ABSTRACT
Grouting in karst areas can take several forms; slurry (or intrusion) grouting; compaction grouting; chemical grouting; and rock surface “seal” or “closure” grouting. Sometimes, sealing the rock/soil interface is all that is necessary, particularly for detention basins. Other times, more massive grout injections are needed. Grout curtains, accelerators, thickeners, primary and secondary grouting patterns, placement by tremie pipe, and formed grout columns, all play a role in remediating a karst site for either existing or future facilities.
The nature of the facility and the subsurface in question can alter the type of grouting program planned. Slurry grouting (starting with a lean mix of sand, cement, and water with a pinch of bentonite) is generally most appropriate for typical karst sites in which voids are found in both the rock and the overlying soils, and when facility loadings are light to moderate. Compaction grouting works best when rock is relatively sound and shallow, otherwise tremendous quantities of grout will be needlessly placed into rock and soil voids.
