Some engineers may choose to design elastomeric bearings to sit on the piers without a connection. The bearing is held in place by frictional resistance only. Paraffin used in natural rubber would bleed out and result in significant decrease in friction. As such, elastomeric bearings would slip away and walk out from their original locations. To solve this problem, neoprene, instead of natural rubber, is used as elastomer because paraffin is absent in neoprene bearings.
This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.