An admixture is a chemical added to a concrete mix, such as an accelerator, retarder, or air-entrainer, to change how the concrete sets, cures, or performs.
In depth
Accelerators speed up set time in cold weather. Retarders slow it down in summer heat. Air-entraining admixtures create microscopic air bubbles that give freezing water somewhere to expand, dramatically improving freeze-thaw resistance, which is critical in northern Illinois.
Admixtures affect the finished slab for its entire life. A driveway poured without air-entrainment in Chicagoland, for example, is far more likely to scale and spall after a few winters of freeze-thaw cycles and de-icing salt.
How Acme applies it. Our polyurethane raising process does not involve concrete admixtures, but understanding the original mix helps us assess slab condition. Our two-component polymer is itself a precisely formulated chemistry, the foam equivalent of a carefully designed mix.
Related terms: Freeze-Thaw Cycle, Scaling, Compressive Strength, Two-Component Polymer
Frequently asked questions
Can an admixture fix concrete that is already poured?
No. Admixtures only work in the wet mix. Once a slab is cured, problems like settlement are fixed with raising and stabilization, not chemistry added later.
Why does air-entrainment matter in Illinois?
Freeze-thaw cycles are the biggest weather stress on local concrete. Entrained air gives freezing water room to expand inside the slab instead of breaking the surface apart.