Air Entraining Admixture — Freeze-Thaw Durability

Primary uses

• Stable air void system generation
• Freeze–thaw durability support
• Workability improvement

Applications

• Exterior precast and hardscape units exposed to Canadian winters
• Cast stone and architectural units in freeze–thaw service
• Concrete exposed to de-icing salts
• Site and infrastructure concrete

Advantages

• Generates the air void system that exterior Canadian concrete depends on for freeze–thaw durability
• Directly addresses de-icing salt scaling exposure common on Canadian projects
• Long-established and specified in Canadian exposure classes

Limitations to consider

• Air content is sensitive to mix temperature, cement source, other admixtures and placing method, so it must be measured, not assumed
• Excess air reduces strength, so the system is a controlled balance rather than a maximisation exercise
• Dosage and resulting air content are established by trial and by measurement in production, not from a catalogue
• Dosage, addition rate, water content and binder proportions are decided by your own mix design and trial batches, not by a catalogue figure. Supplier literature ranges are a starting point for that development work and are not reproduced here as a specification.
• Where the finished element goes into a building, the performance that matters is the performance of your element under the applicable code and project specification, not the property of a single ingredient. Testing and conformity evidence for the finished product are the responsibility of the producer and are established by project-specific testing.
• Mix ratio, pot life, working time, demould time, full-cure schedule, hardness, tear strength, elongation, shrinkage, viscosity and temperature resistance are properties of one specific supplier system. They are never quoted here from memory or by analogy with a similar product; they are read from the supplier data sheet for the exact material offered and confirmed at quotation.

How to choose the right grade

• Start from the problem in the mix — water demand, segregation, set timing, shrinkage or durability — rather than from an admixture category
• List every other admixture already in the mix, because interactions between admixtures are the most common cause of unexpected results
• State the cement and supplementary materials in use, since admixture response is cement-specific
• State the exposure class and the air content the specification requires
• Confirm how air content will be measured and controlled through the plant's own production cycle
• Mould-making and casting behaviour depends on the pattern, the shop temperature and humidity, the mixing method and the operator. A production-representative trial on your own pattern and in your own shop conditions is the only honest way to qualify a material before a run is committed.
• Exact specification is confirmed against supplier documentation at quotation.

Typical grades

• Products the supplier classifies by surfactant chemistry and intended application
• Products intended for precast versus ready-mix production
• Buyers search this category by grade name, and those names describe what the workshop needs rather than what is asserted here. Which grade a specific offer corresponds to, and what the supplier declares for it, is read from the technical documentation issued for the exact material quoted.
• Materials in this category interact: rubbers, releases, sealers, resins, pigments and fillers can inhibit cure, stain a surface or shorten mould life when they are combined outside the combinations the supplier has tested. State every material already in the process at enquiry so compatibility is checked against supplier documentation rather than discovered on the shop floor.
• Reactive materials age in the container, and moisture-sensitive systems age faster once opened. Order against real consumption rather than against a discount, and confirm the shelf life the supplier states for the exact product and pack.