Effective Joining of Pre-cast Concrete Slabs with Self-compacting HSFRCC

Abstract

In the pre-cast construction of concrete structures, the minimization of the joint size and simplification of its design can greatly improve construction efficiency. This paper reports the result of an experimental study on the use of high strength fiber reinforced cementitious composites (HSFRCC) for the joining of precast concrete slabs. In order for the joined slab to have similar bending behavior as a monolithic slab, sufficient bond length between the HSFRCC and reinforcing bars is required to ensure steel yielding before bond failure. To control the material cost, the fiber content in the HSFRCC is limited to 2%. To find a suitable bond length, direct Tension Pull-out Bond Test (DTP-BT) was first conducted on steel bars embedded in HSFRCC with compressive strength of 150 MPa. The testing parameters included the anchorage length (5 d or 8 d, where d is the steel bar diameter, 16 mm) and type of steel bar (straight, hooked and nut at the end). According to the test results, 8 d is sufficient for steel yielding to occur in a joint with 2% of micro-steel fiber. Monolithic slabs as well as slabs with HSFRCC joints were then prepared and tested in bending. Similar load displacement performance was observed for the two kinds of slabs, demonstrating the effectiveness of the HSFRCC joint.