{1.} Cov xuab zeb dag xuab zeb ua los ntawm cov dej hiav txwv, cov pob zeb roob (limy, thiab lwm yam pob zeb .
{{02. Kev tsim cov tsev ua haujlwm, cov ntaub ntawv loj, cov ntaub ntawv cushion, asphalt cov khoom siv armegates .
{{03. tshuab ua cov xuab zeb tsim, cov tsheb ciav hlau siab, thiab nce nkoj siab, thiab cov tsev nyob dav dav hauv thaj teb .
4. Txoj kev sib tsoo zoo nyob rau hauv cov ntaub ntawv sib tsoo hauv tsev, thiab cov khoom siv sib tsoo, ua kom muaj kev lag luam abrasives thiab lwm yam kev lag luam.
