Proficiency Sample Program Overview

CCRL Proficiency Sample Programs also support accreditation programs conducted by others. Participation in proficiency sample programs also permits laboratories to check consistency of their testing. Results from such programs can be used to evaluate quality of testing between laboratories, and to help identify problems with equipment or procedures. Laboratories are required by ASTM C1222 and C1077 to participate in a proficiency sample program. The Proficiency Sample Programs were developed as a means for a laboratory to monitor the quality of its testing between CCRL on-site assessments. The programs are overseen by ASTM Committees C-1 on Cement and C-9 on Concrete and Concrete Aggregates. Responsibility for the assignment of fees is assumed by the committees, and their payment is made to ASTM. The Proficiency Sample Programs are based on the two-sample system described in papers by Youden [1], and by Crandall and Blaine [2] in the 1959 Proceedings of the American Society for Testing and Materials.

All programs are conducted in a similar manner. At intervals of either 6 or 12 months, quantities of two slightly different lots of a material (cements, pozzolans, concrete aggregates, masonry sand, and masonry units) are procured from commercial sources. This material is then homogenized using well defined procedures and divided into individual test samples at the CCRL facility. Special instructions, and all necessary reporting forms, are furnished with each set of samples. The test procedures to be performed are taken from current ASTM specifications. The specified tests are performed and the results reported to the CCRL for review and evaluation. Test results reported by an individual laboratory are treated confidentially as to source. Approximately six weeks after the samples are distributed, all participants receive a preliminary report which shows tentative average values and standard deviations for each determination, based on a limited number of returned results.

Within two months, a detailed final report is distributed. This report contains average values, standard deviations based on all applicable data, and scatter diagrams. In addition, precision values and other statistical information are produced for use by ASTM committees and other interested organizations. Scatter diagrams are prepared for each test performed by the laboratories. For each pair of samples, the test results of the odd-numbered sample are plotted on the X (horizontal) axis, and the results of the even-numbered sample are plotted on the Y (vertical) axis. A substantial variation of its test values from the center of the diagram is generally of concern to a laboratory. A continuing trend of large variations indicates a need for some corrective action, either in apparatus or technique. To focus attention on significant deviations from the average, each laboratory is given a rating on each determination using a rating scale based on the standard deviation. The ratings have no significance beyond indicating the difference between the individual laboratory result and the average for a particular test. To help give meaning to the ratings obtained by an individual laboratory over a given period of time, performance charts were developed. These charts, which are distributed annually to laboratories, visually show a participant's deviation from the average value on the ten most recent sample pairs, thereby providing a means of monitoring the general tendencies and bias of a laboratory's test results. This information gives some indication of a laboratory's overall proficiency for given tests.

References

  1. Youden, W. J., "Statistical Aspects of the Cement Testing Program", Proceedings, American Society for Testing and Materials, Vol. 59, 1959, p. 1120.
  2. Crandall, J. R. and Blaine, R. L., "Statistical Evaluation of Interlaboratory Cement Tests", Proceedings, American Society for Testing and Materials, Vol. 59, 1959, p. 1129.

Portland Cement Proficiency Sample Program

The Portland Cement Proficiency Sample Program provides for the distribution of a pair of chemical and physical test samples of portland cement twice a year. Samples for the physical tests weigh approximately 7 kg each, and are packaged in plastic bags. Samples for the chemical analyses weigh approximately 20 grams each, and are packed in glass vials. Test samples are shipped to participants in July and January. The physical determinations to be made on each sample cover the tests for portland cement to which reference is made in the current edition of ASTM Standard Specification for Portland Cement (C150), and include the following:

  1. Normal Consistency, C187
  2. Time of Setting byVicat Needle, C191
  3. Time of Setting by Gillmore Needles, C266
  4. Autoclave Expansion, C151
  5. Air Content of Mortar, C185
  6. Compressive Strength of Mortar (3, 7, and 28 days), C109
  7. Fineness by Air Permeability Apparatus, C204
  8. Fineness by the Turbidimeter, C115
  9. Fineness by the 45µm (No. 325) Sieve, C430
  10. Early Stiffening (Paste Method), C451
  11. Expansion of Hydraulic Cement Mortar Bars Stored in Water, C1038
  12. Heat of Hydration (7 and 28 days), C186
  13. Heat of Hydration (3 and 7 days), C1702

The same cement is used for both chemical and physical tests. Normally, one vial is furnished with each chemical sample. Additional vials for use in instrumental determinations may be obtained, if requested in advance of the indicated distribution dates. The chemical tests (ASTM C114) to be performed include the following:

  1. Silicon Dioxide (SiO2)
  2. Aluminum Oxide (Al2O3)
  3. Ferric Oxide (Fe2O3)
  4. Calcium Oxide (CaO)
  5. Free Lime
  6. Magnesium Oxide (MgO)
  7. Sulfur Trioxide (SO3)
  8. Loss on Ignition
  9. Sodium Oxide (Na2O)
  10. Potassium Oxide (K2O)
  11. Strontium Oxide (SrO)
  12. Titanium Dioxide (TiO2)
  13. Phosphorus Pentoxide (P2O5)
  14. Zinc Oxide (ZnO)
  15. Manganic Oxide (Mn2O3)
  16. Chloride (Cl)
  17. Insoluble Residue
  18. Carbon Dioxide (CO2)
  19. Limestone Content
  20. Chromium Oxide (Cr2O3)
  21. Tricalcium Silicate (C3S)
  22. Dicalcium Silicate (C2S)
  23. Tricalcium Aluminate (C3A)
  24. Tetracalcium Aluminoferrite (C4AF)

Unless otherwise specified, the procedure to be used in making these tests is the one customarily followed by the laboratory.


Blended Cement Proficiency Sample Program

The Blended Cement Proficiency Sample Program provides for the distribution of one pair of chemical and physical test samples per year. Samples for the physical tests weigh approximately 7 kg each, and are packaged in plastic bags. Samples for the chemical analyses weigh approximately 20 grams each, and are packed in glass vials. Samples are shipped to participants in February.

Physical and chemical determinations on each sample are to be made in accordance with the current edition of the ASTM Specification for Blended Hydraulic Cements (C595) and the various standards and specifications to which it refers.

The physical tests to be performed include the following:

  1. Normal Consistency, C187
  2. Time of Setting by Vicat Needle, C191
  3. Autoclave Expansion, C151
  4. Air Content of Mortar, C185
  5. Density, C188
  6. Compressive Strength of Mortar (3 and 7 day), C109
  7. Fineness by Air Permeability Apparatus, C204
  8. Fineness by the 45µm (No. 325) Sieve, C430
  9. Heat of Hydration (7 and 28 day), C186

The cement used for the chemical tests is the same as that used for the physical tests. The chemical tests (ASTM C114) to be performed are as follows:

  1. Silicon Dioxide (SiO2)
  2. Aluminum Oxide (Al2O3)
  3. Ferric Oxide (Fe2O3)
  4. Calcium Oxide (CaO)
  5. Magnesium Oxide (MgO)
  6. Sulfur Trioxide (SO3)
  7. Sulfide Sulfur (S)
  8. Insoluble Residue
  9. Loss on Ignition
  10. Sodium Oxide (Na2O)
  11. Sulfide Sulfur (S)
  12. Potassium Oxide (K2O)
  13. Phosphorus Pentoxide (P2O5)
  14. Zinc Oxide (ZnO)
  15. Manganic Oxide (Mn2O3)
  16. Chloride (Cl)
  17. Chromium Oxide (Cr2O3)

Unless otherwise specified, the procedure to be used in making these tests is the one customarily followed by the laboratory.


The Masonry Cement Proficiency Sample Program

The Masonry Cement Proficiency Sample Program provides for the distribution of one pair of test samples per year. Each sample weighs approximately 7 kg and is packaged in a plastic bag. Samples are shipped to participants in August. The physical determinations on each sample are to be made in accordance with the current edition of the ASTM Standard Specification for Masonry Cement (C91) and the various methods and specifications to which it refers. The tests to be performed are taken from current ASTM Specification C91 and include the following test methods as modified by C91:

  1. Normal Consistency, C187
  2. Time of Setting by Gillmore Needles, C266
  3. Autoclave Expansion, C151
  4. Air Content of Mortar, C185
  5. Compressive Strength of Mortar (7 and 28 days), C109
  6. Fineness by the 45 ┬Ám (No. 325) Sieve, C430
  7. Water Retention, C1506
  8. Density, C188

Unless otherwise specified, the procedure to be used in making these tests is the one customarily followed by the laboratory.


The Pozzolan Proficiency Sample Program

The Pozzolan Proficiency Sample Program provides for the distribution of a pair of chemical and physical test samples. Both pozzolans used for the chemical sample pair are either ASTM Class C or Class F fly ashes. Samples for the chemical analysis weigh approximately 30 grams each, and are packaged in glass vials. Samples for physical testing include approximately 2.3 kg each of pozzolan,and approximately 18 kg of a companion portland cement. Samples are shipped to participants in July. Physical and chemical determinations on each sample are to be made in accordance with the current edition of the ASTM Standard Test Method for Sampling and Testing Fly Ash or Natural Pozzolans for Use as a Mineral Admixture in Portland-Cement Concrete (C311) and the various methods to which it refers. The tests to be performed are taken from current ASTM Specification C311 and include the following test methods as modified by C311:

  1. Density, C188 or C604
  2. Fineness by 45µm (No. 325) Sieve, C430
  3. Increase of Drying Shrinkage of Mortar Bars, C157
  4. Soundness by Autoclave Soundness, C151
  5. Air-Entrainment of Mortar, C185
  6. Strength Activity Index with Portland Cement
  7. Effectiveness of Mineral Admixtures in Controlling Alkali Silica-Reactions

The chemical tests (ASTM C114) to be performed include the following:

  1. Moisture Content
  2. Silicon Dioxide (SiO2)
  3. Aluminum Oxide (Al2O3)
  4. Ferric Oxide (Fe2O3)
  5. Calcium Oxide (CaO)
  6. Magnesium Oxide (MgO)
  7. Sulfur Trioxide (SO3)
  8. Loss on Ignition
  9. Available Alkalies

Unless otherwise specified, the procedure to be used in making these tests is the one customarily followed by the laboratory.


Concrete Proficiency Sample Program

The Concrete Proficiency Sample Program provides for the distribution of a pair of samples twice a year. For each individual sample portland cement, coarse aggregate, and fine aggregate are packaged separately. The quantity of material needed for this sample makes it necessary to send the sample pair in six cartons, each weighing approximately between 10.5 to 33 kilograms. The material furnished in each sample is sufficient to perform tests for slump, air content, unit weight, and to make two 6 by 12 inch (150 by 300 mm), or three 4 by 8 inch (100 by 200 mm) test cylinders. Samples are shipped to participants in April and November.

The ASTM standards on which prescribed tests are based are as follows:

  1. Making and Curing Concrete Test Specimens in the Laboratory, C192
  2. Slump of Portland Cement Concrete, C143
  3. Unit Weight of Concrete, C138
  4. Air Content of Freshly Mixed Concrete by the Volumetric Method, C173
  5. Air Content of Freshly Mixed Concrete by the Pressure Method, C231
  6. Density of Compressive Strength Specimens, C39
  7. Compressive Strength of Cylindrical Concrete Specimens, C39

Masonry Mortar Proficiency Sample Program

The masonry mortar program provides for the distribution of one pair of test samples per year. The cement portion of each sample weighs approximately 7 kg and is packaged in plastic bags. The masonry sand portion, used for both samples, is packaged in one container of 15kg. The materials for the sample are purchased from commercial sources, homogenized and packaged, and then shipped to the participants.

The tests to be performed are taken from current ASTM Specification C270 and include the following test methods as modified by C270:

  1. Air Content, C91/C185
  2. Compressive Strength, C109
  3. Water Retention, C1506

Concrete Masonry Units Proficiency Sample Program

The concrete masonry unit program provides for the distribution of one pair of test samples per year. Each sample consists of six 4x8x8 inch units for a total of twelve units. The units are procured with the help of the National Concrete Masonry Association (NCMA). Each unit is weighed and categorized, and then packaged. The units are packaged in specially designed corrugated boxes to prevent damage, and mailed to participants. The tests to be performed are taken from current ASTM Specification C140 and include the following:

  1. Measurement of dimensions
    1. Face shell thickness
    2. Web thickness
  2. Compressive Strength
  3. Absorption
  4. Density


Steel Reinforcing Bar

The steel reinforcing bar program provide for the distribution of one pair of test samples per year. Each sample consists of three bars approximately 28 inches in length usually conforming to A615 orA706. The specimens are cut, randomize, and packaged by CCRL. Samples are distributed in July. Tests to be performed the following:

  1. Weight per Unit Length
  2. Measurement of Deformations
  3. Average Height
  4. Gap
  5. Tensile Strength
  6. Yield Strength
  7. Elongation

Potential Alkali Reactivity of Aggregates (ASR)

The ASR program distributes one pair of test samples per year. Two fine aggregates, each weighing around 4000g, are included. One package of portland cement weighing around 2500 g is supplied for use with both fine aggregates.

The fine aggregates are ASTM C33 fine aggregates and the portland cement is an ASTM C150 cement conforming to the ASTM C151 expansion limits listed in ASTM C1260. These materials are purchased from commercial sources, homogenized and packaged for uniformity and then distributed to participating laboratories.

The test results reported by participating laboratories are found in the current ASTM Test Method C1260 Potential Alkali Reactivity of Aggregates (Mortar-Bar Method) and include:

  1. Zero reading
  2. Three intermediate readings
  3. Reading at 14 days after zero reading
  4. Extended readings at 21 and 28 days

Laboratory ratings will be assigned for the 14 day reading.


Participation in the PSP Programs

A laboratory wishing to join any of the programs may do so by sending a request form along with a check made out to ASTM for the full amount of the plus shipping charges. The appropriate request form with program fee and shipping charge can be obtained by contacting CCRL. On receipt of the request and payment, the laboratory is added to the list of participants, sent a letter of confirmation and an invoice marked "paid", and given an individualized laboratory identification number. Requests received less than 60 days prior to the sample distribution cannot be ensured enrollment in the current sample.