IOS ▁software ▁Category : Sym bian ▁software ▁Category : Music ▁search ▁engines ▁Category : Windows ▁Phone ▁software ▁Category : Univers al ▁Windows ▁Platform ▁apps ▁Category : Watch OS ▁software ▁Category : 2 0 1 8 ▁mer gers ▁and ▁ac quis itions ▁Category : App le ▁Inc . ▁services ▁Category : Mobile ▁music ▁apps <0x0A> </s> ▁A ▁re bar ▁spac er ▁is ▁a ▁device ▁that ▁sec ures ▁the ▁rein for cing ▁steel ▁or ▁" re bar " ▁in ▁rein for ced ▁concrete ▁structures ▁as ▁the ▁re bar ▁is ▁assemble d ▁in ▁place ▁prior ▁to ▁the ▁final ▁concrete ▁pour . ▁The ▁spac ers ▁are ▁left ▁in ▁place ▁for ▁the ▁pour ▁to ▁keep ▁the ▁rein for cing ▁in ▁place , ▁and ▁become ▁a ▁permanent ▁part ▁of ▁the ▁structure . ▁ ▁The ▁main ▁categories ▁of ▁re bar ▁spac ers ▁are : ▁Linear ▁Sp ac ers ▁( Π - section ▁profiles , ▁H - section ▁profiles , ▁or ▁other ▁ 3 ▁dimensional ▁shapes ), ▁Point ▁Sp ac ers ▁( w heel ▁spac ers , ▁various ▁tower ▁or ▁chair - like ▁shapes ) ▁ ▁Reb ar ▁spac ers ▁can ▁be ▁divided ▁in ▁three ▁raw ▁materials ▁categories : ▁Con crete ▁spac ers ▁Pl astic ▁spac ers ▁Metal ▁spac ers ▁ ▁The ▁concrete ▁spac ers ▁have ▁the ▁advantage ▁of ▁the ▁same ▁raw ▁material ▁which ▁will ▁improve ▁the ▁wat ert ight ness ▁and ▁strength ▁of ▁the ▁concrete . ▁Pl astic ▁spac ers ▁have ▁the ▁advantage ▁of ▁the ▁low ▁cost ▁production ▁and ▁fast ▁processing . ▁ ▁Function ▁ ▁The ▁engineering ▁study ▁of ▁every