Cebex NK is supplied as a powder additive. The material is a combination of additives that allows the use of a low water/cement ratio with a consequent increase in strength and durability.

An expansion that prevents natural settling and plastic shrinkage of the grout aiding its stability and cohesion, while completely eliminating segregation and exudation of the grout.

Uses

• Cebex NK is an additive for cement slurries where a low water/cement ratio is required.
• It improves flowability and pumpability and eliminates segregation.
• Typically used for grouting vertical prestressed cable ducts, grouting anchor rods and in long vertical wire anchors, where full corrosion protection and even stress distribution is required.

Advantages

• The expansion system compensates for plastic shrinkage and settlement in cementitious grouts.
• Prevents segregation, ensuring complete protection of cables
• Reduced water/cement ratio ensures low permeability and long service life.
• Provides a high flowing slurry with low water/cement ratio, for ease of placement or grouting.
• No ferric content, which can cause corrosion, staining or deterioration.
• Its composition allows high early strengths to be developed without the use of chlorides.

Standards

Cebex NK complies with UNE-EN 934-4:2010 Table 1 as an additive for grouts.

Tests carried out on cement grouts show that these grouts comply with the requirements specified in the standard UNE-EN445:2010 "Grouts for prestressing tendons. "Test methods".

Properties

The following results were obtained at a temperature of 20ºC:

• Appearance: Off-white powder.
• Density: 0,77 gr/cm3
• Chloride ion content: ≤ 0,10% by mass
• Setting times: Cebex NK does not noticeably affect the setting times of cement-based grouts.
• Main application: Cement slurries without segregation.

Application: Compatibility

Compatibility

Cebex NK is suitable for use with all cements complying with the RC-08 standard and can be used in mixtures containing other Fosroc Euco additives. For further information, please contact the Fosroc Euco Technical Department.

Mixing

For best results a mechanical mixer capable of producing a homogeneous slurry is recommended. For quantities up to 35 kg, a high speed drill with a cutting paddle is suitable. For larger quantities, use a turbo mixer with cutting paddle. It is essential to co-ordinate the mixing capacity of the machine and the working capacity. This may require the use of a storage tank fitted with an agitator to maintain fluidity.

Add the required water into the mixer. Then slowly add the Cebex NK without stopping the agitation and then slowly add the cement. Mix continuously for 5 minutes, ensuring that a uniform, fluid consistency is obtained.

Dosage

The recommended dosage will depend on the type of cement and the desired w/c ratio. As a guideline, the dosage ranges from 0.5% to 1.5% s.p.c.

Effects of overdosage

Overdosage of Cebex NK increases the flowability of the grout and may cause air-locking.

Application

Surfaces to be grouted should be prepared ensuring clean, sound and previously water saturated substrates. Free expanding surfaces should be minimised. Grout within 20 minutes of mixing to maximise the expansion process. The usual methods of placing or pumping should be adopted so that the application is continuous.

Grout made with Cebex NK can be pumped up to 2 hours after grouting, depending on the type of cement and temperature.

Cleaning and disposal

Tools and equipment should be cleaned with water immediately after use. Remove hardened material mechanically or with Fosroc Acid Etch.

Limitations

Cebex NK is incompatible with high alumina aluminous cement.

Storage

Cebex NK has a storage life of 12 months if kept in its original container in a dry place. This period may be reduced by high temperatures and humidity.

Precautions

Safety and hygiene

Cebex NK should not come into contact with skin and eyes, or inhalation of dust. Wear suitable protective clothing, gloves, eye/face protection and mask. If skin contact has occurred, wash with plenty of clean water. In case of contact with eyes, rinse immediately with plenty of clean water and seek medical attention.

For further information, please refer to the Material Safety Data Sheet.

Fire

Cebex NK is water based and non-flammable.