Rehabilitation of Concrete Slabs by Sifcon-Overlays

A new means for rehabilitation of severely cracked concrete slabs is a thin overlay of SIFCON (Slurry Infiltrated Fibre Concrete). This high strength concrete with an extremely high content of conventional steel fibres (about 10 % of volume) was invented in the USA and further developed by the central laboratory of Ph. Holzmann AG.. Due to its toughness and ductility it is a promising alternative to prevent reflection cracking in the overlay. A respective test slab 1,4 1,5 rn (17 cm thick concrete slab with an undoweled transverse joint, SIFCON-overlay ill d (liikiess of 5 cm without joint) was laboratory tested in a wheel tracking facility at the University of Technology, Munich. It demonstrated an excellent load transfer behaviour across the joint in the concrete bottom layer. Based on these investigations the rehabilitation of individual deteriorated concrete slabs of a heavily trafficked motorway was performed in 1997 by milling the surface to a depth of about 5 cm and applying the SIFCON-overlay to a maximum length of 20 m without any joints.