Feem ntau muaj 7 steel hlau nyob rau hauv txhua lub prestressed steel strand, thiab tseem muaj 2, 3 thiab 19 steel hlau.Cov hlau xaim hlau tuaj yeem muaj cov hlau lossis tsis yog hlau los tiv thaiv corrosion txheej.HDPE coated nrog anti-corrosion roj los yog paraffin wax yog hu ua unbonded prestressed steel strand.