Vetobond PB434

Saw cut the extremities of the repair locations to a depth of at least 10 mm to avoid feather edging and provide a square edge. Break out the complete repair area to a minimum depth of 6 mm up to the sawn edge. Clean the surface and remove any dust, unsound or contaminated material, plaster, oil, paint, grease, corrosion deposits, or algae.

Breaking out is not required. Roughen the surface and remove any laitance by light scabbling or grit blasting. Remove oil and grease deposits by steam cleaning, detergent scrubbing, or by the use of a proprietary degreaser. A pull-off test should then assess the effectiveness of decontamination.

Expose fully any corroded steel in the repair area and remove all loose scale and corrosion deposits; clean steel to a bright condition paying particular attention to the back of exposed steel bars. Grit blasting is recommended for this process.

If corrosion has occurred due to chlorides’ presence, the steel should be high-pressure washed with clean water immediately after grit blasting to remove corrosion products from pits and imperfections within its surface.

Soak the substrate thoroughly with clean water and remove any excess before commencement. Prepare a slurry primer with 1 volume of Vetobond PB434 to 1 volume of clean water to 3 volumes of fresh cement.

To obtain a smooth consistency, blend the cement slowly into the premixed liquids. Stir the slurry primer frequently during use to offset settlement. Scrub the slurry primer well into the surface of the concrete. Avoid applying too thickly and avoid ‘Puddling.’

The repair mortar, topping, or render must be applied to the wet slurry primer. If the slurry primer dries before applying the mortar, it must be removed and the area reprimed before continuing. In exceptional circumstances, e.g., where a substrate/ repair barrier is required or where the substrate is likely to remain permanently damp, contact Saveto Technical Support.

Mix Vetobond PB434 mortars thoroughly. A forced-action mixer is essential. 

Mixing in a suitably sized drum using an approved spiral paddle at a slow speed (400/500 rpm) heavy-duty drill is acceptable for occasional use. 

A wide range of mix designs is achievable using Vetobond PB434. Typical designs are detailed below:

 1. Patching and repair mortar (Recommenced thickness 6 mm to 40 mm) 

• 50 kgs Ordinary Portland Cement 
• 150 kgs grade C/M sharp sand 
• 10 liters Vetobond PB434 
• 8 liters (Approx.) clean water 

2. Heavy-duty floor screed (Recommended thickness 10mm to 40mm) 

• 50 kgs Ordinary Portland Cement 
• 75 kgs 3 mm to 6 mm granite chips 
• 75 kgs grade C/M sharp sand 
• 10 liters Vetobond PB434 
• 6 liters (Approx.) clean water 

Note: The screed should be of a semi-dry cohesive consistency. 

3. Render (Recommended thickness 6mm to 9mm) 

• 50 kgs Ordinary Portland Cement 
• 150 kgs grade C/M sharp sand 
• 10 liters Vetobond PB434 
• 6 liters (Approx.) clean water 

Note: The render should be of a semi-dry cohesive consistency. 

4. Bonding mortar for slip bricks, tiles, etc.: 

• 50 kgs Ordinary Portland Cement 
• 125 kgs grade C/M sharp sand 
• 10 liters Vetobond PB434 
• 7 liters (approximately) clean water 

Adjust water to give a firm mortar. For fine joints, use grade M/F sand. Support where necessary until the mortar is set. 

The recommended thickness 6mm to 40mm. 

Note: The mix designs are based on the use of dry sand and aggregate. Adjust the water demand relative to the moisture content of the sand and aggregate used. It should also be noted that, due to the frequent inconsistencies of site stored materials and variable conditions, actual results may differ from those published above. 

Weigh the cement, sand, and, where required, aggregate into the mixer and dry blend together for one minute. With the machine in operation, add the pre-mixed Vetobond PB434 and clean water. Continue mixing for 3 minutes to ensure complete dispersal into the sand and cement. Make any small adjustment to the quantity of clean water but do not significantly exceed the amount shown above. Keep adding water to a minimum. Continue mixing up to a maximum of 5 minutes until achieving a smooth and fully homogeneous consistency with the required workability and application properties. Allowance must be made for the moisture content of the sand and aggregate, particularly where they are stored on site.

For application to all surfaces, Vetobond PB434 mortars, toppings, and renders must be well compacted onto the primed substrate by trowel. It is frequently beneficial to work a thin layer of the mortar into the slurry primer and then build it onto this layer. The mortar should completely encapsulate exposed steel reinforcement.

Vetobond PB434 mortars can be applied at a minimum thickness of 6 mm and up to 40 mm thickness, depending on the location and configuration of the repair zone. The thickness achievable in overhead locations without the use of formwork is largely dependent on the profile of the substrate. Refer to the recommended thicknesses shown in the ‘Mix design’ section above.

If the recommended thickness is exceeded and sagging occurs, the affected section must be completely removed and reapplied following the procedure described above.

The use of formwork may facilitate achieving the required build. If formwork is used, it should have properly sealed faces to ensure that no water is absorbed from the repair material. Where thicker sections up to a total thickness of 40 mm are to be built up by hand or trowel application, the surface of the intermediate layers should be scratch keyed and cured with Vetobond AB432.

Application of the slurry primer and a further application of Vetobond PB434 mortar may proceed as soon as this layer has been set.

For more information on mixing & application, refer to Vetobond PB434’s Data Sheet.

Finish Vetobond PB434 mortars with steel, plastic, wood floats, or a damp sponge technique to achieve the desired surface texture. The completed surface should not be overworked.

In cold conditions down to 5°C, use warm water (up to 30°C) to accelerate strength development. Adopt normal precautions for winter working with cementitious materials.

At ambient temperatures above 35°C, store the material in the shade and cool water used for mixing.

Vetobond PB434 mortar, toppings, and renders are cement-based. In common with all cementitious materials, it is a must to cure immediately after finishing by good concrete practice. Use Vetocure XT426 sprayed onto the surface of the finished mortar in a continuous film. In harsh drying conditions, use supplementary curing with polythene sheeting.

Vetobond PB434 mortar repairs are extremely durable and will provide excellent protection to the embedded steel reinforcement within the repaired locations. The surrounding parts of the structure will generally benefit from applying a barrier/decorative coating to limit the advance of chlorides and carbon dioxide, thus bringing them up to the same protective standard as the repair itself.

Saveto recommends the use of the Vetotouch range of protective, anti-carbonation coatings. These products provide a decorative and uniform appearance and protect areas of the structure that might otherwise be at risk from the environment. Apply Vetotouch products over the repair area without prior removal of the Vetobond AB432 curing membrane. This is best achieved by light grit or sandblasting.

Clean tools with water promptly before material hardens. Hardened material can be mechanically removed.