WELCOME
N.C. DEPARTMENT OF TRANSPORTATION
MATERIALS AND TESTS UNIT
CONCRETE CERTIFICATION SCHOOL
CONCRETE MIX
DESIGN
TECHNICIAN
SCHOOL
M& T CONTACTS
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WALTON JONES(RALEIGH)
MARIA LONG (WILLIAMSTON)
DAN ALLEN (WILMINGTON)
DARRELL LUMLEY(RALEIGH)
HENRY TRAYWICK (FAYETTEVILLE)
ROBERT FOSQUE(GREENSBORO)
SANDRA POTTS(SALISBURY)
MARK THOMAS (MATTHEWS)
TRACH CHURCH(WILKESBORO)
CHARLES BULLOCK(ASHEVILLE)
919-733-7091
252-792-7627
910-371-6964
919-556-7606
910-486-1732
336-334-3611
336-993-2300
704-847-1314
336-903-9107
828-298-1516
AME’s
HENRY TRAYWICK
 JESSICA SMITH
 PAM CARRIKER
 KEN HAMBY

DIV 1,2,3,6
DIV 4,5,7
DIV 8,9,10
DIV 11,12,13,14
INSTRUCTOR


WALTON JONES
919-733-7091
PLEASE
TELEPHONES OFF
OR ON VIBRATE
BATHROOMS
CLASS HOURS
SCHEDULE
DAY 1&2
Review Schools, Agg. Gradation, Wt.-Vol.
Relationships
 DAY 3
Admixtures, Placing Conc., ACI Mix Design
 DAY 4
Fly Ash, Mix Design Variations, Hot & Cold
Weather Conc. & Curing, Exam, Review
 DAY 5
Math Exam
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PREREQUISITES FOR CLASS

NCDOT BATCH TECHNICIAN
CERTIFICATION MUST BE
CURRENT, OR MUST HAVE
SUCESSFULLY COMPLETED BATCH
SCHOOL CLASSROOM PORTION
QUESTIONS
REVIEW
Concrete Field & Batch
Technician School
Review Topics
 Components
 Moisture
Of Concrete
Calculations and
Batch Weight Adjustments
 Field
Tests
Components Of Concrete
 Cement
- The bonding agent.
 Sand - Gives workability to the mix.
 Stone - Filler material, aids in
strengthening the mix.
 Water - Causes a chemical reaction
called hydration.
 Air Agent - For freeze/thaw,
durability
 Retarder - Slows setting time.
Components Cont.
 Water
and Cementitious Materials Portland cements, fly ash, slag.
 Fine and Coarse Aggregates Sands and stones (60-80% of mix).
 Chemical Admixtures - Air
entrainers, retarders, water
reducers, super-plastizers.
Components Cont.
 Paste
- A combination of cement,
water, and entrained air.
 Setting Time - The time that it takes
for a cement paste to begin
hardening.
 Mortar - Paste and fine aggregates.
 Concrete - Mortar and coarse
aggregate.
Aggregates
60% to 80% of the volume of the mix is
aggregates.
 Sand may be natural or manufactured
and it’s texture will be from fine to
coarse.
 Stone may be angular from a quarry, or
rounded from a pit.
 Standard stone sizes for structural
concrete from Table 1005-1: #57, #67,
and #78.

Moisture Calculations &
Batch Weight Adjustments
Calculate Total Moisture in fine and
coarse aggregate stockpiles.
 Calculate Free Moisture
Total Moisture - Absorbed Moisture
 Use Free Moisture to calculate batch
weight adjustments.
 Mix designs are based on SSD weights.

TOTAL MOISTURE
Moisture on the surface and the
moisture in the pours and capillaries of
an aggregate.
 Total Moisture is calculated by:
Wet Wt. - Dry Wt.
---------------------- X 100
Dry Wt.

Determine Total Moisture

Given the following weights, determine
the total moisture:
Wet Weight
Dry Weight

555.4 grams
523.2 grams
Is this a Fine or Coarse Aggregate
sample?
Answer
555.4 - 523.2
-----------------523.2
X 100 = 6.2%
This is a Fine Aggregate
sample
Determine Total Moisture

Given the following weights, determine
the total moisture:
Wet Weight
Dry Weight

1534.2 grams
1505.0 grams
Is this a Fine or Coarse Aggregate
sample?
ANSWER
1534.2 - 1505.0
---------------------- X 100 = 1.9%
1505.0
This is a Coarse Aggregate
Sample
Determine Free Moisture
Given the following moistures,
determine the Free Moisture:
Fine Agg.
Total Moisture
6.2%
Absorbed Moisture 0.4%

Coarse Agg.
Total Moisture
1.9%
Absorbed Moisture 0.7%
ANSWER
Fine Aggregate:
6.2% - 0.4% = 5.8%
FREE MOISTURE
Coarse Aggregate:
1.9% - 0.7% = 1.2%
FREE MOISTURE
Batch Weight Adjustment
Problem

Mix design weights are as follows:
Cement 555 lbs
Sand
1222 lbs
Stone
1865 lbs
Water
290 lbs
Sand Adjustment
Using the FREE MOISTURE 5.2%, adjust
sand weight.
 5.2 / 100 = 0.052
 1222 X 0.052 = 63.5 lbs. (Water)
 1222 + 64 = 1286 lbs.

Adjusted Sand Weight = 1286 lbs
Stone Adjustment
Using the FREE MOISTURE 3.6%,
adjust the stone weight.
 3.6 / 100 = 0.036
 1865 X 0.036 = 67.1 lbs. (Water)
 1865 + 67 = 1932 lbs.

Adjusted Stone Wt. = 1932 lbs
Water Adjustment
Total additional water from sand and
stone.
 64 lbs. + 67 lbs. = 131 lbs.
 290 lbs. (design water) - 131 lbs. = 159
lbs.

Adjusted Water Wt. = 159 lbs.
Corrected Batch Weight
Corrected weights for ONE cubic yard:
Cement 555 lbs.
Sand 1286 lbs.
Stone 1932 lbs.
Water 159 lbs.
 What are the weights for a 9 cubic yard
load?

Pull Weights
For a 9 yard load - multiply batch
weights for one yard load times 9.
 Corrected weights for 9 cubic yard load:
Cement 4995 lbs.
Sand
11,574 lbs.
Stone
17,388 lbs.
Water
1431 lbs.

BATCH TOLERANCES
CEMENT MUST BE BATCH WITHIN ±
1% OF MIX DESIGN WEIGHT
 FLY ASH MUST BE BATCHED WITHIN
± 1% OF MIX DESIGN WEIGHT
 SAND MUST BE BATCHED WITHIN ±
2% OF THE MOISTURED
CORRECTED MIX DESIGN WEIGHT

STONE MUST BE BATCHED WITHIN
± 2% OF THE MOISTURE ADJUSTED
MIX DESIGN WEIGHT.
 WATER MUST BE BATCHED WITHIN
± 1% OF THE MOISTURE ADJUSTED
MIX DESIGN AMOUNT.

BATCHING TOLERANCES
CEMENT- ± 1%
 FLY ASH - ± 1%
 SAND- ± 2%
 STONE- ± 2%
 WATER - ± 1%

FIELD TEST
Sampling Freshly Mixed Concrete:
AASHTO T-141
ASTM C-172
Slump Test:
AASHTO T-119
ASTM C-143
Unit Weight:
AASHTO T-121
ASTM C-138
Air Content with Pressure Air Meter:
AASHTO T-152
ASTM C-231
Air Content by Volumetric Method:
AASHTO T-196
ASTM C-173
Air Content by Chace Indicator:
AASHTO T-199
Making and Curing Test Specimens:
AASHTO T-23
ASTM C-31
Temperature of Freshly Mixed Concrete:
ASTM C-1064
NCDOT Certification
Concrete Field Technician:
Qualified to perform concrete
acceptance tests on NCDOT projects.
Certified as a “Grade 1 Field Test
Technician” by ACI.
 Concrete Batch Technician:
Certified to batch Ready Mixed,
Precast, or Prestressed Concrete for
NCDOT projects.

What Does This Mean?
 Anyone
testing or batching
concrete for a NCDOT project shall
be certified.
A
Field and Batch Technician
should be properly trained,
knowledgeable, and competent to
perform their duties.
Concrete Mix Design
Technician
 Learn
how to perform Sieve
Analysis, Fineness Modulus,
Design Concrete Mixes using the
Absolute Volume Method, and Vary
Mixes using the 5% Deviation
Method.
 Pass this course and become
certified to design and vary
concrete mixes.
BREAK