Concrete additives, called admixtures, have been utilized in concrete construction nearly as long as concrete itself. Early builders, such as the Romans, would add animal products like fat or milk to their concrete mixtures to meet their specific construction needs. By definition, additives are any substance outside of water, cement, and aggregate that are added to the concrete mix, either during initial mixing or after placement. In their function, additives alter concrete performance to meet certain concrete criteria unique to each project. Concrete contractors such as The Conco Companies, who provide shotcrete services in the Portland area among other concrete services, knows what admixtures to include depending on the goals of the project, whether it is to enhance the water-reducing, curing retarding, or curing accelerating properties of the concrete mix.
As the name would suggest, accelerating admixtures will speed the process of curing in concrete. Curing is the process by which concrete gains its strength, and without admixtures, takes time and specific temperatures for the concrete to reach its intended compressive strength. Accelerating mixtures are useful in several applications, including in colder climates where the environmental temperatures could prolong the curing process without the accelerant, or with projects that have a short timeline and require a quick turnaround, such as with airplane tarmacs that need to see planes landing the next day.
Curing Retarding Admixtures
As with commercial concrete projects that will call for an accelerating admixture, there will be projects that require a curing retarding admixture. These additives will slow the process of curing and are often used on concrete projects in places that experience hot, dry weather, conditions which can speed up the hardening, or hydration, of the concrete and make it difficult for placement and finishing work to occur before the concrete cures. This admixture can also be useful on projects that involve complex or time consuming decorative finishes, such as large scale or intricate stamping, stenciling, or staining.
Water Reducing Admixtures
Water reducing admixtures leverage the benefit of the fact that lower water content in concrete makes for a stronger concrete when set, and the admixture helps the concrete mixture achieve this without needing to add more cement, which can also be a cost-saving measure. This additive can reduce the amount of water required in the mixture by between 5-30%. Additionally, water reducing admixtures are often utilized on projects that use concrete pumping applications, as it helps improve the flowability of the concrete.
At The Conco Companies, we are one of the leading concrete contractors in the Western U.S. and offer a wide range of quality services and products. Our experience includes providing services for commercial, educational, parking and other construction development as well as public works projects. Please contact us for more information about our full range of premium Portland area concrete services including shotcrete.