Grey Portland Cement — General Purpose Hydraulic Binder

Primary uses

• Hydraulic binder
• Structural strength development
• Matrix formation

Applications

• Structural and utility precast production
• Cast stone and hardscape mixes where colour is not critical
• Repair mortars and grouts
• General concrete products manufacture

Advantages

• The established, widely specified binder that every plant and specifier already understands
• Available in the cement types the specification calls for across Canadian production
• Well characterised in combination with supplementary cementitious materials and admixtures

Limitations to consider

• Grey base colour limits decorative colour development, which pushes visible work toward white cement
• Behaviour with a given admixture set is cement-specific, so a source change requires re-trialling
• Strength class, type and chemical composition are declared by the producer for the exact cement supplied
• 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 element being produced and the specification it has to satisfy, because binder, aggregate and admixture choices are decided together rather than one at a time
• State the placing method — poured, vibrated, sprayed or pressed — since rheology requirements follow from it
• Describe the curing regime and the plant conditions, including whether production continues through a Canadian winter
• Confirm the cement type the specification requires before comparing offers
• Plan re-trialling of the admixture set whenever the cement source changes
• 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

• Cement types as classified in the applicable Canadian standard and declared by the producer
• Products the producer distinguishes by strength class
• 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.