used for computing volume changes due to temperature
variations. Other values, greater or smaller,
should be used instead whenever justified by
climatic conditions at the jobsite. For in-house
design delete all references to design by others.
**************************************************************************
Precast unit design shall conform to ACI 318M/318RM ACI 318/318R and PCI
MNL-122. Design loads for precast concrete shall be as indicated on the
drawings. A differential temperature of [89] [_____] degrees C [160]
[_____] degrees F, between interior and exterior faces of the units, shall
be considered in the design. Stresses due to restrained volume change
caused by shrinkage and temperature differential, handling, transportation
and erection shall be accounted for in the design.
1.4.2
Connections
Connection of units to other members, or to other units shall be of the
type and configuration indicated. The design and sizing of connections for
all design loads shall be by the Contractor.
1.4.3
Concrete Strength
Precast concrete units shall have a 28-day compressive strength of 34 MPa
5000 psi.
1.4.4
Concrete Proportion
Selection of proportions for concrete shall be based on the methodology
presented in ACI 211.1 for normal weight concrete and ACI 211.2 for
lightweight concrete. The concrete proportion shall be developed using the
same type and brand of cement, the same type and gradation of aggregates,
and the same type and brand of admixture that will be used in the
manufacture of precast concrete units for the project. Calcium chloride
shall not be used in precast concrete and admixtures containing chloride
ions, nitrates, or other substances that are corrosive shall not be used in
prestressed concrete.
1.4.5
Calculations
Calculations for design of members and connections not shown shall be made
by a professional engineer experienced in the design of precast
architectural concrete. Calculation shall include the analysis of member
for lifting stresses and the sizing of the lifting inserts.
1.4.6
Mix Design
The Contractor shall submit the mix design formula giving the maximum
nominal coarse aggregate size, the proportions of all ingredients and the
type and amount of any admixtures that will be used in the manufacture of
each strength and type of concrete, prior to commencing operations. The
statement shall be accompanied by test results from an approved testing
laboratory, certifying that the proportions selected will produce concrete
of the properties required. No substitutions shall be made without
additional tests to verify that the concrete properties are satisfactory.
1.5
STORAGE AND INSPECTION AT MANUFACTURER'S PLANT
Precast units temporarily stored at the manufacturer's plant shall be
SECTION 03413A
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