Comparison of long-term behaviour and residual strength of concrete slabs pretensioned with AFRP and steel

A series of ten concrete slabs, six of which pretensioned with AFRP and four pretensioned with steel wires, were tested under short-term and under long-term loading. The slabs, loaded in 4-point bending, have a total length of 3.2 m (span 3m), a width of 280 mm and a total depth of 105 mm. Three slabs, one with 4 AFRP bars, one with 4 steel wires and one with 5 steel wires, have been observed under long-term loading over a period of about 7 years. The long term load of the slabs equalled 10 kN per point load, which is above the decompression load (to simulate severe loading conditions). Recently the slabs have been unloaded and they are currently being tested under quasi-static short-term loading until failure. In this paper results on the long-term behaviour of the slabs are presented and compared with a theoretical analysis. Furthermore, the residual strength of the slab prestressed with AFRP is discussed.