Essent
Customer
Essent Netwerk Limburg B.V., the former regional division of Essent Networks, commissioned SGS INTRON to assess the maintenance condition of over 50 prestressed concrete beams at two 150kV power stations at Neerbeek and Swentibold, The Netherlands. The reason for this request were the cracks that were found in the beams and the wish of Essent to maintain the beams for (at least) another 10 years.
Case
The concrete beams (3 types at several heights) bear the load of the electric cables in the power station. The age of the beams was over 40 years. At the time of the investigation, several beams showed cracks and the reason for this had to be determined. Special care was taken because a part of the beams were prestressed so here destructive testing was out of the question. SGS INTRON was also requested to recommend on the life time expectancy and a repair strategy for some of the beams due to the cracks.
Solution
SGS INTRON choose to use several destructive and non destructive testing methods (NDT) to gain more insight in the maintenance condition. As one of the beams had to be exchanged in the power station anyway, this beam was taken to the SGS INTRON Laboratory to get inspected in detail. SGS INTRON conducted RIMT (Reflectometric Impulse Measurement Technique ) measurements on the prestressed steel reinforcement, ultrasone testing on the concrete, but also core testing to determine the concrete strength and to perform microscopic analysis with respect to crack assessment.
SGS INTRON succeeded in pointing out all the beams that were not in sufficient condition for the next 10 years and to recommend a repair strategy for the other beams.
