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ASTM ACI CONCRETE STRENGTH TECHNICIAN EXAM | ALL
QUESTIONS AND CORRECT ANSWERS | VERIFIED
ANSWERS | LATEST VERSION 2025 | ALREADY GRADED A+
What is ASTM C1231? ---------CORRECT ANSWER-----------------Standard 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 --------- CORRECT 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. ---------CORRECT ANSWER-----------------.47 in (12mm) and .35in (9mm) (C1231) Bearing surfaces of the retaining ring must not have gauges greater than ---------CORRECT ANSWER-----------------.01 inches (.25mm) deep or .05in (32mm) surface area (C1231) For specimen ends, depressions under a straightedge must not exceed ---------CORRECT ANSWER-----------------.2 inches (5mm) measured across any diameter using a round wire edge (C1231) Depressions on ends of specimens that exceed ___ must be corrected by sawing or grinding ---------CORRECT ANSWER----------------- .2in (5mm)
Procedures for capping enable concrete cylinders and cores to meet C617's practice requirements for___ and___. ---------CORRECT ANSWER- ----------------perpendicularity and planeness Capping plates can be made of what material? (C617) ---------CORRECT ANSWER-----------------glass, 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. --------- CORRECT ANSWER-----------------102% and 107% (c1231) Pad thickness must be ---------CORRECT ANSWER----------------- (13 +/- 2mm) (C1231) The diameter of the pad shall not be more than __ smaller than the inside diameter of the retaining ring ---------CORRECT ANSWER--------- --------1/16 in (2mm) (C1231) Neither end of the cylinder shall depart from perpendicularity by more than __ degrees ---------CORRECT ANSWER-----------------. (C1231) Depressions on ends of specimens that exceed .2in (5mm) must be corrected by ___ or ___ ---------CORRECT ANSWER----------------- sawing or grinding
What is ASTM C78 ---------CORRECT ANSWER-----------------Standard test method for Flexural strength of concrete (C78) When measuring the width and depth of the fractured face, take measurements to the nearest ___ ---------CORRECT ANSWER----------------
- .05in (1mm) (C78) Can this test be conducted with a non motorized machine? --------- CORRECT ANSWER-----------------Yes, 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. mm ---------CORRECT ANSWER-----------------leather shims (C78) Gaps in excess of .015in or .4mm shall be eliminated only by --------- CORRECT ANSWER-----------------capping 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? ---------CORRECT ANSWER-----------------R= PL /bd^ (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? ---------CORRECT ANSWER-----------------3Pa /bd^
(C78) What formula is used to calculate the limits of the loading rate? ------- --CORRECT ANSWER-----------------r=Sbd^2 /L (C78) What is the minimum distance from the end of a specimen to the center line of the nearest support? ---------CORRECT ANSWER----------------
- 1 inch (25mm) (C78) You should begin loading the test specimen by applying an initial load between __% and ___% of the estimated ultimate load --------- CORRECT ANSWER-----------------3 and 6% (C78) Flexural strength should be recorded to the nearest ___ psi --------- CORRECT ANSWER-----------------5psi (.05mPa) (C78) Leather shims should have a uniform thickness of ___inches --------- CORRECT ANSWER-----------------.25in (6mm) (C78) How many measurements across each dimension should be taken when determining the average width, depth, and line of fracture? --------- CORRECT ANSWER-----------------3 measurements across each dimension (C78) If a gap is greater than ___inches in width but less than ___ inches, leather shims, capping, or grinding may be used ---------CORRECT ANSWER-----------------greater than .1mm (.004in) but less than .4mm (.015in)
(C617) When capping cylinders it is acceptable to twist but not rock the capping plate in an effort to extrude___ ___ and ___ ___ ---------CORRECT ANSWER-----------------excess material and air voids (C617) Neat cement paste caps can ___ and ___ if allowed to dry --------- CORRECT ANSWER-----------------shrink and crack (C617) The end of a capped cylinder must be plane to within ___in --------- CORRECT ANSWER-----------------.002in (.05mm) (C617) Empty the pot and recharge with fresh material to ensure the oldest material is not reheated more than how many times? ---------CORRECT ANSWER-----------------5 times (C617) Cement paste should be applied to freshly molded cylinder within how many hours after molding to allow for settling of the concrete specimen ---------CORRECT ANSWER-----------------within 2 to 4 hours (C617) The vertical distance between the highest and lowest points on the end of an uncapped cylinder shall not exceed ___ ---------CORRECT ANSWER-----------------1/8 inch (3mm) (C617) The guide bar/bullseye level ensures caps are perpendicular to the axis within __ degrees ---------CORRECT ANSWER-----------------.5 degrees
(C617) Remove and replace any caps having voids or steam pockets greater than __in ---------CORRECT ANSWER-----------------1/4 inch (6mm) (C617) Metal capping plates should be free of gouges greater than ___in -- -------CORRECT ANSWER-----------------.01 inch (25mm) (C617) In general with high strength gypsum paste, a capping plate may be removed within how many minutes without visibly damaging the cap? ------- --CORRECT ANSWER-----------------45 mins What is ASTM C39? ---------CORRECT ANSWER-----------------Standard Test Method for Compressive strength of cylindrical concrete specimens (C39) Compressive strength should be expressed to the nearest ___psi ---- -----CORRECT ANSWER-----------------10 psi (.1 mPA) (C39) A correction factor is needed if the length to diameter ratio is ___ or less ---------CORRECT ANSWER-----------------1.75 or less (C39) A 28 day old specimen must be tested within how many hours of this age? ---------CORRECT ANSWER-----------------20 hours (C39) The percent of error for loads should not exceed what percent? ------- --CORRECT ANSWER-----------------+/- 1%
(C617) For concrete cylinders with compressive strength greater than 7000psi, the maximum average thickness of the cap must be ___in --------- CORRECT ANSWER-----------------1/8 inch (3mm) (C1231) When testing for acceptance, unbonded capping systems are not to be used for concrete with a compressive strength less than ___psi or greater than ____psi ---------CORRECT ANSWER-----------------1,500 psi and 12,000 psi Thickness of the base plate must be at least __mm thick for a retainer greater than 100mm and __ thick for a retainer 100mm or smaller --------- CORRECT ANSWER-----------------12mm and 8mm Thickness of the retaining ring must be __mm thick for a retainers with nominal diameters greater than 100mm and __ thick for a retainers with a diameter of 100mm or smaller ---------CORRECT ANSWER----------------- 12mm and 9mm When qualification tests of unbonded pads are required, they are performed by the _____ or _____. ---------CORRECT ANSWER----------------
- user or supplier of the unbonded pads When the cylinder compressive strength is between 2,500 and 7,000 psi, the shore A durometer hardness should be? ---------CORRECT ANSWER--- -------------- 60
When the cylinder compressive strength is between 4,000 and 7,000 psi, the shore A durometer hardness should be? ---------CORRECT ANSWER--- -------------- 70 When the cylinder compressive strength is between 7,000 and 12,000 psi, the shore A durometer hardness should be? ---------CORRECT ANSWER--- -------------- 70 The average strength of cylinders tested with unbonded caps may not be less than ______ of the average strength of capped or ground companion cylinders, at a confidence level of ______. ---------CORRECT ANSWER----- ------------98%. Confidence level of 95% Qualification testing for unbonded caps must be repeated whenever there is change in (3) ---------CORRECT ANSWER------------------design or dimensions of the retaining ring
- pad thickness or composition
- Shore A hardness by more than 5 units The bearing surface of the retaining rings must be plane to within ___ in ---- -----CORRECT ANSWER-----------------.002in (.05mm) Sulfur mortars and high-strength gypsum cement cubes must demonstrate a minimum compressive strength of _____ psi or the cylinder strength, whichever is greater. ---------CORRECT ANSWER-----------------5000 psi The technician should use a stiff layer of ____ to cap fresh concrete cylinders ---------CORRECT ANSWER-----------------neat cement paste
The ___ bearing block should provide a readily machinable surface for maintenance of the specified surface conditions ---------CORRECT ANSWER-----------------bottom Calibration of compression testing machine is required within an interval not to exceed __ months ---------CORRECT ANSWER----------------- 13 months Report the computed density to the nearest ___kg/m3 (__lb/ft3) --------- CORRECT ANSWER----------------- 10 kg/m3 (1lb/ft3) The percentage of error for loads used in the testing machine should not exceed +/- ___% ---------CORRECT ANSWER-----------------+/- 1% Specimens shall not be tested if individual diameter measurements for the cylinder differ by more than __ % ---------CORRECT ANSWER----------------- 2% Align the _____ of the specimen with the center of thrust of the spherically seated block. ---------CORRECT ANSWER-----------------axis True or false: When placing the lower bearing block on the table or platen, place the hardened face up ---------CORRECT ANSWER-----------------True
The surface of a bearing block that is 200mm (8in) in diameter must be plane to within ____ in any 150 mm (6in) ---------CORRECT ANSWER------- ----------.001in Prior to positioning the test specimen on the lower bearing block, you should ---------CORRECT ANSWER-----------------clean the surface of both bearing blocks as well as the ends of the cylinder The curved surface of the socket should be clean and lubricated with petroleum type oil at least every __ months ---------CORRECT ANSWER---- ------------- 6 True or false: The testing machine should have 2 steel bearing blocks: a spherically seated block and a solid block ---------CORRECT ANSWER------ -----------true The diameter used for calculating the cross sectional area of the test specimen shall be determined to the nearest ___ inch by averaging two diameters measured at right angles to each other at about mid height of the specimen ---------CORRECT ANSWER-----------------.01 inch (.25mm) Calculate the compressive strength by dividing the _____ by the average _____ area determined. ---------CORRECT ANSWER----------------- maximum load, cross sectional C78 The ratio of the horizontal distance between the line of application of the force and the line of the nearest reaction to the depth of the beam shall be ---------CORRECT ANSWER-----------------1 +/-.
The block surface in contact with the specimen shall not depart from plane by more than ___inch ---------CORRECT ANSWER-----------------.002in ASTM Standard dealing with proper capping methods ---------CORRECT ANSWER-----------------C The procedure for capping enables concrete cylinders to meet the standard's requirements for ____ and ____ ---------CORRECT ANSWER---- -------------Planeness and Perpendicularity equipment needed for the capping process include ____, ____ devices, and ____ pots ---------CORRECT ANSWER-----------------plates, alignment, melting Plates for neat cement and high-strength gypsum plaster caps should be made of ____, ____, ____, or ____ ---------CORRECT ANSWER-------------- ---glass, metal, granite, diabase Sulfur mortar cap plates should be formed against _____ or _____ --------- CORRECT ANSWER-----------------metal or stone The purpose of the guide bar or bullseye level is that caps remain perpendicular to the axis of the cylinder within _____ degrees --------- CORRECT ANSWER-----------------.
to avoid accidents during reheating, use melting pots that have _____ _____ ---------CORRECT ANSWER-----------------peripheral heating The technician should use a stiff layer of _____ to cap fresh concrete cylinders. ---------CORRECT ANSWER-----------------Neat Cement Paste Hardened concrete cylinders should be capped with _____ _____ _____ _____, _____ _____ _____, or _____ _____. ---------CORRECT ANSWER- ----------------high strength gypsum paste, neat cement paste or sulfur mortar Plaster of Paris and Portland Cement are examples of suitable high- strength plasters. True or False? ---------CORRECT ANSWER----------------- False- They are not suitable Sulfur mortars and high strength gypsum cement cubes must demonstrate a minimum compressive strength of _____ or _____; whichever is greater. ---------CORRECT ANSWER-----------------5000 psi or 35 MPa or the cylinder's strength The cement paste should be applied to the freshly molded cylinders from _____ to ______ hours after molding. This is to allow ______ of the concrete specimen. ---------CORRECT ANSWER-----------------2 to 4, setting The strength of the cement paste depends on: Choose all that apply: a) water-cement ratio b) time c) equipment used
The melting pot for the sulfur mortar must have a _____ and _____ for _____ ---------CORRECT ANSWER-----------------hood and exhaust for venting Hydrogen Sulfide gas, which may be produced during capping, may be _____ in high concentrations. In lower concentrations, the gas may result in: (5 answers) ---------CORRECT ANSWER-----------------deadly. nausea, stomach distress, dizziness, headache, eye irritation ASTM C1231 deals with the practice of using ______ _____ --------- CORRECT ANSWER-----------------Unbonded caps When qualification tests of unbounded pads are required, they are performed by the ______ or ______ ---------CORRECT ANSWER------------- ----supplier, user ASTM C1231 establishes a maximum number of pad reuses that may not be exceeded under any circumstances. True of false? ---------CORRECT ANSWER-----------------False Unbonded caps are not to be used for acceptance testing of concrete with compressive strength below _____ or above _____. ---------CORRECT ANSWER-----------------1500 psi (10 MPa) - 12000 psi (80 MPa) Polyurethane or Butyl pads with a shore A durometer hardness of 50 that will be used on concrete with a compressive strength of 1500 to 6000 psi
need not be qualified prior to use. True or False? ---------CORRECT ANSWER-----------------False To keep track of pad usage, the user is required to maintain records that include: ---------CORRECT ANSWER-----------------Date the pads were placed in service, the pad durometer, and number of uses If a new neoprene pad with a Shore A durometer hardness of 50 is intended to test concrete cylinders with an anticipated compressive strength between 1500 and 6000 psi, it may be used "as is" from the manufacturer without further qualification testing. True or false? --------- CORRECT ANSWER-----------------True The term "unbonded cap" refers to the combination of a metal retainer and an elastomeric pad. True or false? ---------CORRECT ANSWER----------------
- True ASTM C1231 may be used instead of the capping requirements of ASTM
- True or False? ---------CORRECT ANSWER-----------------True The pads provide a uniform distribution of load from the bearing blocks of the testing amchine by deforming in initial loading to conform to the contour of the ends of the cylinder. True or false? ---------CORRECT ANSWER------- ----------True When qualifying unbonded caps, strengths below _____ % of the average obtained from bonded caps is considered unacceptable ---------CORRECT ANSWER----------------- 98
