Commonwealth of Pennsylvania PA Test Method No. 606 Department of Transportation March 2016 Page 1. Laboratory Testing Section. Method of Test for

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1 Page 1 Laboratory Testing Section Method of Test for 1. Scope OBTAINING AND TESTING DRILLED CORES OF CONCRETE 1.1 This method covers the procedures for obtaining, preparing, and testing cores drilled from concrete for length or for compressive strength determinations. This method replaces previously referenced AASHTO T 24 regarding obtaining and drilling cores of concrete 2. Apparatus 2.1 Core drill, for obtaining cylindrical core specimens diamond drill shall be used. 3. Sampling 3.1 General. Do not take samples of hardened concrete for use in the preparation of strength test specimens until the concrete has reached sufficient compressive strength to permit sample removal without disturbing the bond between the mortar and the coarse aggregate. In general, the concrete shall be 14 days old before the specimens are removed. Cores submitted for evaluation of compressive strength must be at least 28 days old. When preparing strength-test specimens from samples of hardened concrete, do not submit samples that show abnormal defects or samples that have been visibly damaged in the process of removal (Note 1). NOTE 1 - Utilize a pachometer to locate reinforcement. Cores for determining compressive strength that contain embedded reinforcement can yield either higher or lower values than cores without embedded steel and will not be tested with reinforcement present. Cores containing reinforcement can be submitted for testing, provided they are sufficient in length to obtain a L/D of 1.00 after removal of the reinforcement. 3.2 Core Drilling. A core specimen taken perpendicular to a horizontal surface shall be located, when possible, so that its axis is perpendicular to the bed of the concrete as originally placed. A specimen taken perpendicular to a vertical surface, or perpendicular to a surface with a batter, shall be taken from near the middle of a unit of deposit when possible, and not near formed joints or obvious edges of a unit of deposit. 4. Length of Drilled Core Specimens 4.1 Length of Specimens. A core specimen for the determination of length shall have a diameter of at least 2 in.

2 Page Procedure for Length Determination. Measure the lengths of cores in accordance with the provisions of the Method of Measuring Length of Drilled Concrete Cores (PTM 614). 5. Compressive Strength 5.1 Test Specimens. The diameters of core specimens for the determination of compressive strength should be at least 3 times the maximum nominal size of the coarse aggregate used in the concrete, and must be at least twice the maximum nominal size of the coarse aggregate. Obtain the largest practical sized diameter core as possible while avoiding interference and damage or cutting of any structural reinforcement. The length of the specimen, when capped, shall be as nearly as practicable twice its diameter. A core having a maximum height of less than 95% of its diameter before capping or a height less than its diameter after capping shall not be tested. Cores submitted for compressive strength testing shall be not less than 2 nor greater than 6 in diameter. Obtain permission from the District Materials Engineer/Manager or Chief Structural Materials Engineer (for precast or prestressed concrete members) if cores less than 4 in diameter shall be submitted for compressive strength testing. 5.2 End Preparation. The ends of the specimens to be tested in compression shall be essentially smooth, perpendicular to the longitudinal axis, and of the same diameter as the body of the specimen. If necessary, saw or tool the ends of the specimens until the following requirements are met: Projections, if any, shall not extend more than 0.2 in. above the normal plate The planes of the ends shall not depart from perpendicularity to the Longitudinal axis by more than 5 degrees The diameters of the ends shall not depart more than 0.1 in. from the mean diameter of the specimen. 5.3 Moisture Conditioning. Completely submerge the test specimens in lime-saturated water at 73.4 ± 3.0 F for 48 +/- 2 hours prior to performing the compression test. Test the specimens promptly after removal from water storage. During the period between removal from water storage and testing, keep the specimens moist by covering with a wet blanket or burlap or other suitable absorbent fabric. 5.4 Capping. Before making the compression test, cap the ends of the specimens in conformance with procedure prescribed in AASHTO T-231. The capped surfaces of the specimens shall conform to the planeness requirements of PTM 611.

3 Page Measurement. Prior to testing, measure the lengths of the capped specimens to the nearest 0.1 in.. Determine the average diameters by averaging two measurements taken at right angles to each other about the mid-height of the specimens. Measure core diameters to the nearest 0.01 in. whenever possible, but at least to the nearest 0.1 in. 5.6 Testing. Test the specimens in accordance with the applicable provisions of the Method of Test for Compressive Strength of Molded Concrete Cylinders (PTM 604). 5.7 Calculations. Calculate the compressive strength of each specimen using the computed cross-sectional area based on the average diameter of the specimen and any other applicable factors from Table 1 below. If the ratio of length to diameter of the specimen exceeds 2.00, it shall be reduced to as close to 2.00 as practical without exceeding LTS will analyze the results for extreme values using PTM 4 at the 5% significance level and compute the average compressive strength, F cores, after discarding any individual extreme values. The in-place strength of the concrete is computed using equation 5-7: Equation 5-7: F c = F core x F ld x F dia x F mc Equation 5-8: F cores = F core/n where: F c: factored in-place concrete strength of each core as computed by Equation 5-7 F core: unfactored compressive strength of individual core F ld: standard correction factor as indicated in Table 1.0 F dia: variable correction factor based on core diameter as indicated in Table 1.0 F mc: standard correction factor as indicated in Table 1.0 n: total number of cores to be averaged to determine in place concrete strength, averaged to nearest whole psi F cores: average computed in-place concrete strength Table 1.0 Magnitude and accuracy of strength correction factors for converting core strengths into equivalent in-place strengths. Primary Factor Secondary Factor, if applicable 3 Correction Factor ¹ F ld: L/D ratio N/A 1 { αf core}(2 L/D)² Fdia: Core Diameter 2 in. ² in. ² in F mc: core moisture content Soaked 48 (+/- 2 hrs) in water 1.09 ¹ α: Constant (α) equals 3 x 10 ^ - 6 ² See section Utilize the correction factors for the actual core size received:

4 Page 4 Correction Core dia., in. factor, Fmc / / / / / / / / / / / / / / / / / / / / / / / / / / / /

5 Page Report. Report the results as required by PTM 604 with the following information: 6. References Length of test specimen before and after capping, individual core diameter, in-place concrete strength (F core) as computed using equation 5-7 and average in-place concrete strength (F core avg) Compressive strength to the nearest 10 psi when the diameter is measured To the nearest 0.01 in. and to the nearest 50 psi when the diameter is nearest 0.1 in., after correction for length-diameter ratio when required, Direction of application of the load on the specimen with respect to the horizontal plane of the concrete as placed, and The moisture condition at the time of testing. AASHTO: T-24 AASHTO: T-231 ASTMC42 ACI 214.4R-10 End of PTM 606

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