Ceresit CD 25 adheres to crack-free, load-bearing, clean concrete substrates free from any substances, which may impair adhesion. The substrate should have sufficient compressive strength (concrete class above C12/15) and pull-off strength of minimum 1,0 MPa. Concrete Corroded and carbonated concrete and any loose elements should be carefully removed. Any stains the layer of cement wash, anti-adhesion agents, old layers should be mechanically removed. The surface of the concrete should be rough and porous, ensuring good adhesion. The substrate should be mechanically prepared e. g. through abrasive blasting, grounding or milling. Reinforcement The corroded reinforcing bars should have the concrete support removed up to the places which are not corroded. The reinforcing bars should have rust removed by sand – blasting to the degree of cleanliness of Sa 2,5 so that they acquire clear, metallic appearance and then they should be cleaned with compressed oil free air. Before the application of Ceresit CD 25, the uncovered reinforcing bars should be covered with anticorrosion protection CD 30 twice. Concrete substrates should be sprayed with water without any puddles formed and then the slightly damp substrates and the previously protected reinforced steel should be covered with the contact layer Ceresit CD 30. The repair mortar should be applied on the slightly damp contact layer, however, not longer than after 30–60 minutes. In case of exceeding this time, the contact layer should be applied once again provided that the previous layer is completely dry.