Overview
ISO 863:2008 - "Cement - Test methods - Pozzolanicity test for pozzolanic cements" - is the reference procedure for measuring the pozzolanicity of pozzolanic cements. The standard defines a laboratory method to determine whether a cement consumes calcium ions (expressed as CaO) in an aqueous system of defined alkalinity and temperature. It does not apply to Portland pozzolana cements or to pozzolanas.
Keywords: ISO 863:2008, pozzolanicity test, pozzolanic cements, cement test methods, calcium ion concentration.
Key topics and technical requirements
- Principle: Compare the calcium-ion concentration in solution after contact with hydrated cement to the calcium concentration required to saturate a solution of the same alkalinity. A lower Ca2+ concentration indicates positive pozzolanic activity.
- Test mixture and conditions: Typical equilibrium is achieved with 20 g cement in 100 ml water at 40 °C, with assessment after 8 d (sufficient if passed) or 15 d.
- Sample preparation: Homogenize a laboratory sample (≈100 g), sieve to 125 µm or 150 µm, grind retained material to pass the sieve, and store airtight.
- Reagents and standardization:
- EDTA titration (≈0.03 mol/l) is standardized against CaCO3; end-point can be determined photometrically (murexide or mixed indicator) or visually (calcon or Patton and Reeders reagent).
- 0.1 mol/l HCl is standardized using sodium carbonate and methyl orange indicator.
- Apparatus: thermostatically controlled enclosure at (40 ± 1) °C, class A burettes/pipettes, balance (±0.0005 g), pH meter (±0.05), stirrer, and photometric absorbance apparatus for EDTA end-point detection (520 nm / 620 nm options).
- Procedure details: Seal cement/water containers to avoid evaporation, shake uniformly, filter under vacuum after the test period (filtering in
