Gypsum and lime are air-setting binders with wide use: internal plasters, plasterboard, lime mortars for restoration and soil stabilisation. Unlike cement, their behaviour depends strongly on fineness and setting time, which vary considerably between producers and with storage conditions.

Testing determines fineness, setting time and consistence — which together govern workability and the time available for application — along with compressive strength, dry density and volume stability after setting.

For lime, free lime content and purity are direct indicators of reactivity and of production quality. Test methods are given in BS EN 13279-2 for gypsum binders and BS EN 459-2 for building limes.

Note on accreditation: the tests below are carried out by our laboratory to the methods referenced in BS EN 13279-2 and BS EN 459-2, but they are not included in our ISO/IEC 17025 accredited scope (certificate LT 069). Test reports for them are issued without the accreditation symbol.

 

  1. Fineness — particle size distribution, which governs reactivity
  2. Setting time — the time available for mixing and application
  3. Consistence — water required for a paste of standard consistence
  4. Compressive strength — maximum load the hardened material sustains
  5. Volume stability (soundness) — potential for expansion after setting
  6. Dry density — mass per unit volume of the dried material
  7. Air content — volume of air entrained in the paste
  8. Free lime — content of unhydrated CaO
  9. Purity — presence of impurities that reduce performance
  10. Heat of hydration — heat released during reaction with water

Please contact us for further details

Accreditation

Independently verified competence

Our laboratory is accredited by the General Directorate of Accreditation (DPA) of the Republic of Albania to S SH ISO/IEC 17025:2017, “General requirements for the competence of testing and calibration laboratories”.

ISO/IEC170252017
Testing Laboratory

Registration number LT 069. Granted 08.06.2025 and valid until 07.06.2029. The certificate is issued together with its accredited scope.

View certificate (PDF)

ISO/IEC170252017
Calibration Laboratory

Registration number LK 005. Granted 06.08.2025 and valid until 05.08.2029. The certificate is issued together with its accredited scope.

View certificate (PDF)

DPA is a signatory of the EA MLA and the ILAC MRA for testing.