1. Quality Control Testing
Mississippi Concrete Industries Association
Robert Varner, P.E.

2. Topics For Discussion Some Basis for Specifications
Plastic Concrete Properties and Field Test
Curing & Handling Cylinders
ASTM C94 Overview

3. Specification Requirements Compressive Strength f’c
General-use concrete: to 5000 psi
High-Strength: to 20,000+ psi
Known relationships with other concrete properties

4. Specification Requirements Flexural Strength (MR)
Typical values: 450 to days
650 to 750 psi common for pavements
Normal weight concrete approximation: MR = (7.5 to 10) (f’c)0.5

5. Specification Requirements Mix Proportions
Maximum Water Cement Ratio
Table 9-1, 9-2 Pg 150
Make sure w/c correlates with strength
Minimum Cement
Table 9-7 Pg 156

6. Specification Requirements Freshly Mixed Properties
Air Content
Table 8-6 Pg 146
Slump
Table 9-3 Pg 155
Temperature
Maximum Pg 229
Minimum Temperature Table 14-1 Pg 243

7. Specification Requirements Materials
Material Requirements
Cement - ASTM C 150
Fly Ash - ASTM C 618
GGBFS - ASTM C 989
Aggregate - ASTM C 33
Note 2 – Allows the use of state agency grading requirements.

8. Specification Requirements MDOT VS ASTM Fine Agg.
Sieve
ASTM C33 Percent Passing
MDOT
Percent Passing
½ inch Na
100
3/8 inch
97 – 100
No. 4
95 – 100
92 – 100
No. 8
80 – 100
75 – 100
No. 16
50 – 85
45 – 100
No. 30
25 – 60
25 – 70
No. 50
10 – 30
3 – 35
No. 100
2 - 10
0 – 10

9. Testing Freshly Mixed Concrete
Sampling - ASTM C172
Slump - ASTM C143
Temperature - ASTM C1064
Density - ASTM C138
Air Content - ASTM C231/C173
Strength Specimens - ASTM C31

10. Sampling - ASTM C 172 1 ft3 Composite sample Middle of truck
Protect sample

11. Slump - ASTM C143
Consistency: The ability of freshly mixed concrete to flow as measured in the slump test. (expressed in inches of slump)

12. Temperature ASTM C1064 Affects concrete behavior
May be important in trouble-shooting problems
May be a specification issue

13. Density - ASTM C138 Density (Unit Weight)
Weight of concrete divided by a known volume.
Conventional concrete has a unit weight in the range of 137 to 150 pcf
Lightweight: 15 pcf
Heavyweight: 375 pcf
Measured primarily to compute yield

14. yield =  Batch weights (Cement,FA,CA,H2O) Unit Weight
Yield is the volume of concrete produced in a batch (typically expressed in yd 3)
yield =  Batch weights (Cement,FA,CA,H2O) Unit Weight

15. Air Content ASTM C 173 - ASTM C231
Measures entrained (tiny) and entrapped (larger) air voids, expressed as a percentage of the total volume of concrete
Entrained: generally ” to 0.04” Ø
Entrapped: 0.04” Ø and up
Somewhat a function of aggregate characteristics
Non-air-entrained concrete w/ 1” coarse aggregate has about 1-1/2% entrapped air

16. Volumetric Method
ASTM C173

17. Pressure Method ASTM C231

18. Strength Specimens Cylinders Beams Curing Specimens 6 X 12 4 X 8
Standard curing
Field curing

19. Making & Curing Concrete Test Specimens
ASTM C31 Field
ASTM C192 Lab
Compressive Strength of Cylindrical Specimens
ASTM C39

20. Making & Curing Concrete
Test Specimens
ASTM C31 Field
ASTM C192 Lab
ASTM C 78
Flexural Strength -
Third Point Loading

21. Standard Curing
Curing procedures required by ASTM C 31 for strength specimens that are made for:
Acceptance testing
Checking adequacy of mix proportions
Quality control
Includes 2 curing stages:
Initial curing
Final curing

22. Initial Curing Temperature Moisture Time < 6000 psi – 60 to 80 ° F
Prevent moisture loss
Time
Up to 48 hours

23. Transportation of Cylinders To Laboratory
Wait 8 hours after final set
Protect with suitable cushioning material
Protect from freezing
Prevent moisture loss
Transportation time not to exceed 4 hours

24. Final Curing Temperature Moisture Time 73° ± 3° F
Free moisture on surface at all times
Time
Within 30 minutes after removing the molds until testing

25. Field Curing
Temperature and moisture conditions as close as possible to those of the in-place concrete for curing specimens that are made for:
Strength verification prior to putting the structure or pavement into service
Comparison with test results of standard cured specimens or various in-place test methods
Adequacy of curing and protection of concrete in the structure
Strength check for form or shoring removal

26. The Standard Specification for Ready-Mixed Concrete
ASTM C 94 Overview
The Standard Specification for
Ready-Mixed Concrete

27. ASTM C 94: Standard Specification For Ready-Mixed Concrete
By reference in project specifications controls the following:
Materials
Mix-Design Procedures
Batching, Mixing, and Delivery Procedures
Acceptance Criteria
Acceptable Tolerances
Required Quality Control Testing

28. Sect. 4: Basis of Purchase
Sect. 4.2: Unit Weight C 138
Average of at least 3 measurements
Sample taken from midpoint of 3 different trucks using C 172

29. Sect. 5: Ordering Information
Sect. 5.1: In the absence of applicable general specifications, the purchaser shall specify the following:
Coarse Aggregate Size
Slump
Air Content
Unit Weight - structural lightweight
Mix Design Options: A,B,C

30. Sect : Slump Tolerances If Specified AS Maximum To Be Used Only If One Addition Of Water Is Permitted
Plus Tolerance:
Minus Tolerance:
Specified Slump:
If 3 in. If more than
Or less 3 in.
1 1/2” 2 1/2”

31. Sect. 7.1.2: Slump Tolerances If Not Specified AS Maximum Tolerances For Normal Slumps
For Specified Slump of:
2 in. and less
More than 2 through 4 in.
More than 4 in.
Tolerance
± 1/2 in.
± 1 in.
± 1 1/2 in.

32. Slump
Sect. 7.2
Producer responsible for slump to be in tolerance range for a period of 30 min. starting either on the arrival at the job site or after the initial slump adjustment permitted in 12.7, whichever is later.
Exemptions:
First and Last 1/4 yd3
Sect. 12.7
Allows for one time addition of water.

33. Air Sect. 8 Table 1 - Recommended Total Air Content
Sect. 7.2: Tolerance of ± 1.5

34. Discharge of Concrete Sect. 12.7 Completed within 1 ½ hours
Or before drum has revolved 300 revolutions
Whichever comes first

35. Sect. 12.8: Minimum Concrete Temperature As Placed
Section Size, in.
<12
12-36
36-72
>72
Temperature, min F 55 50 45 40
Concrete temperature shall not exceed 90F when using heated materials.

36. Required Quality Control Testing
Sect Technician Certification
Sect Required Test
Slump, Air Content, Density, Temperature, Strength
Sect Required Frequency
Strength
one per day per class of concrete or every yd3
Slump, Air Content, Density, Temperature with each strength test and as necessary for control checks .

37. Strength Criteria For Concrete Acceptance
Sect. 18.1: Cylinders Made and Cured According To ASTM C 31
Sect. 18.2: One Test = Two Cylinder Breaks
Can a cylinder be discarded?
Sect. 18.4: Two Requirements For Strength
Average of any three consecutive test  f’c and
f’c ≤ No test more than 500psi below f ‘c
f’c > 5000 – No test less than 0.90 f’c

38. Required Average Compressive Strength With Standard Deviation Table X1
f’c ≤ 5000 psi
f ‘cr = f ‘c +1.34s
f ‘cr = f ‘c +2.33s-500(psi)
f’c >5000 psi
f’cr = f’c s
f’cr = 0.90f’c s
s = Standard Deviation

39. Required Average Compressive Strength Without Standard Deviation Table X1.2
Required Average Compressive Strength f’c (psi)
f ’c
f ’c
1.10f ’c
Specified Compressive
Strength, f’c (psi)
Less Than 3000
3000 to 5000
Over 5000

40. QC / QA Concepts Quality Control / Quality Assurance
Responsibility to Contractor
Performance Based
Statistical Controlled
Data Comparisons
Pay Reductions

41. Questions? Mississippi Concrete Industries Association
Phone: (601)
website: mississippiconcrete.com