _____% or greater than _____% of the diameter of the cylinder. - answer102% and 107% (c1231) Pad thickness must be - answer(13 +/- 2mm) (C1231) The diameter of the pad shall not be more than __ smaller than the inside diameter of the retaining ring - answer1/16 in (2mm) (C1231) Neither end of the cylinder shall depart from perpendicularity by more than __ degrees - answer.5 (C1231) Depressions on ends of specimens that exceed .2in (5mm) must be corrected by ___ or ___ - answersawing or grinding (C1231) Tolerance on Shore A durometer hardness is +/- __ - answer+/- 5 (C1231) The surface of the base plate that contacts the bearing block must be plane to within ___ in. - answer.002 in (.05mm) Unbonded caps can be used for ASTM C__, C___, and C___ - answerC31, C192, and C42 After application of the load, but before reaching 10% of the anticipated specimen strength, check to see that the axis of the cylinder does not depart from vertical by more than _____ degrees. - answer.5 degrees Qualification tests on an unbonded capping system must be repeated when ever Page2 there are changes in _____ (3) - answer-The design or dimensions of the retaining rings -Pad composition or thickness -The Shore A hardness by more than 5 units After application of the load, but before reaching _____ of the anticipated specimen strength, check to see that the axis of the cylinder does not depart from vertical by more than .5 degrees - answer10% What is ASTM C617 - answerStandard Practice for Capping Cylindrical Concrete Specimens What is ASTM C78 - answerStandard test method for Flexural strength of concrete (C78) When measuring the width and depth of the fractured face, take measurements to the nearest ___ - answer.05in (1mm) (C78) Can this test be conducted with a non motorized machine? - answerYes, so long as it applies force at a constant rate (C78) It is acceptable to use ___ ___ only when the gap between the specimen surface in contact with the blocks is not more than .015in or .40 mm - answerleather shims (C78) Gaps in excess of .015in or .4mm shall be eliminated only by - answercapping or grinding, not leather shims (C78) if the fracture occurs in the middle third of the span length, what formula is used to calculate modulus of rupture? - answerR= PL /bd^2 (C78) If the fracture occurs outside of the middle third but not by more than 5% of the span length, what formula is used to calculate modulus of rupture? - answer3Pa /bd^2 (C78) What formula is used to calculate the limits of the loading rate? - answerr=Sbd^2 /L (C78) What is the minimum distance from the end of a specimen to the center line of the nearest support? - answer1 inch (25mm) (C78) You should begin loading the test specimen by applying an initial load between