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Sika®-CNI (K)

Corrosion inhibiting admixture for concrete

Sika®-CNI (K) is a calcium nitrite based admixture designed to inhibit the corrosion of steel in reinforced concrete. Sika®-CNI (K) contains a minimum of 30 % calcium nitrite by mass. Suitable for use in tropical and hot climatic conditions.
 

Sika®-CNI (K) is a corrosion-inhibiting admixture that provides protection against corrosion in reinforced concrete structures. Sika®-CNI (K) 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 (K) 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 (K) may also be used in concrete elements where chlorides are added initially to the concrete mix. Sika®-CNI (K):
  • 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.
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Usage

Sika®-CNI (K) is a calcium nitrite-based admixture designed to inhibit the corrosion of steel in reinforced concrete. In the high alkalinity of concrete, reinforcing steel builds up a natural passivation layer that protects the steel from corrosion. This passive ferric oxide layer can however be damaged by the presence of chlorides and combined with the presence of moisture and oxygen will lead to corrosion of the steel.    Sika®-CNI (K) 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 chlorides, rust continues to generate in these areas (corrosion pits) and ultimately leads to staining, cracking and spalling of the concrete.     Sika®-CNI (K) fortifies the ferric oxide passivating layer prior to the penetration of chlorides. The nitrite ions in Sika®-CNI (K) will convert ferrous oxide to more resistant ferric oxide, thereby protecting the steel reinforcement from corroding.  

Advantages

Sika®-CNI (K) is a corrosion-inhibiting admixture that provides protection against corrosion in reinforced concrete structures. Sika®-CNI (K) 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 (K) 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 (K) may also be used in concrete elements where chlorides are added initially to the concrete mix. Sika®-CNI (K):
  • 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.

Packaging

200 L drums and 1000 L flowbins

Colour

Yellow liquid

Product Details

Sustainability / Certifications / Approvals

APPROVALS / CERTIFICATES

Sika®-CNI (K) follows the requirements of ASTM C1582; Corrosion Inhibiting Admixture and ASTM C494; Type C, Accelerating Admixture.

 
Product Information

Composition

Calcium Nitrite

Shelf life

24 months from date of production if stored properly

Storage conditions

Store in undamaged, unopened, original sealed packaging in dry conditions at temperatures between +5 °C and +45 °C. Protect from direct sunlight and frost.

Density

~1.23 kg/l (+25 °C)

Total Chloride Ion Content

Nil

(EN 934-2)
Technical Information

Concreting Guidance

The standard rules of good concreting practice for production and placing must be observed when using Sika®-CNI (K) in concrete. Refer to relevant standards.
Fresh concrete must be cured properly especially at high temperatures in order to prevent plastic and drying shrinkage. Use Sika® Antisol® products as a curing agent or apply wet hessian.

Application

Application Information

Compatibility

Sika®-CNI (K) may be combined with all types of Portland cement (OPC and SRC), concretes containing pozzolanic materials such as; GGBS, PFA and micro-silica. It can be used in combination with other Sika admixtures including 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.

We recommend to perform trial mixes to establish the required performance when combining Sika®-CNI (K) with other admixtures. Please consult our Sika Technical Department.

Dispensing

Measure the required quantity manually or by automated dispenser. Add Sika®-CNI (K) 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 (K) and thus maintain the required water/cement ratio. The batch water must be adjusted by reducing 0.85 kg of water per liter of Sika®-CNI (K).
Consumption

Recommended Dosage

The recommended dosage rate will vary between 10 - 30 l/m3 of concrete depending on the severity of the corrosion environment.

In absence of a specified dosage rate, please contact your local Sika representative.

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