Overview
ISO 13765-2:2004 specifies a laboratory method for determining the consistency of refractory mortars using the reciprocating flow table method. It is Part 2 of the ISO 13765 series on refractory mortar testing and defines the procedure to measure mortar spread (flow) after mechanical agitation on a flow table, producing a repeatable flow index result used to characterise workability and application performance.
Key topics and technical requirements
- Scope and principle: Measures increase in diameter of a mortar sample after up-and-down reciprocating motion on a flow table to assess consistency.
- Apparatus:
- Reciprocating flow table and conical mould (table mass ~4 kg ± 0.5 kg; machined drop ~12.7 mm ± 0.1 mm).
- Mixer with stainless-steel bowl (~5 L) and metal blade executing planetary motion; blade/bowl gap checked regularly (3 mm ± 1 mm).
- Thermometer, palette knife, measuring cylinder.
- Sampling: Dry mortars sampled per ISO 8656-1 or as agreed; ready-mixed mortars tested “as received”.
- Procedure:
- Test in triplicate.
- If unused for ≥24 h, run table for 10 revolutions prior to testing.
- Fill mould, strike off, lift mould, operate flow table 25 times in ~15 s, then measure mean diameter in two perpendicular directions.
- Measure mortar temperature to nearest 1 °C; for dry mixes, follow manufacturer’s water dosage and allow 15 min rest unless otherwise specified.
- Calculation and reporting:
- Flow index F (%) = (D − D0) / D0 × 100, where D is mean spread diameter and D0 is mould base diameter.
- Report the mean of three determinations to the nearest 1% and include test conditions, water content (if applicable), temperatures, deviations and anomalies.
Applications and who uses it
- Practical applications:
- Quality control of refractory mortars used in furnaces, kilns, incinerators and other high-temperature linings.
- Comparative evaluation of workability for mortar formulation and process development.
- Verification of consistency for installation and jointing procedures in refractory maintenance and construction.
- Primary users:
- Refractory manufacturers and formulation laboratories
- Quality assurance/test laboratories
- Construction and maintenance teams in metallurgy, ceramics, petrochemical and power industries
- Standards compliance and procurement specialists
Related standards
- ISO 13765 series (other parts include Part 1 - penetrating cone method; Part 3 - joint stability; Part 4 - flexural bonding strength; Part 5 - grain size distribution; Part 6 - moisture content of ready-mixed mortars).
- Normative reference: ISO 8656-1 (sampling of refractory products).
Keywords: ISO 13765-2, refractory mortars, reciprocating flow table method, consistency determination, flow index, refractory mortar testing, workability test.