Product Data Sheet Safety Data Sheet Show all documents

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.

  • 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 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
Product Data Sheet Safety Data Sheet Show all documents

Usage

  • Recommended for conventional steel reinforcement as well as prestressed concrete that will be exposed to chlorides from marine environments or deicing salts.
  • 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.
  • May also be used in concrete elements where chlorides are added initially to the concrete mix.
  • Sika® CNI is a corrosion-inhibiting admixture that provides protection against corrosion in reinforced concrete structures.
  • Extends the service life of reinforced concrete structures. - Recommended for use in all types of reinforced concrete, precast and/or prestressed concrete as well as ready-mix applications.
  • Sika® CNI is also an effective accelerator where high early strength concrete is desired and the use of calcium chloride is prohibited.
 

Advantages

  • 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 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

Packaging

205 L (54 US gal.) drums
1040 (275 US gal.) IBC 
Bulk delivery

Colour

Liquid / Greenish

Product Details

Sustainability / Certifications / Approvals

APPROVALS / CERTIFICATES

Meets the requirements of ASTM C1582, Corrosion Inhibiting Admixture and ASTM C494 / AASHTO M194 Type C, accelerating admixture.

 
Product Information

Shelf Life

2 years when stored in dry warehouse conditions, at temperatures ranging between +10 °C and +27 °C (50 °F and 80 °F).

Storage Conditions

Store at temperatures above +5 °C (40 °F). If frozen, thaw out and agitate thoroughly to return to normal state before use.

Specific Gravity

Approx. 1.3

Application

Application Information

Mixing

Mixing

Measure the required quantity manually or by automated dispenser. 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. Mix water adjustment is necessary to account for the water in Sika® CNI and thus, maintain the required water/cementitious ratio.The batch water must be adjusted by reducing 0.839 kg of water per litre of Sika® CNI.

    
Compatibility with other Admixtures:

Sika® CNI can be used with Portland cements compliant with ASTM, AASHTO or CRD specifications. It can be used in combination with other Sika® admixtures including microsilica, water reducers, superplasticizers, set retarders and air entrainment agents. Admixtures have to be added separately to the concrete mix in order to deliver the results required.

Limitations: 

  • Sika® CNI will not reduce the ingress of chlorides or other aggressive agents.
  • Sika® CNI may slightly reduce the entrained air content and a higher dosage of the air entrainment agent may be required.

  
Consumption

Recommended Dosage

The recommended dosage rate will vary between 10 - 30 L/m3 (2-6 gals. per cubic yard) of concrete, depending on the severity of the corrosion environment. In absence of a specified dosage rate, please contact your Sika Canada Technical Sales Representative. Adjust water content accordingly.

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


Sika® CNI may accelerate the setting time. In order to prevent slump loss or finishing characteristics, a set retarding admixture, like Sika® Plastiment®, may be required, especially in warm weather application. The full accelerating effect of Sika® CNI may be used for cold weather concreting.

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