adding value by increasing the use of recycle (part 2
TRANSCRIPT
Adding Value by Increasing the Use of Recycle (Part 2)
Best Practices in RAP QC and Stockpile Management
36th Annual Rocky Mountain AsphaltConference and Equipment Show
February 19, 2009Denver, Colorado
By Tom BlairDirector of Product Engineering –
Asphalt GroupSchmidt Construction/
Edw. C. Levy Co.
51445 West 12 Mile Rd.Wixom, MI 48393
(248) 675-0103
About the Edw. C. Levy Co.
LEVY IS ONE OF THE LARGEST RECYCLERS IN THE UNITED STATES, AUSTRALIA, AND
THAILAND
WE HAVE BEEN RECYCLING SINCE 1918.
WE PROCESS MILLIONS OF TONS OF SLAG IN THE U.S. PER YEAR THAT IS SOLD AS CONSTRUCTION MATERIALS. WE ALSO RECOVER MORE THAN A MILLION TONS OF METALLICS PER YEAR THAT ARE RECYCLED BACK INTO THE STEEL MAKING PROCESS.
WE PROCESS AND UTILIZE NEARLY A HALF A MILLION TONS OF RECYCLED ASPHALT PAVEMENT (RAP) PER YEAR IN OUR ASPHALT MIXES AND HAVE BEEN USING RAP SINCE 1975.
Edw. C. Levy Co. – U.S.A.Operations in 11 StatesAsphalt Production &
Paving
Sand & Gravel Operations
Quarry Operations
Steel Mill Services
Trucking
Aggregate Docks –Sand, Gravel, Limestone, S.F. Slag, B.F. Slag
Ready Mix Concrete
Asphalt Production & Paving
Colorado
• Asphalt Production & Paving• Quarry Operations• Sand & Gravel Operations• Trucking
DELTA YARDCOLORADO SPRINGS
RAP QUALITY CONTROL AND STOCKPILE MANAGEMENT
A BRIEF HISTORY OF USING RAP
1970’s – EXPERIMENTAL JOBS FROM 70% UP TO 100% RAP ANY WAY WE COULD. NO MIX DESIGNS – DUMP AND RUN. LOTS OF FAILURES
1980’s – CUT HOLES IN PLANTS AND HAD ENVIRONMENTAL ISSUES. LOTS OF STATES USED UP TO 50% RAP. LITTLE OR NO QUALITY CONTROL TESTING. NO VOLUMETRIC AND VERY LITTLE ACCEPTANCE TESTING. MANY MORE FAILURES. THEN RAP COLLARS INVENTED TO PROVIDE A BETTER WAY TO INTRODUCE RAP INTO THE PLANT
1990’s – BETTER PLANT DESIGNS FOR INTRODUCING RAP INTO THE PLANT. THEN COUNTERFLOW PLANTS DESIGNED TO USE HIGH PERCENTAGES OF RAP. VOLUMETRIC TESTING INTRODUCED. LOTS OF QUALITY CONTROL TESTING FOR VOIDS ACCEPTANCE JOBS. MORE QUALITY ASSURANCE TESTING. GOOD RAP MIX PERFORMANCE
A BRIEF HISTORY OF USING RAP (cont.)
LATE 1990’s TO THE PRESENT – EVEN BETTER ASPHALT PLANTS DESIGNED TO RUN HIGHER RAP PERCENTAGES YET BE EVEN MORE ENVIRONMENTALLY FRIENDLY. MORE EMPHASIS ON QUALITY CONTROL. TIGHTER ACCEPTANCE SPECIFICATIONS LIKE PWL. SUPERPAVE INTRODUCED. LOTS OF NEW RESEARCH ON MIXTURE PERFORMANCE AND RAP USE. EXCELLENT RAP MIX PERFORMANCE
REMEMBER WHEN WE FIRST STARTED RECYCLING PAPER AND PLASTIC? THEY USED TOO HIGH OF A RECYCLED MATERIAL CONTENT AND THE PERFORMANCE WAS POOR. NOW THEY USE LESS RECYCLED MATERIAL CONTENT BUT PUT IT IN ALMOST EVERYTHING AND NO ONE KNOWS THE DIFFERENCE. SAME THING WITH AN ALUMINUM CAN OR YOUR NEW CAR. RAP ASPHALT MIXES CAN PERFORM BETTER THAN ALL NEW MATERIAL IF DONE CORRECTLY
THREE MAIN RULES FOR SUCCESSFUL RECYCLING OF
ASPHALT PAVEMENTS
1. THE QUALITY OF THE PRODUCTMADE WITH RECYCLED MATERIALSMUST BE EQUAL TO OR BETTERTHAN THE QUALITY OF THE ORIGINAL PRODUCT. • “AS GOOD OR BETTER” • DON’T USE TOO HIGH OF A RECYCLED
MATERIAL CONTENT.
2. THE RECYCLED PRODUCT PRODUCED MUST BE COST EFFECTIVE.
• SOME DAY IT MAY BE ABLE TO COST MORE WHEN WE GET CREDIT FOR USING RECYCLED MATERIALS.
• THE GREAT THING ABOUT USING RECYCLED ASPHALT PAVEMENT (RAP) IS THAT IT LOWERS THE COST OF THE FINISHED PRODUCT AND CAN PROVIDE AS GOOD OR BETTER FINISHED PRODUCT THAN USING ALL NEW MATERIALS IF DESIGNED PROPERLY.
3. WE MAY NEED TO CHANGE SOMEOF THE OTHER RAW MATERIALS WE USE WITH THE RECYCLEDMATERIAL AND SOME OF OURPROCESSES TO MEET THE FIRST TWO RULES.
• DON’T JUST SUBSTITUTE IN A RECYCLED MATERIAL WITHOUT DESIGNING FOR IT
• MOST OF THE TIME WHEN USING RAP WE NEED TO USE CLEANER AGGREGATES
SO – WHERE DO WE START?
RAW MATERIAL PILE MUST BE CLEAN
DO NOT ALLOW ANYTHING OTHER THAN BROKEN ASPHALT, RETURNED ASPHALT, CLEAN-OUT ASPHALT, OR MILLINGS IN THE RAP RAW MATERIAL PILE. WE ONLY HAVE ONE PILE – ALL GOOD.
CHECK TRUCKS DUMPING MATERIAL IN YOUR RAW MATERIAL PILE FOR CONTAMINATION AND REJECT THEM.
KEEP THE CRAP OUT
• MUST BE CONSTANTLY MONITORED• DON’T WANT ANY TRASH, CONCRETE,
BRICKS, CLAY, WOOD OR TOPSOIL IN THE RAP PILE
• SEND THE JUNK TO THE LANDFILL
KEEP THE RAW MATERIAL PILE BLENDED
SPREAD OUT PLANT CLEAN OUT MATERIAL, WASTED SILO MATERIAL, AND RETURNED MATERIAL SO THAT IT DOESN’T HARDEN INTO BIG CHUCKS. THIS MAKES IT HARD TO CRUSH AND CAN CAUSE POCKETS OF HIGH ASPHALT CONTENT FINISHED PRODUCT
BUILD THE RAW MATERIAL PILE IN LAYERS AND SPREAD OUT MILLINGS SO THAT THE PILE WILL BE UNIFORM IN MATERIAL TYPE WHEN CRUSHED
NOT TOO CONSISTENT
NICE RAW MATERIAL PILE
NOW WHAT DO WE DO WITH IT?
CRUSHING, SCREENING, FRACTIONATING, RAW MILLINGS
SHOULD WE CRUSH OR SCREEN THE RAP?
• IS CRUSHING REALLY NECESSARY? • WHAT IS THE COST DIFFERENCE?• IF WE SCREEN IT, WHAT SIZE?
CRUSHING OR SCREENING THE RAP SHOULD DEPEND ON:
• THE SIZE OF THE MATERIAL IN YOUR RAW MATERIAL PILE
• CRUSHING BREAKS DOWN WEATHERED AGGREGATES AND ALLOWS DEBRIS TO BE REMOVED
• BIGGER IS CHEAPER, SMALLER IS MORE EXPENSIVE AND CREATES MORE FINES BUT BLENDS BETTER AND SEGREGATES LESS
• SCREENING SIZE DEPENDS ON THE TOP SIZE OF THE MIX IT IS GOING INTO. HOWEVER, SMALLER SIZES TRANSFER HEAT BETTER.
SHOULD WE FRACTIONATE IT?
• ADVANTAGES – LESS MOISTURE, LESS STOCKPILE MANAGEMENT, LESS SEGREGATION
• DISADVANTAGES – FINES TURN HARD UNLESS “JUST IN TIME CRUSHING”, WHAT TO DO WITH EXCESS FINES, NO STOCKPILE TO MINIMIZE VARIATIONS OR KEEP THE CRAP OUT, EXTRA FEEDER BINS, YARD SPACE, COST DIFFERENCE
SHOULD WE USE RAW MILLINGS?
• ADVANTAGES – CHEAPER• DISADVANTAGES – POOR HEAT
TRANSFER, MORE YARD SPACE, NO STOCKPILE TO MINIMIZE VARIATIONS AND SCREEN JUNK OUT, SOMETIMES DIFFICULT TO GET A MIX DESIGN IF MILLINGS ARE COMING FROM THE SAME JOB
CRUSHING
BLEND THE RAW MATERIAL PILE WHILE FEEDING THE CRUSHER. MOVE POCKETS OF MILLINGS OR CLEAN-OUT MATERIAL OUT OF THE WAY IF NECESSARY TO HELP KEEP CONSISTENCY OF THE FINISHED PRODUCT.
WORK A LARGE LOADING FACE OF THE RAW MATERIAL PILE TO FEED THE CRUSHER
MAKE SURE THE RAP CRUSHER IS CLEANING DEBRIS OFF HIS SCREEN REGULARLY TO KEEP IT OUT OF THE FINISHED PRODUCT PILE.
BUILD THE FINISHED PRODUCT PILE IN LAYERS. USE A DOZER OR A PROGRAMABLE STACKER
CRUSHING (cont.) DON’T BUILD THE RAP FINISHED PRODUCT
STOCKPILES TOO HIGH. MAKE SURE SOMEONE TAKES SAMPLES OF THE
FINISHED PRODUCT DURING CRUSHING FOR TESTING AT SET INTERVALS. ALSO, TAKE SOME RANDOM SAMPLES TO COMPARE RESULTS.
A GOOD RAP CRUSHER IS YOUR MOST VALUABLE RESOURCE IF HE BLENDS THE RAW MATERIAL AND FINISHED PRODUCT PILES UNIFORMLY AND KEEPS THE BAD MATERIAL AND JUNK OUT. THIS MATERIAL LIKE TOPSOIL, CLAY, TIRES, CONCRETE, BRICKS, AND WOOD MUST BE HAULED TO THE LANDFILL.
KEEP IT TESTED
TEST THE RAP DURING CRUSHING ONCE EVERY 1000 TONS OR MORE AS IT IS BEING PRODUCED
VERIFY PRODUCTION TEST RESULTS LATER WITH LOADING FACE SAMPLES DURING USE
GIVE FEEDBACK TO RAP CRUSHER DURING CRUSHING IF CONSISTENCY IS NOT BEING MET
TEST AND ADJUST THE VOLUMETRIC PROPERTIES OF THE MIX OFTEN TO ENSURE QUALITY
KEEP IT TESTED (cont.)
WATCH OUT IF USING THE IGNITION FURNACE FOR AC CONTENTS OF THE RAP. IT IS BEST TO VERIFY THE RESULTS ONCE IN A WHILE WITH SPLIT SAMPLE TESTING USING A SOLVENT EXTRACTION WITH A GOOD SOLVENT.
TO BE SUCCESSFUL, YOU PROBABLY WILL NEED INCREASED TESTING CAPABILITY FOR RUNNING RAP MIXES BECAUSE THEY CAN TAKE A LITTLE EXTRA WORK.
RAP MIX DESIGN HINTS
START WITH THE RAP AND DESIGN AROUND IT. USE CLEANER AGGREGATES IF NECESSARY TO MEET ALL THE SAME CRITERIA AS FOR VIRGIN MIXES.
MAKE SURE YOU KNOW ALL THE PROPERTIES OF THE RAP; AC CONTENT/STIFFNESS, GRADATION, SPECIFIC GRAVITY AND ABSORPTION, DELETERIOUS, PARTICLE SHAPE, AND ANGULARITY.
WATCH WHAT GRADE OF VIRGIN BINDER YOU SELECT. BUMPING THE TOP AND BOTTOM IS OFTEN TIMES TOO SOFT AND CAN RESULT IN SOFT MIXES. NEW RESEARCH SHOWS CHANGING GRADES OF VIRGIN ASPHALT IN RAP MIXES MAY NOT BE NECESSARY.
FEEDING THE PLANT IF POSSIBLE, AVOID DOUBLE HANDLING THE
FINISHED PRODUCT TO PREVENT SEGREGATION
USE AS BIG OF A LOADING FACE AS POSSIBLE ON THE FINISHED PRODUCT PILE TO FEED THE RAP BIN
LOAD OUT PERPENDICULAR TO THE DIRECTION THE STOCKPILE WAS BUILT IN
SMALLER SIZES OF SCALPER SCREENS ALLOW BETTER HEAT TRANSFER, DRYING, AND MIXING OF THE RAP WITH THE AGGREGATE AND AC.
FEEDING THE PLANT (cont.)
CALIBRATE THE RAP FEEDER OFTEN. WATCH THE PERFORMANCE OF THE
RAP FEEDER AND PREVENT BRIDGING OR FLOW PROBLEMS WITH THE FEEDER. LINE THE BINS.
MAKE SURE YOU HAVE THE CORRECT ASPHALT CEMENT CONTENT OF THE RAP ENTERED INTO YOUR PLANT CONTROLS
KEEP IT HOT
MAKE THE AGGREGATE HOT ENOUGH IN THE PLANT FOR GOOD DRYING AND HEAT TRANSFER TO OCCUR
DON’T RUN THE PLANT TOO FAST
MONITOR MOISTURE CONTENTS OF THE RAP OFTEN AND UPDATE THE PLANT CONTROLS
IF USING STIFFER ASPHALT CEMENTS, MAKE THE MIX HOTTER
WHEN IT IS WET OR COLD USE LESS RAP
TO KEEP IT PERFORMING• BE CAREFUL IF KEEPING THE MIX OVERNIGHT.
WATCH SILO STORAGE TIME AND FOR DELAYS• ADD A LITTLE EXTRA ASPHALT CEMENT TO
ACCOUNT FOR ABSORPTION IF THE MIX WILL BE STORED FOR AN EXTENDED PERIOD
• KNOW THE EFFECTS ON VOLUMETRIC PROPERTIES AND ADJUST ACCORDINGLY. DON’T BE AFRAID TO ADJUST THE MIX PROPERTIES DURING PRODUCTION.
• CONTROL THE VARIABILITY IN ALL PHASES OF THE PROCESS
HOW MUCH SHOULD WE USE?• CAN WE CONTROL THE VOLUMETRIC
PROPERTIES?• CAN YOU GET THE VMA HIGH ENOUGH ABOVE
THE MINIMUM IN THE DESIGN STAGE TO ACCOUNT FOR PLANT DEGRADATION AND ABSORPTION DURING PRODUCTION?
• WHAT ARE THE SPECIFICATION LIMITS?• DO WE HAVE ENOUGH SUPPLY OF RAP?• DO WE HAVE CLEAN AGGREGATES TO BLEND
WITH THE RAP TO MEET VMA AND VOIDS?
HOW MUCH SHOULD WE USE? (cont.)• WHAT ARE OUR PLANT LIMITATIONS?• WHAT ARE OUR AIR PERMIT LIMITATIONS?• IS THERE ANY OPERATIONAL RESISTANCE? • IS THERE ANY CUSTOMER RESISTANCE?• WHAT DO YOU FEEL COMFORTABLE WITH?
LET’S KEEP RAP THE NATIONS TOP RECYCLED
MATERIAL
THANK YOU!
QUESTIONS?