Preheating asphalt e thusa ho fetisetsoa ha eona ka har'a thepa ea ho ritela, ho matlafatsa metsi a yona.
Phallo ena e ntseng e eketseha e lumella asphalt hore e kene ka har'a li-pores le likheo ka mokhoa o atlehileng haholoanyane, ka hona e ntlafatsa haholo bokhoni ba eona ba ho thibela metsi.