Yog vim li cas rau qhov hluav taws kub tsis kam ntawm hluav taws qhov rooj yog yooj yim heev, feem ntau yog siv cov inorganic non-combustible cov ntaub ntawv uas tsis yog hlau, refractory ntoo los yog refractory ntoo khoom. Cov qhov rooj hluav taws tsuas yog ua lub luag haujlwm ib ntus hauv kev tiv thaiv kev sib kis ntawm hluav taws, thiab lub sijhawm tshwj xeeb ntawm hluav taws kub yog nyob ntawm qhov hluav taws kub ntawm cov khoom siv hluav taws kub thiab cov khoom ntim.