Moob tsi txawj design hab pua concrete ah. Tub tsi yog ua rua heavy equipment los rua tsheb nyaav dhlas es tso hlaus ntau ua luaj le. Cov kev nyob tebchaws Amelicas teb concrete tuab les 23- 30 cm peb tsua tso hlaus rua cov joints xwb. Good sub-grade is most important