WET MIX MACADAM(WMM)
WET MIX MACADAM IS A SUB-BASE/BASE COURSE OF THE PAVEMENT WHERE IN CLEAN, CRUSHED GRADED AGGREGATES AND GRANULAR MATERIAL, LIKE, GRADED COARSE SAND ARE MIXED WITH WATER AND ROLLED TO A DENSE MASS ON A PREPARED SURFACE.
WET MIX MACADAM (WMM) CONSTRUCTION IS AN IMPROVEMENT UPON THE CONVENTIONAL WBM AND IS INTENDED TO BE AS AN ALTERNATIVE AND MORE DURABLE PAVEMENT LAYER.
THE WORK MAY BE DONE IN LAYERS. THE THICKNESS OF AN INDIVIDUAL LAYER SHALL NOT BE LESS THAN 75 MM AND CAN BE UP TO 250 MM.
MATERIALS
PHYSICAL REQUIREMENTS:-
COARSE AGGREGATES SHALL BE CRUSHED STONE/CRUSHED GRAVEL/SHINGLE.
NO LESS THAN 90 PERCENT BY WEIGHT OF GRAVEL/SHINGLE RETAINED ON 4.75 MM SIEVE SHALL HAVE AT LEAST TWO FRACTURED FACES.
MATERIALS
IF THE WATER ABSORPTION VALUE OF THE COARSE AGGREGATES IS GREATER THAN 2 PERCENT, A SOUNDNESS TEST SHALL BE CARRIED OUT ON THE MATERIAL AS PER IS:2386 (PART V) WITH SODIUM SULPHATE WHICH SHOULD NOT EXCEED 12 PERCENT.
LOSANGELESAPPRATUS IMPACTVALUEAPPRATUS
GRADING REQUIREMENTS:-
NOTE:- THE FRACTION PASSING THE 75 MICRON SIEVE SHALL NOT BE GREATER THAN TWO-THIRDS OF THE FRACTION PASSING THE 600 MICRON SIEVE.
MATERIALS SHALL HAVE PARTICLE SIZE DISTRIBUTION AND PARTICLE SHAPE WHICH PROVIDE HIGH MECHANICAL STABILITY AND SHOULD CONTAIN SUFFICIENT FINES TO PRODUCE A DENSE MATERIAL WHEN COMPACTED.
IF THE AMOUNT OF FINE AGGREGATE PRODUCED DURING THE CRUSHING OPERATION IS INSUFFICIENT, NON-PLASTIC ANGULAR SAND MAY BE USED TO MAKE UP FOR THE DEFICIENCY.
IN CONSTRUCTING A CRUSHED STONE ROAD BASE, THE AIM SHOULDBETOACHIEVEMAXIMUM IMPERMEABILITY COMPATIBLE WITH GOOD COMPACTION AND HIGH STABILITY UNDER TRAFFIC
CONSTRUCTION OPERATIONS
PREPARATION OF SUB-BASE/BASE:-THE SURFACE OF THE SUB-BASE/BASE TO RECEIVE THE WMM COURSE SHALL BE PREPARED TO THE SPECIFIED LINE SAND CROSS-FALL (CAMBER) AND MADE FREE OF DUST AND OTHER EXTRANEOUS MATTER.
ANY RUTS OR SOFT YIELDING PLACES SHALL BE CORRECTED IN AN APPROVED MANNER AND ROLLED UNTIL A FIRM SURFACE IS OBTAINED IF NECESSARY BY SPRINKLING WATER.
NOTES:-
LAYING OF WMM OVER AN EXISTING BITUMINOUS SURFACE IS NOT PERMITTED.
THE WORK OF LAYING OF WET MIX MACADAM SHALL NOT BE DONE DURING RAIN.
PROVISION OF LATERAL CONFINEMENT OF WET MIX LAYER:-
THIS SHALL BE DONE BY LAYING MATERIALS OF ADJOINING SHOULDERS ALONG WITH THAT OF THE WET MIX LAYER.
THE SEQUENCE OF OPERATIONS SHALL BE SUCH THAT THE CONSTRUCTION OF THE SHOULDER IS DONE IN LAYERS EACH MATCHING THE THICKNESS OF THE ADJOINING PAVEMENT LAYER.
ONLY AFTER A LAYER OF PAVEMENT AND CORRESPONDING LAYERS IN THE SHOULDER HAVE BEEN LAID AND COMPACTED, THE CONSTRUCTION OF THE NEXT LAYER OF PAVEMENT AND SHOULDER SHALL BE TAKEN UP.
PREPARATION OF MIX
WHEN THE WMM MIX IS THE CRUSHER RUN MATERIAL, IT SHALL BE STOCKPILED WITH THE FRONTEND LOADER.
BEFORE SENDING THE MIX FOR LAYING, THE STOCKPILE SHALL BE WATERED AND HOMOGENEOUSLY MIXED, AND LOADED TO THE TIPPER/DUMPER.
OPTIMUM MOISTURE FOR MIXING SHALL BE THE LABORATORY OMC.
WHILE ADDING WATER, DUE ALLOWANCE SHOULD BE MADE FOR EVAPORATION LOSSES.
HOWEVER, AT THE TIME OF COMPACTION,WATER IN THE WET MIX SHOULD NOT VARY BY MORE THAN ± 2 PERCENT.
SPREADING OF MIX
IMMEDIATELY AFTER MIXING, THE MIXED MATERIAL SHALL BE TRANSPORTED TO THE SITE AND SPREAD UNIFORMLY AND EVENLY UPON THE PREPARED SUB-BASE/BASE IN REQUIRED QUANTITIES.
HAULINGOFTHE MIXOVERA FRESHLY COMPLETED STRETCH IS NOT PERMITTED.
TRANSPORTATION OF MIX IS USUALLY DONE BY TIPPING TRUCKS.
IN ORDER TO AVOID MOISTURE LOSS IN TRANSIT DUE TO EVAPORATION, THE MIX SHOULD BE COVERED WITH TARPAULIN.
THE MATERIAL IS USUALLY KEPT WET DURING TRANSPORT AND LAYING.
THEMIXMAYBE SPREAD BY A PAVER FINISHER.
A SINGLE FULL-WIDTH PAVER OR TWO PAVERS OF LESSER WIDTH WORKING IN TANDEM WITHIN THE SHORT DISTANCES SHOULD BE USED FOR OBTAINING GOOD RESULTS.
IN MULTILAYER CONSTRUCTION THE BOTTOM LAYERS MAYBE ALLOWED TO BE LAID BY MOTOR GRADER.
IN EXCEPTIONAL CASES, FOR PORTIONS WHERE MECHANICAL MEANS CAN NOT BE USED, A MANUAL METHOD OF SPREADING CAN BE ADOPTED.
THE SURFACE OF THE LAYER AS SPREADSHALLBE CAREFULLY CHECKED WITH TEMPLATES AND ALL HIGH OR LOW SPOTS REMEDIED BY REMOVING OR ADDING WET MIX MATERIAL AS MAY BE REQUIRED.
THELAYERTHICKNESSMAY BE CHECKED BY DEPTH BLOCKS DURING CONSTRUCTION.
NO SEGREGATION OF COARSE OR FINE PARTICLES SHALL BE ALLOWED.
THE LAYER AS SPREADS ALL BE OF UNIFORM GRADATION AND SHALL NOT HAVE POCKETS OF FINE MATERIALS.
COMPACTION:-
COMPACTION SHALL BE DONE WITH THE HELP OF SMOOTH- A WHEELED ROLLER (OR VIBRATORY ROLLER WITHOUT VIBRATION), VIBRATORY ROLLER, PNEUMATIC-TYRED ROLLER, ETC. HAVING MINIMUM STATIC WEIGHT OF 100 KN.
IN CONFINED SPACES, WHERE STANDARD ROAD ROLLER CAN NOT BE USED, MINI COMPACTION EQUIPMENT LIKE RAMMERS, VIBRATORY PLATE COMPACTORS, VIBRO TAMPER, PLATE RAMMERS, ETC. MAYBE USED.
INITIAL SETTING OF PARAMETERS FOR COMPACTION TRIAL
NOTES:-
1. IN PORTIONS HAVING UNI-DIRECTIONAL SUPERELEVATION,
ROLLING SHALL COMMENCE FROM THE LOWER EDGE AND PROGRESS GRADUALLY TOWARDS THE UPPER EDGE.
THEREAFTER ROLLER SHOULD PROGRESS PARALLEL TO THE CENTER LINE OF THE ROAD, UNIFORMLY OVERLAPPING EACH PRECEDING TRACK BY AT LEAST ONE-THIRD OF WIDTH UNTIL THE ENTIRE SURFACE HAS TO BE ENROLLED.
THE SPEED OF THE ROLLER SHALL NOT EXCEED 5 KM/HR.
2. INPORTIONSOFCAMBER,
ROLLING SHOULD BEGIN AT THE EDGE WITH THE ROLLER RUNNING FORWARD AND BACKWARD UNTIL THE EDGE HAS BEEN COMPACTED FIRMLY.
THE ROLLER THEN PROGRESSES GRADUALLY TOWARDS THE CENTER PARALLEL TO THE CENTER LINE OF THE ROAD UNIFORMLY OVER LAPPINGEACH OF THE PROCEEDING TRACK BY AT LEAST ONE-THIRD WIDTH.
THE PROCESS OF COMPACTION IS THEN TO BE REPEATED FROM THE OTHER EDGE OF THE PAVEMENT UP TO THE CENTER LINE UNTIL THE ENTIRE PAVEMENT IS COMPACTED.
FREQUENCY OF QUALITY CONTROL TESTS OF WMM
SETTING & DRYING:-
THE LAID WET MIX MACADAM COURSE SHALL BE ALLOWED TO DRY FOR 24 HOURS BEFORE PRIMING.
OPENING TO TRAFFIC
NO VEHICULAR TRAFFIC EXCEPT CONSTRUCTION VEHICLES WITH A SPEED LESS THAN 5 KM/HR SHALL BE ALLOWED ON THE FINISHED WMM SURFACE.
MEASUREMENTS FOR PAYMENT
WET MIX MACADAM SHALL BE MEASURED AS FINISHED WORK IN POSITION IN CUM.