Corrosion Inhibitors - Sika® CNI

CORROSION INHIBITING ADMIXTURE

Sika® CNI is a calcium nitrite-based admixture designed to inhibit the corrosion of steel in reinforced concrete. Sika® CNI contains a minimum of 30% calcium nitrite by mass and meets the requirements of ASTM C1582, Corrosion Inhibiting Admixture and ASTM C494 / AASHTO M194 Type C.

Sika® CNI is recommended for conventional steel reinforcement as well as prestressed or post-tensioned concrete that will be exposed to chlorides from marine environments or deicing salts. Sika® CNI will extend the service life of structures by effectively inhibiting corrosion, in areas such as parking garage decks and support structures, bridge decks, marine structures and many others. Sika® CNI is a corrosion-inhibiting admixture that provides protection against corrosion in reinforced concrete structures. Sika® CNI:

• Extends the service life of reinforced concrete structures.
• Is recommended for use in all types of reinforced concrete, precast and/or prestressed concrete as well as ready mix applications.

Sika® CNI can be used as an accelerating admixture that provides:

• Accelerated setting time across a wide range of temperatures.
• Increased early and ultimate compressive and flexural strengths

Sika® CNI does not contain intentionally added chlorides.

Usage

In the high alkalinity of concrete, reinforcing steel builds up a natural passivation layer. This layer protects the steel from corrosion. This passive ferric oxide layer however can be damaged by the presence of chlorides and combined with the presence of moisture and oxygen which will lead to corrosion of the steel. Sika® CNI will help oxidize the steel to form ferric oxide, which resists chloride attack. This reduces the areas of ferrous oxide ions that are susceptible to attack by chlorides. Ferrous oxide creates a ferrous oxide complex (rust), if attacked by chlorides. In the presence of these chlorides, rust continues to generate in these areas (corrosion pits) and ultimately leads to staining, cracking and spalling of the concrete. Sika® CNI fortifies the ferric oxide passivating layer prior to the penetration of chlorides. The nitrite ions in Sika® CNI will convert ferrous oxide to more resistant ferric oxide, thereby protecting the steel reinforcement from corroding. Sika® CNI is also an effective accelerator where high early strength concrete is desired and the use of calcium chloride is prohibited.

Advantages

Sika® CNI is recommended for conventional steel reinforcement as well as prestressed or post-tensioned concrete that will be exposed to chlorides from marine environments or deicing salts. Sika® CNI will extend the service life of structures by effectively inhibiting corrosion, in areas such as parking garage decks and support structures, bridge decks, marine structures and many others. Sika® CNI is a corrosion-inhibiting admixture that provides protection against corrosion in reinforced concrete structures. Sika® CNI:

• Extends the service life of reinforced concrete structures.
• Is recommended for use in all types of reinforced concrete, precast and/or prestressed concrete as well as ready mix applications.

Sika® CNI can be used as an accelerating admixture that provides:

• Accelerated setting time across a wide range of temperatures.
• Increased early and ultimate compressive and flexural strengths

Sika® CNI does not contain intentionally added chlorides.

Packaging

Available in 55 gallon (208 liter) drums, 275 gallon (1040 liters) totes and bulk delivery.

Color

Greenish Liquid

Product Details

Product Information

Shelf Life

Shelf life when stored in dry warehouse conditions between 50 °F and 80 °F (10-27 °C) is one year.

Storage Conditions

Sika® CNI should be stored above 40 °F (5 °C). If frozen, thaw and agitate thoroughly to return to a normal state. Protect from direct sunlight.

Specific gravity

Approx. 1.300

Application

Application Information

Mixing

Measure the required quantity by automated dispenser or manually. Add Sika® CNI directly into the freshly mixed concrete at the end of the batching cycle. When used in combination with other admixtures, care must be taken to dispense each admixture separately into the mix, and mix thoroughly. Do not mix with dry cement.

Mix water adjustment is necessary to account for the water in Sika® CNI to maintain the required water/cementitious ratio. The batch water must be adjusted by reducing 7.0 lbs. (0.839 kg) of water per gal. (Liter) of Sika® CNI.

Compatibility :

Sika® CNI can be used in combination with other Sika admixtures and can be successfully used in mix designs utilizing supplementary cementitious materials. Sika® CNI may slightly reduce the air content and a higher dosage of the air entrainment agent may be required.

Consumption

Recommended Dosage

The recommended dosage rate for corrosion inhibiting applications will vary between 2 - 6 gallons per cubic yard (10-30 L /m³) of concrete, depending on the severity of the corrosion environment.

The typical dosage rate for set accelerating applications will vary between 10-120 fl. oz. / 100 lbs. (650-7820 ml / 100 kg.) of cement.

In order to prevent slump loss, a set retarding admixture, hydration controlling admixture or workability retaining admixture may be required, especially in warm weather applications.

In absence of a specified dosage rate, or to the extent specialized materials (such as microsilica) are specified, extreme ambient project conditions are encountered, or other unusual project conditions require special consideration outside the recommended dosage.

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