a.
If the specified compressive strength f'c is less than 20 MPa
3,000 psi,
f'cr = f'c + 6.9 MPa f'cr = f'c + 1000 psi
b.
If the specified compressive strength f'c is 20 to 35 MPa 3,000 to
5,000 psi,
f'cr = f'c + 8.3 MPa f'cr = f'c + 1,200 psi
c.
If the specified compressive strength f'c is over 35 MPa 5,000 psi,
f'cr = f'c + 9.7 MPa f'cr = f'c + 1,400 psi
1.9.5
Average Flexural Strength Required for Mixtures
**************************************************************************
NOTE: Retain this paragraph when flexural strength
mixtures are used.
**************************************************************************
The mixture proportions selected during mixture design studies for flexural
strength mixtures and the mixture used during concrete production shall be
designed and adjusted during concrete production as approved, except that
the overdesign for average flexural strength shall simply be 15 percent
greater than the specified flexural strength at all times.
1.9.6
Mix Design for Bonded Topping for Heavy Duty Floors
**************************************************************************
NOTE: Retain this paragraph when design requires
heavy duty floors.
**************************************************************************
The concrete mix design for bonded topping for heavy duty floors shall
contain the greatest practical proportion of coarse aggregate within the
specified proportion limits. The mix shall be designed to produce concrete
having a 28-day strength of at least 34.5 MPa 5000 psi. Concrete for the
topping shall consist of the following proportions, by weight:
1.00 part portland cement
1.15 to 1.25 parts fine aggregate
1.80 to 2.00 parts coarse aggregate
Maximum w/c shall be 0.33. The topping concrete shall not be
air-entrained. The concrete shall be mixed so as to produce a mixture of
the driest consistency possible to work with a sawing motion of the
strike-off and which can be floated and compacted as specified without
producing water or excess cement at the surface. In no case shall slump
exceed 25 mm 1 inch as determined by ASTM C 143/C 143M.
1.10
STORAGE OF MATERIALS
Cement and other cementitious materials shall be stored in weathertight
buildings, bins, or silos which will exclude moisture and contaminants and
keep each material completely separated. Aggregate stockpiles shall be
arranged and used in a manner to avoid excessive segregation and to prevent
contamination with other materials or with other sizes of aggregates.
SECTION 03300A
Page 23
Previous Page
