| 摘要 |
19 CONCRETE RAFT FOUNDATION A concrete raft foundation is cast integrally to form an upper slab and a plurality of downwardly depending joists in the form of a grid pattern on the underside of the slab. The joists are defined in the casting process by wooden box forms which are laid on the ground prior to the casting process. The wooden box forms are defined by planar sheet material and reinforcing posts. The rebar for the concrete slab and the joists is supported in position by support elements carried on the box forms. Each box form includes a base plate which projects outwardly to define a shoulder onto which the concrete is cast. A duct can be cast into the concrete at the periphery.
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