4.1.5 Cistern Construction

4.1.4 Cistern Construction

By: Yuzki Wang

Courtyard cistern construction consists of 8 steps:

1. Excavation Excavate a pit in dimension of 2.7m in height, 5.5m in length and 5.5m in width

2. Floor construction Base construction with plain concrete and a layer of coarse gravel underneath for a firm bottom. Concrete reinforced with mesh reinforcement. Leave concrete 8-12 hours to cure

3. Brick laying Lay bricks on four sides to make solid walls. Leave 100-200mm space between brick walls and the pit for later side reinforcement. Mortar brick in ratio of 1:4 (1 cement : 4 sand)

4. Concrete render Water brick walls before starting concrete rendering to encourage better bind between cement and bricks. Render bricks with concrete mixture in ratio of 1:3 (1 cement : 3 sand) along with 400-500 ml of waterproofing. Double coat brick walls to achieve better durability. Each coat is let to cure for 8-12 hours.

5. Beam construction Set up temporary popping and formwork for beam construction. Pour concrete into formwork and let it cure for 12-16 hours.

6. Top construction Apply recycled timber shuttering on top of beams along with recycled cardboards and mesh reinforcement. Set up formwork for top construction and allow for access points. Bind and tie the shuttering with metal wire. Pour concrete in ratio of 1:2:4 (1 cement: 2 sand :4 coarse gravel). Let concrete set for 10-12 hours then apply pond curing. Remove formwork after a minimum of 10-12 days

7. Side reinforcement Place reinforcement bars in the gap between the pit and brick walls, pour concrete in a ratio of 1:2:4 and let it sit for 8-12 days.

8. Opening construction Lay bricks around the cistern access opening. Use mortar in ratio of 1:4

Figure 47 Courtyard Cistern Construction Sequence

Drawn by Y.Wang, (2021).