READYMIX INDUSTRY

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READYMIX INDUSTRY
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READY MIX INDUSTRY (BASED ON ASTM C94)

• BASIS OF PURCHASE
• BATCHING
• MIXING
• TRANSPORTING

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BASIS OF PURCHASE
IN ABSENCE OF A DESIGNATED SPECIFICATION, A
PURCHASER MUST REQUEST

• DESIGNATED SIZE OR SIZES OF AGGREGATE
• SLUMP REQUIRED
• AIR ENTRAINMENT AIR TEST AT PLACEMENT
• THE CHOICE OF OPTION A,B,OR C FOR
• PROPORTIONING THE MIX
• DRY UNIT WEIGHT FOR YIELD TEST
• (FOR STRUCTURAL LIGHTWEIGHT CONCRETE)

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BASIS OF PURCHASE

• OPTION A OR C (ASTM C94)
• MANUFACTURER ASSUMES FULL RESPONSIBILITY
• FOR SELECTING THE MIX PROPORTIONS
• PURCHASE HAS TO DECIDE ON THE 28 DAY
• STRENGTH
• OPTION B (IN ADDITION)
• PURCHASE MUST SPECIFY MIN. ALLOWABLE CEMENT
• CONTENT TO BE USED IN THE MIX DESIGN

• DESIGNATED SIZE OR SIZES OF AGGREGATE
• SLUMP REQUIRED
• AIR ENTRAINMENT AIR TEST AT PLACEMENT
• OVEN DRY WEIGHT FOR YIELD TEST (UNIT DRY WT.)

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BASIS OF PURCHASE

• OPTION B continued (ASTM C94)
• PURCHASER ASSUMING THE RESPONSIBILITY FOR
• PROPORTIONING THE CONCRETE MIXTURE
• SPECIFY CEMENT CONTENT PER CY
• SPECIFY WATER CONTENT PER CY
• THE TYPE AND DOSAGE FOR ALL THE ADMIXTURE
• SIZE OF AGGREGATE AND SLUMP REQUIRED

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BATCHING

• MEASURED BY WEIGHT
• CEMENT
• FINE AND COARSE AGGREGATE
• FLYASH AND POZZOLANS
• MEASURED BY WEIGHT AND VOLUME
• WATER
• ADMIXTURE

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BATCHING
BATCH PLANTS

• HOPPER CAN WEIGH CUMULATIVELY OR
• INDIVIDUALLY
• AGGREGATES WATER CONTENT HAS TO BE
• DETERMINED
• TOTAL MOISTURE WATER CONTENT
• TOTAL WET WT. DRY AGG WT. OF MOISTURE
• POWDERED ADMIXTURE ARE MEASURED BY WEIGHT
• LIQUID ADMIXTURE ARE MEASURED BY WEIGHT OR
• VOLUME

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BATCHING
BATCH PLANTS

• WEIGH BATCHER
• TRUCK MIXERS
• COARSE AGG SHOULD BE DISCHARGED BEFORE
• OTHER INGREDIENTS
• ALL SCALES HAVE TO BE CALIBRATED

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MIXING
MIXERS AND AGITATORS

• STATIONARY MIXERS
• I.E. TILTING DRUM MIXER DISCHARGES WHILE
  TILTING
• THE MIXING, IN OPPOSE TO A NON-TILTING
  MIXER
• TRUCK MIXERS (AVG CAPACITY IS 8-9 YDS)
• Note the cliché Give me the whole nine yards!
• FRONT DISCHARGE
• REAR DISCHARGE
• SHOULD NOT EXCEED 63 OF THE DRUM VOLUME
• AGITATORS (MAYBE TRUCK MIXERS OR AGITATORS)
• MUST BE ABLE TO DELIVER THOROUGHLY MIX
• CONCRETE TO THE JOBSITE
• SHOULD NOT EXCEED 80 OF THE DRUM VOLUME

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MIXING
UNIFORMITY TEST
SAMPLES MUST HAVE THE SAME SLUMP-
SLUMP TEST UNIT WT. YIELD TEST AIR
CONTENT AIR METER OR AIR TEST STRENGTH
COMPRESSION TEST
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MIXING
MIXING AND DELIVERY

• CENTRAL MIX CONCRETE THAT IS MIXED COMPLETELY
  IN A STATIONARY MIXER
• SHRINK MIX- CONCRETE THAT IS FIRST PARTIALLY
  MIXED IN A STATIONARY MIXER, AND THEN MIXED
  COMPLETELY IN A TRUCK MIXER
• TRUCK MIX CONCRETE THAT IS COMPLETELY MIXED IN A
  TRUCK MIXER, 70-100 REVOLUTIONS AT THE MIXING
  SPEED

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MIXING
NON-AGITATING MIXING

• REQUIRES SLUMP TEST
• USED FOR SHORTER HAULS

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TRANSPORTING
JOB SITE CONTROL

• NO ADDITIONAL WATER CAN BE ADDED EXCEPT IF SLUMP
  DOES NOT REACH SPECIFIED SPEC. AND THE WATER
  CEMENT RATIO IS NOT INCREASED
• SHRINK MIX- CONCRETE THAT IS FIRST PARTIALLY
  MIXED IN A STATIONARY MIXER, AND THEN MIXED
  COMPLETELY IN A TRUCK MIXER
• TRUCK MIX CONCRETE THAT IS COMPLETELY MIXED IN A
  TRUCK MIXER, 70-100 REVOLUTIONS AT THE MIXING
  SPEED

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TRANSPORTING
INSPECTION AT THE JOBSITE

• CONCRETE MUST BE TESTED FOR SLUMP, AIR CONTENT,
  AND
• STRENGTH
• ACI CERTIFICATION FOR CONCRETE FIELD TESTING
  TECHNICIAN
• GRADE LEVEL I
• ONE STRENGTH TEST IS PREPARED FOR EVERY 150 CY
  AND AT
• LEAST ONE FOR EACH DAY THE CONCRETE IS
  DELIVERED OR FOR EACH CLASS OF CONCRETE (I.E.
  CLASS A,B OR C )
• AT LEAST THREE STRENGTH TEST SHOULD BE MADE AND
• AVERAGE
• I.E. FOR A 4000 PSI CONCRETE
• THREE SAMPLES - 4400 3600 4300 GIVES AN AVERAGE
  4100
• AND NONE OF THEM ARE LESS THAN 500 PSI BELOW THE
  SPECIFY STRENGTH