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CAST -IN-PLACE CONCRETE Section 03300 15-1207 B. Four identical cylinder samples for strength tests of each class of concrete placed each day shall be taken not less than once a day, or not less than once for each 50 cubic yards of concrete, or not less than once for each 2,000 square feet of surface area for slabs or walls. In addition, samples for strength tests for each class of concrete shall be taken for seven-day tests at the beginning of the concrete work or whenever the mix or aggregate is changed. C. Strength tests will be conducted by the Testing Lab on one cylinder at seven (7) days and two cylinders at twenty-eight (28) days. The fourth remaining cylinder will be available for testing at fifty-six (56) days if the 28 -day cylinder test results do not meet the required design strength. D. On a given project, if the total volume of concrete is such that the frequency of testing required by paragraph B. above would provide less than five strength tests for a given class of concrete, tests shall be made from at least five randomly selected batches or from each batch if fewer than five batches are used. E. Cost of retests and coring due to low strength or defective concrete will be paid by School District and back -charged to the Contractor. F. Moisture and PH Testing of Concrete Slab -On -Grade and Above -Grade Concrete, scheduled to receive any kind of floor finish material; The following tests shall be arranged for and paid for by the contractor to confirm that substrate is ready to receive the specific finish materials: Perform concrete Slab Moisture and pH Testing utilizing ASTM testing methods and practices referenced herein: ASTM F 710 — Standard Practice for Preparing Concrete Floors to Receive Resilient Flooring, ASTM F 1869 — Standard Test Method for Measuring Moisture Vapor Emission Rate of Concrete Subfloor Using Anhydrous Calcium Chloride and ASTM F 2170 — Standard Test Method for Determining Relative Humidity in Concrete Floor Slabs Using In Situ Probes. a. The number of tests required is determined by the square -footage of the project: For areas scheduled to receive Floor Coverings, three (3) tests are required for the first 1,000 square feet, and one (1) additional test for each 1,000 square feet thereafter. b. Moisture Testing must be performed in the same service temperature and humidity environment that the floor covering is going to be in. The building must be enclosed, and the HVAC system should be on for a minimum period of 48 hours prior to and during testing. Otherwise, the results may not accurately reflect the amount of moisture which is present in the slab or would normally be emitted from the concrete during normal operating conditions. If the service temperature and humidity is unattainable, the internal conditions of the building shall have been maintained within the following temperature and humidity range for at least 48 hours: temperature: 650 to 85°F, and relatively humidity: 40% to 60%. C. Properly document and submit all results and procedures including environmental conditions to the Architect a minimum of 10 days prior to scheduled installation date of floor covering. 3. The Contractor or installer is not allowed to conduct these tests. The Contractor shall provide access for and cooperate with the following independent third party, pre - approved testing lab: Independent Floor Testing & Inspection, Inc. (IFTI) 11