1. ACI Concrete Mix Design
N.C. DEPARTMENT OF TRANSPORTATION
MATERIALS AND TESTS UNIT
CONCRETE CERTIFICATION SCHOOL

2. 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.

3. 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.

4. 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.

5. 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.

6. 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.

7. Design
Acceptance of the mix design does not relieve the Contractor of the responsibility to furnish an end product meeting specifications requirements.

8. ACI Concrete Mix Design
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)

9. Pg 81
Mix Design Process
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

10. Design Coarse aggregates N.C. Specifications
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

11. ACI Table 5.3.6
Pg 85
Volume of Coarse Aggregate Per Unit of Volume of Concrete

13. 5 Basic Ingredients Cement Fine Aggregate Coarse Aggregate Water Air
Pg 87
Cement
Fine Aggregate
Coarse Aggregate
Water
Air
The combined total absolute volume should be 27 cubic feet

14. Mix Design Worksheets Fine Aggregate Data Coarse Aggregate Data
ACI Table 5.3.6
Table

15. Example, pg 83
Using information provided, design a NCDOT Class A mix.

16. Pg 83

17. Cement
Cement amount is determined from Table based on the class of concrete specified, vibrated or non vibrated.

18. 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.

19. Water
The amount of cement and the W/C ratio are used to determine the quantity of water.

20. 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.

21. Cement
Pg 84

22. Water 564 x .488 = 275 = 33.0 gallons 8.33 33.0 = 4.40 cu.ft./ cu.yd.
7.5

23. 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.

24. Coarse Aggregate
Pg 85
Use ACI Table 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 %.

25. Use ACI Table 5.3.6 to determine that 62% of the mix must be dry rodded coarse aggregate.
.062 x 27 cu.ft. = cu.ft/cu.yd.
16.74 x pcf = 1741 Lbs of stone
1741 / (2.86 x 62.4) = 9.76 cu.ft./ cu.yd

26. Pg 87
Fine Aggregate
Total the absolute volumes of the other materials

27. Determine the volume of the fine aggregate
27.00 cu.ft.
cu.ft
8.35 cu.ft.
weight of sand required is
8.35 cu ft x 2.63 x 62.4 = 1370 Lbs

28. ACI Worksheet Example
Fine Agg
Coarse Agg
Table 5.3.6
Table

29. Problem 1 1 Class AAvib AE Sand-Lilesville Stone-Matthews Q
Pg 105
Class AAvib AE
Sand-Lilesville
Stone-Matthews Q
Fine agg wkst
Coarse agg wkst
Table 5.3.1
Table 1

30. Problem 2 2 Class Avib AE Sand-Emery Pit Stone-Kannapolis Q
Pg 106
Class Avib AE
Sand-Emery Pit
Stone-Kannapolis Q
Fine agg wkst
Coarse agg wkst
Table 5.3.1
Table 2

31. Problem 3 3 Class AAvib AE Sand-Great Pit Stone-Crabtree Q
Fine agg wkst
Coarse agg wkst
Table 5.3.1
Table 3

32. Problem 4 4 Class Bnonvib AE Sand-Boone Q Stone-Mt Airy Q
Fine agg wkst
Coarse agg wkst
Table 5.3.1
Table 4

33. Problem 5 5 Class AvibAE Sand-Johnsonville Pit Stone-Greystone Q
Fine agg wkst
Coarse agg wkst
Table 5.3.1
Table 5

34. Problem 6 6 Class BvibAE Sand-Candor Pit Stone-North Q Fine agg wkst
Coarse agg wkst
Table 5.3.1
Table 6

35. Problem 7 7 Class AAvibAE Sand-Pageland Q Stone-Matthews Q
Fine agg wkst
Coarse agg wkst
Table 5.3.1
Table 7

36. Problem 8 8 Class BnonvibAE Sand-Lilesville Pit Stone-Elkin Q
Fine agg wkst
Coarse agg wkst
Table 5.3.1
Table 8

37. Mix Designs Using Fly Ash
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.

38. Maximum Water - Cementitious Material Ratio Table

39. 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.

40. Cement
Multiply 20% times the 564 pounds of cement for Class A to get pounds. Subtract from original cement pounds to get 451 pounds.
(564 X .20) = 451 pounds of cement

41. 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

42. Water
Multiply max W/C ratio of .512 times the total amount of cementitious material.
(.512 X 586) / = 34.5 gallons
The design process for the remaining components remains the same.
flyash example

43. Problem 9 Fly Ash 9 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
Fly Ash wkst 9

44. Problem 9 Cement and Fly Ash quantity Cement 639 x .20 = 128
= 511 Lbs Cement
Fly Ash 18 x 1.2 = 154 Lbs Fly Ash

45. THAT'S ALL
questions ???