Ultra high performance concrete (UHPC)
UHPC is an extremely strong and durable concrete with small steel fibers, which can be used in places where a slender and yet very strong construction is needed. The concrete technology is well-known in the building industry.
The Forida Tower exploits the potential and advantages of UHPC. When using UHPC instead of regular concrete a lesser volume of concrete is needed. The material UHPC has the following important properties compared to regular concrete.
The good durability is achieved due to the concrete mix. A high degree of compactness is obtained by a water/powder ratio less than 0.25 and the use of ultraﬁne particles such as silica fume and micro ﬁllers.
The dense matrix of UHPC prevents deleterious impacts from penetrating into the matrix. The mechanisms that can cause conventional concrete to deteriorate are not present.
Great freeze/thaw resistance
Research concludes that UHPC mixes show an extremely high freeze-thaw resistance to water with or without deicing salts. This is attributed to the very low moisture uptake by the UHPC.
Tests and research have shown that the carbonization depth is less than the detection limit of app. 0.5 mm.
Tests show, that even with a severe chloride exposure it will take more than 100 years before the chlorides penetrate to the reinforcing bars, even with only 10 mm of cover. Further investigation shows that even if a large amount of chloride is introduced into the mixing water when the elements are produced, there will be no corrosion of the reinforcing bars.
The concrete cover that satisﬁes the environmental conditions depends on the structural class and the surrounding environment. For FORIDA Towers the structural class is S1 and the exposure class is CX4, XD1/XS1, XF2. The minimum concrete cover for the environmental conditions is 10 mm according to AFGC table 3.3 NF.