2400 33RD ST 2018-01-02 MF Import

SECTION 01400 QUALITY CONTROL not less than one test per hour during continuous pours. Slump shall be tested in accordance with ASTM C143. c. Strength Tests: Strength tests per ASTM C39 shall be performed on test specirn(:n prepared in accordance with either ASTM C192 for Laboratory Cured Specimen or ASTM C31 for Field Cured Specimen. Strength tests shall conform with the following: 1) Test specimen (cylinders) shall be taken so as to represent as nearly as possible the batch of concrete from which they are taken. 2) Tests shall be performed for each 150 cubic yards of each separate mix design of concrete or fraction thereof being placed each day. 3) The quantity of test specimen shall be produced in order to achieve the following: At least one test at 7 days, at least one test at 28 days and at least two tests at the specified test age as indicated on the structural drawings. 4) An additional test specimen shall be produced should it be necessary to perform further testing. This specimen is to be discarded should the additional testing not be necessary. 5) The strength level of an individual class of concrete for the cured specimen shail be satisfactory if both of the following requirements are met: (1) Average of all sets of three consecutive strength tests equal or exceed the specified compressive strength, (2) No individual class of concrete strength test (average of two cylinders) falls below the specified compressive strength by more than 500 psi. 6) Report exact mix tested, minimum size of aggregate, location of pour in the work, cylinder identification, date of receipt of cylinder in laboratory, cement brand and type, and admixtures used. Investigation of Low -Strength Test Results: When any strength test of laboratory -cured or field -cured test cylinder falls below the specified strength requirement by more than 500 psi, or if tests of field cured cylinders indicate deficiencies in protection and curing, steps shall be taken to assure that load -carrying capacity of the structure is not jeopardized. a. Nondestructive testing in accordance with ASTM C597, ASTM C803, or ASTM C805 may be permitted by the Resident Engineer to determine the relative strengths at various locations in the structure as an aid in evaluating concrete strength in place or for selecting areas to be cored. Such tests, unless properly calibrated and correlated with other test data, shall not be used as a basis for acceptance or rejection. b. When strength of concrete in place is considered potentially deficient, cores shall be obtained and tested in accordance with ASTM C42 . At least three representative cores shall be taken from each member or area of concrete in place that is considered potentially deficient. The location of cores shall be determined by the Resident Engineer to least impair the strength of the structure. c. If the concrete in the structure will be dry under service conditions, the cores shall be air-dried (temperature 60 to 80 degrees F), relative humidity less than 60 percent for seven days before testing and shall be tested dry. If the concrete in the Capital Projects Commuter Rail 01400-5 IFB No. RTA/CP 21-06 Everett Station Phase 2 QUALITY CONTROL