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Publication Number: FHWA-HRT-05-057
Date: October 2006

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PROPOSED CHANGE TO AASHTO Standard Specifications for Methods of Testing

(X) Revision or ( ) Addition T 22

T 22 Standard Method of Test for Compressive Strength of Cylindrical Concrete Specimens

Item No. 1

Revise Section 6.2 as follows:

6.2 Neither end of compressive test specimens when tested shall depart from perpendicularity to the axis by more than 0.5o (approximately equivalent to a difference in height of 1.6 mm (1/16 in.) for a 152 mm (6 in.) diameter cylinder). The ends of compression test specimens that are not plane within 0.050 mm (0.002 in.) shall be sawed, ground, or capped in accordance with T 231 to meet that tolerance; or if the ends meet the requirements of A6, then neoprene caps with steel controllers may be used instead of capping.

Item No. 2

In Section 7.3, add a test age of 56 days as follows:

Test Age Permissible Tolerance

12 hr

±0.25 h or 2.1 percent

24 hr

±0.5 h or 2.1 percent

3 days

2 h or 2.8 percent

7 days

6 h or 3.6 percent

28 days

20 h or 3.0 percent

56 days

40 h or 3 .0 percent

90 days

2 days or 2.2 percent

Item No. 3

Revise Section 7.5.1 as follows:

7.5.1 For testing machines of the screw type, and hydraulically operated machines, the load shall be applied at a rate of movement (platen to crosshead measurement) corresponding to a loading rate on the specimens within the range of 0.20 to 0.30 MPa/s (29 to 44 psi/s). The designated rate of movement shall be maintained at least during the latter half of the anticipated loading phase of the testing cycle.

Item No. 4

10.1 The single operator precision of tests of individual 152x305-mm (6x12-in.) cylinders made from a well - mixed sample of concrete for cylinders made in a laboratory environment and under normal field conditions is as follows:

  Coefficient of Variation Acceptable Range of
    2 results 3 results

Single operator

     

Laboratory conditions

2.37 %

6.6 %

7.8 %

Field conditions

2.87 %

8.0 %

9.5 %

The above values are applicable to 152x305-mm (6x12-in.) cylinders with compressive strengths between 15 and 55 MPa (2000 and 8000 psi). They are derived from CCRL concrete reference sample data for laboratory conditions and a collection of 1265 test reports from 225 commercial testing laboratories in 1978.2


2 Research Report RR:CO9-1006 on file at ASTM Headquarters.

Item No. 5

Either replace Appendix A with ASTM C 1231 or delete Appendix A and adopt ASTM C 1231 as a separate test method with appropriate editorial changes to references to other test methods.

Other Affected Test Methods or Sections

Item Nos. 1, 2, and 3

None

Item Nos. 4 and 5

Other specifications that reference T 22

Background

Item No. 1

T 231 only describes capping.(1) It does not describe sawing or grinding as implied by the existing wording. The proposed revisions will correct an error.

Item No. 2

An age of 56 days is frequently used for testing high-strength concrete and is particularly applicable to precast, prestressed high-strength concrete members.(2) It is also used in the FHWA Definition of HPC.(3)

Item No. 3

The current requirement that the moving head of a screw-type machine shall travel at a rate of approximately 1.3 mm/min (0.05 in/min) when the machine is running idle can result in vastly different stress rates depending on machine and specimen stiffnesses. The proposed revision will provide the same specimen loading rate for both screw type and hydraulic machines.

The existing loading rate for hydraulically operated machines is 0.14 to 0.34 MPa/s (20 to 50 psi/s). Based on research at NIST,(4) a range of loading between 0.20 and 0.30 MPa/s (29 to 44 psi/s) is proposed to reduce testing variability.

Item No. 4

The proposed revision will make T 22 consistent with ASTM C 39.(5)

Item No. 5

The existing Appendix A to T 22 describes procedures for testing 152x305-mm (6x12-in) cylinders using neoprene caps or other reusable cap systems. No limit is specified for the maximum concrete compressive strength that may be tested using T 22. However, the criteria for acceptance of alternate systems only requires testing concrete with compressive strengths up to 41.4 MPa (6000 psi).

ASTM C 1231(6) describes procedures for testing 6x12-in (150x500-mm) or 4x8-in (100x200-mm) cylinders using unbonded caps. It is applicable for concrete compressive strengths up to 12,000 psi (80 MPa).

For high-strength concrete, 4x8-in (152x305-mm) cylinders are often used because of the limited capacity of available testing machines. Additionally, commercial match-curing systems are only available for 4x8-in (152x305-mm) cylinders. The proposed revision will permit the use of 4x8-in (152x305-mm) cylinders.

Anticipated Effect on Bridges

Item No. 1

None.

Item No. 2

Clarify a testing procedure.

Item No. 3

Improved quality control.

Item No. 4

Clarify a testing procedure.

Item No. 5

Facilitate QC testing programs for high-strength concrete.

References

  1. AASHTO T 231 Standard Method of Test for Capping Cylindrical Concrete Specimens.
  2. High Performance Concrete, Compact Disc, Federal Highway Administration, Version 3.0, February 2003.
  3. Goodspeed, C. H., Vanikar, S., and Cook, R., "High Performance Concrete Defined for Highway Structures," Concrete International, Vol. 18, No. 2, February 1996, pp. 62-67.
  4. Carino, N. J., Guthrie, W. F., and Lagergren, E. S., "Effects of Testing Variables on the Measured Compressive Strength of High-Strength (90 MPa) Concrete," NISTIR 5405, NIST, October 1994, 141 pp.
  5. ASTM C 39 Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens.
  6. ASTM C 1231 Standard Practice for Use of Unbonded Caps in Determination of Compressive Strength of Hardened Concrete Cylinders.

(Submitted by: )

PROPOSED CHANGE TO AASHTO Standard Specifications for Methods of Testing

(X) Revision or ( ) Addition T 23

T 23 Standard Method of Test for Making and Curing Concrete Test Specimens in the Field

Item No. 1

Revise Section 8.3.1 as follows:

8.3.1 Methods of ConsolidationPreparation of satisfactory specimens requires different methods of consolidation. Except for self-consolidating concrete, the methods of consolidation are rodding, and internal or external vibration. Base the selection method of consolidation on the slump, unless the method is stated in the specifications under which the work is being performed. Rod or vibrate concretes with slump of 25 mm (1 in.) or greater. Vibrate concretes with slumps of less than 25 mm (1 in.). Concretes of such low water content that they cannot be properly consolidated by the methods described herein, or requiring other sizes and shapes of specimens to represent the product or structure, are not covered by this method. Specimens for such concretes shall be made in accordance with the requirements of Method T 126 with regard to specimen size and shape and method of consolidation.

Item No. 2

Table 1—Number of Layers Required for Specimens currently reads as follows:

Specimen Type and Size Mode of Number of Layers

as Total Depth, mm (in.) Compaction or Depth of Layers

Cylinders:

300 12 or less rodding 3 equal layers

Over 300 (12) rodding 100 mm (4 in.) depth as near as practicable

Over 300 (12) to 460 (18) vibration 2 equal layers

Over 18 (460) vibration 200 mm (8 in.) depth as near as practicable

Revise to read as follows:

Specimen Type and Size Mode of Number of Layer

Compaction or Depth of Layers

Cylinders:

100 (4) rodding 2 equal layers

150 (6) rodding 3 equal layers

225 (9) rodding 4 equal layers

100(4) vibration 2 equal layers

150 (6) vibration 2 equal layers with 2 insertions per layer

225 (9) vibration 2 equal layers with 4 insertions per layer

Over 225 (9) vibration 200 mm (8 in.) depth as near as practicable

Item No. 3

Revise Section 8.3.3.1 as follows:

8.3.3.1 Internal VibrationThe diameter of the vibrating element, or thickness of a square vibrating element, shall be in accordance with the requirements of Section 4.5. The diameter of a round vibrator shall be no more than one-fourth the diameter of the cylinder mold or one-fourth the width of the beam mold. Other shaped vibrators shall have a perimeter equivalent to the circumference of an appropriate round vibrator. In compacting the specimen. . . .

Item No. 4

Revise Section 9.2.1 as follows:

9.2.1 Initial CuringAfter molding, the specimens shall be stored in a temperature range between 16 to 27°C (60 to 80°F), and in a moist environment preventing any loss of moisture up to 48 hours (Note 2). For concrete mixtures with a specified strength of 40 MPa (6,000 psi) or greater, the initial curing temperature shall be between 20 and 26°C (68 and 78°F). At all times the temperature. . .

Other Affected Test Methods or Sections

None

Background

Item Nos. 1 and 2

These revisions will make T 23 consistent with ASTM C 31-00 and are based on results reported in ACI SP 172.(1)

Self-consolidating concretes are commonly used in Japan, Canada, and Europe and are being used more and more in the USA. They do not need to be mechanically consolidated and test methods should not require it.

Item No. 3

This revision will make T 23 consistent with ASTM C 31-00 and allow a reasonable smaller diameter size vibrator.

Item No. 4

This revision will make T 23 consistent with ASTM C 31-00. For high-strength concrete, a higher amount of cementitious material including pozzolans or slag is generally used. Therefore, these concretes are more sensitive to heat and a stricter control on initial curing temperature is necessary.

Anticipated Effect on Bridges

Improved test procedures for quality control.

References

  1. Carino, N. J., Mulling, G. M., and Guthrie, W. F., "Evaluation of the ASTM Standard Consolidation Requirements for Preparing High-Strength Concrete Cylinders," High-Performance Concrete: Design and Materials and Recent Advances in Concrete Technology, Publication SP 172, American Concrete Institute, Farmington Hills, MI, 1998, pp. 733-768.

(Submitted by: )

PROPOSED CHANGE TO AASHTO Standard Specifications for Methods of Testing

(X) Revision or ( ) Addition T24

T 24 Standard Method of Test for Obtaining and Testing Drilled Cores and Sawed Beams of Concrete

Item No. 1

Change Section 6.2.2 as follows:

6.2.2 The end surfaces shall not depart from perpendicularity to the longitudinal axis by more than 0.5 degrees, and . . .

Item No. 2

Revise Section 6.4 as follows:

6.4 CappingBefore making the compression test, saw or gr i nd the ends of the specimens in accordance with the tolerance requirements of Method T 22 or cap the ends of the specimens in conformance with the procedure prescribed in the applicable section of T 231. The capped surfaces of the specimens shall conform to the planeness requirements of T 231.

Item No. 3

In Section 6.7.2, revise footnote a as follows:

aThese correction factors apply to lightweight concrete weighing between 1600 and 1920 Kg/m3 (100 and 120 lb/ft3) and to normal weight concrete. They are applicable to concrete dry or soaked at the time of loading. Values not given in the table shall be determined by interpolation. The correction factors are applicable for nominal concrete strengths from 13.8 to 41.4 MPa (2000 to 6000 psi). For strengths above 70 MPa (10,000 psi), test data on concrete cores show that the correction factors may be larger than the values listed. Thus, these factors should be applied to high-strength concrete with caution. (Correction factors depend on various conditions such as strength and elastic moduli. Average values are given in the table.)

Other Affected Test Methods or Sections

None

Background

Item No. 1

Change is needed to make T 24 consistent with tolerances in ASTM C 42(1) and AASHTO T 22.(2)

Item No. 2

Section 6.4 currently requires that drilled cores be capped in accordance with AASHTO T 231.(3) Test method T 231 specifies the use of high-strength gypsum plaster or sulfur mortar for drilled concrete cores. This excludes the use of cores with ends that are sawed, ground, or tested with neoprene caps. Sawed or ground specimens are often used as the basis for establishing that capping systems are suitable for use with high-strength concrete. As such, the procedure needs to be included in T 24. The revision will make T 24 more consistent with ASTM C 42.

Item No. 3

The strength correction factors have been established for conventional strength concrete. Their applicability with high-strength concrete has not been clearly established.

Anticipated Effect on Bridges

Clarify a testing procedure.

References

  1. ASTM C 42 Standard Test Method for Obtaining and Testing Drilled Cores and Sawed Beams of Concrete.
  2. AASHTO T 22 Standard Method of Test for Compressive Strength of Cylindrical Concrete Specimens.
  3. AASHTO T 231 Standard Method of Test for Capping Cylindrical Concrete Specimens.

(Submitted by: )

PROPOSED CHANGE TO AASHTO Standard Specifications for Methods of Testing

( ) Revision or (X) Addition T 106

T 106 Standard Method of Test for Compressive Strength of Hydraulic Cement Mortar (Using 50‑mm or 2-in. Cube Specimens)

Item No. 1

Revise Table 3—Testing Time Tolerances as follows:

Test Age Permissible Tolerance

24 hours ± 1/2 hour

3 days ± 1 hour

7 days ± 3 hours

28 days ± 12 hours

56 days ± 24 hours

Item No. 2

Add to Table 4—Precision, footnote a as follows:

aThese numbers represent, respectively, the (IS percent) and (D2S percent) limits as described in Practice C 670. Precision data for tests at ages of 24 hours and 56 days are not available.

Other Affected Test Methods or Sections

None

Background

Item Nos. 1 and 2

56 days is a common age for HPC and is used in the FHWA definition of HPC even though the definition is for concrete and this test method covers mortars.(1) A permissible tolerance of ± 24 hours at 56 days is recommended until research shows otherwise.

Anticipated Effect on Bridges

More economical bridges when HPC is used.

References

  1. Goodspeed, C. H., Vanikar, S., and Cook, R., "High Performance Concrete Defined for Highway Structures," Concrete International, Vol. 18, No. 2, February 1996, pp. 62-67.

(Submitted by: )

PROPOSED CHANGE TO AASHTO Standard Specifications for Methods of Testing

(X) Revision or ( ) Addition T 126

T 126 Standard Method of Test for Making and Curing Concrete Test Specimens in the Laboratory

Revise Section 7.4.1 as follows:

7.4.1 Methods of ConsolidationPreparation of satisfactory specimens requires different methods of consolidation. Except for self-consolidating concrete, the methods of consolidation are rodding, and internal or external vibration. Base the selection of the method of consolidation. . .

Other Affected Test Methods or Sections

None

Background

Self-consolidating concrete does not require any mechanical consolidation and test methods should not require it.

Anticipated Effect on Bridges

More appropriate procedure for making test specimens of self-consolidating concrete.

References

None

(Submitted by: )

PROPOSED CHANGE TO AASHTO Standard Specifications for Methods of Testing

( ) Revision or (X) Addition T 132

T 132 Standard Method of Test for Tensile Strength of Hydraulic Cement Mortars

Item No. 1

Revise Section 8.1.1 as follows:

8.1.1 The proportions of the standard mortar shall be 1 part cement to 3 parts standard sand by weight. When supplementary cementing materials are used, they shall replace a portion of the portland cement as required. The quantities of dry materials to be mixed at one time in the batch of mortar shall be no less than 1,000 nor more than 1,200 g for making six briquets and no less than 1,500 nor more than 1,800 g for making nine briquets. The percentage of water used in the standard mortar shall depend upon the percentage of water required to produce a neat cement paste of normal consistency from the same sample of cement and shall be as indicated in Table 2, the values being in percentage of the combined dry weights of the cement and standard sand. Determine the percentage of water required to produce a neat cement paste of normal consistency in accordance with T 129.

Item No. 2

Revise the table in Section 8.4.1 as follows:

Test Age Permissible Tolerance

24 hours ± 1/2 hour

3 days ± 1 hour

7 days ± 3 hours

28 days ± 12 hours

56 days ± 24 hours

Other Affected Test Methods or Sections

None

Background

Item No. 1

Supplementary cementing materials, such as fly ash, slag, or silica fume, are widely used in HPC and mortars and need to be included in T 132.(1)

Item No. 2

56 days is a common age for HPC and is used in the FHWA definition of HPC even though the definition is for concrete and this test method covers mortars.(2) A permissible tolerance of + 24 hours is recommended until research shows otherwise.

Anticipated Effect on Bridges

More economical and improved durability of concrete.

References

  1. High Performance Concrete, Compact Disc, Federal Highway Administration, Version 3.0, February 2003.
  2. Goodspeed, C. H., Vanikar, S., and Cook, R., "High Performance Concrete Defined for Highway Structures," Concrete International, Vol. 18, No. 2, February 1996, pp. 62-67.

(Submitted by: )

PROPOSED CHANGE TO AASHTO Standard Specifications for Methods of Testing

(X) Revision or ( ) Addition T 157

T 157 Standard Method of Test for Air-Entraining Admixtures for Concrete

Item No. 1

Revise Section 4.1 as follows:

4.1 Cementitious MaterialsThe cementitious materials used in any series of tests shall be either the cement proposed for specific work in accordance with Section 4.4, a Type I or Type II cement conforming to M 85, or a blend of two or more cements of the same type, in equal part, or a cement conforming to M 240 or ASTM C 1157. Each cement of the blend shall conform to the requirements of Type I or Type II of M 85, or M 240 or ASTM C 1157. If a blend of cements is used, it shall be a combination which produces an air content of less than 10 percent when tested in accordance with T 137 (Note 3).

Item No. 2

Revise Section 4.4 as follows:

4.4 Materials for Test for Specific Uses—When it is desired to test an air-entraining admixture for use in specific work, the cementitious material s and aggregates used should be representative of those proposed for use in the work, and the concrete mixtures should be designed to have the cementitious materials content specified for use in the work (Note 13). If the maximum size of coarse aggregate is greater than 25.0 mm (1 in.), the freshly mixed concrete shall be screened over a 25.0-mm (1-in.) sieve prior to fabricating the test specimens in accordance with the wet sieving procedure described in T 141. When other admixtures are intended to be used in the production of concrete, they should be included in the trial batch .

Item No. 3

Revise Section 10.1.1 as follows:

10.1.1 Compressive Strength—T22. Test specimens at ages 3, 7, 28, 56, and 180 days, and 1 year (Note 5). Calculate . . .

Item No. 4

Revise Section 13.1.6 as follows:

13.1.6 Detailed data on the concrete mixtures used, including amounts and proportions of admixtures used, actual amounts of cementitious materials, water-cementitious materials ratios, ratios of fine to total aggregates, consistency, and air content.

Other Affected Test Methods or Sections

None

Background

Item Nos. 1 and 2

Most HPC contains pozzolans, silica fume, or slag. The effectiveness of air-entraining admixtures is affected by the use of pozzolans, silica fume, or slag or other admixtures. Consequently, all cementitious materials and admixtures proposed for the specific work should be included.

Item No. 3

Test age of 56 days is common for HPC and is used in the FHWA definition of HPC.(1)

Item No. 4

It is very common to use other cementitious materials with portland cements. Consequently, the term cementitious materials should be used.

Anticipated Effect on Bridges

More realistic test to evaluate effectiveness of air-entraining admixtures.

References

  1. Goodspeed, C. H., Vanikar, S., and Cook, R., "High Performance Concrete Defined for Highway Structures," Concrete International, Vol. 18, No. 2, February 1996, pp. 62-67.

(Submitted by: )

PROPOSED CHANGE TO AASHTO Standard Specifications for Methods of Testing

(X) Revision or ( ) Addition T 158

T 158 Standard Method of Test for Bleeding of Concrete

In Section 5.1, revise the first sentence as follows:

5.1 For concrete made in the laboratory prepare the concrete as described in T 126 .

Other Affected Test Methods or Sections

None

Background

The correct test method stated is T 126.(1)

Anticipated Effect on Bridges

None

References

  1. AASHTO T 126 Standard Method of Test for Making and Curing Concrete Test Specimens in the Laboratory.

(Submitted by: )

PROPOSED CHANGE TO AASHTO Standard Specifications for Methods of Testing

( ) Revision or (X) Addition T 161

T 161 Standard Method of Test for Resistance of Concrete to Rapid Freezing and Thawing

Revise Note 5 as follows:

Note 5—It is not recommended that specimens be continued in the test after their relative dynamic modulus of elasticity has fallen below 50 percent. It is recommended that the test be discontinued when the relative dynamic modulus of elasticity falls below 50 percent. For concretes designated as high performance concretes (HPC) that can become critically saturated and will be subjected to cycles of freezing and thawing, a lower limit of 80 percent for the relative dynamic modulus should be used.

Other Affected Test Methods or Sections

None

Background

The change in the first sentence is to clarify the meaning. The addition of a second sentence is to address high performance concrete. Section 8.3 of AASHTO T 161 states that the test shall be continued until the test specimen has been subjected to 300 cycles or until its relative dynamic modulus of elasticity reaches 60 percent of the initial modulus, whichever occurs first, unless other limits are specified (Note 5). For high performance concrete, a decrease in the relative dynamic modulus to 60 percent is a severe decrease. Results from the FHWA Showcase bridges have demonstrated that it is possible to achieve a relative dynamic modulus of 80 percent after 300 cycles.(1) The lower limit of 80 percent coincides with the lower limit of Grade 2 for freeze-thaw durability as defined by FHWA.(2)

Anticipated Effect on Bridges

Improved freeze-thaw durability.

References

  1. High Performance Concrete, Compact Disc, Federal Highway Administration, Version 3.0, February 2003.
  2. Goodspeed, C. H., Vanikar, S., and Cook, R., "High Performance Concrete Defined for Highway Structures," Concrete International, Vol. 18, No. 2, February 1996, pp. 62-67.

(Submitted by: )

PROPOSED CHANGE TO AASHTO Standard Specifications for Methods of Testing

( ) Revision or (X) Addition T 188

T 188 Standard Method of Test for Evaluation by Freezing and Thawing of Air-Entraining Additions to Portland Cement

Item No. 1

Revise the title as follows:

Standard Method of Test for Evaluation by Freezing and Thawing of Air-Entraining Additions to Hydraulic Cement

Item No. 2

Revise first sentence of Section 4.1 as follows:

4.1 A concrete mixture, using cement containing the air-entraining agent in an amount such that the cement meets the requirements of M 85 or M 240 for air-entraining cements shall be proportioned to have an actual cement content of 335 ± 2.8 kg/m3 (564 ± 5 lb/yd3). The water content of the mixtures shall be adjusted to provide a slump of 63.5 ± 12.7 mm (21/2 ± 1/2 in.). The ratio of fine aggregate to total aggregate shall be adjusted to the optimum for concrete to be consolidated by hand rodding. Recommended values for the percentage of fine aggregate in the total aggregate by absolute volume are: for angular coarse aggregate, 41; for rounded coarse aggregate, 36. If other admixtures are to be used in the intended concrete application, they shall be included in the concrete mixture.

Other Affected Test Methods or Sections

Other specifications and test methods that reference the title of T 188

Background

Item No. 1

Supplementary cementing materials are commonly used in HPC. Therefore, this method needs to encompass all hydraulic cements.

Item No. 2

M 240 covers blended hydraulic cements, which are commonly used in HPC and should be included in T 188.

Bags are not the proper measurements.

Air-void parameters are affected by the presence of other admixtures. Consequently, other admixtures should be included in the concrete mixture.

Anticipated Effect on Bridges

Improved test procedures for durability.

References

None

(Submitted by: )

PROPOSED CHANGE TO AASHTO Standard Specifications for Methods of Testing

(X) Revision or ( ) Addition T 231

T 231 Standard Method of Test for Capping Cylindrical Concrete Specimens

Item No. 1

5.1 The strength of the capping material and the thickness of the caps shall conform to the requirements of Table 1.

Table 1—Compressive Strength and Maximum Thickness of Capping Materials

Cylinder Compressive Strength MPa (psi) Minimum Strength of Capping Material Maximum Average Thickness of Cap Maximum Thickness Any Part of Cap

3.5 to 50 MPa (500 to 7000 psi)

35 MPa (5000 psi) or cylinder strength hichever is greater

6 mm (1/4 in.)

8 mm (5/16 in.)

greater than 50 MPa (7000 psi)

Compressive strength not less than cylinder strength, except as provided in 5.1.1

3 mm (1/8 in.)

5 mm (3/16 in.)

5.1.1 If sulfur mortar, high-strength gypsum plaster, and other materials except neat cement paste are to be used to test concrete with a strength greater than 50 MPa (7000 psi), the manufacturer or the user of the material must provide documentation:

5.1.1.1 That the average strength of 15 cylinders capped with the material is not less than 98 percent of the average strength of 15 companion cylinders capped with neat cement paste or 15 cylinders ground plane to within 0.05 mm (0.002 in.).

5.1.1.2 That the standard deviation of the strengths of the capped cylinders is not greater than 1.57 times that of the standard deviation of the reference cylinders.

5.1.1.3 That the cap thickness requirements were met in the qualification tests, and

5.1.1.4 Of the hardening time of the caps used in the qualification tests.

5.1.2 Additionally, the qualification test report must include the compressive strength of 50-mm (2‑in.) cubes of the material qualified and of neat cement paste cubes, if used. Capping materials conforming to these requirements are permitted to be used for cylinders with strengths up to 20 percent greater than the concrete tested in these qualification tests. The manufacturer must requalify lots of material manufactured on an annual basis or whenever there is a change in the formulation or the raw materials. The user of the material must retain a copy of the qualification results, and the dates of manufacture of material qualified and of the material currently being used. See Table 2.

Table 2—Sample Report of Qualification of a Capping Material

Note—Manufacturer: Testing Supplies Co.

Capping Material: Super Strong AAA-Sulfor mortar

Lot: 12a45 Date Tested: 11/3/98

Signed by:_____________________________________(testing agency and responsible official)

Item Capping Material Control Cylinders Ratio Criteria Pass/Fail

Concrete Cylinder Test Data

Type of capping material

Sulfur

Ground

     

Average Concrete

Strength, MPa (psi)

76.2 (11,061)

75.9 (11,008)

1.005

>0.98 Xc

Pass

Standard Deviation, MPa (psi)

2.59 (376)

1.72 (250)

1.504

< 1.57 C

Pass

Number of cylinders tested

15

15

     

Cap age when cylinders tested

7 days

na

     

Capping Material Test Data

Average cap thickness,

mm (in.)

2.8 (0.11)

na

     

Compressive strength of

50-mm (2-in.) cubes,

MPa (psi)

91 (12,195)

       

Cube age when tested

7 days

       

Maximum concrete strength qualified, MPa (psi)

     

1.2 Av. Str = 91.5 (13,273)a

aNominally a specified strength of 75 MPa (11,000 psi) and perhaps somewhat higher.

5.1.3 The compressive strength of capping materials shall be determined by testing 50-mm (2-in.) cubes following the procedure described in T 106. Except for sulfur mortars, molding procedures shall be as in T 106 unless other procedures are required to eliminate large entrapped air voids. See ASTM C 472 for alternative compaction procedures. Cure cubes in the same environment for the same length of time as the material used to cap specimens.

5.1.4 The strength of the capping material shall be determined on receipt of a new lot and at intervals not exceeding three months. If a given lot of the capping material fails to conform to the strength requirements, it shall not be used, and strength tests of the replacement material shall be made weekly until four consecutive determinations conform to specification requirements.

5.2 Neat Hydraulic Cement Paste:

5.2.1 Make qualification tests of the neat hydraulic cement paste prior to use for capping to establish the effects of water-cement ratio and age on compressive strength of 50-mm (2-in.) cubes.

Note 2—The cements used generally conform to M 85 Types I, II, or III; however, M 240 blended cements, calcium aluminate, or other hydraulic cements producing acceptable strengths may be used.

5.2.2 Mix the neat cement paste to the desired consistency at a water-cement ratio equal to or less than that required to produce the required strength, generally 2 to 4 h ours before the paste is to be used (Note 3). Remix as necessary to maintain acceptable consistency (Note 4). Some retempering of the paste is acceptable if the required water-cement ratio is not exceeded. Optimum consistency is generally produced at water-cement ratios of 0.32 to 0.36 by mass for Type I and Type II cements and 0.35 to 0.39 by mass for Type III cements.

Note 3—Freshly mixed pastes tend to bleed, shrink, and make unacceptable caps. The 2 to 4 h ours period is generally appropriate for portland cements.

Note 4—The required consistency of the paste is determined by the appearance of the cap when it is stripped. Fluid paste results in streaks in the cap. Stiff paste results in thick caps.

5.3 High-Strength Gypsum Cement Paste:

5.3.1 No fillers or extenders may be added to neat high-strength gypsum cement paste subsequent to the manufacture of the cement (Note 5). Qualification tests shall be made to determine the effects of water-cement ratio and age on compressive strength of 50-mm (2-in.) cubes. Retarders may be used to extend working time, but their effects on required water-cement ratio and strength must be determined (Note 6).

Note 5—Low-strength molding plaster, plaster of paris, or mixtures of plaster of paris and portland cement are unsuitable for capping.

Note 6—The water-gypsum cement ratio should be between 0.26 and 0.30. Use of low water-cement ratios and vigorous mixing will usually permit development of 35 MPa (5000 psi) at ages of 1 or 2 h ours . Higher water-gypsum cement ratios extend working time, but reduce strength.

5.3.2 Mix the neat gypsum cement paste at the desired water-cement ratio and use it promptly since it sets rapidly.

5.4 Sulfur Mortar:

5.4.1 Proprietary or laboratory prepared sulfur mortars are permitted if allowed to harden a minimum of 2 h ours before testing concrete with strength less than 35 MPa (5000 psi). For concrete strengths of 35 MPa (5000 psi) or greater, sulfur mortar caps must be allowed to harden at least 16 h ours before testing, unless a shorter time has been shown to be suitable as specified in 5.1.1

Item No. 2

Renumber existing Section 5.2.2.1 as Section 5.4.2 and delete Section 5.3

Item No. 3.

Revise last sentence of existing Section 5.2.2.1 (new Section 5.4.2) to read as follows:

After storage at room temperature to the desired age, but not less than 2 hours, test cubes in compression following the procedure described in T 106 and calculate the compressive strength in megapascals (pounds per square inch).

Item No. 4

In section 2.1 AASHTO Standards, add M 240 Blended Hydraulic Cement

Other Affected Test Methods or Sections

None

Background

Numerous revisions have been made to ASTM C 617 to improve the capping procedures for use with high-strength concrete.(1) Similar revisions have not been introduced into T 231. The proposed changes will make the capping procedures similar in both documents and make AASHTO T 231 more suitable for use with high-strength concrete.(2)

Anticipated Effect on Bridges

Improved quality control procedures.

References

  1. ASTM C 617 Standard Practice for Capping Cylindrical Concrete Specimens.
  2. Lobo, C. L., Mullings, G. M., and Gaynor, R. D., "Effect of Capping Materials and Procedures on the Measured Compressive Strength of High Strength Concrete," Cement, Concrete and Aggregates, Vol. 16, No. 2, December, 1994, pp. 173-180.

(Submitted by: )

PROPOSED CHANGE TO AASHTO Standard Specifications for Methods of Testing

( ) Revision or (X) Addition T 259

T 259 Standard Method of Test for Resistance of Concrete to Chloride Ion Penetration

Item No. 1

In Section 2.1 revise Note 1 to read as follows:

Note 1—This method contemplates the use of a minimum of four specimens for each evaluation with each slab not less than 75 mm (3 in.) thick and with a minimum surface area of 0.018 m2 (28 in.2).

Item No 2

Add a note in Section 3.4 as follows:

3.4 The slabs with dams shall be subjected to continuous ponding with 3-percent sodium chloride solution to a depth of approximately 13 mm (0.5 in.) for 90 days (Note X) . Glass plates shall be placed over the ponded solutions to retard evaporation of the solution. Placement of the glass plates shall not be done in such a manner that the surface of the slab is sealed from the surrounding atmosphere. Additional solution shall be added if necessary to maintain the 13 mm (0.5 in.) depth. All slabs shall then be returned to the drying room as specified under Section 2.2.

Note X—Low permeability concretes may need longer ponding periods than 90 days.

Other Affected Test Methods or Sections

None

Background

Item No. 1

It is more convenient to use cylindrical specimens for this test. This revision allows the use of 6-in (150-mm) diameter cylinders.

Item No. 2

The 90-day ponding is not long enough to discern differences between concretes using 13-mm (0.5‑in) thick layers for the determination of chloride contents.(1) If thin layers of 1 or 2 mm (0.04 or 0.08 in) are used, 90-day ponding may be sufficient. For example, in Nordtest 443 test, thin layers are used and the specimens are ponded for 35 days.(2)

Anticipated Effect on Bridges

Improved test procedures.

References

  1. Ozyildirim, C., "Permeability Specifications for High-Performance Concrete Decks," Transportation Research Record No. 1610, Concrete in Construction, Transportation Research Board, Washington, DC, 1998, pp. 1-5.
  2. 2. Nordtest, "NT Build 443 Concrete, Hardened: Accelerated Chloride Penetration," Espoo, Finland , 5 pp.

(Submitted by: )

PROPOSED CHANGE TO AASHTO Standard Specifications for Methods of Testing

( ) Revision or (X) Addition T 277

T 277 Standard Method of Test for Electrical Indication of Concrete's Ability to Resist Chloride Ion Penetration

Revise Section 8.1 as follows:

8.1 Sample preparation and selection depends on the purpose of the test. For evaluation of materials or their proportions, samples may be (a) cores from test slabs or from large diameter cylinders or (b) 100-mm (4-in.) diameter cast cylinders. For evaluation of structures, samples may be (a) cores from the structure or (b) 100-mm (4-in.) diameter cylinders cast and cured at the field site. Coring shall be done with a drilling rig equipped with a 100-mm (4-in.) diameter diamond dressed core bit. Select and core samples following procedures in T 24. Cylinders cast in the laboratory shall be prepared following procedures in T 126. Unless specified otherwise, test specimens shall be moist cured for 56 days prior to the start of specimen preparation . When accelerated curing is specified for testing at 28 days, moist cure specimens at 23°C (73°F) for one week and at 38°C (100°F) for three weeks.

Other Affected Test Methods or Sections

None

Background

The curing procedure and age are not given in the current method. This leads to confusion and inconsistencies. Higher heat at 100 °F allows the penetrability expected at 6 months to be determined at 28 days.(1)

Anticipated Effect on Bridges

More representative determination of the penetrability leading to more durable structures.

References

  1. Ozyildirim, C., "Permeability Specifications for High-Performance Concrete Decks," Transportation Research Record No. 1610, Concrete in Construction, Transportation Research Board, Washington, DC, 1998, pp. 1-5.

(Submitted by: )

PROPOSED CHANGE TO AASHTO Standard Specifications for Methods of Testing

(X) Revision or ( ) Addition T 285

Part II Tests, Table of Contents, Subject Sequence

Move the listing of T 285 in the Table of Contents from the subject heading of Concrete, Curing Materials, and Admixtures to Metallic Materials for Bridges.

Other Affected Test Methods or Sections

None

Background

Test Method T 285 is currently listed under Concrete, Curing Materials, and Admixtures in the Table of Contents—Subject Index of Part II Tests. It should be listed under Metallic Materials for Bridges where other tests related to metals are listed.

Anticipated Effect on Bridges

None

References

None

(Submitted by: )

PROPOSED CHANGE TO AASHTO Standard Specifications for Methods of Testing

( ) Revision or (X) Addition T XX1 (Slump Flow)

A proposed test procedure on slump flow is attached. Slump flow is intended for self-consolidating concrete.

The test procedure is based on AASHTO T 119.(1)

Other Affected Test Methods or Sections

None

Background

Self-consolidating concrete (SCC) is a concrete that consolidates under its own mass, without adding any supplementary consolidation energy.(2,3) SCC is successfully used in congested areas and thin sections where it is difficult to place concrete and consolidate with vibrators.(4) SCC workability cannot be measured by the regular slump test since the concrete flows and spreads. The appropriate test is the measurement of the slump flow, which is the diameter of the spread.

Anticipated Effect on Bridges

More realistic measure of the flow characteristics of self-consolidating concrete.

References

  1. AASHTO T 119 Standard Method of Test for Slump of Hydraulic Cement Concrete.
  2. Okamura, H. and Ouchi, M., "Self-Compacting Concrete - Development, Present Use and Future," Self Compacting Concrete: Proceedings of the First International RILEM Symposium, Ed. Skarendahl, A. and Petersson, O., France , 1999, 790 pp.
  3. Khayat, K. H., "Self-Consolidating Concrete—A New Class of HPC," HPC Bridge Views, Issue No. 18, November/December 2001, pp. 2.
  4. Campion, M. J. and Jost, P., "Self-Compacting Concrete: Expanding the Possibilities of Concrete Design and Placement," Concrete International, Vol. 2, No. 4, April 2000, pp. 31-34.

(Submitted by: )

AASHTO T XX1

Standard Method of Test for Slump Flow of Hydraulic Cement Concrete

1. SCOPE

1.1. This test method covers determination of slump flow of hydraulic cement concrete.

1.2. The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

1.3. This standard does not purport to address all of the safety concerns 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.

1.4. The text of the standard reference notes provide explanatory material and shall not be considered as requirements of the standard.

2. REFERENCED DOCUMENTS

2.1. AASHTO Standards:

T 119 Slump of Hydraulic Cement Concrete

T 141 Sampling Freshly Mixed Concrete

3. SUMMARY OF TEST METHOD

3.1. A sample of freshly mixed concrete is placed in a mold, shaped as the frustum of a cone, in one lift. The mold is raised, and the concrete allowed to subside. The average diameter and time of the concrete spread are measured and reported as the slump flow diameter and slump flow time of the concrete.

4. SIGNIFICANCE AND USE

4.1. This test method is intended to provide the user with a procedure to determine slump flow of self-consolidating hydraulic cement concretes (Note 1).

Note 1—This test method monitors the consistency of unhardened concrete. The slump flow increases proportionally with the water content and the amount of water-reducing admixtures of a given concrete mixture. The slump flow of a mixture is a time and temperature dependent property. Care should therefore be taken in relating slump flow results obtained under field conditions to strength or durability. Slump flow also provides a visual indication of the potential of the concrete for segregation.

4.2. This test method is considered applicable to plastic concrete having coarse aggregate up to 37.5 mm (1-1/2 in.) in size. If the coarse aggregate is larger than 37.5 mm (1-1/2 in.) in size, the test method is applicable when it is performed on the fraction of concrete passing a 37.5-mm (1-1/2 in.) sieve, with the larger aggregate being removed in accordance with the section titled "Additional Procedure for Large Maximum Size Aggregate Concrete" in T 141.

4.3. This test method is applicable to plastic, cohesive, and flowing concrete (Note 2).

Note 2—Concretes having slumps less than 190 mm (7-1/2 in.) tested in accordance with AASHTO T 119 may not be adequately flowing for this test to have significance. Caution should be exercised in interpreting such results.

5. APPARATUS

5.1. Mold—The test specimen shall be formed in a mold made of metal not readily attacked by the cement paste. The metal shall not be thinner than 1.5 mm (0.060 in.) and if formed by the spinning process, there shall be no point on the mold at which the thickness is less than 1.15 mm (0.045 in.). The mold shall be in the form of the lateral surface of the frustum of a cone with the base 200 mm (8 in.) in diameter, the top 100 mm (4 in.) in diameter, and the height 300 mm (12 in.). Individual diameters and heights shall be within 3 mm (1/8 in.) of the prescribed dimensions. The base and the top shall be open and parallel to each other and at right angles to the axis of the cone. The mold shall be provided with foot pieces and handles similar to those shown in Fig. 1 of T 119. The mold shall be constructed without a seam. The interior of the mold shall be relatively smooth and free from projections. The mold shall be free from dents, deformations, or adhered mortar. A mold, which clamps to a nonabsorbent base plate is acceptable, instead of the one illustrated in T 199, provided that the clamping arrangement is such that it can be fully released without movement of the mold and the base is large enough to contain all the concrete.

5.1.1. Mold with Alternative Materials:

5.1.1.1. Materials other than metal are permitted if the following requirements are met: The mold shall meet the shape, height, and internal dimensional requirements of 5.1. The mold shall be nonabsorbent, resistant to impact forces, and sufficiently rigid to maintain the specified dimensions and tolerances during use. The mold shall be demonstrated to provide test results comparable to those obtained when using a metal mold meeting the requirements of 5.1. Comparability shall be demonstrated on behalf of the manufacturer by an independent testing laboratory. A test for comparability shall consist of at least 10 pairs of comparisons performed at each of three different slump flows ranging from 500 mm (20 in.) to 700 mm (28 in.). No individual test results shall vary by more than 25 mm (1 in.) from that obtained using the metal mold. The average test results of each slump flow range obtained using the mold constructed of alternative material shall not vary by more than 15 mm (0.6 in.) from the average of test results obtained using the metal mold. If any changes in material or method of manufacture are made, tests for comparability shall be repeated. Because the slump flow is time and temperature dependent, perform the comparability test by alternating the use of cones and utilizing several technicians to minimize the time between test procedures.

5.1.1.2. If the condition of any individual mold is suspected of being out of tolerance from the as-manufactured condition, a single comparative test shall be performed. If the test results differ by more than 25 mm (1 in.) from that obtained using the metal mold, the mold shall be removed from service.

5.2. Base Plate—Base plate shall be a flat nonabsorbent, rigid material of at least 700 x 700 mm (28 x 28 in.). The table surface shall have concentric circle marks showing 200‑mm (8-in.) and 500-mm (20-in.) diameter circles.

6. SAMPLE

6.1. The sample of concrete from which test specimens are made shall be representative of the entire batch. It shall be obtained in accordance with T 141.

7. PROCEDURE

7.1. Dampen the mold and place it on the inner circle of the base plate or on a flat, moist, nonabsorbent (rigid) surface with the concentric circles marked as stated in 5.2. During the filling, the operator shall hold the mold firmly by standing on its two-foot pieces. From the sample of concrete obtained in accordance with Section 6, immediately fill the mold.

7.2. In filling the mold, heap the concrete above the mold and strike off the surface of the concrete by means of screeding with a rod or bar. Remove concrete from the area surrounding the base of the mold to preclude any interference with the movement of flowing concrete. Remove the mold immediately from the concrete by raising it carefully in a vertical direction. Start the time measurement and raise the mold a distance of 300 mm (12 in.) in 5 ± 2 seconds by a steady upward lift with no lateral or torsional motion. Complete the entire test from the start of the filling through removal of the mold without interruption and complete it within an elapsed time of 2-1/2 minutes.

7.3. Measure the time when the concrete diameter reaches the 500-mm (20-in.) diameter circle. Wait for the flow to stop and immediately measure the diameters of the spread in two perpendicular directions.

7.4. Visually inspect the stability of the concrete mixture by observing the distribution of the coarse aggregate fraction throughout the spread, particularly along the perimeter. Visually rate the stability according to the following criteria:

  1. No evidence of segregation in the concrete spread and no ring of mortar surrounding the spread
  2. A peripheral mortar ring with a radial width of less than 10 mm (3/8 in.) and/or an aggregate pile in the spread
  3. Segregation as evidenced by a peripheral mortar ring with a radial width of 10 mm (3/8 in.) or greater and/or a large aggregate pile in the spread

8. CALCULATION

Calculate the slump flow as the average diameter of the spread measured at two perpendicular directions to each other.

9. REPORT

9.1. Report the slump flow in terms of millimeters (inches) to the nearest 5 mm (1/4 in.) diameter of the spread:

Example: Slump flow = 650 mm (25-1/2 in.)

9.2. Report the slump flow time to the nearest 0.5 seconds

Example: Slump flow time = 3.5 seconds

9.3. Record the stability of the concrete mixture from the visual inspection performed in 7.4.

10. PRECISION AND BIAS

10.1. Precision:

10.1.1. Interlaboratory Test Method—No interlaboratory test program has been run on this test method. Since it is not possible to provide equivalent concretes at various test sites free of errors from sources other than the slump measurement, a multilaboratory precision statement on different concretes would not be meaningful.

10.1.2. Multi-Operator Test Results—Data not available at this time.

10.2. Bias—This test method has no bias since slump flow is defined only in terms of this test method.

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