Regresar

Reinforcing dikes with sheet piles made of high performance concrete

Abstract:

A few years ago a dangerous situation existed near the rivers in the Netherlands, after an unusual long period of dry weather. After this period of dryness large cracks developed themselves in the dikes and an instable situation could occur. For that reason dikes had to be reinforced to maintain the required level of safety. The idea was raised up to use prefabricated prestressed concrete sheet piles in order to reinforce the dike. These sheet piles were drilled into the dike without disturbing its stability. However, the traditional 120 mm thick sheet pile had to be reduced in thickness to prevent stability problems Therefore a joint project between Spanbeton and Delft University of Technology was initiated and has resulted in the development of a very thin concrete sheet pile. It was found in a comparison study that the use of high strength fibre reinforced self-compacting concrete resulted in the most economical sheet pile. Various concrete mixes with different aggregate distributions were investigated. It was shown that aggregates, available at the local Dutch market as sand in large quantities with a maximum diameter of 2 mm, could be used instead of the previously developed laboratory aggregates composed out of separate fractions. This optimized sheet pile is only 45mm thick and the applied concrete cover on the applied prestressing strands is only 15 to 20mm. The local government asked the University to prove that the durability of 100 years could be met. Durability tests on mixtures containing a sand fraction widely available on the market, demonstrated that after 2 years of accelerated testing, neither carbonation nor chloride penetration could be observed. Relatively low mass loss was found after 56 freeze-thaw cycles using de-icing salt.