platzhalter
K E I M C O N C R E T A L ® – THE B E A U T Y O F C O N C R E T E ! 21 WHAT CAUSES CONCRETE DECAY? PROTECTIVE OPTIONS FOR CONCRETE External influences, manufacturing faults or defects in workmanship, constructive shortcomings or combinations thereof may result in serious concrete decay. Good concrete, very low carbonation WEATHERING PROTECTION Silicate coatings can protect concrete surfaces longterm from weathering thanks to their strengthening action (silicification). An extra treatment of the substrate with a hydrophobing agent even increases the weathering protection. Carbonation zone is very close to the reinforcement CO 2 PROTECTION The concrete surface must be sealed in such a way that CO 2 cannot penetrate. For a functioning CO 2 protection the pores and blowholes have to be always closed by filling (full-cover filling) before coating. Just a coating alone would be insufficient in this case. FOR ETERNITY Concrete is used wherever protection and safety are requested. Foundations, bridges, tunnels or skyscrapers have to withstand strongest environmental influences. Even concrete, formerly promoted as being »forever«, is not spared from decay. CONSTRUCTIVE DEFICIENCIES DURING THE BUILDING BOOM The use of concrete has been increased since the middle of the 20th century. But at that time quality requirements and technologies were not at today‘s level. So, you may come across older concrete buildings with ageing phenomena and decay such as spalling and corrosion. The causes are manifold, entailing a considerable need for renovation. HAZARDS In the course of time concrete is attacked by weathering and thus allows water and pollutants to enter. Moss and algae growth lead to visual shortcomings and increase the damaging effect. A high water absorption in combination with frost will destroy the structure of the concrete causing rust on the reinforcement and leads to considerable damages. OVERVIEW OF HAZARDS – Weather – Water – Shallow depth of cover – De-icing salts – Constructive deficiencies Reinforcement is already located in the carbonated area High chloride load Large areas of the reinforcement are close or right at the concrete surface WATER PROTECTION Water accumulation in the concrete is prevented by a high water-repellency of the outside surface and extreme water vapour permeability from inside to the outside (rust protection by keeping the concrete dry). CHLORIDE PROTECTION Chloride salts are transported into the concrete by water. Chloride protection also means water protection. In this way the penetration of chloride-loaded water is prevented and dry concrete guaranteed. Chlorides that are already present in the concrete cannot become active. ADDITIONAL COVERING Additional cover with a concrete replacement material is required for lasting protection. By spray application of an extra layer thickness from 1 to 3 cm is the material strongly compacted in order to avoid carbonation. A subsequent coating of the surface is performed for visual reasons and as weathering protection. Carbonated concrete Non-carbonated concrete Carbonation end Steel reinforcement
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