Cement Admixtures : structural Construction

Structural construction projects require the use of concrete, which consists of cement, water, aggregates, and cement admixtures, to help achieve optimal results with the final construction. An important note is that admixtures are added to the concrete when it’s mixed, and are more correctly referred to as concrete admixtures, not cement admixtures.

Cement is an ingredient of concrete that comprises aluminum, calcium, silicon, and other materials. It may also include certain types of additives to enhance specific properties, such as strength and durability, which are critical for structural construction. 

Most construction projects use Portland cement because of its reliability. This type of cement consists of a variety of compounds, including dicalcium and tricalcium silicate, along with tetra-calcium aluminoferrite and tricalcium aluminate. In addition to these base compounds, cement may contain supplemental cementitious material (SCM), also known as pozzolans, to improve certain properties. 

A good cement mixture will help form the concrete mix used for completing various types of structural construction elements.

Concrete structural construction

Structural construction entails the use of reliable concrete with equally reliable cement content for constructing various components that help support buildings. Concrete helps form foundations, skeletal structures, and load-bearing elements that must withstand many conditions and heavy applied loads.

The cement that goes into the structures’ concrete mixture will depend on various influencing factors, such as flexural and compressive strength requirements, exposure to sulfates in soil, earth movement, and the overall complexity of the construction.

To help meet the needs of each construction project, concrete may require the incorporation of different types of property-enhancing admixtures.

Admixtures for strength

To enhance the strength of cement and concrete, concrete may contain different types of admixtures, including:

Chemical admixtures

Cement used in structural construction may contain certain types of chemical admixtures that improve the cement’s strength via chemical reactions. Concrete structures may use chemical admixtures such as accelerators and corrosion inhibitors, along with water-reducing admixtures. Accelerating admixtures are particularly helpful in enhancing early strength, shortening curing times, and boosting durability.

Mineral admixtures

Concrete may also use mineral admixtures for improved strength. Many construction applications use natural pozzolans, ground granulated blast furnace slag, or fly ash, all of which help reduce the amount of Portland cement required while providing additional benefits including reduced permeability, increased strength, and improved workability.

Fiber admixtures

Fiber admixtures (usually referred to as just “fibers”) help prevent small cracks in concrete from propagating further. They can also help increase flexural strength of the concrete, but are difficult to work with in concrete because of reduced workability. 

Admixtures for durability

Other cement and concrete admixtures could improve durability in several key ways. For example, air-entrained admixtures help protect concrete from damage resulting from freeze/thaw cycles by infusing the cement with small bubbles. The bubbles provide a space for water to expand into when it freezes, protecting the concrete structure. These and other admixtures may help reduce permeability, shrinkage, and cracking, as well as spalling, delaminating, and scaling.

Additionally, corrosion-inhibiting admixtures can prevent the corrosion of rebar and metal structures within concrete structures. 

Use the right admixtures for your structural construction application

Concrete containing appropriate admixtures will help meet all requirements for strength, durability, and other properties. The key is to know what admixtures and additives to include based on the specific properties needed.