Types of Concrete Admixtures

Published on 25th March, 2017

concrete admixtures

Concrete Admixtures or Additives are materials added to concrete during the mixing process to modify one or more of the properties of concrete in fresh or hardened state.

CONMIX offers a wide range of concrete admixtures for producing concrete of desired properties ranging from water-reducers, retarders, accelerators, water-proofers, air-entrainers, viscosity-modifiers, corrosion inhibitors and polypropylene fibers. The basic range of CONMIX concrete admixtures available are of the following three types:

Lignosulphonate Based (Ligno)

They are the oldest generation of admixtures and are one of the first products used for water-reduction and retardation in concrete manufacturing. The possible water-reduction capacity of these admixtures is 8-12% compared to a control mix and the general dosage is 0.5 – 1.5% by weight of cement. CONMIX produces this group of admixtures under the MegaFlow P range (MegaFlow P, MegaFlow P4, MegaFlow P401 and MegaFlow N10 series).

Sulphonated Naphthalene Formaldehyde (SNF)

SNF is the most widely used admixtures type in the world. The possible water reduction capacity of these admixtures is 15-35% compared to a control mix and the general dosage is 0.5 – 3% by weight of cement. They can be used in combination with the lingo group of admixtures as well and are capable of producing very good slump retention properties. SNF admixtures can be produced with properties of retardation as well as acceleration. CONMIX produces this group of admixtures under the MegaFlow SP range (MegaFlow SP4…MegaFlow SP402, MegaFlow SP1…MegaFlow SP103 and MegaFlow N20 series).

Polycarboxylic Ether (PCE)

PCE based admixtures are the latest generation and most recent type of admixtures developed. The possible water reduction capacity of these admixtures can be as high as 45% compared to a control mix and the general dosage is 0.5 – 2% by weight of cement. These admixtures are widely used for production of high workability, self-compacting and very high strength concrete of up to even C100 grades. These admixtures can be used in combination with ligno based admixtures but not in combination with SNF based admixtures. PCE admixtures can be produced with properties of retardation as well as acceleration. Conmix produces this group of admixtures under the MegaFlow 110…MegaFlow 2000…MegaFlow 3000 and MegaFlow N30 series.

Apart from these major types of concrete admixtures used for retardation, acceleration, slump retention and strength enhancement in concrete, there is a range to additional special purpose admixtures that CONMIX produces.

Air Entraining Admixtures

Air entrainment is the process by which many small air bubbles are incorporated into concrete. These air bubbles are dispersed throughout the hardened cement paste but are not, by definition, part of the paste. CONMIX produces MegaAir which is the air entraining admixture used to entrain additional air in concrete where desired and to produce concrete for cold-storages where freeze-thaw issues are prevalent and to produce concrete of density up to 1600 Kg/m³.

Corrosion Inhibiting Admixtures

Corrosion of steel in concrete is a result of the ingress of chlorides into the composite structure of concrete and steel. The volume of by-product of corrosion reaction produces 2-3 times volume greater than volume of steel they are produced from. This causes tensile stresses and thereafter spalling and eventually failure of concrete. Corrosion inhibitors like MegaAdd CI from CONMIX increase the threshold concentration of chlorides at which the corrosion process will initiate.

Water Proofing Admixtures

Water-tight concrete or concrete with very high durability requirements is a basic necessity for structural units like water-tanks, underground structures and swimming pools. CONMIX produces liquid water proofing admixtures like MegaAdd WL1, MegaAdd WL2 and MegaAdd WL3 and powdered product MegaAdd WP, which can be added as a raw material during the production stage of concrete and enhances the water-proofing property of the produced concrete. Water absorption levels as low as 1% are possible with these products, making the concrete practically water-tight.

Shrinkage Compensating Admixtures

Cracking of concrete is an accepted phenomenon which reduces the durability and sustainability of concrete structures. The formation of cracks is a result of shrinkage, mainly due to loss of moisture from the concrete. CONMIX produces shrinkage compensating admixture NanoGrout Aid, which can be added during the mixing process of concrete production. This helps reduce the surface tension in the capillary pores, thereby reducing the shrinkage and cracking of concrete.

Viscosity Modifying and Anti-Washout Admixtures

While placing concrete underwater or where the combined aggregates are not well graded, there are chances of segregation of fines from the mixture during placement. CONMIX produces MegaAdd VE which is used to improve the consistency of the concrete mix and avoids the segregation issues in mixes with ill-graded combined aggregates. It also helps in production of self compacting concrete in combination with PCE admixtures, improving the consistency of flowing concrete.

The entire range of CONMIX Concrete Admixtures is available directly through the company or the vast network of Certified Agents throughout the MENA region.