Control Samples
Control samples are any type of well-known samples used to verify the correctness of the analyzes / tests. These control samples are fully known to the customer in terms of their type, values of certain parameters and values of their standard deviations and uncertainties. They can also be used as blind samples. Blind sample - a sample known by the submitter but submitted to an analyst in such a way that its identification as a check/control sample is unknown.
Control samples are used for laboratory control purposes to verify the validity of the test results in terms of their reliability.
PTS Bulgaria Ltd. offers control samples that are left over from a certain PT scheme. Each control sample is accompanied by a certificate stating the values of the relevant characteristics, together with their standard deviations and standard uncertainties, as determined in the respective PT scheme. The control samples are not certified reference materials.
Available control samples:
| Type of the sample | Subject of PT scheme № | Parameter with known values of the result and its standard deviation and standard uncertainty | Code of the standard |
|---|---|---|---|
| Fine aggregates (marine and natural or crushed sand) | PTS 25/09-T-1 | Water-soluble chloride content | Volhard method (EN 1744-1:2009+A1:2012, Clause 7) – Reference method |
| Water-soluble chloride content | Mohr method (EN 1744-1:2009+A1:2012, Clause 9) – Alternative method | ||
| Total sulfur content | EN 1744-1:2009+A1:2012, Clause 11.1 | ||
| Cement | PTS 25/07-T-1 | Compressive strength | EN 196-1:2016 |
| Standard consistency | EN 196-3:2016, clause 5 | ||
| Initial setting time | EN 196-3:2016, clause 6 | ||
| Final setting time | EN 196-3:2016, clause 6 | ||
| Soundness | EN 196-3:2016, clause 7 | ||
| Bitumen | PTS 25/01-T-2 | Penetration | EN 1426:2024 |
| Softening point | EN 1427:2015 | ||
| Percentage of change in mass | EN 12607-1:2024 | ||
| Percentage of retained penetration at 25 °C | EN 12607-1:2024, EN 1426:2024 | ||
| Change in ring and ball softening point | EN 12607-1:2024, EN 1427:2015 | ||
| Density | EN 15326:2007+A1:2009 | ||
| Solubility | EN 12592:2014 | ||
| Aggregates | PTS 25/01-T-1 | Overall flakiness index | EN 933-3:2012 |
| Shape index | EN 933-4:2008 | ||
| Resistance to wear - micro Deval coefficient | EN 1097-1:2023 | ||
| Resistance to fragmentation - Los Angeles coefficient | EN 1097-2:2020 | ||
| Loose bulk density | EN 1097-3:1998 | ||
| Asphalt/bituminous mixture | PTS 24/07-T-2 | Soluble binder content | EN 12697-1:2020 |
| Particle size distribution | EN 12697-2:2015+A1:2019 | ||
| Maximum density | EN 12697-5:2018, Procedure A (item 9.2) | ||
| Bulk density | EN 12697-6:2020, Procedure B (item 9.3) | ||
| Stability | EN 12697-34:2020 | ||
| Flow | EN 12697-34:2020 | ||
| Filler | PTS 24/07-T-1 | Particle size distribution according | EN 933-1:2012 |
| Particle size distribution according of filler | EN 933-10:2009 | ||
| Methylene blue value | EN 933-9, Annex A | ||
| Particle density of filler | EN 1097-7:2022 | ||
| Water content | EN 1097-5:2008 | ||
| Bitumen | PTS 23/04 | Penetration | EN 1426:2015 |
| Softening point | EN 1427:2015 | ||
| Density | EN 15326:2007+A1:2009 | ||
| Flash point | EN ISO 2592:2017 | ||
| Solubility | EN 12592:2014 | ||
| Fraass breaking point | EN 12593:2015 |
The price of the control sample depends on the number of parameters selected in the Order for Control Sample. It shall be equal to the participation fee corresponding to the selected number of parameters, in accordance with the invitation for participation in the respective proficiency testing scheme of which the control sample formed part as a reserve sample.