AASHTO R 81-2017 Standard Practice for Static Segregation of Hardened Self-Consolidating Concrete (SCC) Cylinders.pdf

1、Standard Practice for Static Segregation of Hardened Self-Consolidating Concrete (SCC) Cylinders AASHTO Designation: R 81-171Technical Section: 3c, Hardened Concrete Release: Group 1 (April 2017) American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite

2、249 Washington, D.C. 20001 TS-3c R 81-1 AASHTO Standard Practice for Static Segregation of Hardened Self-Consolidating Concrete (SCC) Cylinders AASHTO Designation: R 81-171Technical Section: 3c, Hardened Concrete Release: Group 1 (April 2017) 1. SCOPE 1.1. This method covers procedures for determini

3、ng the static segregation resistance (stability) of self-consolidating concrete (SCC) using hardened test specimens. 1.2. The concrete used to make the molded specimens shall be sampled after all on-site adjustments have been made to the mixture proportions, including the addition of mix water and a

4、dmixtures. 1.3. The text of this standard references notes and footnotes that provide explanatory information. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements for this standard. 1.4. The values stated in SI units are to be regarded as the sta

5、ndard. 1.5. 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 establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2. REF

6、ERENCED DOCUMENTS 2.1. AASHTO Standards: M 205M/M 205, Molds for Forming Concrete Test Cylinders Vertically R 60, Sampling Freshly Mixed Concrete T 22, Compressive Strength of Cylindrical Concrete Specimens T 24M/T 24, Obtaining and Testing Drilled Cores and Sawed Beams of Concrete 3. SIGNIFICANCE A

7、ND USE 3.1. This method provides a visual assessment of static segregation resistance of SCC using a hardened visual stability index (HVSI) to evaluate molded or cored hardened concrete cylinders cut lengthwise in two. 3.2. If the specimens are made and cured as specified herein, the resulting stati

8、c segregation test data are able to be used for the following purposes: 2017 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c R 81-2 AASHTO 3.2.1. Acceptance testing for specified static segregation limi

9、ts; 3.2.2. Checking the adequacy of mixture proportions to resist static segregation; and 3.2.3. Quality control. 4. APPARATUS 4.1. Molds, Cylinder150-by-300-mm (6-by-12-in.) cylinder molds for casting concrete test specimens shall conform to the requirements of M 205M/M 205. 4.2. Small ToolsHandhel

10、d wood or metal float or trowel. 4.3. SawThe saw shall have a diamond or silicon-carbide cutting edge and shall be capable of cutting specimens without excessive heating or shock. 4.4. Core DrillThe core drill shall conform to the requirements of T 24M/T 24. 4.5. A suitable container for filling spe

11、cimen molds with SCC. Note 1Experience has shown pails and plastic cylinder molds to be suitable containers. 5. SAMPLING CONCRETE 5.1. Samples of freshly mixed SCC used to fabricate test specimens under this standard shall be obtained in accordance with R 60. 5.2. Cored test specimens taken from har

12、dened self-consolidating concrete under this standard shall be obtained in accordance with T 24M/T 24, except for the following: 5.2.1. Cored test specimens may be taken so that the axis is perpendicular or parallel to the concrete as it was originally placed, and 5.2.2. Cored test specimens shall h

13、ave a minimum diameter of 50 mm (2 in.) and sufficient length to assess extent of static segregation resistance. 5.3. Record the identification of the test specimens with respect to the location of the concrete represented and the time of casting. 6. MOLDING AND CURING SPECIMENS OF FRESHLY MIXED SCC

14、 6.1. Making Specimens: 6.1.1. A minimum of two fresh test specimens shall be molded as near as practicable to the place where they are to be stored. If it is not practicable to mold the specimens where they will be stored, move them to the place of storage immediately after strike off. Place molds

15、on a rigid surface free from vibration and other disturbances. The supporting surface shall be level to within 20 mm/m (0.25 in./ft). 6.1.2. Specimen molds shall be filled in one lift, poured using a suitable container without vibration, rodding, or tapping. 6.1.3. Strike off the surface of the conc

16、rete level with the top of the mold using a float or trowel. 2017 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c R 81-3 AASHTO 6.2. Curing: 6.2.1. Immediately after molding and finishing, the specimens

17、 shall be capped with a plastic cylinder lid and stored for a period up to 24 h at a minimum temperature of 16C (60F). 7. PROCEDURE 7.1. Before subjecting the specimens to sawing, they either shall have a minimum curing period of 24 h or shall attain a minimum compressive strength of 6200 kPa (900 p

18、si) according to T 22. 7.2. Specimens shall be sawn lengthwise down the center. If a specimen cannot be satisfactorily sawed smooth for lack of curing, then the remaining specimen(s) shall remain undisturbed for an additional minimum curing period of 24 h before being subjected to sawing. 7.3. Make

19、a visual assessment of the cut planes of the hardened concrete cylinder or core using the criteria in Table 1 and illustrated in Figures 1 through 6. The cut planes shall be wetted to facilitate visual inspection. For cores taken perpendicular to the concrete as it was originally placed, the “top” a

20、nd “bottom” of the cut plane shall be oriented parallel to the direction of placement. Table 1Hardened Visual Stability Index (HVSI) HVSI Criteria 0, stable No mortar layer at the top of the cut plane and no variance in size and percent area of coarse aggregate distribution from top to bottom. 1, st

21、able Slight mortar layer, less than or equal to 6 mm (1/4in.) tall, at the top of the cut plane and slight variance in size and percent area of coarse aggregate distribution from top to bottom. 2, unstable Mortar layer, less than or equal to 25 mm (1 in.) tall, at the top of the cut plane and distin

22、ct variance in size and percent area of coarse aggregate distribution from top to bottom. 3, unstable Clearly segregated as evidenced by a mortar layer greater than 25 mm (1 in.) tall and considerable variance in size and percent area of coarse aggregate distribution from top to bottom. 8. REPORT 8.

23、1. Report the following information: 8.1.1. Identification number; 8.1.2. Location of concrete represented; 8.1.3. Date and time of molding; 8.1.4. HVSI for each hardened specimen; and 8.1.5. Results of any other tests on the fresh concrete and any deviations from the standard test methods. 2017 by

24、the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c R 81-4 AASHTO Single Coarse Aggregate Mixture Uniformly Graded Coarse Aggregate Mixture Figure 1HVSI = 0, Stable Figure 2HVSI = 0, Stable 2017 by the America

25、n Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c R 81-5 AASHTO Single Coarse Aggregate Mixture Uniformly Graded Coarse Aggregate Mixture Figure 3HVSI = 1, Stable Figure 4HVSI = 1, Stable 2017 by the American Associati

26、on of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c R 81-6 AASHTO Single Coarse Aggregate Mixture Uniformly Graded Coarse Aggregate Mixture Figure 5HVSI = 3, Unstable Figure 6HVSI = 3, Unstable 9. KEYWORDS 9.1. Aggregate mixture; h

27、ardened visual stability index; HVSI; stability; static segregation resistance. 1Formerly AASHTO Provisional Standard PP 58. First published as a full standard in 2017. 2017 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.