The document discusses various methods for proportioning concrete mixtures, including the water-cement ratio method, weight method, absolute volume method, and using field experience data. It provides details on using statistical analysis of strength test results and trial mixtures to establish mix designs that meet requirements for compressive strength, slump, and air content. The absolute volume method involves calculating the absolute volumes of ingredients based on their densities to determine proper mix proportions.

1. CON 124
Basic Concrete Mix Design Proportioning
Session 4
Proportioning Methods

2. Methods for Proportioning Concrete
Mixtures
 Water-cement ratio method
 Weight method
 Absolute volume method
 Field experience (statistical data)
 Trial mixtures

3. Design of Concrete Mixtures
 Establishment of specific concrete
characteristics
 Relative Density (Specific Gravity)
 Absolute volume calculation (27 Cubic Ft)
 Durability Issues
 Selection of proportions of available materials
to produce concrete of required properties,
with the greatest economy

4. Concrete Mixture Design from
Field Data
 Strength-Test Data
 Standard Deviations show mixture is
acceptable
 Durability aspects must be met
 Statistical data should represent the same
material, proportions, and concreting
conditions

5. Proportioning Data for Proposed Work
 Concrete Strength within 7MPa (1000 psi)
 Data should represent at least 30 consecutive tests or two
groups representing of consecutive tests totaling at least 30
tests (average of two cylinders)
 If data between 15-29 tests, an adjusted Std. Dev. (S) is
multiplied by modification factor from Table 11
 Modified Std. Dev. (S) is then used in equations 1-3 from Table
12
 When field strength test records do not meet the above, then
the required average strength of concrete can be obtained
from Table 13 (Table 9-11)

6. Proportioning from Field Data
Number of tests
Modification factor for
standard deviation
Less than 15 see next slide
15 1.16
20 1.08
25 1.03
30 or more 1.00
Modification Factor for Standard
Deviation ( 30 Tests)
Table 11: Modification factor for standard deviation when less than 30 tests are
available. Interpolated for design mixtures modified standard deviation to be
used to determine required average strength. Adapted from ACI 318.

7. Proportioning from Field Data
Required Strength When Data Are Available to Establish
a Standard Deviation
Specified compressive
strength, f'c, psi
Required average
compressive strength, f'cr, psi
5000
f'cr = f'c+ 1.34s
f'cr = f'c + 2.33s - 500
Use larger value
Over 5000
f'cr = f'c+ 1.34s
f'cr = 0.90f'c + 2.33s
Use larger value Inch-Pound
Table 12: Required Average Compressive Strength When Data Are
Available to Establish a Standard Deviation (Inch-Pound)
Adapted from ACI 318.

8. Proportioning from Field Data
Required Strength When Data Are Not Available
to Establish a Standard Deviation
Specified compressive
strength, f'c, psi
Required average
compressive strength, f'cr, psi
Less than 3000 f'c + 1000
3000 to 5000 f'c + 1200
Over 5000 1.10f'c + 700
Inch-Pound
Table 13: (Inch-Pound Units). Required Average Compressive Strength
When Data Are Not Available to Establish a Standard Deviation
Adapted from ACI 318.

9. Proportioning by Trial Mixtures
 Trial batching verifies that a concrete mixture meets
design requirements prior to use in construction.
 The trial mixtures should use the same materials
proposed for the work.
 Three mixtures with three different water-cementing
materials ratios or cementing materials contents
should be made.
 The trial mixtures should have a slump and air content
within ±20 mm (±0.75 in.) and ± 0.5%, respectively, of
the maximum permitted.
 Three cylinders for each water-cementing materials
ratio should be tested at 28 days.

10. Proportioning by Trial Mixtures
 Approved mixture must meet required average
compressive strength
 Three trial mixtures using three different water to
cementing materials ratios
 Slump and Air Content within +/- 20 mm(+/- 0.75 in.) and
+/- 0.5%
 Cylinders cured as per ASTM C192 (AASHTO T126)
 Plot water to cementing ratio to strength curve
 Test the properties of the newly proportioned
mixture

11. Proportioning Concrete Ingredients
 Arbitrary assignment (1:2:3), volumetric
 Void Ratio
 Fineness Modulus
 Surface Area of Aggregates
 Cement Content
 Best approach
 Select proportions based on past experience
 Reliable test data established relationship between
strength and water to cementing materials ratio

12. Plotting of Water to Cementing Ratio to
Compressive Strength

13. Satisfactory Job Mixture
 Required Strength
 Minimum Cementing Materials Content or Maximum
Water to Cementing Materials Ratio
 Nominal Maximum Size Aggregate
 Necessary Amounts of Fine and Coarse Aggregate
(saturated surface dry condition, SSD)
 Air Content
 Desired Slump

14. Saturated Surface-Dry Density
(SSD-Density)
where
DSSD is density in the SSD condition
M1 is the SSD mass in air, kg (lb)
M2 is the apparent mass immersed in water, kg (lb)
is the density of water, 1000 kg/m3 (62.4 lb/ft3)
21
1
MM
M
DSSD

15. Slump Test
Slump test for consistency of concrete. Left figure illustrates a lower
slump, right figure a higher slump.

16. Air Content
Pressure method
ASTM C 231
(AASHTO T 152)
Volumetric method
ASTM C 173
(AASHTO T 196)
Air indicator method
AASHTO T 199

17. Tests, Measurements,
Calculations
 Tests for slump, air content, and temperature
on trial mixture
 Density (Unit Weight) and Yield
 Absolute Volume

18. Density (Unit Weight), Yield
 In accordance with ASTM C138
 Density (Unit Weight): Pounds/Cubic ft
 Yield: Cubic Feet
 Calculation, Dividing total mass of materials
batched to density of freshly mixed concrete

19. Density (Unit Weight) and Yield
Fresh concrete is measured in a
container of known volume to
determine density (unit weight)
• Scale must be sensitive to 0.3% of
anticipated mass of sample and
container
• Size of container varies according
to the size of the aggregate, the
7-L (25-ft3) air meter container
for up tp 25-mm (1-in.) nominal
max. size aggregate: 14-L (0.5 ft3)
container for aggregates up to 50
mm (2-in.)
• Container should be calibrated at
least annually (ASTM C 1077)

20. Density (Unit Weight) and Yield
ASTM C 138
(AASHTO T 121)
Density (Unit Weight),
Yield, and Air Content
(Gravimetric) of Concrete
ASTM C 1040
(AASHTO T 271)
• Density of Unhardened
and Hardened Concrete
in Place By Nuclear
Methods

21. Absolute Volume
 Volume of a granular material is the volume of
the solid matter in the particles without
volume of air spaces
 Yield of freshly mixed concrete is equal to the
sum of the absolute volumes of the concrete
ingredients

22. Proportioning Concrete Mixtures
Absolute Volume Method
Dry Rodded Density Absolute Volume Density

23. Proportioning Concrete Mixtures
Absolute Volume Method
Abs Vol Density = Weight/Volume
(no voids)
Specific Gravity =
Abs Vol Density / Density of Water
Vol

24. Proportioning Concrete Mixtures
Absolute Volume Method
Abs Vol=Wt/(Specific Gravity x Density of Water)
Weight=Abs Vol x Specific Gravity x Density of Water
Density of Water = 62.4 lbs per cu ft ( @ 40C)

25. Material Density Values
 Portland Cement Relative Density (Specific
Gravity) value: 3.15
 Blended Cements Relative Density Ranges: 2.90
to 3.15
 Fly Ash Relative Density value: 1.9 to2.8
 Slag Relative Density value: 2.85 to 2.95
 Water Relative Density value: 1.0
 Normal Aggregates Relative Density value: 2.4 to
2.9

26. Design Review Flowchart

27. Design Review Flowchart

28. Design Review Flowchart

29. Design Review Flowchart

30. Questions?
Email cemtek@netzero.net