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READYMIX INDUSTRY
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  1. READYMIX INDUSTRY

  2. READY MIX INDUSTRY (BASED ON ASTM C94) • BASIS OF PURCHASE • BATCHING • MIXING • TRANSPORTING

  3. 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)

  4. 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.)

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

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

  7. 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

  8. BATCHING BATCH PLANTS • WEIGH BATCHER • TRUCK MIXERS • COARSE AGG SHOULD BE DISCHARGED BEFORE • OTHER INGREDIENTS • ALL SCALES HAVE TO BE CALIBRATED

  9. 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

  10. 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

  11. 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

  12. MIXING NON-AGITATING MIXING • REQUIRES SLUMP TEST • USED FOR SHORTER HAULS

  13. 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

  14. 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