Mixing
At the mixing stage, it is important for the additive to mix evenly in the cement. If the dry matters are mixed first, the cement is poured in the mixer followed by slowly adding the additive in the rotating mixer. The mixture is mixed dry for a while before water is added.
Alternatively, the additive can also be mixed in the mixing water before the cement is added in the water. Allow the additive to dissolve for approximately 3 minutes. To avoid segmentation of the grouting paste, the finished paste should not be left standing for a long time without mixing.
Mixing water (clean, drinkable water) is used in an amount of 10 litres per 25 kg bag of cement: if the mixing water is natural water, its acidity may slow down the bonding of the injection paste. If a preliminary test carried out at the work site suggests the above, take this delay into account when planning the work.
Work instructions
The product must be carefully mixed before use. One 0.25 l measure of the QD-45 additive, added in an amount of Ciment Fondu Lafarge cement contained in one 25 kg bag, provides a working time of appr. 45 minutes for the grouting paste. After this, the grouting concrete cures fast. Boring can be commenced after approximately two hours from mixing water in the cement. The additive is an acidic mixture, so rubber gloves, respiratory protectors, and eye protectors need to be worn.
Other considerations
Cold air slows down the bonding of cement, whereas hot conditions correspondingly accelerate bonding. Acidic mixing water, too, slows down the bonding of injection paste. We always recommend the bonding rate to be checked at the work site condition in question before commencing work. A work site test may be performed as follows, for example:
- Mix together 2.5 kg of Ciment Fondu cement and 25 ml of QD-45 additive
- Add 1 L of mixing water used at the site to the cement additive mixture, and mix
This mixing ratio should provide a working time of approximately 45 minutes, and the concrete should warm up heavily for approximately 10 to 20 minutes from the start of bonding, after which the concrete slowly cools down. After about two hours after adding water, the concrete is hard enough for drilling work to begin. If the goal is to make the concrete even harder, wait for about 3 h after adding water.
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