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ASTM ACI CONCRETE STRENGTH TECHNICIAN EXAM 2025 |
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ASTM standard dealing with compressive strength of cylindrical concrete specimens ---------CORRECT ANSWER-----------------C ASTM C39 measures the compressive strength of cylindrical concrete specimens that weigh less than 800 kg/m3 (50 lb/ft3). True or false --------- CORRECT ANSWER-----------------False.. weigh more than ASTM C39 consists of applying a compressive axial load to molded cylinders or cores at any rate until failure occurs. True or false? --------- CORRECT ANSWER-----------------False, Specified Rate Results obtained from the compressive strength test method will depend on many things, such as the size and ____ of the specimen, batching, _____ procedures, the age, temperature and _____ conditions during curing. ------ ---CORRECT ANSWER-----------------shape, mixing, moisture ASTM C39 is used to determine ____ _____ of cylindrical specimens. ------ ---CORRECT ANSWER-----------------Compressive Strength The calibration of the testing machines must be verified under 4 conditions: at least ____, upon original installation, or after _____, after making _____ or adjustments, and whenever there is reason to suspect the _____ of the indicated load ---------CORRECT ANSWER-----------------annually, relocation, repairs, accuracy
The machine must be power operated and apply the load intermittently. True or False? ---------CORRECT ANSWER-----------------False Supplemental means of loading for calibration may be power or hand operated. True or False? ---------CORRECT ANSWER-----------------True The percentage of error for loads used in the machine should not exceed _____ of the indicated load. ---------CORRECT ANSWER-----------------+_ 1 % The testing machine should have 2 steel bearing blocks: a spherically seated block and a solid block. True or false? ---------CORRECT ANSWER- ----------------True The _____ and _____ of the spherically seated bearing block must be designed so the steel in the contact area doesn't permanently deform when loaded to the capacity of the testing machine. ---------CORRECT ANSWER- ----------------ball and socketq The curved surface of the socket should be kept _____ and lubricated with _____ _____ _____ ---------CORRECT ANSWER-----------------clean, petroleum-based oil
Prior to testing the specimen, verify that the load indicator is _____ --------- CORRECT ANSWER-----------------zeroed Apply the load _____ and without ______ ---------CORRECT ANSWER------ -----------continuously, shock A higher rate of loading shall be permitted during the application of the first half of the nticipated loading phase, true or false? ---------CORRECT ANSWER-----------------True When the specimen fails, record the ____ _____ carried by the specimen during the test and note the ______ _______ ---------CORRECT ANSWER- ----------------Max Load, Fracture Type Calculate the compressive strength by dividing the _____ _____ by the average _____ _____ ______ ---------CORRECT ANSWER----------------- max load , cross sectional area What should a test report include? ---------CORRECT ANSWER----------------
- id #, max load, age of specimen, cross sectional area, any defects in specimens or caps This ASTM standard deals with the flexural strength of concrete --------- CORRECT ANSWER-----------------ASTM C
The ____ _____ of Portland cement concrete is its ability to resist failure due to _____ stresses ---------CORRECT ANSWER-----------------flexural strength, bending 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)
(C1231) Tolerance on Shore A durometer hardness is +/- __ --------- CORRECT ANSWER-----------------+/- 5 (C1231) The surface of the base plate that contacts the bearing block must be plane to within ___ in. ---------CORRECT ANSWER-----------------.002 in (.05mm) Unbonded caps can be used for ASTM C__, C___, and C___ --------- CORRECT ANSWER-----------------C31, C192, and C 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. ---------CORRECT ANSWER-----------------.5 degrees Qualification tests on an unbonded capping system must be repeated when ever there are changes in _____ (3) ---------CORRECT 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 ---------CORRECT ANSWER-- ---------------10% What is ASTM C617 ---------CORRECT ANSWER-----------------Standard Practice for Capping Cylindrical Concrete Specimens
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) How should force on the specimen be loaded? ---------CORRECT ANSWER-----------------continuously and without shock (C78) Apply the load at a rate that constantly increases the maximum stress on the tension face between __psi/min and __psi/min --------- CORRECT ANSWER-----------------between 125psi/min and 175 psi/min (.9MPa/min and 1.2MPa/min (C78) The span length of a test specimen should be within what percent of three times the depth of the specimen as tested? ---------CORRECT ANSWER-----------------within 2% of three times the depth (C617) Sulfur should be heated to what temperature range? --------- CORRECT ANSWER-----------------265 and 290 degrees F (c617) Measure and record thickness of the cap to the nearest ___in --------
- CORRECT ANSWER-----------------.01inch (C617) When capping cylinders it is acceptable to ___ but not rock the capping plate in an effort to extrude excess material and air voids --------- CORRECT ANSWER-----------------twist (C617) What type of gas can be produced when sulfur mortar is contaminated with organic material? ---------CORRECT ANSWER------------- ----Hydrogen sulfide gas
(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
What ASTM standard describes the apparatus, materials, and procedures for capping freshly molded concrete cylinders with neat cement? --------- CORRECT ANSWER-----------------ASTM C (C617) Plate size for capping must exceed the diameter of the test specimen by __in ---------CORRECT ANSWER-----------------1 inch (25mm) (c617) Guide bars and bullseyes are used to ensure that no single cap departs from perpendicularity to the axis by more than how many degrees - --------CORRECT ANSWER-----------------.5 degrees (C617) Sulfur mortar caps are formed against metal or stone plates. The recessed area that receives molten sulfur must not be deeper than ___in --- ------CORRECT ANSWER-----------------1/2 inch (12mm) (C617) If concrete strength is less than 5000psi, caps shall harden for a minimum of how many hours ---------CORRECT ANSWER----------------- 2 hours (C617) If concrete strength is greater than 5000psi, caps shall harden for a minimum of how many hours ---------CORRECT ANSWER----------------- 16 hours
(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
measure and record the thickness of a piece of cap to the nearest __ in ---- -----CORRECT ANSWER-----------------.01 in (.2mm) The ends of freshly molded cylinders can be capped with what material? --- ------CORRECT ANSWER-----------------Neat cement paste only (not high strength gypsum paste) In all cases, capping plates shall be at least __ in. greater in diameter than that of the test specimen ---------CORRECT ANSWER-----------------1 in (25mm) When checking the thickness of a cap, obtain at least __ random pieces distributed over the entire area of the cap ---------CORRECT ANSWER------ ----------- 6 ASTM C617 planeness of a cap is checked with a straight edge and feeler gauge to ensure that the surface of the cap does not depart from plane by more than __inches ---------CORRECT ANSWER-----------------.002inches When the diameter of the bearing face of a spherically seated block exceeds the diameter of the specimen by more than 13mm concentric circles not more than __ mm deep and __mm wide shall be inscribed to ensure proper centering ---------CORRECT ANSWER-----------------.8mm and 1mm
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
While measuring the specimens after the test procedure, if a fracture occurs at a capped section, do you include the thickness of the cap in your calculations? ---------CORRECT ANSWER-----------------Yes, include the thickness of the cap in the measurement (c78) The block surface in contact with the specimen shall not depart from plane by more than ___inch ---------CORRECT ANSWER----------------- .002in (.05mm) (C78) when measuring the width and depth dimensions of the fractured face, take measurements to the nearest ---------CORRECT ANSWER-------- ---------1 mm (.05in) The drying of the surface of the test specimen will result in a ___ of the measured flexural strength ---------CORRECT ANSWER----------------- reduction For flexural strength, the testing equipment must be capable of maintaining distances between load applying and support blocks constant within +/- ___in. ---------CORRECT ANSWER-----------------+/- .05inches (+/-1mm) For flexural strength, the final report should include both the average width and depth to the nearest __ inch ---------CORRECT ANSWER----------------- .05inches (1mm)
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-----------------.
