CRC 528: Large-scale tests
Table of contents
Project data
Titel | Title |
Report in the yearbook 2010
Strengthening of Large-size Slabs with TRC
Within the SFB 528 numerous tests have been carried out concerning bending bearing capacity of reinforced concrete slabs being strengthened by textile reinforced concrete (TRC). As a rule the research was based on relatively small reinforced concrete slabs with span widths of 1.6 m. The strengthening was formed by textile fabric from alkali-resistant glass or carbon with different yarn finenesses and reinforcement degrees. Parallel to these tests we developed calculation models making possible the prediction of the maximum bending bearing capacity of the strengthened components. Now the concern was to check whether the results and calculation models having been achieved until now were applicable to considerably larger reinforced concrete units. Furthermore the proof was to be shown, that notably larger reinforcement degrees of the strengthening than tested were safely producible.
This time the reinforced concrete slabs were 7.0 m long, 1.0 m wide and 0.23 m thick, therefore corresponded to real dimensions in a building. They received a steel reinforcement of 5 Øs 12 in longitudinal direction with an intersection of 20 cm. The transverse reinforcement was formed by Øs = 12 mm with an intersection of 15 cm. The concrete covering was 25 mm. Before strengthening with TRC the reinforced concrete slabs were sand blasted so as to ensure a rough composite joint. After the following prewetting the TRC was applied using Carbon fabric SGL Grid 600 which has a considerably larger yarn cross section than the fabrics used before.
Beside an unstrengthened reference slab four slabs being strengthened by one to four layers of textile reinforcement were tested in the four point bending test. The slab span width was hereby 6.75 m; the distance between the two points of load application was 1.5 m. As expected notably larger bearing capacities could be verified for the TRC strengthened slabs compared to the unstrengthened reference ones. The load-carrying capacity increased evenly with growing layer numbers. Four layers of carbon reinforcement augmented the bearing capacity to 3.5 times the unstrengthened one. Furthermore we observed a diminution of the deflection with a growing layer number and equal load level.
The comparison of the experimentally and calculative determined load-carrying capacities showed variations of less than 10 %. Thus we were able to proof the usability of the bending measuring models developed beforehand for large span widths and high reinforcement degrees.