RESTRAINED SHRINKAGE CRACKING IN FIBER-REINFORCED CONCRETE - A NOVEL TEST TECHNIQUE

A novel experimental technique was developed to assess the cracking po tential of cement-based materials when used as a bonded overlay. Speci mens were cast directly on to a substrate and the assembly was subject ed to a drying environment to induce cracking. Lengths and widths of t he resulting cracks in the overlay were monitored as a function of tim e. The use of fibers was found to be very effective not only in reduci ng the widths of the shrinkage cracks but also in allowing multiple cr acking to occur. Interestingly, these two phenomena occurred only up t o a fiber volume fraction of 0.5%; at 1% by volume of fibers, only min imal cracking was seen to occur even under a particularly severe envir onment.