Abstract: This invention relates to methods and apparatus for inducing planes of weakness in hydraulically bound materials, for example roller compacted concrete. A crack inducer vehicle for fabricating pre-cracked hydraulically bound materials, the vehicle comprises: a groove former to form a groove in fresh hydraulically bound material prior to curing, said groove former having a first, lowered position for forming a groove in said fresh hydraulically bound material, and a second, raised position; and a system to apply a de-bonding agent into said groove such that when said hydraulically bound material has cured it preferentially cracks along a said groove.