Kayayyakin karfen da aka rigaya ya sami babban ci gaba tun daga shekarun 1950 na karnin da ya gabata, akwai manyan maki biyu a cikin yanayin ci gabansa. Na farko, ƙarfin kayan yana ƙaruwa a hankali, don haka rage girman da nauyin abubuwan da aka riga aka tsara, har ma ya rage farashin aikin; Na biyu, a kan tushen inganta ƙarfi, ya kamata mu mai da hankali ga ci gaban kayan da high anti-lalata yi, don inganta karko na prestressed karfe aka gyara da kuma ajiye goyon baya halin kaka.