Uses

    To produce air entrained concrete for increased durability and resistance to damage by frost and deicing salts. Typical applications include concrete roads and bridge decks, airport runways and taxiways and other extensive areas of concrete exposed to potential frost damage.

  • To improve cohesion and workability of concrete mixes where poorly graded aggregates must be used and bleeding, segregation or sand runs occur.
    As part of a combined admixture system for the production of ready mixed retarded mortar.

ADVANTAGES

  • Air entrainment increases the resistance of concrete to attack by frost and de-icing salts, reducing problems of surface scaling and concrete failure.

  • Entrained air bubbles assist in the formation of a stable cohesive mix, reducing segregation and bleeding.

  • Air entrainment improves workability and helps produce a dense, uniform, close textured surface free from gravel nests and sand runs, so further enhancing durability.

  • Excellent air bubble stability allows use with a wide range of aggregate qualities and mix conditions.

Standards compliance

SIGMABOND-AI complies with BS 5075 Part 2, BS 4887 Part 1, ASTM C260 and with the Department of Transport Specification for Highway Works.

Description

SIGMABOND-AI is a chloride free air entraining admixture based on neutralized Vinson resin. It is supplied as a translucent water white which instantly disperses in water.

SIGMABOND-AI acts at the interface between the mixing water and cement/aggregate particles to produce microscopic air bubbles, which are evenly distributed throughout the concrete.

The entrained air enhances durability by providing protection against the rapid temperature changes found in freezing and thawing conditions and with the use of de-icing salts.

Air entraining admixture
Technical support

Sigmapolychem pvt ltd offers technical support service to specifies, end users and contractors, as well as onsite technical assistance in locations all over the country.

Properties

Appearance : Translucent white liquid

Properties

Chloride content : Nil to BS 5075

Specific gravity : 1.01 at 270C

pH : 6.5

Alkali content : Typically less than 14.0g Na2O equivalent /litre of admixture.

pH : Minimum 6

Factors affecting air entrainment :

Sand content : The quantity of air entrained will increase with increasing sand content - typically an increase in sand content from 36 to 46% will raise the air content from 4.5 to 6.0%. Cement fineness and content : The amount of air entrained reduces with an increase in cement fineness or content.

Aggregate quality : Silt content variations can adversely affect the degree of air entrainment. This is particularly relevant to the use of crushed aggregate during inclement weather. Excessive silt content may render SIGMABOND-AI ineffective.

Organic impurities : Carbon can reduce the effectiveness of SIGMABOND-AI. This does not normally create a problem, but caution should be exercised when using PFA or some pigments. Where this type of material is to be used alternative admixtures are available.

Concrete temperature : A temperature increase will reduce air content. In practice, daily fluctuations are much smaller and do not cause significant variation.

Mixing and pumping : Air content will increase with increased time of mixing up to about two minutes in stationary mixers and about 15 minutes in transit mixers. Thereafter, the air content generally remains constant for a considerable period. Small losses of air may occur during pumping. With long pipelines, air content in excess of 5% may seriously reduce the efficiency of the pump.

SIGMABOND-AI

Compaction of concrete : Prolonged vibration should be avoided.

For specific technical assistance and advice on any of the above aspects, please contact sigmapolychem pvt ltd.

Setting time : Negligible effect at normal dosage rate.

Compatibility : SIGMABOND-AI can be used with all types of Portland cements and is generally compatible with other admixtures. It is recommended that all admixtures be added to concrete separately.

Reduced permeability : The microscopic air bubbles introduced by use of SIGMABOND-AI break up the capillary structure within concrete and hence reduce water permeability.

Durability : Reducing the water permeability of concrete offers increased resistance to weather exposure and attack in aggressive environments.

Frost resistance : The addition of SIGMABOND-AI produces controlled air space.

Compressive strength : A 15% free water reduction is often possible with SIGMABOND-AI. This resultant increased compressive strength normally offsets the anticipated strength loss associated with air entrainment, thus producing air entrained concrete with no increase in cement content.

Resistance to salts : Air entrainment increases the resistance of concrete to surface scaling, which is an adverse effect associated with repeated exposure to marine salts or application of de-icing salts to the concrete surface.

Precautions
Health and safety instructions

SIGMABOND-AI is non-toxic. Any splashes should be rinsed thoroughly with water. Splashes to the eyes should be washed immediately with water and medical advice should be sought.

Fire

SIGMABOND-AI is non-flammable.