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u i the Department. The Engineer may also require the Contractor to perform additional strength testing as necessary to determine structural adequacy of the concrete. Furnish either a structural analysis performed by the Contractor's Engineer of Record to establish strength adequacy or drilled core samples as specified in 346 -10.3 to determine the in -place strength of the LOT of concrete in question at no additional expense to the Department. Obtain the Engineers approval before taking any core samples. When the concrete is deemed to have low strength, obtain and test the cores and report the data to the Engineer within 14 days of the 28 day compressive strength tests. Core strength test results obtained from the structure will be accepted by both the Contractor and the Department as the in -place strength of the LOT of concrete in question. The core strength test results will be final and used in lieu of the cylinder strength test results for determination of structural adequacy and any pay adjustment. The Department will calculate the strength value to be the average of the compressive strengths of the three individual cores. This will be accepted as the actual measured value. 346 -10.2 Determination of Structural Adequacy: If core strength test results are less than 500 psi [3.5 MPa] or 10 %, whichever is greater, below the specified minimum strength, consider the concrete represented by the cores structurally adequate. If the core strength test results are more than 10% or 500 psi [3.5 MPa], whichever is greater, below the specified minimum strength, the Department will consider the concrete represented by the cores structurally questionable. Submit a structural analysis performed by the Contractor's Engineer of Record. If the results of the structural analysis, approved by the Department, indicates adequate strength to serve its intended purpose with adequate durability, the Contractor may leave the concrete in place subject to the requirements of jl 346-11, otherwise, remove and replace the LOT of concrete in question at no additional expense to the Department. 346 -10.3 Coring for Determination of Structural Adequacy: Furnish three undamaged core samples taken from the same approximate location as where the structural questionable concrete represented by the low strength concrete test cylinders was placed. Select the location of the drilled cores so that the structure is not impaired and does not sustain permanent damage after repairing the core holes. Obtain the approval of the Engineer to core, and of the core location prior to drilling. 346 -10.4 Core Conditioning and Testing: The Department will test the cores in accordance with ASTM C 42 [ASTM C 42M]. The Engineer will make the determination whether to test the cores in a dry or wet condition. If the Engineer decides to test the cores in a wet condition, immerse the cores in water for at least 40 hours, and test the cores wet. The cores will be tested within 3 -days after obtaining the samples. 346 -11 Pay Adjustments for Low Strength Concrete. 346 -11.1 General: Any LOT of concrete failing to meet the specified minimum strength as defined in 346 -3, 346 -9, 346 -10 and satisfactorily meeting all other requirements of the Contract Documents, including structural adequacy, the Engineer will �j individually reduce the price of each low strength LOT in accordance with this Section. 346 -11.2 Basis for Pay Adjustments: When an acceptance strength test result falls more than 10% or 500 psi [3.5 MPa], whichever is greater, below the specified minimum strength, core samples may be obtained from the respective LOT of concrete represented by the low acceptance strength test result for determining pay adjustments. Price adjustment will be applied to the certified invoice price the Contractor paid for the concrete. March 2007 01000 -106 03- 4122.D �„ t