Kev txhim kho cov kua dej waterproud tau undergone qhov kev hloov pauv ntawm cov ntaub ntawv cov khoom siv hluavtaws, los ntawm ib leeg mus rau ntau ib puag ncig ib puag ncig ib puag ncig ib puag ncig ib puag ncig. Cov ntaub ntawv tsis muaj cua sov feem ntau yog raws cov ntaub ntawv ntuj tsim, xws li asphalt thiab tar, nrog kev txwv thiab kev ua haujlwm tsawg. Nrog rau kev txhim kho kev tshawb fawb thiab thev naus laus zis, cov khoom siv dej tsis muaj kev tsim tawm ntawm cov khoom tiv thaiv dej ib puag ncig thiab cov khoom siv lim dej ua haujlwm tau tshwm sim.
