REPAIR OF DEFECTS

3.3.4

Cover of Reinforcement

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NOTE: Use 19 mm (3/4 inch) if grading No. 1 in

paragraph AGGREGATES is selected; otherwise, use 40

mm (1-1/2 inches).

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The following minimum cover shall be provided.

a. For shotcrete used as linings, coatings, slab, or wall:[ 19 mm 3/4

inch.][ 40 mm. 1-1/2 inches.]

b. For required structural reinforcement in beams, girders, and

columns: 40 mm. 1-1/2 inches.

3.3.5

Placement Precautions

The following precautions shall be taken during placement.

a. Placement shall be stopped if drying or stiffening of the mixture

takes place at any time prior to delivery to the nozzle.

b. Rebound or previously expended material shall not be used in the

shotcrete mixture.

3.4

REPAIR OF DEFECTS

3.4.1

Defects

Defective areas larger than 31 000 square millimeters 48 square inches or

50 mm 2 inches deep shall be removed and replaced with fresh shotcrete.

These defects include honeycombing, lamination, dry patches, voids, or sand

pockets. Defective areas shall be removed in accordance with the

procedures described in paragraph EXISTING CONCRETE and replaced with fresh

shotcrete.

3.4.1.1

Repairs

All repairs shall be made within 1 week of the time the deficiency is

discovered. All unacceptable materials shall be removed and repaired by

the procedures described in the following two paragraphs. Voids and holes

left by the removal of tie rods in all permanently exposed surfaces not to

be backfilled and in surfaces to be exposed to water shall be reamed and

completely filled with dry-patching mortar as specified below.

3.4.1.2

Minor Patching

Minor patching may be accomplished with a dry-pack mixture, or with

materials as approved by the Contracting Officer. Patches that exceed

0.003 cubic meters 0.1 cubic foot in volume shall receive a brush coat of

approved epoxy resin meeting ASTM C 881/C 881M, Type II, as a prime coat.

Care shall be taken not to spill epoxy or overcoat the repair surface so

that the epoxy runs or is squeezed out onto the surface which will remain

exposed to view. Epoxy resin shall be used in strict conformance with

manufacturer's recommendations with special attention paid to pot life,

safety, and thin film tack time.

SECTION 03371

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