Txhawm rau daws qhov teeb meem tam sim no ntawm kev ua haujlwm qis, tus nqi siab thiab kev tiv thaiv ib puag ncig ntawm lub tshuab thauj khoom hauv kev lag luam aggregate, peb lub tuam txhab tau tsim thiab tsim cov khoom lag luam rau cov khoom lag luam sandstone aggregate kev lag luam, absorbing txawv teb chaws cov kev paub dhau los - ntse xov tooj. rov qab.