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Frequently Asked Soil-Cement Questions
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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. This action does not permanently damage the cement-treated
base, since it is still “green” and will regain the
strength lost due to the micro-cracking procedure.
The use of micro-cracking is still under evaluation. Results show
that it will reduce the amount and severity of cracks, although
it may not always eliminate reflection cracking. In addition, there
does not appear to be a “down-side” to the process,
since no negative effects of micro-cracking have been observed.
More information on reflective cracking in cement-treated bases
can be found in the following PCA documents:
Reflective Cracking
in Cement Stabilized Pavements (IS537)
Minimizing Cracking
in Cement-Treated Materials for Improved Performance (RD123)
The latest information on micro-cracking can be found in a recent
paper from Texas Transportation Institute: “Use
of Microcracking to Reduce Shrinkage Cracking in Cement-Treated
Bases.”
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