International Building Code Section 1913

International Building Code 1913.1

General. Shotcrete is mortar or concrete that is pneumatically
projected at high velocity onto a surface. Except as
specified in this section, shotcrete shall conform to the requirements
of this chapter for plain or reinforced concrete.

International Building Code 1913.10

Strength tests. Strength tests for shotcrete shall be
made by an approved agency on specimens that are representative
of the work and which have been water soaked for at least
24 hours prior to testing. When the maximum-size aggregate is
larger than 3/8 inch (9.5 mm), specimens shall consist of not less
than three 3-inch-diameter (76 mm) cores or 3-inch (76 mm)
cubes. When the maximum-size aggregate is 3/8 inch (9.5 mm)
or smaller, specimens shall consist of not less than
2-inch-diameter (51 mm) cores or 2-inch (51 mm) cubes.

Sampling. Specimens shall be taken from the
in-place work or from test panels, and shall be taken at least
once each shift, but not less than one for each 50 cubic yards
(38.2 m3) of shotcrete.

Panel criteria. When the maximum-size aggregate
is larger than 3/8 inch (9.5 mm), the test panels shall
have minimum dimensions of 18 inches by 18 inches (457
mm by 457 mm). When the maximum size aggregate is 3/8
inch (9.5 mm) or smaller, the test panels shall have minimum
dimensions of 12 inches by 12 inches (305mmby 305
mm). Panels shall be shot in the same position as the work,
during the course of the work and by the nozzlemen doing
the work. The conditions under which the panels are cured
shall be the same as the work.

Acceptance criteria. The average compressive
strength of three cores from the in-placework or a single test
panel shall equal or exceed 0.85 f c with no single core less
than 0.75 f c. The average compressive strength of three
cubes taken from the in-place work or a single test panel
shall equal or exceed f c with no individual cube less than
0.88 f c. To check accuracy, locations represented by erratic
core or cube strengths shall be retested.

International Building Code 1913.10.1

Sampling. Specimens shall be taken from the
in-place work or from test panels, and shall be taken at least
once each shift, but not less than one for each 50 cubic yards
(38.2 m3) of shotcrete.

International Building Code 1913.10.2

International Building Code 1913.10.3

International Building Code 1913.2

Proportions and materials. Shotcrete proportions
shall be selected that allow suitable placement procedures
using the delivery equipment selected and shall result in finished
in-place hardened shotcrete meeting the strength requirements
of this code.

International Building Code 1913.3

Aggregate. Coarse aggregate, if used, shall not exceed
3/4 inch (19.1 mm).

International Building Code 1913.4

Reinforcement. Reinforcement used in shotcrete construction
shall comply with the provisions of Sections 1913.4.1
through 1913.4.4.

Size. The maximum size of reinforcement shall be
No. 5 bars unless it is demonstrated by preconstruction tests
that adequate encasement of larger bars will be achieved.

Clearance. When No. 5 or smaller bars are used,
there shall be a minimum clearance between parallel reinforcement
bars of 21/2 inches (64 mm). When bars larger
than No. 5 are permitted, there shall be a minimum clearance
between parallel bars equal to six diameters of the bars
used. When two curtains of steel are provided, the curtain
nearer the nozzle shall have a minimum spacing equal to 12
bar diameters and the remaining curtain shall have a minimum
spacing of six bar diameters.
Exception: Subject to the approval of the building official,
required clearances shall be reduced where it is
demonstrated by preconstruction tests that adequate
encasement of the bars used in the design will be
achieved.

Splices. Lap splices of reinforcing bars shall utilize
the noncontact lap splice method with a minimum clearance
of 2 inches (51 mm) between bars. The use of contact
lap splices necessary for support of the reinforcing is permitted
when approved by the building official, based on satisfactory
preconstruction tests that show that adequate
encasement of the bars will be achieved, and provided that
the splice is oriented so that a plane through the center of the
spliced bars is perpendicular to the surface of the shotcrete.

Spirally tied columns. Shotcrete shall not be
applied to spirally tied columns.

International Building Code 1913.4.1

Size. The maximum size of reinforcement shall be
No. 5 bars unless it is demonstrated by preconstruction tests
that adequate encasement of larger bars will be achieved.

International Building Code 1913.4.2

International Building Code 1913.4.3

International Building Code 1913.4.4

Spirally tied columns. Shotcrete shall not be
applied to spirally tied columns.

International Building Code 1913.5

Preconstruction tests. When required by the building
official, a test panel shall be shot, cured, cored or sawn, examined
and tested prior to commencement of the project. The
sample panel shall be representative of the project and simulate
job conditions as closely as possible. The panel thickness and
reinforcing shall reproduce the thickest and most congested
area specified in the structural design. It shall be shot at the
same angle, using the same nozzleman and with the same concrete
mix design that will be used on the project. The equipment
used in preconstruction testing shall be the same
equipment used in the work requiring such testing, unless substitute
equipment is approved by the building official.

International Building Code 1913.6

Rebound. Any rebound or accumulated loose aggregate
shall be removed from the surfaces to be covered prior to
placing the initial or any succeeding layers of shotcrete.
Rebound shall not be used as aggregate.

International Building Code 1913.7

Joints. Except where permitted herein, unfinished
work shall not be allowed to stand for more than 30 minutes
unless edges are sloped to a thin edge. For structural elements
that will be under compression and for construction joints
shown on the approved construction documents, square joints
are permitted. Before placing additional material adjacent to
previously applied work, sloping and square edges shall be
cleaned and wetted.

2006 INTERNATIONAL BUILDING CODE 381
CONCRETE

International Building Code 1913.8

Damage. In-place shotcrete that exhibits sags, sloughs,
segregation, honeycombing, sand pockets or other obvious
defects shall be removed and replaced. Shotcrete above sags
and sloughs shall be removed and replaced while still plastic.

International Building Code 1913.9

Curing. During the curing periods specified herein,
shotcrete shall be maintained above 40F (4C) and in moist
condition.

Initial curing. Shotcrete shall be kept continuously
moist for 24 hours after shotcreting is complete or
shall be sealed with an approved curing compound.

Final curing. Final curing shall continue for seven
days after shotcreting, or for three days if highearly-
strength cement is used, or until the specified strength
is obtained. Final curing shall consist of the initial curing
process or the shotcrete shall be covered with an approved
moisture-retaining cover.

Natural curing. Natural curing shall not be used
in lieu of that specified in this section unless the relative
humidity remains at or above 85 percent, and is authorized
by the registered design professional and approved by the
building official.

International Building Code 1913.9.1