ACI Concrete
Mix Design
N.C. DEPARTMENT OF TRANSPORTATION
MATERIALS AND TESTS UNIT
CONCRETE CERTIFICATION SCHOOL
Design Process
Pg 78
Determine the quantities of fine and
coarse aggregate necessary to provide
concrete meeting the requirement of he
specifications using the absolute
volume basis.
 Submit mix designs for each class of
concrete to be used in the work.

Design
Submit mix designs in terms of
saturated surface dry weights on M&T
form 312U at least 35 days prior to
using the proposed mix.
 Adjust batch proportions to compensate
for surface moisture contained in the
aggregates at the time of batching.

Design

Changes in the saturated surface dry
mix proportions will not be permitted
unless revised mix designs have been
submitted to the Engineer and have
been determined to be acceptable for
use.
Design
Accompany Form 312U with a listing of
laboratory test results of aggregate
gradation, air content, slump, and
compressive strength.
 List the compressive strength of at least
three 6” x 12” or 4” x 8” cylinders at the
age of 7 and 28 days.

Design

Pg 79
When the combination of materials is
such that the compressive strength and/
or workable slump can not be obtained
at the minimum specified cement
content with the maximum allowable
water-cement ratio, increase the cement
at non cost to the Department by
whatever amount is required without
exceeding the allowable W/C ratio.
Design

Acceptance of the mix design does not
relieve the Contractor of the
responsibility to furnish an end product
meeting specifications requirements.
Pg 80
ACI Concrete Mix Design

The NC DOH has adopted the ACI
absolute volume method of design and
requires this method be used in the
design of all concrete mixes.

Remember:
Absolute Volume= Weight / (SG x 62.4)
Mix Design Process

Pg 81
Before calculations can begin on a
concrete mix design, some info has to
be supplied.
• Class of concrete to be designed
• Type of placement, vibrated or non
vibrated
• Fine aggregates
• Specific Gravity
• Fineness Modulus
Design
• Coarse aggregates
•
•
•
•
Nominal maximum size of aggregate
Specific Gravity
Dry-rodded unit weight
Rounded or angular aggregate
• N.C. Specifications
• Min. Cement content, W/C ratio, air
content, Nom. Maximum aggregate
size
ACI Table 5.3.6
Pg 85
Volume of Coarse Aggregate Per Unit of
Volume of Concrete
Nominal
Max size
of
aggregat
e
Volume of Dry-rodded coarse aggregate* per unit Volume of Concrete for
Different Fineness Moduli of Sand
Fineness Modulus of Sand
inches
2.30
2.40
2.50
2.60
2.70
2.80
2.90
3.00
3/8”
0.51
0.50
0.49
0.48
0.47
0.46
0.45
0.44
½”
0.60
0.59
0.58
0.57
0.56
0.55
0.54
0.53
¾”
0.67
0.66
0.65
0.64
0.63
0.62
0.61
0.60
1”
0.72
0.71
0.70
0.69
0.68
0.67
0.66
0.65
1 ½”
0.76
0.75
0.74
0.73
0.72
0.71
0.70
0.69
2”
0.79
0.78
0.77
0.76
0.75
0.74
0.73
0.72
3”
0.83
0.82
0.81
0.80
0.79
0.78
0.77
0.76
5 Basic Ingredients
Pg 87
Cement
 Fine Aggregate
 Coarse Aggregate
 Water
 Air
The combined total absolute
volume should be 27 cubic feet

Mix Design Worksheets

Fine Aggregate Data

Coarse Aggregate Data

ACI Table 5.3.6

Table 1000-1
Example, pg 83
Using information provided, design a
NCDOT Class A mix.
Pg 83
Min. Cement
Max W/C ratio
Agg. Shape
Nom Max size
Air Content
Slump
FM of sand
SG sand
SG stone
D.R. UW
564 pounds
.488
rounded
¾“
6
3”
2.75
2.63
2.86
104.0 pcf
Cement

Cement amount is determined from
Table 1000-1 based on the class of
concrete specified, vibrated or non
vibrated.
Max W/C Ratio
Maximum water cement ratio is based
on aggregate shape.
 Air entrained concrete has a different
ratio than non air entrained concrete.

Water

The amount of cement and the W/C
ratio are used to determine the quantity
of water.
Aggregate

The aggregate data sheets are used to
get the FM of he sand, SG of sand and
stone, and the dry rodded unit weight of
the stone.
Cement
Pg 84
564____ = 2.87 cuft/cuyd
315 x 62.4
Water
564 x .488 = 275 = 33.0 gallons
8.33
33.0 = 4.40 cu.ft./ cu.yd.
7.5
Air
.06 x 27 cu.ft. = 1.62 cu.ft./cu.yd.

Because air does not have a SG, the
6% volume that is displace by air is
used.
Coarse Aggregate
Pg 85
Use ACI Table 5.3.6 to determine the %
of the concrete mix that should be
coarse aggregate.
 Use the nominal maximum size
aggregate and the fineness modulus of
the sand to determine the %.

Use ACI Table 5.3.6 to determine that
62% of the mix must be dry rodded
coarse aggregate.
 .062 x 27 cu.ft. = 16.74 cu.ft/cu.yd.
 16.74 x 104.0 pcf = 1741 Lbs of stone
 1741 / (2.86 x 62.4) = 9.76 cu.ft./ cu.yd

Pg 87
Fine Aggregate

Total the absolute volumes of the other
materials
Cement
Water
Air
Stone
Total
Design
564 Lbs
33.0 gals
6%
1741Lbs
Abs Vol
2.87
4.40
1.62
9.76
18.65
Determine the volume of the fine
aggregate
27.00 cu.ft.
- 18.65 cu.ft
8.35 cu.ft.
 weight of sand required is
8.35 cu ft x 2.63 x 62.4 = 1370 Lbs

ACI Worksheet Example
Fine Agg
 Coarse Agg
 Table 5.3.6
 Table 1000-1

Problem 1
Class AAvib AE
 Sand-Lilesville
 Stone-Matthews Q
Fine agg wkst
Coarse agg wkst
Table 5.3.1
Table 1000-1

Pg 105
Problem 2
Class Avib AE
 Sand-Emery Pit
 Stone-Kannapolis Q
Fine agg wkst
Coarse agg wkst
Table 5.3.1
Table 1000-1

Pg 106
Problem 3
Class AAvib AE
 Sand-Great Pit
 Stone-Crabtree Q
Fine agg wkst
Coarse agg wkst
Table 5.3.1
Table 1000-1

Problem 4
Class Bnonvib AE
 Sand-Boone Q
 Stone-Mt Airy Q
Fine agg wkst
Coarse agg wkst
Table 5.3.1
Table 1000-1

Problem 5
Class AvibAE
 Sand-Johnsonville Pit
 Stone-Greystone Q
Fine agg wkst
Coarse agg wkst
Table 5.3.1
Table 1000-1

Problem 6
Class BvibAE
 Sand-Candor Pit
 Stone-North Q
Fine agg wkst
Coarse agg wkst
Table 5.3.1
Table 1000-1

Problem 7
Class AAvibAE
 Sand-Pageland Q
 Stone-Matthews Q
Fine agg wkst
Coarse agg wkst
Table 5.3.1
Table 1000-1

Problem 8
Class BnonvibAE
 Sand-Lilesville Pit
 Stone-Elkin Q
Fine agg wkst
Coarse agg wkst
Table 5.3.1
Table 1000-1

Pg 97
Mix Designs Using Fly Ash
Fly Ash may be substituted for Portland
cement up to 20% by weight of the
required cement.
 Substitute at the rate of at least 1.2
pounds of Fly Ash per pound of cement.

Maximum Water Cementitious Material Ratio
Table
Class
Round
Angular
Concrete Aggregate Aggregate
AA
.366
.410
A
.469
.512
B
.469
.545
Example pg 91

Design a Class A Fly Ash mix using the
South McDowell Q # 57 stone and
Rocky River sand. Substitute Fly Ash
for 20% of the cement. Use 1.5 gallons
less than the max water.
Cement
Multiply 20% times the 564 pounds of
cement for Class A to get 112.8 pounds.
Subtract from original cement pounds
to get 451 pounds.
 (564 X .20) - 113 = 451 pounds of
cement

Fly Ash
Multiply 112.8 times 1.2 to get 135
pounds of Fly Ash.
 112.8 X 1.2 = 135 pounds of Fly Ash

Water
Multiply max W/C ratio of .512 times the
total amount of cementitious material.
 (.512 X 586) / 8.33 - 1.5 = 34.5 gallons

– The design process for the remaining
components remains the same.
Problem 9 Fly Ash
Class AAvibAE Fly Ash
 Sand-Great Pit
 Stone-Greystone Q
 20% replacement SG Fly Ash 2.26
Fine agg wkst
Coarse agg wkst
Table 5.3.1
Table 1000-1
Fly Ash wkst

Problem 9

Cement and Fly Ash quantity
Cement 639 x .20 = 128
639 -128 = 511 Lbs Cement
Fly Ash 18 x 1.2 = 154 Lbs Fly Ash