1、Standard Method of Test for Measuring Length of Drilled Concrete Cores AASHTO Designation: T 148-151ASTM Designation: C174/C174M-13 American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-3c T 148-1 AASHTO Standard Method
2、of Test for Measuring Length of Drilled Concrete Cores AASHTO Designation: T 148-151ASTM Designation: C174/C174M-13 1. SCOPE 1.1. This test method covers determination of the thickness of a concrete pavement, slab, or structural element by measuring the length of a core drilled from a concrete struc
3、ture. 1.2. The values stated in SI units are to be regarded as the standard. 1.3. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to consult and establish appropriate safety and health practi
4、ces and determine the applicability of regulatory limitations prior to use. 2. SIGNIFICANCE AND USE 2.1. This method is used to determine the compliance of concrete construction with design specifications. It is especially important in determining the thickness of pavements and other slab constructi
5、on. 3. APPARATUS 3.1. The apparatus shall consist of a 3-point calipering device that will measure the length of axial elements of the core. While the details of the mechanical design are not prescribed, the apparatus shall conform to the requirements of Sections 3.2 to 3.6. 3.2. The apparatus shall
6、 be so designed that the specimen will be held with its axis in a vertical position by three symmetrically placed supports bearing against the lower end. These supports shall be short posts or studs of hardened steel, and the ends that bear against the surface of the specimen shall be rounded to a r
7、adius of not less than 6 mm (0.25 in.) and not more than 13 mm (0.50 in.). 3.3. The apparatus shall provide for the accommodation of specimens of different nominal lengths over a range of at least 100 to 250 mm (4 to 10 in.). 3.4. The calipering device shall be so designed that it will be possible t
8、o make a length measurement at the center of the upper end of the specimen and at eight additional points spaced at equal intervals along the circumference of a circle whose center point coincides with that of the end area of the specimen and whose radius is not less than one half nor more than thre
9、e fourths of the radius of the specimen. 3.5. The measuring rod or other device that makes contact with the end surface of the specimen for measurement shall be rounded to a radius of 3 mm (0.125 in.). The scale on which the length 2015 by the American Association of State Highway and Transportation
10、 Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 148-2 AASHTO readings are made shall be marked with clear, definite, accurately spaced graduations. The spacing of the graduations shall be 1.0 mm (0.10 in.) or a decimal part thereof. 3.6. The apparatus shall be st
11、able and sufficiently rigid to maintain its shape and alignment without a distortion or deflection of more than 0.25 mm (0.01 in.) during all normal measuring operations. 3.7. Verification GaugesSuitable gauges for verification are right circular cylinders with flat ends and a diameter approximately
12、 equal to the diameter of cores intending to be measured and a length in the range of the required measurements. To accommodate various core lengths, gauges are available in several lengths. To minimize uncertainty of the measurement, the length of the cylinder at the perimeter shall be determined a
13、ccurately to 0.05 mm 0.002 in. using calibrated measuring instruments. The flatness of the ends shall not depart from a plane by more than 0.02 mm 0.001 in. in any 150 mm 6 in. of cylinders 150 mm 6 in. in diameter or larger, or by more than 0.02 mm 0.001 in. in the diameter of any smaller cylinder.
14、 4. TEST SPECIMENS 4.1. Cores used as specimens for length measurement shall be in every way representative of the concrete in the structure from which they are removed. The specimen shall be drilled with the axis normal to the surface of the structure, and the ends shall be free from all conditions
15、 not typical of the surfaces of the structure. Cores that show abnormal defects or that have been damaged appreciably in the drilling operation shall not be used. If a core drilled from a pavement or structure placed on dense-graded aggregate base course includes particles of the aggregate bonded to
16、 the bottom surface of the concrete, the bonded particles shall be removed by wedging or by chisel and hammer applied so as to expose the lower surface of the concrete. If the concrete is placed on an open-graded aggregate base course, the mortar in the concrete may penetrate into the base and surro
17、und some particles. Use sufficient force with a wedge or chisel and hammer to remove bonded particles but not such force as to fracture particles substantially surrounded by mortar. If during the removal of bonded aggregate the concrete is broken so that the instructions of Section 5.4 cannot be fol
18、lowed, the core shall not be used for length measurement. 5. PROCEDURE 5.1. Before any measurements of the core length are made, verify the apparatus with suitable gauges, as defined in 3.7, so that errors caused by mechanical imperfections in the apparatus are known. If the difference between the l
19、ength measured with the apparatus and the known length of the verification gauge exceeds 0.25 mm 0.01 in., apply suitable corrections to the core length measurements. 5.2. Place the specimen in the measuring apparatus with the smooth end of the core, that is, the end that represents the upper surfac
20、e of the pavement slab or a formed surface in the case of other structures, placed down so as to bear against the three hardened-steel supports. So place the specimen on the supports that the central measuring position of the measuring apparatus is directly over the midpoint of the upper end of the
21、specimen. 5.3. Make nine measurements of the length on each specimen, one at the central position and one each at eight additional positions spaced at equal intervals along the circumference of the circle of measurement. Read each of these nine measurements to the nearest 1.0 mm 0.05 in. 5.4. If, in
22、 the course of the measuring operation, it is discovered that at one or more of the measuring points the surface of the specimen is not representative of the general plane of the core end because of a small projection or depression, the specimen shall be rotated slightly about its axis and a complet
23、e set of nine measurements made with the specimen in the new position. With cores 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 148-3 AASHTO from pavements placed over open-graded aggregate bas
24、es, the foregoing provisions frequently cannot be met because of the great number of projections or voids on the bottom surface. 6. REPORT 6.1. The individual observations shall be recorded to the nearest 1.0 mm 0.05 in., and the average of the nine measurements expressed to the nearest 1.0 mm 0.1 i
25、n. shall be reported as the length of the concrete core. 7. PRECISION AND BIAS 7.1. Precision: 7.1.1. 3-Point CaliperNo statement is made about the precision of this test procedure. An interlaboratory test program for the determination of core length by this procedure is being studied by ASTM Subcom
26、mittee C09.69 and will be included in a later revision of this test method. 7.2. BiasSince there are not acceptable reference cores suitable for determining the bias of these procedures, no statement on bias is being made. 8. KEYWORDS 8.1. 3-point caliper; concrete; cores; length measurement; thickn
27、ess measurement. 1This method is the same as ASTM C174/C174M-13 except for the following: Section 1.2 of C174/C174M allows either the SI units or inch-pound units to be regarded as standard. Figure 1 of C174/C174M is not included. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.
