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ACI - Concrete Strength Testing Technician (CSTT)
Detailed Questions and Expert Answers
Standard Practice for Capping Cylindrical Concrete Specimens - ANS ASTM C Procedures for capping enable concrete cylinders and cores to meet C617's practice requirements for___ and___. C617 - ANS perpendicularity, planeness C617, 3. ____ ____ can be made of glass, machined metal, polished granite, or diabase. C617 - ANS Capping plates C617, 4. Sulfur caps can be formed against ___ or___ plates. C617 - ANS metal, stone C617, 4. The working surface of a capping plate shall not depart from a plane by more than ___ inch ( ___ mm) in 6 inches (150 mm).
C617 - ANS 0.002 inch (0.05 mm) C617, 4. Device used in conjunction with a capping plate to ensure perpendicularity. C617 - ANS Alignment device C617, 4. Perpendicularity requirement of the axis of a cylindrical specimen is ___°. C617 - ANS 0.5° C617, 4. The element of a melting pot that ensures against accidents during the reheating of cooled sulfur. C617 - ANS Peripheral Heating C617, 4.3. Temperature of the sulfur mortar pot / materials. C617 - ANS 265 - 290°F (130 - 145°C)
C617, Note: 7 Sulfur and gypsum cubes minimum compressive strength is ____ or the cylinder strength, whichever is greater. C617 - ANS 5000 psi C617, Table 1 Strength of the Neat Cement Paste depends on ___ , ___ , and ___. C617 - ANS Water cement ratio, time, type of cement C617, 5.2.1 & Note: 4 These are avoided when a slight twisting motion is applied while capping. C617 - ANS Air voids and excess paste C617, 6. Sulfur material should not be used more than ___ times. C617 - ANS five C617, 6.2.
When capping concrete cylinders with a compressive strength of 5000 psi ( MPa) or greater, it is permitted to reuse sulfur mortar compound recovered or from the capping operation of old caps. (T/F) C617 - ANS False C617, 6.2. Sulfur mortar should be kept away from ____ while heating. C617 - ANS water C617, 6.2. Sulfur mortar should be kept under a ___ with an ___ for venting. C617 - ANS hood, exhaust fan C617, 6.2.4. Standard Practice for Use of Unbonded Caps in Determination of Compressive Strength of Hardened Concrete Cylinders. - ANS ASTM C Neoprene pads shall be ____ ±____÷ inch ( ____ ±____ mm) thick, and their diameter shall not be more than ¹⁄₁₆" smaller than the inside diameter of the retaining ring.
C1231, 5.
The thickness of the retaining ring for >4" is ____ (____ mm) and for ≤4" is ____ (____ mm) for the metal fixtures. C1231 - ANS 0.47" [12 mm] , 0.35" [9 mm] C1231, 5. The bearing surfaces shall not have gouges, grooves, protrusions, or indentations greater than ____ inch (mm) deep. C1231 - ANS 0.01 inch (0.25 mm) C1231, 5. Cylinders shall be made in accordance with ASTM procedure ____ or ____. C1231 - ANS C31 or C C1231, 6. Depressions in the concrete cylinder shall not exceed ____ inch (____ mm), with grinding, sawing, or capping being the correction. C1231 - ANS 0.20" (5 mm)
C1231, 6.
When tests are made to establish a permissible number of reuses exceeding Table 1, the tests within ____ psi (____ MPa) of the highest strength level will be qualified to be included in the reuse count. C1231 - ANS 2000 psi (14 MPa) C1231, 8.4. Qualification tests of unbonded caps are to be performed by the ____. C1231 - ANS supplier or user C1231, 8. ASTM C1231 establishes a maximum number of pad reuses that may not be exceeded under any circumstances. (T/F) C1231 - ANS False C1231, 1. Psi range in which unbonded caps can be used is ____ - ____ psi (____ - ____ MPa).
ASTM C1231 can be used instead of the capping requirements of what practice? C1231 - ANS ASTM C C1231, 4. The pads provide a uniform distribution of load from the bearing blocks of the testing machine by deforming in initial loading to conform to the contour of the ends of the cylinder. (T/F) C1231 - ANS True C1231, 4. When qualifying unbonded caps, strengths below ___ of the average obtained from bonded caps is considered unacceptable. C1231 - ANS 98% C1231, 8. ASTM C1231 contains step-by-step procedures for aligning the specimens in the testing machine through initial loading. (T/F) - ANS False C39, 8
The diameter of the pads shall not be more than ____ inch ( ____ mm) smaller than the inside diameter of the retaining ring. C1231 - ANS ¹⁄₁₆" (2 mm) C1231, 5.2. Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens
- ANS ASTM C ASTM C39 is limited to concrete having a density in excess of ____ lb/ft³ (____ kg/m³). C39 - ANS 50 lb/ft³ (800 kg/m³) C39, 1. What is the formula to calculate the compressive strength (inch-pounds) according to ASTM C39? (Use at least ____ digits for 𝝅) C39 - ANS compressive strength = Max Load / Area ƒcm = ( 4 × Pmax ) ÷ ( 𝝅 × D² ) five
C39 - ANS upper, lower, steel, hardened C39, 6.2 & 6.2. A ____ seated upper block and ____ lower block shall be on the machine. C39 - ANS spherically, solid C39, 6.2.4.1 & 6.2.5. Bearing faces shall be at least ___ % greater than the diameter of the specimen. C39 - ANS 3% C39, 6.2. Bearing faces shall not depart from a plane by more than ___ inch ( ____ mm) over any ____ inch ( ____ mm) length. C39 - ANS 0.001" (0.02 mm) , 6" (150 mm) C39, 6.2. Align the axis of the specimen with the center of thrust of the ____ block. C39 - ANS upper bearing
C39, 8.
Final centering of the specimen shall be made with reference to the ____ bearing block. C39 - ANS upper C39, Note 11 The minimum thickness of the bottom block is ____ inch ( ____ mm) when new. C39 - ANS 1.0" (22.5 mm) C39, 6.2.5. Every ____ months, clean and lubricate the ____ surfaces of the socket and of the ____ portion of the upper bearing block. C39 - ANS six , curved , spherical C39, 6.2.4. The ____ bearing face shall be able to be tilted at least __ degrees in any direction. C39 - ANS upper , 4°
C39, 8.
Specimens shall be tested in the ___ condition. C39 - ANS moist C39, 8. What should the load indicator be set to before testing the specimen? C39 - ANS Zero C39, 8.4. Alignment of the unbonded caps can be verified after application of load, up to ____ % of the final load. C39 - ANS 10% C39, 8.4. Load shall be applied at a rate of ____ psi/sec ( ____ MPa/sec ) C39 - ANS 35 ±7 psi/sec (0.25 ±0.05 MPa/sec) C39, 8.5.
How long is a higher rate permitted for loading? C39 - ANS first ½ of the anticipated loading C39, 8.5. Compressive strength should be expressed to the nearest ____ psi ( ____ MPa). C39 - ANS 10 psi (0.1 MPa) C39, 10.1. What is the density calculation? C39 - ANS ρs = ( 4 × 10⁶ × W ) ÷ ( L × D² × π ) ρs = specimen density, lb/ft³ [kg/m³], W = mass of specimen in air, lb [kg], L = average measured length, inch [mm], D = average measured diameter, inch [mm] C39, 9.3.
Standard Test Method of Flexural Strength of Concrete (Using Simple Beam with Third-Point Loading) - ANS ASTM C Hand-operated machines having pumps that do not provide a continuous loading in one stoke are not permitted. (T/F) C78 - ANS True C78, 5. Forces applied to the beam will be applied ____ to the face of the specimen and applied without eccentricity. C78 - ANS perpendicularly C78, 5. The testing equipment must be capable of maintaining span length and distance between load-applying and support blocks constant within ____ inch (____ mm). C78 - ANS ±0.05 inch (±1.0 mm) C78, 5.2. Load-bearing and support blocks shall not be greater than ___ inches (____ mm) in height and extend entirely across or beyond ____ ____ ____ of the specimen.
C78 - ANS 2.5 inches (65 mm) , the full width C78, 5.2. Load-bearing and support blocks should be half as wide as the specimen. (T/F) C78 - ANS False C78, 5.2. In relation to the applied force, the loading system should be centered during the procedure. (T/F) C78 - ANS True C78, 7. Leather shims can be used if suitable contact is not made. (T/F) C78 - ANS True. C78, 7. Leather shims can be used only when the gap is less than ___ inch (____ mm). Gaps greater than ____ inch (____ mm) shall be eliminated only by capping or grinding.
