BY: CASIMIR J. BOGNACKI, PE, FACI CHIEF OF MATERIALS ENGINEERING 90 MINUTES TO DISCHARGE A CONCRETE TRUCK - IS THIS REQUIREMENT OUTDATED? PRESENTATION TO CONCRETE INDUSTRY BOARD FEBRUARY 22, 2017 BY: CASIMIR J. BOGNACKI, PE, FACI CHIEF OF MATERIALS ENGINEERING

ASTM C-94 “DISCHARGE OF THE CONCRETE SHALL BE COMPLETED WITHIN 1.5 HOURS OR BEFORE THE DRUM HAS REVOLVED 300 REVOLUTION; WHICHEVER COMES FIRST AFTER THE INTRODUCTION OF THE MIXING WATER TO THE CEMENT.” “THESE LIMITATIONS ARE PERMITTED TO BE WAIVED BY THE PURCHASER IF THE CONCRETE IS OF SUCH SLUMP AFTER THE 1.5 HOURS OR 300 REVOLUTIONS LIMIT HAS BEEN REACHED THAT IT CAN BE PLACED, WITHOUT THE ADDITION OF WATER TO THE BATCH.” “IN HOT WEATHER OR UNDER CONDITIONS CONTRIBUTING TO QUICK STIFFENING OF THE CONCRETE, A TIME LESS THAN 1.5 HOURS IS PERMITTED TO BE SPECIFIED BY THE PURCHASER.”

ACI 301 4.3.2.2 LIMITS ON DISCHARGE – UNLESS OTHERWISE SPECIFIED, DISCHARGE LIMITS SHALL COMPLY WITH ASTM C94. IF DISCHARGE IS ACCEPTABLE AFTER MORE THAN 90 MINUTES HAVE ELAPSED SINCE BATCHING, VERIFY THAT AIR CONTENT OF AIR-ENTRAINED CONCRETE, SLUMP AND TEMPERATURE OF CONCRETE ARE AS SPECIFIED.

THE PORT AUTHORITY OF NY & NJ CONCRETE TRUCK DISCHARGE SPECIFICATION CAN EXCEED THE 90 MINUTES AND 300 REVOLUTIONS PROVIDING THE FOLLOWING ARE MET: CONCRETE IS WORKABLE. CAN BE REDOSED WITH A HRWR TO REGAIN WORKABILITY. IF THE CONCRETE IS AIR-ENTRAINED, AIR MUST BE WITHIN ACCEPTABLE LIMITS. CAN BE REDOSED WITH AIR-ENTRAINING AGENT. TEMPERATURE OF CONCRETE MUST MEET SPECIFICATION REQUIREMENTS. WATER IN MIX CANNOT EXCEED THE WATER CONTENT APPROVED IN CONRETE MIX PROPORTIONS.

THE PORT AUTHORITY OF NY & NJ’ EXPERIENCE WITH 90 MINUTE DISCHARGE DURING THE SUMMER, WE HAVE LESS THAN 90 MINUTES TO DISCHARGE A LOAD OF CONCRETE. IN PARTICULAR, IF THE w/cm RATIO IS .4 OR LESS AND MAINTAINED. FOR HIGH-STRENGTH CONCRETE, fc > 10,000 PSI, WITH A W/CM LESS THAN .3, THESE MIX PROPORTIONS HAVE BEEN FOUND NOT TO BE WORKABLE IN LESS THAN 90 MINUTES. A HYDRATION CONTROL ADMIXTURE MUST BE INCORPORATED INTO THE MIX.

THE PORT AUTHORITY EXPERIENCE CONCRETE DISCHARGED AFTER 90 MINUTES AND UP TO 180 MINUTES, THAT MET PLASTIC CONCRETE PROPERTIES ALSO MET HARDENED CONCRETE REQUIREMENTS FOR STRENGTH AND DURABILITY. PROPER DOSAGE OF HYDRATION CONTROL ADMIXTURE IS CRITICAL FOR UNFORMED CONCRETE. IT IS ALSO IMPORTANT FOR FORMED CONCRETE. TESTS SHOULD BE PERFORMED TO DETERMINE PROPER DOSAGE OF HYDRATION CONTROL ADMIXTURE AND HRWR. REDOSING CHARTS SHOULD BE ON-SITE FOR HRWR AND AIR ENTRAINMENT.

THE PORT AUTHORITY EXPERIENCE

GOETHALS BRIDGE DRILLED SHAFT CONCRETE MIX DESIGN – 5000 psi BRAND MATERIAL RECOMMENDED PROPORTIONS PER CUBIC YARD LA FARGE TYPE I/II CEMENT (LBS) 460 STI PRO ASH FLY ASH (LBS) 200 PHOENIX (BARNEGAT, NJ) SAND (LBS) 1395 #57 TILCON (MT. HOPE, NJ) STONE 1 (LBS) 850 #8 (MT. HOPE, NJ) STONE 2 (LBS) 700 NJ POTABLE WATER (LBS) 247.0 WATER (GAL) 29.7 MB-VR (BASF) ADMIX 1 (OZ) 13.0 GLENIUM 7500 (BASF) ADMIX 2 (OZ) 68.0 DELVO STABILIZER (BASF) ADMIX 3 (OZ) 55.0

GOETHALS BRIDGE DRILLED SHAFT CONCRETE MIX DESIGN 5000 psi CAT IV LESS THAN 90 MINUTES GREATER THAN 90 MINUTES TIME (MIN) 28-DAY COMPR. 28-DAY ACCEL COUL. MIN. 30 5310 192 91 6593 94 MAX. 90 11466 1325 213 11210 1305 AVG. 68 8177 418 117 8319 423 ST. DEV. 13 986 166 22 859 172 TOTAL TESTS 266 175