ReadyMix Industry - Njit

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29 Νοε 2013 (πριν από 3 χρόνια και 7 μήνες)

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READYMIX

INDUSTRY


BASIS OF PURCHASE




BATCHING



MIXING



TRANSPORTING



READY MIX INDUSTRY

(BASED ON ASTM C94)


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)

IN ABSENCE OF A DESIGNATED SPECIFICATION, A
PURCHASER MUST REQUEST:

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.)

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

BASIS OF PURCHASE:

MEASURED BY WEIGHT



CEMENT



FINE AND COARSE AGGREGATE



FLYASH AND POZZOLANS


MEASURED BY WEIGHT AND VOLUME



WATER



ADMIXTURE



BATCHING


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


BATCHING

BATCH PLANTS


WEIGH BATCHER



TRUCK MIXERS



COARSE AGG SHOULD BE DISCHARGED BEFORE


OTHER INGREDIENTS



ALL SCALES HAVE TO BE CALIBRATED

BATCH PLANTS

BATCHING

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

MIXERS AND AGITATORS

MIXING



SAMPLES MUST HAVE THE SAME:



SLUMP
-

SLUMP TEST


UNIT WT.


YIELD TEST


AIR CONTENT


AIR METER OR AIR TEST


STRENGTH


COMPRESSION TEST

UNIFORMITY TEST

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

MIXING

NON
-
AGITATING MIXING


REQUIRES SLUMP TEST



USED FOR SHORTER HAULS


MIXING

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

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

TRANSPORTING