AS 2891.14.15:2018 pdf download.Methods of sampling and testing asphalt Method 14.15: Mean, standard deviation coefficient of variation and characteristic values.
I SCOPE
This Standard sets out the method for calculating the mean, the unbiased standard deviation, coefficient of variation and characteristic values of a set of test results. These values are most commonly specified for density ratio and per cent air voids determined in accordance with AS/NZS 2891.14.5 but may also be applied to other test results for asphalt, other construction materials and processes.
2 REFERENCED DOCUMENTS
The following documents are referred to in this Standard: AS 1289 Methods of testing soils for engineering purposes 1289.1.4.1 Method 1.4.1: Sampling and preparation of soils—Selection of sampling or test sites—Random number method 1289.1.4.2 Method 1.4.2: Sampling and preparation of soils—Selection of sampling or test sites—Stratified random number method ASINZS 2891 Methods of sampling and testing asphalt 2891.14.5 Method 14.5: Field density tests—Density ratio and percent air voids of compacted asphalt Main Roads Western Australia Engineering Road Note 8, Statistically based quality control for density in road construction.
3 GENERAL
When any or all of the mean, standard deviation, coefficient of variation and characteristic values of a set of test results are to be determined, they shall be calculated in accordance with this Standard. It shall be permissible to reject abnormal test results before performing the calculation. A result may be assessed as being abnormal only if a specific reason for its abnormality is clearly evident (see Main Roads Western Australia Engineering Road Note 8). The reason for its rejection shall be reported. In practice, specifications may require that test sites for each result be essentially randomly selected in accordance with an appropriate test method such as AS 1289.1.4.1 or AS 1289.1.4.2. The actual statistical values to be calculated will depend on the specification requirements. Individual results obtained in the appropriate test shall not be rounded before use in calculations. As the results to be reported have been subject to statistical analysis, they shall be reported to a greater precision than that indicated in the individual test methods, but to not more than one extra significant figure (for example, for density ratio determined in accordance with ASINZS 289 1.14.5 where individual results are reported to the nearest 0.5%, the statistical values may be reported to the nearest 0.1%). NOTE: The acceptance constant (k) is usually detailed in the specification. However, when this value is not specified, the commonly used values are shown in Table Al of Appendix A. Alternatively, the value may be derived from the tables listed in Main Roads Western Australia Engineering Road Note 8.
5 TEST REPORT
The following shall be reported, as required: The characteristic values of the test results and the acceptance constant used. The mean value of the test results. The standard deviation of the test results. The number of individual values used. Any individual results excluded from the calculations and the reason for the rejection. Reference to this Standard, AS 2891.14.15. Additional information, as required by the test methods used to determine individual values, shall also be reported.The acceptance constant (k) is usually detailed in the specification. However, when this value is not specified, the commonly used values are shown in Table Al. Other values may be derived from the tables listed in Main Roads Western Australia, Engineering Road Note 8.AS 2891.14.15 pdf download.