Grade Trowellable – Migrating Corrosion Inhibitor

durarep GT-MCI is a pre-mixed ready to use single component polymer modified, cementitious repair mortar containing a migrating corrosion inhibitor (MCI).

durarep GT-MCI is based on blended cements, graded siliceous aggregate, proprietary chemical additives, fillers and anti-desiccants. durarep GT-MCI is intended for use in hot climatic conditions as a structural repair mortar for the repair and reinstatement of concrete structures and masonry elements. The mortar is suitable for use in aggressive environmental conditions, and where superior chloride and carbon dioxide resistance is required.

When durarep GT-MCI is mixed with water, migrating corrosion inhibitor (MCI) is activated to inhibit anodic as well as cathodic steel corrosion processes, not only in contact with the steel, but also by migration through the concrete porosity reaching the rebars.

The migrating corrosion inhibitor (MCI) is a superior technical solution to extend the life time expectancy of reinforced concrete subjected to aggressive corrosion promoters such as oxygen, humidity, chlorides from marine environments.


durarep GT-MCI is particularly suitable for use in hot climatic conditions for repairs to concrete and masonry. The mortar has been formulated for patching in vertical and overhead applications without formwork as well as for large area rendering.

  • Ready to use (pre-blended)
  • Low permeability resists carbonation and chloride attack
  • Formulated for use in hot climatic conditions
  • Can be used in applications without formwork
  • High build, does not require multiple applications
  • Non-shrink
  • Chloride-free
  • Repair inhibits anodic as well as cathodic steel corrosion processes, not only in contact with the steel, but also by migration through the concrete porosity reaching the rebars
  • Repairs extend the life time expectancy of reinforced concrete subjected to aggressive corrosion conditions
Surface Preparation

Square cut all edges to be repaired to a minimum of 10 mm deep. If the rebar is to be exposed, remove concrete to a minimum of 25 mm behind the rebar.

Never feather edge the product.

Remove all dust and unsound debris contaminants and corrosion deposits.

In areas that do not require demolition and where the concrete is in good sound condition but additional cover is required, roughen the surface by scabbling or grit blasting the surface to remove laitance.

Expose corroded rebar and remove all loose scale and corrosion deposits.

Grit blasting is recommended for this purpose and particular care must be taken to ensure that the back of the rebar is cleaned as well. If corrosion has occurred due to chloride attack, the rebar should be high-pressure washed with clean water directly after the grit blasting application.

Bonding / Priming

Reinforcing steel: Apply one coat of durarep ZR primer at the rate of 7.5 m²/litre and allow to dry (see separate data sheet).

Substrate priming: All areas to be treated should be thoroughly saturated with clean water. Remove excess water from the surface prior to applying one coat of durabond GP bonding liquid at the rate of 3 to 4 m²/ litre. Firmly brush the durabond GP into the surface with a hard-bristle brush ensuring that the primer bonds well to the substrate. durarep GTMCI can be applied to the durabond GP as soon as it becomes tacky.

In critical applications when a substrate repair barrier is required or in applications where the substrate is permanently wet. epidermix® 345 epoxy bonding agent should be used (See separate data sheet).

Compressive strengths – MPa ASTM C109
24 hours 14
28 days 25
Flexural strength – MPa
28 days 6
Tensile strength – MPa
28 days 2
Coefficient of thermal expansion 9 to 12 x 10–6/ °C
Setting time 2 – 4 hours
Wet density 1875 kg/m³ @ 0,20 water: grout ratio
Chemical resistance Resists acid gas, chloride ions, oxygen
& water

Mixing should be carried out using a forced action mixer. Do not use free fall mixers. For single-bag mixing, a heavy-duty drill fitted with a spiral paddle is suitable. Mix product at slow speed (400 – 500 r/ min) Add 4 – 5 litres of water to a suitable container and while stirring slowly add the durarep GT-MCI to the water and mix for 5 minutes until the mix is homogeneous and lump free.

Do not exceed the stipulated amount of 5 litres of mixing water. Never mix part-bag batches.


25 kg of durarep GT-MCI powder mixed with 5 litres of water yields approximately 16 litres. One 25 kg bag durarep GT-MCI covers 1,60 m² @ 10 mm thick. durabond GP applied as a bonding liquid, covers 4 – 6 m²/litre; as a curing compound, 5 m²/litre. epidermix® 345 covers 10 m²/2 kg kit.


durarep GT-MCI is applied by hand or trowel to the primed substrate by packing and tamping the product into place using a trowel and gloved hand.

Care must be taken to ensure that the durarep GT-MCI is properly compacted against and around the exposed treated rebar. durarep GT-MCI can be applied up to 50 mm thick on large vertical sections and 100 mm thick on smaller pockets. On overhead application the durarep GT-MCI should not exceed 20 mm thick per application.

However multiple layers can follow in rapid succession. dura. rep GTMCI should not be applied thicker than 100 mm per application. If the profile dictates that the mortar must be thicker than 100 mm, then multiple layers are to be applied by hand or trowel. The intermediate layer should be scratch keyed and cured with durabond GP. The cured layer is then re-primed prior to application of the next layer of durarep GT-MCI

For larger rendered surfaces durarep GT-MCI should never be applied less than 10 mm thick.

Spray application:

durarep GT-MCI Sprayable can be spray applied using suitable wet or dry spray techniques and machinery. Spray applied application allows for rapid high-build placement due to increased compaction and densities achieved with this method. For further details regarding equipment and application techniques, consult a.b.e.®’s technical department.

durarep GT-MCI Sprayable is finished by striking off the surface with a straight edge or wood float. Finish with a steel trowel, wood float or sponge, depending on the finish and texture required.


For durarep GT-MCI and durabond GP, clean tools with water before setting. Hardened material can only be removed by mechanical means (durarep GT-MCI).

For durarep ZR primer, durabond GP(dried) and epidermix® 345 (wet only) clean all tools with abe® super brush cleaner.

Protection on Completion

Like all cement based materials durarep GT-MCI requires curing. As soon as the surface will not be marred, apply durabond GP, by brush or spray, at the rate of 6 – 9 m2/litre.

Temperature & Relative Humidity

durarep GT-MCI is intended for hot climates, it can however be used in more moderate climates. Surface and ambient temperature must be at least + 5°C and climbing, ideally between 20 °C and 35 °C. In hot climates above 35 °C additional care should be taken to ensure that when durarep GT-MCI is being used, the material should be stored in the shade, and mixing water should be cool. If required, consider using ice water to cool the mix.

Model Specification

Structural and general purpose cementitious mortar for concrete repairs in tropical climates. 

The repair mortar will be durarep GT-MCI, a single-component, general purpose, cementitious mortar applied in accordance with the recommendations of a.b.e.® , including durarep ZR primer for steel and durabond GP acrylic bonding agent or epidermix® 345 where necessary. The mortar will have a minimum 28-day compressive strength of 30 MPa.


durarep GT-MCI is supplied in 25 kg polyethylene lined paper bags.

durabond GP primer is supplied in 5, 20, and 200 litre drums. durarep ZR primer is supplied in 1 litre tins.

Handling & Storage

This product has a shelf life of 12 months if kept in a dry cool place in the original packaging. In more extreme conditions this period might be shortened. Surface and ambient temperature must be at least 5 °C and rising, ideally between 20 °C and 30 °C. period might be shortened.

Health & Safety

Product safety information required for safe use is not included. Before handling, read product and safety data sheets and container labels for safe use, physical and health hazard information. The safety data sheet is available from your local a.b.e.®  sales representative.

Important Note

This data sheet is issued as a guide to the use of the product(s) concerned. Whilst a.b.e.® endeavours to ensure that any advice, recommendation, specification or information is accurate and correct, the company cannot accept any liability for application – because a.b.e.® has no direct or continuous control over where and how a.b.e.® products are applied.

Further Information

Where other products are to be used in conjunction with this material, the relevant technical data sheets should be consulted to determine total

a.b.e.® has a wealth of technical and practical experience built up over the years in the company’s pursuit of excellence in building and construction

Please consult our website for our latest datasheets.