Civil MDC

Specification for Cast-in-Place Concrete Pipe (ACI 346M-09) 2

Specification for Cast-in-Place Concrete Pipe (ACI 346M-09)

Description

3.1.1.1 Excavation—Excavate trench to establish gradeand alignment. Trench shall be shaped to outside diameter ofpipe to provide trench form. Trench form shall provide a full,firm, and continuous support by undisturbed earth, rock, orcompacted fill. Trench form shall be stable and free ofprotrusions, mud, debris, and running water. Maintain trenchform moisture in a manner such that water does not escapethe wet concrete. Remove boulders projecting into the trenchto at least 152 mm beyond trench form. Fill the resulting voidin accordance with 3.1.1.3 or with concrete.

3.1.1.2 Unstable soils—Stabilize or over excavatenoncohesive, unstable strata, or lenses of loose sand, silt, orother noncohesive soils within trench form. Reconstruct asengineered fill.

3.1.1.2.a Sensitive clays in trench form shall bestabilized or over excavated and trench form reconstructedas engineered fill.

3.1.1.3 Trench repair—Reconstitute the grade by fillingvoids with sand, pea gravel, crushed rock, or noncohesivesoil. Compact material used to reconstitute the grade to aminimum of 95% maximum dry density in accordance withASTM D698, unless specified otherwise.

3.1.1.4 Backfill material—In-place backfill materialshall meet compaction requirement, as specified in ContractDocuments.


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