What is micro-cracking (or pre-cracking) of cement-treated bases?
Micro-cracking is a construction process used to reduce the potential for reflective cracks in pavements that have cement-treated bases (CTB). Sometimes in the US this is also referred to as pre-cracking, but care must be used with this term because in Europe pre-cracking refers to the construction of control joints in CTB. Micro-cracking was first tried in Austria, and is currently being researched in the US at the Texas Transportation Institute. Any cement-treated material will shrink slightly as it cures and gains strength. Thin cracks in a cement-treated base occur naturally every 20 – 40 feet as the result of this shrinkage. The objective of micro-cracking is to induce hundreds of tiny cracks to accommodate the shrinkage, rather than individual cracks that have the potential to reflect up into the surface layer. Micro-cracking is accomplished by loading the CTB with a vibrating roller approximately 2 days after construction. About 4 passes of the roller will complete the process.
