Detailed specifications for precast concrete manhole

The material concrete is C30, with a water resistance grade of S8, and the steel reinforcement is HPB235, HRB335.

2. Lay 100mm thick mixed sand and gravel under the base during inspection and installation. Seal the joints with 1:2 waterproof mortar.

3. Pre-cast manholes are connected to reinforced concrete pipes using a 1:2 mortar joint.

4. During backfilling, simultaneously fill around the well chamber or well shaft. The density of the backfill soil should meet the road surface requirements but not be less than 95%. Within the frozen soil depth range, backfill with non-expansive soil to a width of 00mm to meet subgrade requirements.

5. Select φ1200 or 1500 specifications according to design (all units in mm).