Admixtures are ingredients in concrete mix designs that are used to alter the properties of the concrete. Different types of admixtures can be used to change the concrete's viscosity, permeability, set time, water requirements, and more.
Because they allow you to modify the properties of both wet and hardened concrete, admixtures are beneficial for cost effectively meeting structural requirements and maintaining the quality of concrete during mixing, transporting, placing, and curing – especially in adverse conditions. For over 80 years, ready-mix producers have used to GCP’s admixtures in their concrete mix designs to improve strength, durability, and workability. Our concrete admixtures can also help our customers reduce their carbon footprint by:
- Reducing the amount of cement in the mix without affecting concrete strength, thereby reducing CO2 emissions
- Allowing for the use of locally sourced materials that would otherwise be deemed unusable for concrete mixes
- Providing a less energy-intensive way of recycling returned concrete
- Extending the service life of concrete structures
On this page, you can learn about different types of concrete admixtures and how they are used. Click on any of the admixture types listed below to see all of the GCP products and technical documents related to it.
Superplasticizers – High-range water reducers that comply with ASTM standards. They provide consistency across air entrainment and cement chemistries. They can also produce high slump at low dosages.
Mid-range water reducers – These concrete admixtures provide superior placeability and finishing for flatwork in commercial and high-end residential construction.
Water reducers – This set of water reducers provide superior water reduction, compressive strength, and set time control. They work synergistically with other polycarbonate based mid- and high-range water reducers.
Organic water reducers – Organic water reducers are made with modified lignosulfonates containing a catalyst which promotes more complete hydration of Portland cement.
Clay mitigators – These mid-range water-reducing admixtures mitigate the deleterious effects of swellable clays, permitting the use of polycarboxylate-based admixtures while maintaining the many benefits that polycarboxylate-based admixtures bring to concrete.
Air entraining agents – Entrapped air can increase concrete durability in freezing climates because it allows water in the concrete to expand when it freezes – reducing the internal pressure caused by ice formation. These liquid air-entraining admixtures are designed to generate specification-quality air systems in paving concrete mixes, and provide uniform, predictable performance.
Air detraining agents – These liquid air-detraining admixtures reduce the level of plastic air in non air-entrained concrete.
Strength & Durability Enhancers
Corrosion inhibitor – Chemically inhibits the corrosive action of chlorides on reinforcing steel and prestressed strands in concrete.
High-reactivity metakaolin admixture – High-reactivity metakaolin admixture (or HRMK) is a highly processed aluminosilicate pozzolanic mineral, derived from the clay mineral kaolinite. It dramatically improves the overall durability of concrete, primarily by reducing permeability and increasing compressive and flexural strengths.
Low-slump admixture – Low-slump admixtures are used to improve the workability of very low or zero-slump concrete without increasing water content.
Macro synthetic fibers – These additives are intended to replace welded wire mesh (WWM) as a unique form of high-strength, high-modulus synthetic reinforcement that is evenly distributed throughout the concrete matrix. Macro fibers add toughness, impact and fatigue resistance to concrete.
Alkali-silica reactivity (ASR) mitigation – These liquid admixtures can mitigate and control ASR in concrete when using potentially reactive aggregates or sand with high or moderate-alkali cement, or where there are sources of external alkalis.
Architectural finishing – Decorative chemical solutions, such as in-form surface retarders, release agents, and finish protectors that provide beautiful, consistent and long-lasting architectural finishes.
Bonding agent – This type of admixture uses internally plasticized, high polymer resin in water to increase the bond strength between fresh and hardened concrete.
CLSM – These concrete admixtures are used to make Controlled Low Strength Material (CLSM) that is highly flowable, volume stable, and excavatable in the future.
Hydration stabilizer – This type of concrete admixture is used to stabilize mixer wash water and returned or leftover concrete for extended periods – “pausing” the curing process and allowing for use of the materials when specified or allowed.
Rheology modifiers – Rheology modifying admixtures increase the viscosity of the concrete while still allowing it to flow without segregation. Concrete mix designs that incorporate rheology modifiers can be used to produce self-consolidating concrete (SCC), reduce the required pressure when pumping concrete, and for underwater or anti-washout applications.
Set accelerators – Set accelerators make wet concrete set faster for increased early strength development and earlier form removal.
Set retarders – These aqueous solutions make wet concrete set slower to allow enough time for placement operations.
Shrinkage reducers – These liquid admixtures for concrete dramatically reduce drying shrinkage and the potential for drying shrinkage-induced cracking and curling.
Silica fume – A dry, densified microsilica powder is added to concrete to increase compressive and flexural strengths, increase durability, reduce permeability, and improve hydraulic abrasion/erosion resistance.
Water repellent – An admixture, in stable dispersion of stearate and other water repellent compounds, that is added to concrete to make it hydrophobic when set.
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