1-mix design welcome - Carolinas Ready Mixed Concrete
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Transcript 1-mix design welcome - Carolinas Ready Mixed Concrete
WELCOME
N.C. DEPARTMENT OF TRANSPORTATION
MATERIALS AND TESTS UNIT
CONCRETE CERTIFICATION SCHOOL
CONCRETE MIX
DESIGN
TECHNICIAN
SCHOOL
M& T CONTACTS
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
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