Cement - What Is It?

Cement is a hydraulic mineral binder obtained from mineral raw materials (marl or limestone and clay) fired into clinker in a cement kiln and then ground with gypsum, which acts as a setting time regulator. It is used to prepare cement mortars, cement-lime mortars, and concrete. Cement is widely used in construction for bonding building materials.

Cement is a commonly used structural adhesive, meaning it is a mixture that, when combined with water and other components, can harden in both water and air. Once this slurry hardens, it forms strong and durable construction materials such as concrete, mortar, and plaster.

Concrete is used to construct slabs, reinforced concrete floors, and stairs. Mortar is essential for building walls from bricks, hollow blocks, or stones. Plaster is applied to finish both interior and exterior walls. Paving stones, piles, and fence boards are made from cement-containing mixtures. Depending on its composition, cement comes in various types.

There are many specialized cement products available on the market, and various types of cement are suitable for home construction.

Cement Classification:

• CEM I – Portland cement
• CEM II – Composite Portland cement
• CEM III – Blast furnace cement
• CEM IV – Pozzolanic cement
• CEM V – Multi-component cement

Strength Classes

Depending on compressive strength (measured after 28 days) according to PN-EN 196-1, cement is classified into three strength classes (compressive strength in N/mm²; 1 MPa = 1 N/mm²):

• Class 32.5
• Class 42.5
• Class 52.5

These three classes are further divided based on early strength:

• Cement with high early strength (marked with R): 32.5R, 42.5R, 52.5R
• Cement with normal early strength (marked with N): 32.5N, 42.5N, 52.5N

Composition of Cement

• Main Components – Specially selected inorganic materials, constituting more than 5% of the total mass of all primary and secondary components.
• Secondary Components – Specially selected inorganic materials, constituting no more than 5% of the total mass.
• Calcium Sulfate – Added during cement production to regulate setting time. It can appear as gypsum, hemihydrate, or anhydrite, or a mixture of these. Gypsum and anhydrite occur as natural materials, but calcium sulfate can also be obtained as a by-product of industrial processes.
• Additives – Used to facilitate production or enhance the properties of cement. The total amount of additives should not exceed 1% of the cement mass (except for pigments). Organic additives should not exceed 0.5% of cement mass in dry form and must not cause reinforcement corrosion or deteriorate the properties of cement, concrete, or mortar.

If admixtures are added to cement (for concrete, mortar, or grouts) according to EN 934 standards, the standardized name of the admixture must be indicated on the packaging or in the delivery documentation.

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