Guidelines for Permeable Interlocking Concrete Pavements (PICP) in South Africa Volume 1 Clogging in Permeable Interlocking Concrete Pavement (PICP). Guidelines for Permeable Interlocking Concrete Pavements (PICP) in South Africa Volume 1 Clogging in Permeable Interlocking Concrete Pavement (PICP). Posted in .