Basic Principles Of Asphalt Compaction
Contents
1. FAYAT GROUP Basic Principles of Asphalt Compaction Compaction methods Compaction equipment Rolling technique ES b5 T7 li nn y Wa OF n E a E _ LY TTT Tet ty Pty ty ty III ll TIJ P A maanen Pre TTT TTT PHHH HIT 5 En y HSE HEHA HEHE IEEE ENNE Masthead BOMAG GmbH Fayat Group Germany all rights reserved Publisher BOMAG GmbH Hellerwald D 56154 Boppard Project management Dipl Ing H J Kloubert BOMAG GmbH Boppard www bomag com Publisher s notes The publication in its entirety is protected by copyright All details data results etc contained in this book have been created by the project management to the best of knowledge and reviewed with greatest care However errors as to the contents can never be completely ruled out The project management can therefore not assume liability for any possible incorrectness as to the contents of this book 1 Edition 02 2009 Foreword The asphalt layers of a road pavement should be able to reliably carry the traffic loads and to discharge these to the substructure or subbase in order to prevent harmf2. gt 20 gt 25 gt 20 lt 10 lt 10 lt 10 E 1 0 gt 1 1 gt 1 1 50 70 2 50 70 50 70 30 45 70 100 70 100 PmB 45 30 45 2 421055 4 0 to 6 0 4 5 to 6 5 4 0 to 7 0 3 0 to 7 0 3 0 to 7 0 135 5 135 5 135 5 5 0 to 8 5 4 0t0 8 5 only for profile com pensation not for 125 to 210 95 to 210 classes SV to III and traffic areas with special loads gt 97 gt 96 thickness up to gt 3 cm 1 When adding asphalt granulate in the form of milling asphalt from surface layers the natural sand content in the resultant mix must not exceed 5 M 2 Only in exceptional cases Fig 93 Composition and properties of asphalt binder courses A5 Asphalt wearing courses The wearing course is the top part of the asphalt road pavement It therefore needs to be properly sealed and deformation resistant The surface must keep its grip also when subjected to traffic It should also be wear resistant and weather proof Furthermore the wearing course must be flexible fairly silent but still with maximum grip It consists of a well graded mineral mix the particle size of the mix ranges from 0 5 to 0 16 mm and bitumen acting as binder Typical applications are roads and motorways airports layers on bridges agricultural roads and cycle paths Depending on the category of road and the expected traffic loads different wearing course concepts can be realized As an example coarse mix with a higher chipping content and a higher la
3. 37 11 Compaction measurement and documentation systems 39 12 APPENDIX 0100a0aaeieieirsierseeenen 43 A1 Road construction classes 43 A2 Mix types and layer thicknesses 43 A3 Asphalt base course annen 44 A4 Asphalt binder course 44 A5 Asphalt wearing courses 45 Asphalt Concrete 46 Stone mastic asphalt 48 A6 Combined surface base course BONSLLUCHON zen san 50 A7 Bitumen types neven 50 List of rules and literature 52 1 Basic principles of asphalt compaction 1 1 Principles Rolled asphalts are divided into base courses asphalt binder courses and asphalt wearing courses Asphalt concrete stone mastic asphalt and porous asphalts are used for asphalt wearing courses The laid mix must be compacted to such a degree that an increase in density or a reduction of porosity in the asphalt layer is achieved On this air voids pavement VE formation subgrade embankment Fig 1 Structure and properties of an asphalt road At the same time the compaction machine should produce a level asphalt layer as desired for driving comfort and a wearing course with closed and smooth surface structure but with maximum grip Objectives of compaction Compaction Quality performance characteristics Higher density Evenness Defined air voids Skid resistance High stability and
4. CS 0 22 0 32 over 60 3 to 10 10 to 80 Explanations 1 Mix types AO only for full depth asphalt pavements 2 Mix type A only for lower layer of base course Over size max mm wm wenns wege van vn 2 3 4 6 7 Base courses have the function of distributing loads they should therefore be particularly stable and must be paved true to profile Moreover they should protect the substructure against moisture rain Marshall flow Air void content Minimum Marshall binder stability content at 60 C min a m vo 8 9 10 3 9 2 0 1 5t0 4 0 4 0 to 20 0 4 3 3 0 1 5t0 4 0 4 0 to 14 0 3 9 4 0 1 5t0 4 0 4 0 to 12 0 3 6 5 0 1 5104 0 4 0 to 10 0 3 6 8 0 1 5 to 5 0 5 0 to 10 3 Mix type CS for construction class SV and subject to special loads traffic areas minimum 60 crushed grain gt 2 mm ratio of crushed sand to natural sand min 1 1 4 Mix types B C CS possible for all other pavements or construction classes B limited 5 for the use of paving bitumen 6 Determination on marshall samples Fig 92 Composition and properties of asphalt base courses A4 Asphalt binder course On roads with higher traffic loads construction class Ill and higher the binder course is applied to the tack coated base course as a single layer As already indi cated by its name this layer bonds the wearing course to the base course itthereby has the function of a com pensating layer to optimize the evenness Apart fr
5. Closed surface wear resistance Fig 2 Objectives of compaction NO one must make sure that the demanded degree of compaction is reached and that the limit values for the void content are complied with This results in an enhanced stability of the layers and thus in a higher resistance against deformation Good compaction also has a positive effect on the wear resistance of the wearing course riding quality skid resistance impermeability Asphalt wearing course impermeability shear resistant Asphalt binder course y Asphalt base course bearing capacity subbase capping layer 1 2 Influence of the mix composition The composition of asphalt mixes varies widely in dependence on the expected loads caused by traffic and weather They therefore also have quite different compaction properties The compactibility of the asphalt mix depends on the composition of minerals as well as the quality and viscosity of the bitumen and thus also on the temperature of the mix mix design properties application e low stability e lightly e sensitive to trafficked roads shoving e secondary roads e sensitive to e local roads rippling e cycle ways A aid e easy to e parking areas E compact gravel low small max low high penetration stone content stone size filler content bitumen high max stone size crushed aggregate high stone content Fig 3 Composition of asphalt mix Asphalt mixes for roads wit
6. The benefit of the split drum are the reduced shearing non split split forces when compacting highly sensitive asphalt layers 3 in curves urban applications The risk of the asphalt cracking in the area of the drum edges is considerably reduced BW 151 BW 154 BW 170 BW 174 non split drum split drum Fig 28 Split and non split drums 4 2 Sprinkling system Large tandem rollers are normally designed with two water pumps 1 spare pump Combination rollers are equipped with an additional pump to spray the rubber tires with emulsion All rollers are equipped with interval switches to save water With the switches the water quantity can be exactly metered for the application The following applies in general The drum surface should be moist but not wet This requires an excellent view to the drum surface Fig 29 The sprinkling system Switch for Type of mix Explanation sprinkling system Stage 3 5 Asphalt concrete Asphalt C 100 140 Stage 5 8 Chip mastic asphalt Asphalt C gt 150 Stage 12 Permanent sprinkling Fig 30 Reference values to preselect the sprinkler interval Note Stage 12 of the sprinkler switch is used to check the work is started During work it is only used to wet the function of the sprinkling system at standstill before drum surface instantaneously and quickly 15 4 3 Speed level Gui 5 Fig 31 Speed level selection BW 174 AD E Fig 32 Speed level
7. selection BW 161 AD 4 Fig 33 Option Speedometer 16 On tandem rollers the rolling and transport speeds of the machine are controlled with the travel lever on pneumatic tired rollers with the throttle pedal Depending on the roller type the desired final speed can be pre set with a speed range switch which particularly serves this purpose On pivot steered rollers the maximum travel speed can be pre selected with a 24 stage switch This speed is then reached when the travel lever is fully operated in forward reverse which guarantees uniform compaction On heavy articulated roller BW 161 AD and higher the speed can generally be adjusted in two steps from working speed to transport speed This enables perfect adaptation of the travel hydraulics to the prevailing construction site conditions An analog speedometer is also available optionally On rollers with ASPHALT MANAGER the speed a digital display BOP shows the speed as standard 4 4 Edge compressing and cutting equipment Fig 34 Edge compressing unit Fig 35 Conical roll Fig 36 Cutting wheel All small tandem rollers with edge cutting unit weight range up to 4 t are equipped with three tools ex factory a Compression roller with 45 angle b Cutting wheel c Tapered roller For large tandem rollers compression rollers 45 or 60 angle and a cutting wheel are optionally available The free edges of asphalt layers must be compresse
8. skeleton the cavities of which are to a large extent filled with mastic like mortar Due to its special composition this mix is highly wear resistant deformation and fatigue proof However for the same reason it is also difficult to compact and should therefore preferably be compacted with heavy rollers 8 10 t at high temperatures High grade chip high grade As a measure to enhance the initial grip after paving crushed sand or multiple crushed chipping should be spread on the still hot surface at the earliest after the second roller pass crushed sand stone dust Particle size mm 0 11 Grain fraction lt 0 09 mm wgt 9 to 13 Grain fraction gt 2 mm wgt 73 to 80 Grain fraction gt 5 mm wgt 60 to 70 Grain fraction gt 8 mm wgt gt 40 Grain fraction gt 11 2 mm wgt lt 10 Crushed sand natural sand ratio 1 0 Binder Binder type 50 70 PmB 45 Binder content wgt gt 6 5 Stabilizing additives Content in mix wgt Mix Marshall specimen Compaction temperature C 135 5 Air void Vol 3 0 to 4 0 Layer Paving thickness cm 3 5 to 4 0 Paving weight kg m2 85 to 100 Paving thickness cm 2 5 t0 5 0 Paving weight kg m2 60 to 125 Degree of compaction Air void Vol lt 6 0 1 Only in exceptional cases Multiple crushed chipping crushed sand Natural sand rock flour 0 8 0 8 0 5 10to 13 8to 13 8 to 13 73 to 80 70 to 80 60 to 70 551070 45 to 70 lt 10 lt 10 lt 10 1 0 gt 1 1
9. v 1000 F m h Meaning F Area output by rolling m h f Reduction factor 0 75 b Effective rolling width m 90 of drum width because of overlapping v Mean rolling speed km h n Number of passes feb v h 8 1000 n M t h Meaning M Volumetric output t h f Reduction factor 0 75 b Effective rolling width m 90 of drum width because of overlapping v Mean rolling speed km h h Layer thickness of material to be compacted m da Density of mix to be compacted t m a 2 4 2 5 t m n s Number of passes The following average speeds are recommended 4 to 6 knvh for initial compression 3 to 5 km h for main compaction 3 to 5 km h for main compaction 6 to 8 km h for subsequent rolling ironing 4 to 8 km h for main compaction 10 to 12 km h for subseguent rolling Fig 48 Recommended rolling speeds The number of necessary rolling passes can only be estimated in advance on the basis of experience or must be determined by compaction tests In each individual case the number of passes depends on the compaction resistance and the temperature of the mix 24 statically with tandem rollers statically with tandem rollers Vibration statically with tandem rollers Pneumatic tired roller Pneumatic tired roller the thickness of the layer the rolling speed the roller type and the operating mode of the machine The following tables contain empirical value
10. 3 0 Paving thickness cm 5 0 6 0 4 0 5 0 3 5 45 3 0 4 0 2 0 3 0 or paving weight kg m 120 150 95 125 85 115 75 100 45 75 Degree of compaction gt 97 gt 97 gt 97 gt 97 gt 96 Air void content Vol 70 lt 7 0 lt 6 0 lt 6 0 lt 6 0 Explanations 1 Only in exceptional cases 2 With a content of gt 20 M blast furnace or steel mill slag the water absorption must be determined instead of the porosity calculation The same limit values apply 3 Only for construction class III 4 Only for construction class III for traffic areas subjected to exceptional loads Fig 94 Composition and properties of asphalt concrete 46 Asphalt concrete 0 11 O A NO O O O 00 O Percentage finer by mass Percentage bigger by mass O O 0 09 0 25 0 71 Mesh size iel Square hole diameter in mm Fig 95 grain size distribution curve of asphalt concrete 0 11 47 Stone mastic asphalt SMA Stone mastic asphalt is a special type of asphalt for wearing courses It is a mineral mix with a higher bitumen and stone content It has a high content of the coarsest particles of each fraction The binders used normally are road construction bitumen types or for exceptionally heavy traffic loads polymer modified bitumen types with stabilizing additives They primarily work as binder carriers The mineral composition follows the principle of gap grading This results in a self supporting chipping
11. OPS 4 7 Working light BOMAG rollers can be equipped with a 230 V power connection for large area illumination of over night construction sites A balloon with very bright halogen lamps 2 kW enables uniform illumination of the construction site around the roller approx 500 m Fig 43 Tandem roller with 230 V electrical connection 20 5 Technical data of asphalt rollers BOMAG offers optimally adapted tandem and The following tables give the user a complete overview combination rollers in the weight ranges from 1 5 4 t of the most important roller data in a particular weight and from 7 14 t to suit the vast variety of applications class in asphalt compaction en Small tandem rollers Weight class t 1 5 2 5 3 2 4 2 Linear load kg cm 8 13 13 15 Working width mm 800 1200 1300 1380 Engine power kW 12 25 25 35 Amplitude mm 0 4 0 5 0 4 0 5 Frequency Hz 50 70 45 60 Centrifugal force kN 20 45 25 50 Fig 44 Characteristics of small tandem rollers Weight class 7 10 10 14 Linear load En 25 30 27 32 Working width mm 1500 1680 2000 2135 Engine power kW 55 75 75 100 Amplitude mm 0 3 0 7 0 1 0 0 35 0 85 0 0 95 Frequency Hz 40 60 45 40 60 40 50 Centrifugal force kN 70 90 160 170 85 130 150 250 Operating weight with cabin AM ASPHALT MANAGER effective amplitude Fig 45 Characteristics of large tandem rollers Due to its highly sensitive kneading and flexing effect of the wheels the rolle
12. S BW 174 340 320 300 Evie MN m2 N 220 90 92 94 96 98 100 Degree of compaction Fig 84 Example of a correlation between degree of compaction and E 39 Operating and display elements BOP for ASPHALT MANAGER E display only used in Amplitude display the menu for functions on IN Speedometer le Operating mode Automatic only used in the menu for optional functions Display of vibra tion direction or amplitude stage In manual mode F9 F10 or P1 Amplitude selection in manual mode Fig 85 BOMAG Operation Panel BOP Force level switch In automatic mode both the maximum compaction power and the depth effect can be limited 3 stages are available for this purpose This is limitation is very beneficial if the subbase under the layer to be compacted is not stable Temperature display The temperature is continuously recorded as asphalt surface temperature Depending on layer thickness ambient temperature and wind force the mix temperature in the core of the layer may be up to 40 C higher Compaction should be completed when a surface temperature of 80 C is reached 40 If the setpoint is exceeded the E dis play will change from yellow to green Only used if machine is equipped with printer and a measufrement is to be documented F5 Start measurement F6 Stop measurement F7 Measurement printout F8 Delete measurement when changing tra
13. a too heavy roller 10 Basic rules for compaction work Very high quality demands apply for the compaction of The roller operator himself is also able to influence these asphalt They are intended to achieve a load bearing quality characteristics by following some general rules and wear resistant pavement able to cope with the expected loads Minimum values concerning evenness and durable grip of the surface must also be fulfilled Start compaction work as early as possible This also applies when using heavy rollers directly behind the finisher However the flatness produced by the finisher must not be disturbed Start edge compression as early as possible so that the mix is still deformable Drum and tires must be sprayed with a sufficient amount of water to prevent mix from sticking to the drum Drum and tires should be damp but not wet The sprinkling water is evaporated by the hot mix which looses heat and thereby reduces the available compaction time Sprinkling with interval control reduces the required amount of water similar to the addition of dispersant agent to the sprinkling water Start smoothly and do not reverse jerkily Do not vibrate at standstill to avoid the formation of ruts Only switch on vibration when driving when reversing switch off vibration before the actual reversing point is reached or use the automatic vibration shut down feature On cross sloped carriageways always start to compact from the lowe
14. alt mix is easy to compact in case of porous asphalts and thin layers and when ironing wearing courses and the finish of the surfaces of wearing and base courses or of light traffic roads Here the pneumatic tired roller is normally combined with a smooth drum roller Contact pressure 0 20 0 80 MPa Compaction effect Ground contact and kneeding effect Important machine characteristics e Wheel load e Tire inflation pressure ie Asphalt binder course ur Sand Fig 9 Static compaction with pneumatic tired roller 6 2 3 Vibratory compaction Vibratory rollers are very powerful versatile and require considerably less passes than static rollers The vibration reduces the internal friction in the mineral mix so that the interaction between deadweight and dynamic load increases the density Besides the static linear load other factors like vibrating low Amplitude Application e asphalt surfacing e asphalt bases e overlay compaction on granular bases Compaction principle static pressure and dynamic energy key parameters e static linear load mass frequency and amplitude are therefore also decisive for the compaction effect For optimal compaction of different layer thicknesses bigger tandem vibratory rollers in most cases with two amplitudes and two frequencies are required high Amplitude Application e asphalt bases e granular bases e cement bound bases e subbases e vibratin
15. ck a A yellow slight jumping gt A aa red strong jumping Sa Menu with special functions for Language and service settings Escape E level display F13 F14 or P3 Force level switch for automatic mode Temperature display for asphalt surface Fig 86 Asphalt Manager with BCM 05 Rollers with ASPHALT MANAGER can be equipped with the documentation system BCM 05 and a GPS system to record all data This system enables complete and watertight docu mentation of all stiffness values E MN m as phalt surface temperatures during compaction roller application values frequency amplitude speed position of the compacting machine and number of passes for large scale construction projects Fig 87 Continuous compaction control on asphalt CCCA The application of a continuous compaction control on asphalt CCCA requires the use of the following modules BCM 05 display with BCM 05 mobile software BCMO5 office software BCM 05 Positioning software GPS system USB memory sticks are used to transfer data from BCM 05 to the construction site office Here the data are evaluated and managed with the BCM 05 Office program module Fig 89 CCCA documentation of measuring values and passes 41 11 42 12 Appendix A1 Road construction classes The total thickness of the road pavement and the gradation of the individual layers w
16. d with suitable tools like e g edge compressing rollers The special shape of the tapered roller enables the roller driver to compact right against lateral limitations e g walls of buildings Since this usually only possible with light tandem rollers the conical roll is only intended for tandem rollers with a weight of lt 4 t The cutting wheel enables clean cutting of wearing courses along edges and middle joint as well as along curb stones edge of gutters 17 Inclination1 1 45 Inclination 2 1 approx 60 Fig 37 Compressing rollers and cutting wheel 4 iF x C3 Fig 39 The compressing roller produces a slanted and smooth layer edge J Fir RE i ie a r Jk ee EE ll 4 y Bh A oy 4 mn En in j 1 pr qe ha yor s gt cea 18 Working with compressing roller or cutting wheel requires some experience The attached tools can generally be conveniently operated from the operator s stand For this purpose the machine is equipped with a hydraulic pressing system Depending on the application it may be necessary to readjust the final stop for the swivel arm roller position below drum Tandem rollers can also be equipped with two com pressing rollers front right and rear left 4 5 Chip spreader For accurate distribution of chips over the asphalt surface BOMAG offers attachment spreaders with various capacities for rollers in the weight class from 2 5 to 4t as well as from 7 10 t Prec
17. g mass e amplitude e frequency Ben Aspahlt wearing course ER Asphalt base course Fa Gravel sand Fig 10 Vibratory compaction using tandem rollers with circular exciter system The rolling speed should be 3 to 6 km h Thickness of the asphalt layer Too many passes with vibration can cause harmful loosening of material and disturbances in the structure Number of passes with vibration with various tandem vibratory rollers K low amplitude G high amplitude Assumption Compaction temperature gt 100 C 4t Machine with 10 6 8 4 8 K G 4 6 K G one amplitude IS 6 8 G 4 6 G only 18 6 8 G 4 8 G 1 pass 1 pass in f dori Chip mastic d 2 1 2 K stat pass 1 2 K stat pass bua m d 4 4 6 K stat pass 4 6 K stat pass porous asphalt d 4 1 2 K stat pass Fig 11 Typical values for the number of vibratory passes 2 2 4 Controlled compaction with ASPHALT MANAGER With controlled compaction the required compaction energy is determined and automatically adjusted In automatic mode no adjustments must be made by the driver Rollers with ASPHALT MANAGER work with a directed exciter system it is automatically regulated During compactionthe effective amplitude is optimally and continuously adapted to the actual conditions Grain damages and disturbances in the structure of the asphalt are effectively prevented Besides working in automatic mode the roller driver is also able to
18. gt 1 1 50 70 70 100 70 100 PmB 45 169 220 gt 70 gt 7 0 Se 0 3 to 1 5 135 5 135 5 135 5 3 0 to 4 0 2 0 to 4 0 2 0 to 4 0 3 0 to 4 0 2 0 to 4 0 2 0 to 4 0 70 to 100 45 to 100 45 to 75 2 0 to 4 0 45 to 100 gt 97 Fig 96 Composition and properties of stone mastic asphalt 48 Stone mastic asphalt 0 11 S 100 9 amp wn 0 80 20 3 2 60 40 is O 5 40 60 0 O ab 3 20 80 airi 20 3 a 0989 100 amp 009 0 25 0 71 2 So Mesh size Square hole diameter in mm Fig 97 Grain size distribution curve of stone mastic asphalt 0 11S 49 A6 Combined surface base course construction This course is a single layer bituminous paving which fulfils the function of both base and wearing course It is normally used for less heavily trafficked roads construction class VI and asphalt pavements with small total thickness as well as low demands on the deformation resistance The usually used particle size is 0 16 consisting of a particle graded mineral mix and road construction bitumen 70 100 Since round grain material natural sand gravel is frequently used the material can also be highly sensitive to scuffing during compaction work Combination rollers are therefore frequently used to compact single course constructions Layer thicknesses from 6 to 10 cm are quite common A7 Bitumen types Road construction bitumen is a distillation product from treatment of
19. h high traffic loads are designed for high deformation resistance They are characterized by a bulky mineral skeleton structure i e high stone contents coarse grain a high pro portion of crushed grains in the sand range crushed sand and stiff bituminous mortar These mixes are dif ficult to compact and require high compaction efforts Asphalt mixes for roads with low traffic volumes normally contain a lower proportion of stones a con siderably high amount of natural sand and soft bituminous mortar Mix instable soft gt Low stability high filler content e high stability e high internal e heavily trafficked roads friction e motorways e difficult to e country roads compact e national roads e airports low penetration bitumen They are normally easy to compact therefore do not require high compaction efforts but due to their lacking stability when hot after laying may react very sensitively to the use of heavy compaction equipment or to a too early start of compaction work This may quickly result in material displacements and the formation of bow waves Mix stiff stiff High stability Fig 4 Rolling behaviour with different asphalt mixes 1 3 Influence of the mix temperature The temperature of the mix during compaction is of high significance for the compaction effort required With too high mix temperatures the compaction by a roller is supported by the low viscosity of the bit
20. he layer and at the same time enables an early start of compaction while the mix temperatures are still high This favourably supports the compaction effect of the rollers and final compaction can be achieved with only a few roller passes Fig 7 Laying and compacting with the BOMAG BF 600 P and the BOMAG BW 174 AD AM 2 2 Static compaction Static compaction is achieved by the deadweight of the roller Tandem rollers and pneumatic tired rollers are used for this purpose Compared with vibratory compaction the compaction effect is relatively low With tandem rollers compaction is influenced by the static linear load kg cm of the drum with pneumatic tired rollers by the wheel load t and the tire inflation pressure MPa L Linear load 10 30 kg cm Aspahlt SEE Fan Gravel sand wearing course Fig 8 Static compaction with tandem rollers Asphalt base course With the kneading and flexing effect of their wheels pneumatic tired rollers achieve a special quality in static compaction It leads to a homogeneous distribution of the mix and closes the pores on the surface The main areas of application are the pre profiling and processing of easy to compact mixes Application e Surface treatment e Initial compaction of sensitive asphalt layers e Surface sealing on wearing courses Static compaction with tandem rollers makes sense if the initial compaction by the finisher was only low if the asph
21. ision spreaders BS 150 and BS 160 with vibrating spreading screed are available for the large tandem rollers hydraulically driven roller type spreaders BS 100 and BS 120 can be attached to the light tandem rollers The objective of this measure is the application of grit to the asphalt surface to enhance the initial grip Spreading widths from 1 00 m to 1 80 m are possible The spreading quantity can be adjusted by varying the hopper inclination angle at constant working speed The hopper itself can be easily detached from the roller by simply disconnecting a hydraulic quick release coupling The hopper can be conveniently filled on site by means of a wheel loader Maine I A SL iis Mr TE EA Fig 40 BW 154 with BS 150 Precision chip spreader The attachment spreaders BS 100 or BS 120 are hydraulically driven roller type spreaders for installation on small tandem rollers of the 2 5 4t class Fig 41 BW 120 with attachment spreader BS 100 and foldable roll over protection structure 19 4 6 ROPS Roll Over Protection Structure All small tandem rollers can be optionally equipped with a roll over protection structure rigid or foldable All large rollers are either equipped with a ROPS cab standard in EU countries or with ROPS FOPS with protection against falling down objects ROPS Roll Over Protection Structure FOPS Falling Object Protection Structure Fig 42 Articulated roller with ROPS F
22. it is stipulated in the ZTV Asphalt StB DIN 1995 DIN EN 12591 B200 37 44 160 210 160 220 35 43 160 220 B80 44 49 70 100 70 100 43 51 70 100 B65 49 54 50 70 50 70 46 54 50 70 B45 54 59 35 50 30 45 52 60 30 45 B25 59 97 20 30 20 30 55 63 20 30 Fig 99 Old and new classification of bitumen types 51 List of rules and literature ZTV Asphalt StB 01 Zus tzliche Technische Vertragsbedingungen und Richtlinien fur den Bau von Fahrbahndecken aus Asphalt Ausgabe 2001 ZTV T StB 02 Zus tzliche Technische Vertragsbedingungen und Richtlinien f r Tragschichten im Stra enbau RStO 01 Richtlinien f r die Standardisierung des Oberbaues von Verkehrsfl chen Merkblatt f r das Verdichten von Asphalt 2005 FGSV Floss R 2001 Compaction Technology in Earthwork Highway and Transportation Engineering BOMAG Fachbuch Boppard Dubner R Einbauen und Verdichten von Asphaltmischgut ARBIT Schriftenreihe H 53 52 53 54 55 01 09 PRE 109 016 BOMAG GmbH Hellerwald D 56154 Boppard Tel 49 6742 100 0 Fax 49 6742 3090 E Mail germany bomag com www bomag com
23. ith respect to type and thickness are divided into construction classes according to the traffic load In Germany the most suitable road design is taken acc to certain criteria Construction class Equival 10 t axle passes in Mio from tables with standardized traffic area pavements These tables can be found in the Richtlinien fur die Standardisierung des Oberbaues von Verkehrsfl chen currently RStO 01 Guidelines for the standardization of traffic area pavements CERO Thickn of frost prot pavement 55 65 75 85 65 65 75 Les 55 05 75 les 45155 os 75 45 55 65 1757 Asphalt bearing course on frost blanket layer Wearing course Binder course E Asphalt base course E 10 Frost blanket layer E Thickness of frost blanket layer 31 41 51 25186 451 98 RAS SON 492 59 33 43 53 27 37 47 57 21 fol l Sil 2 86 457155 Fig 90 Examples for road construction with asphalt pavement acc to RStO A2 Mix types and layer thicknesses When designing asphalt layers one must consider the ratio of layer thickness and biggest grain By experience the layer thickness should here by 3 4 as big as the biggest grain used in the asphalt layer Otherwise negative properties with respect to compactibility and Layer Types of mixes ATELE ONIE Asphalt concrete 0 5 Asphalt concrete 0 8 Asphalt concrete 0 11 Asphalt concrete 0 11S Asphalt concrete 0 16S Stone mastic asphalt 0 5 Stone mastic asphalt 0 8 St
24. ling system Fig 52 Filling the water tanks checking the water nozzles Activities before starting work e Check the nozzles clean or replace if necessary e Fill the water tanks e In case of frost drain the complete water e Check the water filter in case of frost sprinkling system unscrew all nozzles unscrew the filter to drain the pump Fig 53 Fuel level engine oil check e Check the engine oil level e Check the fuel level e General function test Brake light warning horn hazard light 27 Fig 54 The scrapers must be in contact Scrapers should always touch the drum uniformly e Foldable scrapers are maintenance free Function and characteristics of scrapers e Fixed scrapers must be checked at regular intervals and readjusted when required e Even distribution of sprinkling water e Removal of large particles Fig 55 Recommended tire pressures With pneumatic tired rollers the efficiency of compaction mainly depends on the tire pressure In dependence on the corresponding wheel load the correct pressure must be adjusted so that the wheels have an even contact area The working speeds range from 4 to 8 km h Fig 56 Pressure distribution and optimal tire contact area 28 8 Rolling pattern 8 1 Compacting when paving with one finisher Depending on the paving width of the finisher one or several rollers will be used side by side The respective rolled tracks should overlap by a
25. mineral oil The specific requirements are Stipulated in the European standard DIN EN 12591 This standard replaces the old German standard DIN 1995 Polymer modified bitumen PmB is an industrially manufactured mix of bitumen and polymer materials The polymer materials thereby change the viscoelastic behaviour of the bitumen As a result the bitumen sticks better to the minerals it has a larger plasticity span larger range between breaking point and softening point and a high elasticity It is therefore particularly suitable for areas subjected to high traffic loads chip mastic asphalts and porous asphalt layers 50 Minerals a o natura Particle size mm 0 16 Grain fraction lt 0 09 mm wgt 7 to 12 Grain fraction gt 2mm wgt 50 to 70 Grain fraction gt 11 2 mm wgt 10 to 20 Grain fraction gt 16mm wgt lt 10 Binder Binder type 70 100 160 220 Binder content wgt gt 5 2 Mix Marshall specimen Mix ratio Vol 1 0 to 3 0 Compaction temperature c 18545 Marshall stability kN gt 4 0 Marshall flow mm 2 0 to 5 0 Layer Paving thickness cm 5 0 to 10 0 or paving weight kg m 120 to 250 Degree of compaction gt 96 Air void Vol O Fig 98 Composition and properties of the com bined surface base course construction The designation of the individual bitumen types follows the penetration limits The selection of a bitumen type depends on the expected traffic loads under due consideration of the workability
26. ndem rollers in the weight range from 7 to 14 t with working widths of 1 50 m 1 68 m 2 00 m and 2 13 m are used for medium to large scale construction projects Vibration e only front e _or only rear e or both drums Drums e split or non split On rollers with central oscillating articulated joint both drums remain in track even when cornering left right The rollers have a standard crabwalk facility of 170 mm to either side This facilitates among others the compaction along edges and the moving away from lateral limitations 11 3 6 Pivot steered tandem rollers Fig 23 Pivot steered tandem rollers ER Fig 24 Types of steering with pivot steering 3 7 Steering systems Pivot steered tandem rollers are available in the 7 and 10 t weight range with working widths of 1 50 m and 1 68 m The travel and vibration drives are hydrostatic Vibration front and or rear Drums front and rear split or non split The BOMAG pivot steering is a particularly conven ient electric steering system The driver can choose from the following settings Diagonal left right Only front Only rear Synchronous steering both drums Automatically front or rear depending on travel direction Fig 25 Pivot steering On pivot steered rollers both drums can either be steered together synchronous steering or individually at front or rear Pivot steered rollers are additionally designed with a large adjustable crabwalk
27. o 2 0 kg m2 with particle size 2 5 mm for wearing courses gt 0 8 mm Timing The chips should be applied to the surface of the still hot wearing course at a time when it can still be pressed in by rolling This should take place at the earliest after the 2nd rolling pass 33 Fig 71 BW 174 AP with precision chip spreader BS 180 Gritting asphalt surfaces requires a uniform and precise spreading technique Since years BOMAG for this purpose delivers the approved and patented precision chip spreader BS 180 for installation on 7 to 10 t tandem rollers The vibratory screed under the hopper distributes the chip evenly across the full rolling width An excellent and reproducible spreading quality is reached with a constant rolling speed of approx 4 6 km h Additional advantage With an even and accurate distribution of the chip a significantly lower chip quantity 600 800 g m is very often required in contrast to the reference values stated above The hopper can be optionally moved sideways Fig 72 Chip hopper laterally displaceable 34 Fig 73 Spreading quantity Evenly exact The material spread over a test section is weighed for the initial determination of the spreading quantity per m For this purpose the material spread over a reference area 1m is swept up and weighed The spreading quantity depends on the inclination of the hopper see angle scale on hopper anda constant speed of the roller a
28. olling a longitudinal joint with oncoming traffic the rolling pattern 1 3 should be used This produces a solid stable basis from which the roller can finally roll the longitudinal joint Y he Y b N l L b N A a N Fig 70 Compacting a longitudinal joint 8 8 Application of chips to wearing courses The grip of asphalt wearing courses is a very significant factor within the framework of general traffic safety With the introduction of the ZTV Asphalt StB 01 the requirements concerning grip from the date of acceptance right to the end of the warranty period were determined in terms of figures and since 01 01 2002 are a fixed part of construction contracts in Germany These requirements apply for roads or construction class SV and to VI The right spreading technique is all what matters Skid resistance is a characteristic of road surfaces which is essentially determined by the concept of the mix and the paving technique The initial grip is fundamentally influenced by paving i e by correct rolling and chip distribution Chip material Crushed sand or multiple crushed chipping raw or binder coated is normally used The material should only be used dry and free of dust Chip quantity The quantity is among others determined by the particle size of the wearing course and is generally in the range of 0 5 to 1 0 kg m with particle size 1 3 mm for wearing courses up to 0 8 mm 1 0 t
29. om this the binder course also absorbs a significant part of the shearing strain caused by traffic The particle size of the mix is in the region of 0 11 to 0 22 mm 44 Typical applications are highly stressed traffic areas Mix types used for asphalt binder courses must have very high and durable deformation resistance properties Multiple crushed stones with durable edges are used for this purpose The mix has a high proportion of coarse particles and crushed sand and therefore shows a tendency of demixing during haulage to the construction site and paving with a finisher Asphalt binders generally require a high compaction level High grade chip high grade 0 16 S High grade chip high grade sand stone dust Minerals Particle size fraction mm 0 22 Grain fraction lt 0 09 mm wgt 4to8 Grain fraction gt 2 mm wgt 70 to 80 Grain fraction gt 8 mm wgt Grain fraction gt 11 2 mm wgt Grain fraction gt 16 mm wgt 225 Grain fraction gt 22 4 mm wgt lt 10 Crushed sand natural sand ratio 1 0 Binder Binder type Grade 50 70 30 45 PmB 45 Binder content Wat 4 0 to 5 0 Mix Air void content of the Marshall specimen Vol 5 0 to 7 0 Compaction temperature C 135 5 Layer Paving thickness cm 7 0 to 10 0 or Course weight kg m2 170 to 250 Degree of compaction gt 97 gt 97 crushed sand natural sand stone dust 0 16 0 16 0 11 4t08 3 to9 3 to 9 70 to 75 60 to 75 50 to 70
30. ompaction by finisher e Too early use of too heavy rollers e After paving the time until starting compaction is too long the surface has cooled down the core is still too hot the roller penetrates the skin e The machine displaces the paved material on the subbase the subbase is dirty or insufficiently sprayed e The asphalt surface is quenched wind too much sprinkling water e Compaction of too thick layers on inclinations the thrust forces of the roller cannot be absorbed e Use of so called short mixes high amount of and poorly graded natural sand low amount of bitumen e Layer is over compacted e Demixing phenomena as a result of poor mix distribution Longitudinal cracks Longitudinal cracks reach through the entire layer The most frequent causes are e Faults in the subbase e Shearing of the mix under a heavy roller paving thick layers a heavy roller has to wait a long time the surface cools down and forms a skin with a hot core zone the mix is sheared off during rolling e Insufficient initial compaction e Layer is over compacted 36 Fig 79 Longitudinal cracks e Poor stability of the mix due to its composition especially the high contents of natural sands e Too high temperature of asphalt mix e Poor bonding of layers e Too high binder content in mix e Demixing phenomena as a result of poor mix distribution Fig 80 Transverse and longitudinal cracks cause by the use of
31. one mastic asphalt 0 8S Stone mastic asphalt 0 11S Mastic asphalt 0 5 Mastic asphalt 0 5 Mastic asphalt 0 11 Mastic asphalt 0 11S Asphalt binder O 11 Asphalt binder 0 16 Asphalt binder 0 16S Asphalt binder 0 22S Asphalt base layers Mix types 0 22 Mix types 0 32 Asphalt binder courses deformation resistance can be expected In general the layer thickness follows the regulations ZTV Asphalt StB and RstO German regulations Recommended layer thickness for specifications cm Layer thickn acc to ZTV Asphalt StB or ZTVT StB cm 2 0 to 3 0 3 0 to 4 0 3 0 3 5 to 4 5 4 0 4 0 to 5 0 4 0 5 0 to 6 0 5 0 2 0 to 3 0 2 0 2 0 to 4 0 3 0 3 0 to 4 0 3 5 3 5 to 4 0 4 0 2 0 to 3 0 2 0 2 9 10 3 5 25 3 5 to 4 0 3 5 3 5 to 4 0 39 only for profile compens 4 0 to 8 5 5 0 5 0 to 8 5 6 0 7 0 to 10 0 8 0 28 0 28 0 28 0 28 0 Fig 91 Asphalt mix types and the corresponding layer thicknesses 43 A3 Asphalt base course For new road constructions the asphalt base course single or multi layer is laid on the unbonded frost blanket layer gravel or crushed rock layer of the pavement It mostly consists of a mixture of coarse particle materials 0 32 mm or 0 22 mm with additives and bitumen Particle Particle Particle size size size gt 2mm lt 0 09 Type of mix 0 2 to 0 32 0 to 80 2 to 20 20 0 2 to 0 32 Oto 35 4 to 20 10 0 22 0 32 over 35 3to 12 10 to 60 0 22 0 32 over 60 3 to 10 10 to 80
32. pprox 4 6 km h With constant working speed the spreading quantity can be changed by tilting the hopper accordingly ee Fig 74 Spreading guantity regulation 9 Compaction and paving faults Frequently occurring problems in practice when rolling asphalt layers can be traced back to various causes Fig 75 Scuffing of mix in front ofthe drum Scuffing of asphalt mix in front of the roller The roller pushes a bow wave in front Possible causes are e Too heavy roller high linear load with to small drum diameter e In stable mix is compacted too early at a too high temperature Recommendation e Use a lighter roller e Initial compaction with pneumatic tired roller or combination roller e Later start of compaction with reduced mix temperature Fig 76 Mix sticking to the drums Mix sticking to the drum Possible causes are e The mix is compacted at a too high temperature e The drums are insufficiently sprayed with water Recommendation e Before starting compaction work set to permanent sprinkling stage 12 to wet the drums all around Fig 77 Cambering along the side of the drum Cambering along the side of the drum The following causes are possible e Insufficient initial compaction e Mix too hot e Wrong composition of mix 35 Fig 78 Transverse cracks behind drum Transverse cracks Transverse cracks normally do not reach very deep Possible causes are e Low initial c
33. pre select a certain direction of vibration manual mode low dynamic energy due to horizontally directed vibrations Compaction effect Deadweight and dynamic energy the compaction effect is automatically There are six different directions available ranging from vertical to horizontal similar to oscillation Due to their excellent adaptability rollers with ASPHALT MANAGER are highly suitable for the complete spectrum of asphalt applications Manual mode with horizontal vibrations is recommended for the compaction of layers on bridges on in multi storey car parks or in the vicinity of structures which may be sensitive to vibrations high dynamic energy due to vertically directed vibrations adapted to compactibility of material layer thickness and subbase Application all soil types Fa Gravel sand granular bases and subbases Fig 12 Vibratory compaction ASPHALT MANAGER with directed exciter system o Universal use Higher compaction performance without the risk of grain destruction e Uniform compaction by continuous adaptation of the compaction energy e Better evenness and more uniform surface structure on asphalt layers e Unproblematic behaviour of the roller when compacting along edges and joints e Optimally suited for layers on bridges and in the vicinity of constructions that may be sensitive to vibrations similar to oscillation e Equipped with compaction and temperature measuring facilitie
34. r edge towards the higher edge This way the mix compacted by the roller acts as an abutment which supports the roller If possible displace and steer the roller only on compacted material to avoid misplacements of material Never stop the roller on still hot mix since this could deform the layer 10 Always park the machine across the paving direction to be able to iron out any possible ruts Fig 81 Basic rules of asphalt compaction 37 38 11 Compaction measurement and documentation systems Rollers with ASPHALT MANAGER automatically regulate the required compaction energy by matching the effective amplitude to the prevailing conditions At the same time the stiffness modulus EViB MN m is continuously determined and the asphalt surface temperature is measured by an infrared sensor The related information is displayed in the BOMAG Operation Panel BOP This enables easy tracking of the compaction progress Fig 82 Asphalt Manager with compaction measuring system With an assumed uniform stiffness of the layer subbase and a compaction temperature in the range of gt 100 C good correlations between density and E can be determined on site by comparative measurements Experience shows that the roller integrated measuring technique facilitates the compaction quality of asphalt layers Fig 83 Compaction measurement for comparison with E Correlation Evig degree of compaction A 65 SMA 0 8
35. r is particularly significant for purely static compaction Pneumatic tires rollers Weight class t 8 27 Wheel load kg 1000 3000 Ballast t 5 12 Tire size 11 00 20 18 PR Number of tires 4 front 4 rear Working width mm 2050 Speed km h 20 Engine power kW 75 100 Fig 46 Characteristics of rubber tired rollers 21 22 6 Compaction performance The area or volumetric output of the laying and compaction equipment is interdependent These two outputs must therefore be exactly planned and calculated in mutual dependence The area output depends on the laying width the working speed and the utilization factor of the finisher The quantitative output results from the amount of mix and the area output of the finisher The area output or volumetric output of the compaction machines is influenced by the available rolling time as well as the number operating mode rolling speed and rolling width of the machines The combination of compaction equipment to be used must follow the objectives of anumber of influential factors and various quality criteria such as e g adequate compaction even surface with closed pores internal bonding of layers compaction of joints Fig 47 E and EEE an layer using three finishers and five vibratory rollers 10t Laying width gt 10m daily output gt 3 000t 23 The following formula is used to calculate the practical rolled area output F and the quantitative output M of a roller f b
36. rollers u 10 3 4 Pneumatic tired rollers omm 10 3 5 Articulated tandem rollers 11 3 6 Pivot steered tandem rollers 12 3 7 Steering systems neee 12 4 Equipment characteristics of tandem and combination rollers 15 4 1 Split and non split drums os 15 4 2 Sprinkling system enn 15 4 3 Speed level switch 0ssseeeeeeeeeeeees 16 4 4 Edge compressing and cutting equipment 17 4 5 Chip spreader een 19 4 6 ROPS Roll Over Protection Structure 20 4 2 Working NG een 20 5 Technical data of asphalt rollers 21 6 Compaction performance 23 7 Preparing the compaction equipment 27 8 Rolling patterns 29 8 1 Compacting when paving with one finisher 29 8 2 Compacting when paving with two finishers 30 8 3 Asphalt compaction with tandem rollers only 30 8 4 Asphalt compaction with rubber tired and tandem tolles 31 8 5 Compacting asphalt layers with crown 31 8 6 Compacting in CUFVES nee 32 8 7 Compacting seams and joints Transverse joints Longitudinal One 32 8 8 Application of chips to wearing courses 33 9 Compaction and paving faults 35 10 Basic rules for compaction work on asphalt mixes
37. rollers 3 3 Combination rollers Fig 18 Combination roller 3 4 Pneumatic tired rollers Fig 19 Pneumatic tired roller 10 Light articulated tandem rollers are ride on rollers in the weight class from 1 3 to 4 2 t and working widths ranging from 80 cm to 138 cm They are designed with hydrostatic travel and vibration systems for both drums Combination rollers are designed with a vibrating drum and a wheel set They are particularly suitable for asphalt compaction on inclinations for repairs and patchwork in the construction of footpaths cycle paths and car parks Combination rollers are available in the class ranging from 1 5 to 2 5 t and also from 7 to 10 t Pneumatic tired rollers are designed with a steering oscillating axle at the front and a rigid drive axle at the rear With an additional ballast of 10 t the deadweight of these rollers can be increased to 24 or 27 t respectively The compaction effect is achieved with the deadweight of the machine and the kneading and flexing effect of the wheels The tire inflation pressure affects the efficiency of compaction e g the number of passes 7 L l L i i I Fig 20 Wheel position of the pneumatic tired roller 3 5 Articulated tandem rollers Fig 21 Articulated tandem rollers Fig 22 Steering concept articulated steered 40 mm Both axles are equipped with 4 compactor wheels each the wheels overlap track offset by approx Heavy ta
38. rollers The use of a pneumatic tired roller is not mandatory Utilizing a high temperature level approx 140 160 C has highest priority The number of rolling passes with vibration depends on the layer thickness 30 the linear load and the weather conditions Depending on the stability and initial compaction of the mix it is most sensible to start with static initial compaction and subsequently continue the main compaction process with vibration 8 4 Asphalt compaction with rubber tired and tandem rollers Fig 61 Rolling concept with pneumatic tired and tandem rollers Critical mixes which are sensitive to scuffing as may be used for binder and base courses or combined surface base course constructions are initially compacted with pneumatic tired rollers Here the wheels produce a highly beneficial kneading and flexing effect without the danger of scuffing or tearing Tandem rollers 7 10 t are normally used for final compaction Fig 62 Initial compaction pneumatic tired roller BW 24 RH 8 5 Compacting asphalt layers with crown I Fig 63 Compacting a crown profile On traffic areas with crown profile the longitudinal joint should be compacted in such a way that a closed joint of identical height is produced This requires a certain level of experience and diligence from the roller driver es Fig 64 Main compaction BW 174 AD 31 8 6 Compacting curves both drums
39. s Fig 13 Benefits of rollers with Asphalt Manager 8 3 Compaction equipment 3 1 Hand guided compaction equipment Fig 14 Tampers Fig 16 Hand guided rollers Tamper Tampers belong to the smallest compaction machines used on construction sites They are used under confined spatial conditions where larger compaction machines cannot be used They are available in the weight class from 60 80 kg Tampers are powered by modern 4 stroke gasoline engines or more rarely by diesel engines The engine driven eccentric crank drive causes the fast vertical movement of the tamper foot Vibratory plates Forward running and reversible vibratory plates are used for the compaction of small or confined asphalt surfaces They are available in the weight range from 50 150 kg with working widths ranging from 45 to 60 cm Vibratory plates are powered by gasoline or diesel engines The exciter system directed vibrator is driven via V belt and centrifugal clutch The movement direction of reversible plates is achieved by adjusting the directed vibrator accordingly Hand guided tandem rollers Hand guided tandem rollers are available in the weight range from 600 1000 kg with working widths ranging from 60 cm 75 cm Both drums are either mechanically driven by a 2 stage mechanical gearbox or by a hydrostatic drive These rollers work with double vibration 3 2 Light tandem rollers Fig 17 light articulated tandem
40. s for the area output m2 h and the quantitative output t h of compaction equipment from BOMAG Machine type Operating weight ch t 1 5 2 5 3 0 4 5 7 9 10 14 1 5 2 5 3 0 4 5 7 10 2 4 cm 250 450 400 800 600 1500 1000 2200 250 450 400 800 600 1500 Area output m h with layer thickness 6 8cm 200 350 250 600 500 900 800 1200 200 300 250 500 500 800 10 14 cm 150 300 250 450 400 700 600 900 150 250 250 400 400 650 Combination roller Fig 49 Practical area output of compaction equipment in asphalt construction Machine type Operating weight Volumetric output t h with layer thickness t 2 4 cm 6 8 cm 10 14 cm 1 5 2 5 10 40 25 60 40 100 3 0 4 5 20 60 40 90 70 160 7 9 40 100 70 160 120 220 10 14 70 120 100 200 180 280 1 5 2 5 10 35 20 55 35 90 3 0 4 5 20 55 35 80 65 140 7 10 35 100 60 170 90 200 _ Combination roller Fig 50 Practical volumetric output of compaction equipment in asphalt construction 26 7 Preparing the compaction equipment In order to be able to perform high quality compaction before work is started Possible faults which could work the tools required forthis work mustbe optimally later cause major problems during compaction work maintained or checked for functionality This includes can thereby be detected at an early stage thorough inspection of the machine with respect to engine hydraulic system and water sprink
41. split Fig 65 Cornering with articulated rollers Articulated rollers should be used with crabwalk when compacting along the edge of the carriageway This enables the roller driver to direct his attention to one drum when compacting the edge 8 7 Compacting seams and joints Transverse joints Transverse joint MM hot asphalt Fig 67 Transverse joint without traffic cold asphalt In order to compact transverse joints across the direction of paving the roller drives with only 5 20 cm of the drum on the hot uncompacted layer and then moves bit by bit onto the hot layer Since the manoeuvring space is in most case quite limited a small and manoeuvrable compaction machine should be used for this purpose If the available space is not big enough for manoeuvring the transverse joint can 32 both drums split Fig 66 Cornering with pivot steering Longitudinal joints Longitudinal joint E hot asphalt Fig 68 Longitudinal joint without traffic cold asphalt also be rolled or even paved diagonally to the paving direction When compacting a longitudinal joint without oncoming traffic approx 20 cm of the hot mix is compacted The major part of the drum rolls over the cold stable material This produces a closed joint with identical height without misplacements Longitudinal 9 u hot asphalt joint cold asphalt Fig 69 Longitudinal joint with traffic When r
42. t least 15 cm to make sure that no uncompacted strips are left out The same number of passes should be rolled on each track to ensure even compaction over the entire paving width Fig 57 Sequence of the compaction process several fields The roller always follows the same rolled track back to the already cooled down load bearing area where it is then reversed If a curbstone compaction will start right at the outer edge Depending on mix initial compaction and layer thickness it is recommended to finish the rolled track behind the finisher field 1 with a slight radius to improve the transverse evenness of the surface Fig 58 BW 154 AP compacting a wearing course with a curbstone 29 8 2 Compacting when paving with two finishers 15 30cm 15 30cm Fig 59 Rolling concept with 2 pavers When paving with staggered finishers hot on hot the joint should be compacted at the earliest possible time For this purpose the rollers compact e g in the right hand field from the outer edges towards the middle In the left hand field the joint is rolled immediately FAN iii I Here the rolled field overlaps the right field by 15 cm This forces an intensive and dense connection between both tracks 8 3 Asphalt compaction with tandem rollers only y Fig 60 Rolling concept with tandem roller All types of mixes base binder and wearing courses can generally be compacted with tandem vibratory
43. ul deformation This equally applies for load burdens resulting from weather and temperature stress Besides the mix composition and the paving the compaction of the mix is of utmost importance with respect to the quality and the service life of the road On the construction site successful compaction mainly depends on the compaction technique the knowledge and the experience of the roller driver In this book we present an overview of compaction techniques and equipment It contains explanations to the different rolling patterns and a number of basic rules and notes for successful compaction of rolled asphalt The BOMAG Asphalt Compaction Handbook should serve as source of information for practicians involved in pavement construction and facilitate the use of compaction equipment in asphalt construction Table of contents 1 Basic principles of asphalt compaction 2 o nee 2 1 2 Influence of the mix composition 3 1 3 Influence of the mix temperature 4 2 Compaction methods 2 1 Initial compaction with the finisher 5 22 Dae COMPAGNON rara 6 2 3 Vibratory COMPAGNON sneren 7 2 4 Controlled compaction with ASPHALT MANAGER8 3 Compaction equipment 9 3 1 Hand guided compaction equipment Tampers Vibratory plates Hand guided tandem rollers 9 3 2 Light tandem rollers eenn 10 3 3 Combination
44. umen The bitumen acts as a lubricant and reduces the internal friction in the mineral mix Due to the progressing stiffening of the bitumen caused by cooling the compaction effort increases considerably under low temperatures Compaction therefore should as a general rule be started as soon as possible Compaction temperatures between 100 and 140 C have been found most favourable for the conventional bitumen types Compaction should be completed when the temperature has dropped to between 80 and 100 C End of compaction Favourable compaction temperature Compaction effort Start of compaction 180 200 C 40 60 80 100 120 140 160 Mix temperature in C Fig 5 Effect of the compaction temperature on the compaction effort 2 Compaction methods 2 1 Initial compaction with the finisher With a low pre compaction by the finisher the use of a light roller to initially press down the mix is a very sensible decision because too heavy roller may adversely affect the evenness of the layer and depending on the stability of the hot mix may cause undesired displacements and misplacements in the material In such a case tandem vibratory rollers should drive the first two passes without vibration LE EEE da Scd y RAS m Fear Jt Gn pa E de w ie le u Fig 6 Initial compaction by the finisher Ea a E High initial compaction by the finisher has a favourable effect on the evenness of t
45. up to 120 mm 12 Pivot steered rollers are optimally suited for both small scale constructions e g crossings roundabouts sharp bents as well as large area projects e g A roads and motorways Fig 26 Crabwalk On pivot steered rollers full advantage can be made of the large crabwalk up to 120 mm The weight of the roller is distributed over a larger area the roller does not sink in so deep Unproblematic initial compaction of sensitive materials with high asphalt temperature Final ironing of large areas The roller has a larger distance to the still instable edge of the asphalt layer Fig 27 Articulated steering Tandem rollers with articulated steering have a central articulated oscillating joint between the drums This ensures that both drums run in track even when cornering When using the crabwalk the rear drum is offset either to the left or the right Due to their design the tracks of tandem rollers can be offset by lt 17 cm Practical benefits of the crabwalk facility Unproblematic steering away from curb stones Rational working with the edge compressing cone Avoids sharp edged track marks from the drum edges in the asphalt surface 13 14 4 Equipment characteristics of tandem and combination rollers 4 1 Split and non split drums Tandem rollers with an operating weight of 7 t and Less shearing forces in tight curves higher are available with split or non split drums
46. yer thickness is used for roads with higher traffic loads Fine particle mixes with low air void content and lower layer thickness are particularly suitable for roads with low traffic loads 45 Asphalt concrete Asphalt concrete is as indicated by the name a miner al mix based on the concrete principle It contains all types of particle sizes from zero up to the respective larger particle size in an appropriately adjusted ratio The mean crushed aggregate content is approx 50 weight Minerals High grade chipping high grade crushed sand natural sand stone dust Particle size mm 0 16 0 11 0 11 0 8 0 5 Grain fraction lt 0 09 mm weight 6to 10 6 to 10 7 to 13 7 to 13 8 to 15 Grain fraction gt 2mm weight 55 to 65 50 to 60 40 to 60 35 to 60 30 to 50 Grain fraction gt 5mm weight 2 15 lt 10 Grain fraction gt 8mm weight 25 to 40 15 to 30 gt 15 lt 10 Grain fraction gt 11 2 mm weight 215 lt 10 lt 10 i Grain fraction gt 16mm weight 10 Crushed sand natural sand ratio Binder Grade 50 70 50 70 70 100 70 100 70 100 70 100 70 100 50 70 50 70 160 220 Binder content weight 5 2 6 5 6 9 7 2 6 2 7 5 6 4 7 7 6 8 8 0 Marshall specimen Compaction temperature C 3555 Air void content Vol a Class I II III a St SLW 3 0 to 5 0 3 0 to 5 0 b Class Il a IV 2 0 to 4 0 2 0 to 4 0 c Class V VI St SLW a rural roads 1 0 to 3 0 1 0 to 3 0 1 0 to
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