外文翻譯---多孔磨耗層在不同的馬歇爾壓實(shí)作用下的特性

1、Characterization of porous friction course mixes for differentMarshall compaction effortsDepartment of Cvili Engnieernig,Natoina lInsttiute of Technology Karnataka,Surathka,lMangaolre 575 025,IndiaABSTRACTPorous fr

2、iction courses(PFCs)are mainly recommended as surface drainage layers on high-speed roadcorridors and runway pavements.Permeability and sound attenuation characteristics are considered to bet he indicesf orp erformancea

3、 ssessmento fP FCs.Oneo ft her easonsf or thel osso fp ermeabilityi nP FCs is densification under heavy traffic.But,resistance to ravelling too,is of main concern in the case of under-compacted PFCs.This paper summarises

4、 the details of laboratory investigation on the characterization of PFC mixes corresponding to four different gradations and two binder contents,for three levels of the Marshallc ompaction.Thef indings oft he investigat

5、ions uggestt hat thes electiono ft hec ompaction level for PFC mix design should be based on the design traffic level,and the gradation selected.2009 Elsevier Ltd.All rights reserved.Keywords: Porous friction course P

6、orous asphalt Marshall compaction Air voids Voids in coarse aggregate Permeability Moisture susceptibilityAbrasion loss1. IntroductionPorous friction courses(PFCs)are typical open-graded asphaltic mixe

7、s,composed of relatively uniformly-graded aggregate and asphalt cement or modified binders,and are mainly used to serve as drainage layers,either at the pavement surface or within the pavement structure[1].Pavements sur

8、faced with open-graded asphaltic mixes were found to improve wet weather skid-resistance,minimize hydroplaning,reduce splash and spray,improve night visibility during wet weather conditions,and reduce traffic tyrenoise

9、[2,3].In countries like the United States of America,Japan,the United Kingdom,Malaysia,Australia,New Zealand,and South Africa,open-graded mixes are in use as surface layers over high-speed and heavily trafficked highway

10、 pavements[2–8].These are also recommended for surfacing runway pavements[9-10].Many agencies around the world use different terminologies for open-graded mixes,and specifications that are slightly different.The various

11、 terminologies used include open-graded asphalt(OGA), porous asphalt(PA),open-graded friction course(OGFC),and porous friction course(PFC).. 1.1 BackgroundThe higha irv oidsc ontenti nP FCsc ontributet owardsp avement

12、surface Straight-run bitumen and crushed stone aggregates are the major constituents of PFC mixes.The straight-run paving grade bitumen used in the present investigation was supplied by Mangalore Refinery and Petrochemi

13、cals Limited(MRPL),Manga- lore.Crushed granite stone aggregates obtained from local stone-crushing plants were used in this study.Table 2 shows some of the physical properties of bitumen and aggregates tested in accorda

14、nce with the requirements of the ASTM D 946[27]and ASTM D7064[15],respectively.Ordinary Portland Cement(OPC)was used as a part of the mineral filler,constituting 2%by mass of total aggregates weighing 1000 g.The procedur

15、e adopted for preparation of the PFC specimens was quite the same as that adopted for dense graded asphalt,as suggested in Asphalt Institute Manual Series-2[28].The properties of compacted mixes investigated include bul

16、k specific gravity (Gmb),air voids content(Va),stone-on-stone contact condition,per-meability(K),moisture susceptibility,and unaged abrasion loss.These properties were evaluated in accordance with the guidelines of the A

17、STM D 7064[15].Table 3 provides details on the tests performed for various experimental mixes.Three observations were made on each experimental mix.3. Characterization of PFC mixes3.1.Bulk specific gravity of compacted m

18、ixThe tests for bulk specific gravity of compacted mixes(Gmb) were performed on 24 mixes as described in Table 3,with three replicates for each mix.The Gmb of each compacted mix was determined using the geometric measure

19、ments of diameter,height,and the mass of the specimen in air,in accordance with ASTM D 7064[15].The individual and mean Gmb values were found to be in the range of 1.935–2.249,and 1.984–2.226,respectively,as shown in Fi

20、g.2.It is evident that an increase in the compaction effort will lead to densification of the mix,resulting in higher densities.Further,it is evident from the 95%confidence intervals that there is no significant differe

21、nce between the mean Gmb values among the mixes with binder contents of 4.5%and 5.0%when compared,for a particular gradation and compaction level.The mixes with gradations G1 and G4 exhibited higher and lower Gmb values

22、,respectively,especially since G4 comprised of coarser aggregates.The mean Gmb values for the mixes with gradations G2 and G3 are approximately the same,as the minor differences in gradations have not affected the Gmb

23、values significantly.3.2.Air voidsThe air voids(Va)content in a compacted mix is related to the Gmb and the theoretical maximum density(Gmm)of the uncompacted mix,determined in accordance with the ASTM D 2041[30].The i

24、ncrease in the compaction effort results in higher Gmb, resulting in a decrease in Va.Fig.3 shows the individual plot of Va for each mix.It also indicates the mean Va of the individual mixes tested,and the 95%confidence

25、 interval for the mean.The line connecting the mean Va shows the trend in variations of the Va with the compaction effort.The individual and mean Va values were found to be in the range of 10– 22%,and 10–20%,respectivel