6. LPC Bituminous Mixtures Design Guide, Sept 2007. - Aapaq.org

More documents

Recommendations

Info

LPC Bituminous Mixtures Design Guide- Mix Design Procedure -3.3.2 Thick layer mixtures for surface or binder course – AC-BBSG, AC-BBS,AC-BBMEFigure 21: Cross-section of a AC-BBSG(Asphalt Concrete Béton Bitumineux Semi-Grenu)Figure 22: Surface appearance of a AC-BBSG(Asphalt Concrete Béton Bitumineux Semi-Grenu)3.3.2.1 Remarks concerning mix componentsAggregatesFor some fine aggregates from basalt aggregates, crushed slag and certain highlyacidicgranite materials, either mixed fillers or lime must be employed.Most hard limestone fine aggregates provide for a good level of workability: thepercent passing 2 mm on the AC-BBSG or AC-BBME grading curves must bereduced to approximately 30% (or even less).Some natural fillers from fine aggregate are noxious even if harmfulnessspecifications have been satisfied. For example, dolomite (cleanliness of sands withan sand equivalent rating ≥ 70, the blue value (stain) ≥ 2 g (i.e. approximately MBF ≥2,000 g/kg)) leads to water resistance problems, as do certain forms of tuff, despite ablue value that lies on the order of 0,8 g.The amphibolites-gneiss yield poor I/C (r/R) ratios for the watersensitivity, while theamphibolite-diorite results are quite strong.The brittleness of the fine aggregate would provide an indicator of the contributionfrom fines towards rutting resistance.The angularity of fine aggregate affects mix stability.It is advised to be cautious of ground fine aggregate and fine aggregate (or all-inaggregate) output from crushers with a revolving floorplate. The shape of mineralparticles could make the mixture more sensitive to rutting.- Granite: water resistance requires verification.- Basalt: binder content to be adapted to better account for eventual absorption.- Limestone: coarse limestone aggregates are not permitted for use in wearingcourses (on the national highway network).- 90 -
LPC Bituminous Mixtures Design Guide- Mix Design Procedure -- Angularity and shape: the angularity of coarse gravel influences texture, as doesthe coarse aggregate shape. An overly regular shape would be deleterious and isto be avoided.The flakiness index FI must preferably lie between 10 and 15.For a AC14-BBSG mixture:A percent passing of 34% with 2 mm sieve conducted at a texture in situ at ATD =0,4 mm.A percent passing of 28% with 2 mm sieve conducted at a texture in situ at ATD =0,7 mm.Binders and additivesFor a AC-BBSG mixture, the following is used:- 35/50 grade pure bitumen in the case of heavy loadings and altitudes lower than500 m, or a 50/70 grade in more typical cases and eventually a 70/100 grade inmountainous zones with harsh climate (categories advised in the StandardsApplication Guide); and- special bitumen with low thermal susceptibility, or a polymer-modified bitumen forspecific loading conditions (ramps, intersections, bus lanes). Adding 0,5% to 0,8%polyethylene serves to improve rutting resistance (in particular for the purpose ofobtaining a Category 3).A AC-BBS (“soft flexible asphalt concrete for low trafficked pavements) mixture is toinclude:- 50/70 or 70/100 paving grade bitumen.For a AC-BBME mix, the following are used:=> 35/50 grade bitumen, potentially combined with additives;=> "hard" bitumen, but not from 10/20 category, whether modified by polymers or not.3.3.2.2 Composition of the granular mixThe initial particle size distribution curves for AC-BBSG, AC- and AC-BBME aregiven in Table 25. It should be pointed out that the AC-BBS mix comprises a widerrange of application thicknesses (4 to 12 cm) than both AC-BBSG and AC-BBME.This difference could lead to targeting a higher percent passing value at 2-mm sieve(capable of reaching 40%).Table 25 – Initial AC-BBSG, AC-BBS and AC-BBME grading curvePercent passingsieve, in mmTypical valuesD = 14 mmTypical valuesD = 10 mmMinimumTargetvalueMaximumMinimumTargetvalue10 78 97Maximum6,3 47 52 58 45 57 684 47 522 25 31 35 27 34 390,063 6,3 6,8 7,2 6,3 6,7 7,2- 91 -
Page 1 and 2:
LPC Bituminous Mixtures Design Guid
Page 3 and 4:
Page 5 and 6:
Page 7 and 8:
Table of ContentsPREFACE ..........
Page 9 and 10:
3.4.4 Discontinuity ...............
Page 11 and 12:
Table of illustrationsFigure 1: Gyr
Page 13 and 14:
Table 40 - Adjustment to average te
Page 15:
Page 18 and 19:
Page 20 and 21:
Page 22 and 23:
Page 24 and 25:
Page 26 and 27:
Page 28 and 29:
Page 30 and 31:
Page 32 and 33:
Page 34 and 35:
Page 36 and 37:
Page 38 and 39:
Page 40 and 41: LPC Bituminous Mixtures Design Guid
Page 89: LPC Bituminous Mixtures Design Guid
Page 125: LPC Bituminous Mixtures Design Guid
Page 140 and 141:
Page 142 and 143:
Page 144 and 145:
Page 146 and 147:
Page 149 and 150:
Page 151 and 152:
Page 153 and 154:
Page 155 and 156:
Page 157 and 158:
Page 159 and 160:
Page 161 and 162:
Page 163 and 164:
Page 165 and 166:
Page 167 and 168:
Page 169 and 170:
Page 171 and 172:
DefinitionIdentificationDesignation
Page 173 and 174:
Page 175 and 176:
Page 177 and 178:
Page 179 and 180:
Page 181 and 182:
Page 183 and 184:
Page 185 and 186:
Page 187 and 188:
Page 189 and 190:
Page 191 and 192:
Page 193 and 194:
Page 195 and 196:
Page 197 and 198:
show all

6. LPC Bituminous Mixtures Design Guide, Sept 2007. - Aapaq.org

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?