prEN 196-16

prEN 196-16 is a draft CEN standard for the square prism method used to assess the sulfate resistance of cement. It specifies how mortar prisms are prepared, cured, exposed to a defined sulfate solution, measured over time, and reported so laboratories can judge the SR characteristic of cements, especially CEM III/A cements and binders with pozzolanic main constituents.

What does prEN 196-16 specify?

prEN 196-16 specifies a laboratory test on cast mortar specimens for evaluating sulfate resistance under controlled exposure conditions. The method is intended to accelerate external sulfate attack by using a fixed sulfate solution concentration and a long exposure period.

prEN 196-16 is organized into clauses 1 to 12: scope, normative references, terms and definitions, general description, apparatus and solution, cements, preparation of test specimens, conditioning, testing procedure, measurements, analysis, and test report, followed by a bibliography. The structure takes a user from specimen preparation through to the final report.

What are the key requirements of prEN 196-16?

• Clause 4 - test principle: prEN 196-16 evaluates sulfate resistance with the square-based prisms method (SQPM) on mortar specimens cured in water for 28 days and then immersed in sulfate solution at 20 ± 2 °C. In practice, this creates a controlled comparison between specimens kept in water and specimens exposed to sulfate attack.

• Clause 5.2 - containers: prEN 196-16 requires light-proof, non-reactive containers with enough volume for 1.0 ± 0.1 l of solution and a solution depth of at least 25 mm. This matters because the exposure conditions must stay stable and the container must not affect the specimens or solution.

• Clause 5.3 - sulfate solution: prEN 196-16 uses a sulfate solution with a concentration of 16 ± 0.5 g SO4/l, prepared from Na2SO4 or Na2SO4·10 H2O of analytical purity. This gives a defined and repeatable exposure severity.

• Clauses 7 and 8 - specimen preparation and conditioning: prEN 196-16 uses mortar made according to EN 196-1, with 6 prisms of (20 × 20 × 160) mm and two stainless steel studs. After demoulding, 3 prisms are placed in each of 2 containers with distilled water, with spacing around the prisms and supports under them. For the reader, this fixes specimen geometry and storage so results are comparable.

• Clause 9 - start of exposure: prEN 196-16 measures the prism length at 28 days after curing, using calibrated equipment and a reference bar, before moving 3 prisms to distilled water and 3 to sulfate solution. The sulfate solution is replaced every 28 days, while the water is kept and topped up if needed.

• Clause 10 - monitoring: prEN 196-16 requires length measurements after 4, 8, 12, 16, 20, 26, 29, 40 and 52 weeks, with photographs and notes on visible damage such as cracks, exudations and deposits. This gives both numerical expansion data and a visual record of deterioration.

• Clause 11 - analysis: prEN 196-16 calculates length change relative to the 160 mm prism length, excluding pins, and reports mean values from 3 specimens versus time. In practice, the user tracks expansion as a durability indicator and can plot it to show the trend clearly.

• Clause 12 - test report: prEN 196-16 requires the report to identify the cement, specimen type and size, dates, curing and conditioning, exposure periods, gauge length, individual and mean results for length, mass and specific weight, any deviations, and photographic records. This makes the test auditable and usable for technical decisions.

What terms does prEN 196-16 define?

• Sulfate resistance (SR characteristic): the ability of a cement binder to be used in concrete exposed to sulfate attack.
• Square-based prisms method (SQPM): the test method used in prEN 196-16 for measuring prism length change during sulfate exposure.
• CEM III/A: a cement type named in the scope as a particularly suitable application for this method.
• Pozzolanic main constituents: main cement constituents highlighted in the scope as relevant to this test method.
• Na2SO4: sodium sulfate, used to prepare the sulfate solution in the test.
• Reference bar: the calibration item used before length measurements to check or adjust the measuring apparatus.

Who uses prEN 196-16?

prEN 196-16 is used by cement laboratories, testing organizations, and quality teams that need to assess sulfate resistance of cements and related binders. It is relevant to cement producers, purchasers, and technical specifiers working with CEM III/A cements and binders with pozzolanic main constituents. It is also useful for conformity assessment and product qualification work where controlled durability testing is needed.

Which standards are used with prEN 196-16?

• EN 196-1: provides the mortar and strength-testing framework used for preparing the specimens in this method.
• EN 197-1: is the framework mentioned in the introduction for the cements to which this test method is applied.
• EAD 150004-00-0301, Annex B: lists this test method and shows its use in European Assessment Document work.

What does the prEN 196-16 document contain?

prEN 196-16 contains the test apparatus requirements, including the container dimensions and the sulfate solution preparation. It also gives the specimen preparation sequence, the conditioning arrangement, the exposure schedule, and the measurement intervals. The analysis clause provides the way to calculate length variation and present it over time.

The document also specifies what the report must record, including specimen identification, curing and conditioning details, individual results, mean values, mass and specific weight changes, deviations, and photographic records. In practice, this means the standard supports both technical testing and traceable reporting.