What are ADMIXTURES?
Admixtures are natural or manufactured chemicals that are added to the concrete before or during mixing. The most often used admixtures are air-entraining agents, water reducers, water-reducing retarders and accelerators.
Our concrete experts will carefully select the correct admixture for your project.
WHY Use Admixtures?
Admixtures give special properties to fresh or hardened concrete. Admixtures may enhance the durability, workability or strength characteristics of a given concrete mixture. Admixtures are used to overcome difficult construction situations, such as hot or cold weather placements, pumping requirements, early strength requirements, or very low water-cement ratio specifications.
Click the at the end of each description below to view more details.
ACCELERATORS - This admixture is meant to accelerate cement hydration which results in shorter setting times and increased early strengths. This product is mostly used during the colder, winter months.
Daraset® 400 is a non-corrosive, non-chloride admixture for concrete. It accelerates cement hydration resulting in shortened setting times and increased early compressive and flexural strengths. Daraset 400 does not contain calcium chloride and is formulated to comply with ASTM C494 Type C, and can be used at any dosage to comply with ACI 318 guidelines for chloride content of concrete.
Daraset® 400 set accelerator may be used wherever it is desirable to reduce the setting time of concrete and/or to increase its early compressive and flexural strengths. For mixes designed with pozzolans, such as fly ash or slag, Daraset 400 set accelerator can help offset the retarding effects of these materials, especially in cooler temperatures.
In cold weather, Daraset 400 may be used to reduce the time that it takes the concrete to set prior to finishing. Typical results show that when concrete containing Daraset 400 is poured at 50°F (10°C), the concrete will set up to 2 hours faster than the reference concrete.
When used in the manufacture of precast concrete, Daraset 400 speeds the concrete’s strength development allowing for earlier form removals and more efficient production. Daraset 400 can also be used in masonry mortar to obtain higher early strengths and accelerated setting time effects.
- Accelerates setting time
- Increases early compressive and flexural strengths
- Offsets the retarding effects of pozzolans such as slag or fly ash
Daraset 400 set accelerator provides setting time results and early strength development similar to that provided by calcium chloride, but without the potential corrosive effects. Daraset 400 can, therefore, at recommended dosage rates, safely be used where the potential corrosion of embedded or stressed steel must be avoided. It can also be used in concrete that is to be placed on steel clad or zinc coated steel decks where corrosion must be similarly avoided.
Compatibility with Other Admixtures
Daraset 400 is compatible with most GCP admixtures.
In concrete mixtures, Daraset 400 accelerates the chemical reaction between Portland cement and water. It speeds up the formation of gel—the binder that bonds concrete aggregates together. Accelerated gel formation in turn shortens the setting time of concrete, compensates for the set-slowing effects of cooler weather and contributes to the development of higher early strengths.
RETARDERS - This admixture delays cement hydration which lengthens setting times. This product is mostly used during the warm summer months and/or when travel distance becomes a concern.
RECOVER® is a ready-to-use aqueous solution of chemical compounds specifically designed to stabilize the hydration of cement concretes. The ingredients are factory pre-mixed in exact proportions under strict quality control to provide uniform results. One gallon weighs approximately 9.6 lbs (1.15 kg/L).
- Eliminates the need to discharge wash water from the mixer
- Prevents the waste of unused concrete
- Provides predictable extended set for continuous placement on mass concrete and tremie projects, or on long hauls to remote sites
Set Time Control
RECOVER® is used in situations where a controlled set time extension is required. Examples include: extended hauls, large continuous pours or pre-batching of concrete for later use.
Compatibility with Other Admixtures and Batch Sequencing
RECOVER® is compatible with most GCP admixtures as long as it is added separately to the concrete mix, usually through the water holding tank discharge line. In general, it is recommended that RECOVER® be added to the concrete mix near the end of the batch sequence for optimum performance.
WATER REDUCER - This admixture increases the strength, workabilty, finishabilty, and pumpability of your concrete.
ZYLA® 625 water-reducing admixture is a proprietary formulation incorporating polycarboxylate and highly purified specialty organic chemicals. It promotes more complete hydration of cement and has minimal effect on concrete air entrainment. The ZYLA® product line of water reducers is specially formulated to have a synergistic effect with polycarboxylate-based mid-range and high-range water reducers that improve flat-work finishability. This product is manufactured under rigid controls that provide uniform, predictable performance.
- Minimal impact on concrete air content
- Better control of water reduction and setting times as compared to traditional lignin-based water reducers
- Synergistic performance of polycarboxylate-based mid-range and high-range water reducers, which include water reduction, concrete strength and air control
- In the hardened state, improves the compressive and flexural strengths at all ages of concrete versus traditional lignin-based water reducers
ZYLA® 625 water reducer is used to produce concrete mixes with lower water content (typically 3% to 10% reduction), greater plasticity and higher compressive strengths. It is suitable for normal weight and light weight concrete in ready-mix, precast and prestressed applications.
The unique chemistry of ZYLA® 625 product positively impacts the finishability of concrete by providing a creamier and more homogenous texture, with more uniform bleed rate relative to traditional lignin-based water reducers. The influence of ZYLA® 625 product on the finishability of lean mixes has been particularly noticeable. Floating and troweling, by machine or hand, imparts a smooth, close tolerance surface.
Compatibility with Other Admixtures and Batch Sequencing
ZYLA® 625 water reducer is compatible with most admixtures as long as they are added separately to the concrete mix, usually through the water holding tank discharge line.
AIR ENTRAINMENT - This admixture increases the durability of your concrete particularly in areas exposed to freezing and thawing and is recommended for projects above 2,000 ft. in elevation.
Air-entraining admixture for enhanced resistance to freeze thaw action
Daravair® is an aqueous solution of completely neutralised vinsol resin and is produced at a high concentration and low viscosity. Daravair has been specifically formulated to be used in both masonry mortar and concrete.
Features and Benefits
- Through the purposeful entrainment of air, Daravair markedly increases the durability of concrete to all exposures particularly to freezing and thawing.
- It has also demonstrated a remarkable ability to impart resistance to the action of frost and deicing salts as well as sulfate, sea and alkaline waters.
Daravair may be used wherever the purposeful entrainment of air is required by concrete specifications. It is particularly useful in mass concrete and in high cement factor, low slump paving mixes, which require efficient, effective air-entraining admixtures. Daravair entrains air readily even under adverse conditions such as described above or when fly ash or manufactured sand is used in the concrete mix.
Air Entraining Action
Air is incroporated into the concrete by the mechanics of mixing but stabilised into millions of discrete semi-microscopic bubbles in the presence of a specifically designed air-entraining admixture such as Daravair.
These air bubbles act much like flexible ball bearings increasing the mobility, or plasticity and workability of the concrete. This permits a reduction in mixing water with no loss of slump. Placeability is improved. Bleeding, green shrinkage and segregation are minimised.
Compatibility wth Other Admixtures
Daravair is compatible in concrete with all known accelerating admixtures, water-reducing admixtures and water-reducing retarders. By combining the separate effects of air entrainment with the dispersion of a water-reducing admixture, the water requirement of concrete may be reduced with proportional increases in strength and improvement in durability.
FIBER - Concrete fibers can increase the strength of your concrete and protect against cracking.
Synthetic fiber for concrete
SINTA™ M3019 are synthetic micro fibers for concrete made from 100% virgin polypropylene. Designed specifically for use in concrete, they are alkali resistant, non-absorptive and completely non-corrosive. Their use protects concrete from stresses which cause cracking during the first 24 hours after placement while it is most vulnerable.
SINTA™ M3019 may be used in any application where decreased plastic shrinkage cracking and improved durability are desired. Specifically, such applications include but are not limited to, slabs on grade, pavements, overlays, sloped walls, pools, shotcrete, stucco, precast and prestressed products. It is suggested that this product be used in conjunction with properly compacted base materials and jointing in accordance with ACI guidelines and standards.
SINTA™ M3019 may be used as an alternative to welded wire fabric, depending on the application. SINTA™ M3019 may not be used as a replacement for structural or post-crack control steel reinforcement. For temperature or shrinkage post-crack control, please consult a GCP Applied Technologies representative regarding our STRUX® synthetic macro fibers.
SINTA™ M3019 uniformly distribute multi–dimensionally throughout the concrete. The fibers in the fresh concrete matrix provide reinforcement for the mixture while its tensile strength is weakest The reinforcement reduces the formation of all types of early age cracking. This cracking caused by plastic shrinkage, settlement and other internal stresses would otherwise permanently weaken the resultant concrete. The concrete permeability is decreased, while the surface characteristics, impact and toughness properties are slightly improved. Together these effects work synergistically to produce a long-term, better quality, more durable and serviceable concrete.
- Reduces plastic shrinkage cracking and improves durability
- Protects concrete from stresses that cause cracking
- Provides cost effective control of plastic shrinkage
- Provides overall higher quality of concrete
Compatibility with Other Admixtures
SINTA™ M3019 are compatible with all GCP admixtures. Their action in concrete is purely mechanical and will not affect the hydration process.