Concrete Additives: structural Construction

Enhancing Concrete Strength and Durability for Structural Construction

Standard concrete is usually insufficient when construction and project managers must design and construct foundational, skeletal, or load-bearing structures or elements. For such projects, construction managers often need concrete with different properties, such as high flexural strength or reduced permeability. Accordingly, they must rely on cement additives and concrete admixtures to achieve the properties they require.

Concrete for Structural Construction

Cement is the primary binding ingredient of concrete. Cement manufacturers may add certain additives during the cement manufacturing process, or engineers may add specific admixtures during the concrete mixing process to enhance the finished concrete. When it comes to structural construction, finished concrete elements typically must have considerable compressive and flexural strength, given that they must support the weight of other components. They are often exposed to the elements and must also be resistant to water, wind, and varying temperatures. While the concrete must be strong and durable, it must also be workable for ease of construction.

Admixtures for Concrete Strength

Civil engineers designing concrete mixtures commonly rely on chemical admixtures, such as accelerators and water reducers, to increase concrete strength. Accelerators decrease the time it takes for concrete to set and locks in strength at an early stage, though the use of accelerators must be considered relative to job-site temperatures. Water reducers also increase concrete strength while reducing its water content and helping the crews place the concrete more efficiently. There are also high-range water reducers, otherwise known as superplasticizers, that can reduce water content by as much as 40 percent and increase its strength. Project and construction managers can also use microfibers to improve the strength of reinforced concrete structures. Macro fibers can enhance wire-reinforced concrete and add durability and shrinkage resistance. Additionally, several mineral admixtures, such as silica fume and blast furnace slag, can improve concrete strength.

Admixtures for Durability

Several admixtures are also proven aids when it comes to increasing concrete’s durability. Air-entrainers improve concrete’s resistance to damage from the natural freeze-thaw cycle. There are also specialty admixtures, such as corrosion inhibitors, that mitigate the risks of rust and corrosion, admixtures that reduce permeability and alkali reactivity, and shrinkage-reducing admixtures, among others. Specialty admixtures are frequently used to ensure that concrete used in structural construction meets exact technical specifications and job-site requirements. Without them, load-bearing or foundational concrete may be at increased risk of cracking, spalling, delaminating, or scaling. In addition, rebar and metal structures may be especially vulnerable to rust and corrosion from weather or chemical element exposure.