GS.TS. PHM DUY HU (Ch bin) PGS.TS. V C CHNH TS. O VN NG THS. NGUYN THANH SANG B TNG ASPHALT NH XUT BN GIAO THNG VN TI Vin khoa hc v cng ngh xy dng giao thng Trng i hc GTVT Huuphamduy@gmail.com LI NI U Btngasphaltvccvtliuhnhpkhongbitumkhclvtliuchnh xy dng mt ng t v sn bay, ng st v cc cng trnh thu li.Ni dung ca gio trnh trnh by v cc nguyn l, vt liu ch to, cc tnh cht vt l v c hc, phng php thit k thnh phn, cng ngh ch to b tng asphalt.Gio trnh bao gm 12 chng c phn cng bin son nh sau: Ch bin: Chng 1, 2, 3, 4, 5, 6, 9GS. TS. Phm Duy Hu Chng 7, 8PGS.TS. V c Chnh Chng 7, 11, 12TS. o Vn ng Chng 9, 10ThS. Nguyn Thanh Sang Giotrnhltiliuhctpchosinhvinchuynngnhvtliuvcngngh xydng,sinhvinngnhxydngcngtrnhgiaothngcaTrngihcGiao thng Vn ti. Gio trnh cn l ti liu tham kho cho cc k s xy dng giao thng v xy dng dn dng, cc hc vin cao hc, nghin cu sinh v cc c gi cn quan tm.Trong qu trnh bin son chng ti nhn c kin ng gp ca cc ng nghip, cc nh khoa hc k thut thuc B GTVT, B Xy dng v cc trng i hc trong v ngoi nc. Chng ti nhn c cc ti liu qu bu ca trng Xy dng ng v t ca Nga v cc ti liu ca cng ty Shell Anh Quc. Chng ti rt cm n v mong nhn c kin ng gp ca bn c cho cun sch c hon thin hn. Cc tc gi CC T KHA Phm Duy Hu, B tng asphalt, bitum, vt liu khong, b tng ri ngui, bnMarshall,cutrccabtngasphalt,hnhpvtliukhong-bitum, SMA. Chng 1 KHI NIM V PHN LOI B TNG ASPHALT 1.1.KHI NIM B tng asphalt l vt liu khongbitum xy dng ng, nhn c khi lm c hn hp b tng asphalt. Hn hp b tng asphalt bao gm dm (hoc si), ct, bt khong,bitumdum,phgia.Hnhpcthitkhplvgianhitt1201600C. Thnh phn ca b tng asphalt theo khi lng thng thng nh sau: dm:2065%;ct:3066%;btkhong:414%;bitum:57%;vphgiatutheoktqu th nghim. Trncschtktdnhhuc(bitum,gurng,nhtng)trongxydng ng thng dng cc vt liu hn hp khong v cht kt dnh hu c. Ph bin nht v c cht lng cao nht t vt liu khongbi tum l b tng asphalt. B tng asphalt l sn phm nhn c khi lm c v rn chc hn hp asphaltb tng. Hnhpbtngasphaltbaogm:dm,ct,btkhongvbitumcla chn thnh phn hp l, nho trn v gia cng thnh mt hn hp ng nht. Ct liu ln lm tng khi lng hn hp, lm gim gi thnh ca b tng asphalt v tng cng vnnh.Ctliunhkhitrnvibitumtothnhvaasphaltlmtngtnh do ca hn hp, nh hng n kh nng lm vic v phm vi ng dng ca b tng asphalt. Bt khong lm thay i t l ct liu nh lm hn hp c hn v tng t l b mt ca cc ct liu, n kt hp vi bitum to nn cht kt dnh mi bao bc v bi trn b mt ct liu. Cht lng ca b tng asphalt ph thuc vo ngun gcca ct liu, bt khong v qunh/ nht ca bitum.B tng asphalt l tt nht so vi cc hn hp vt liu khongbitum khc ch n c c, cng , n nh v bn cao do s tham gia ca bt khong trong thnh phn. Btngasphaltcsdnglmlpphmtngclnggiaothngcao nh ng cao tc, ng thnh ph v sn bay. B tng asphalt i hi kt cu pha di c cng cao m bo khng b nt gy trong qu trnh khai thc. ng thi vic ci tin nhm m bo cho xe chy vi tc cao l vn cn ang tip tc nghin cu. Cng v n nh ca b tng asphalt c hnh thnh nh s lin kt gia ct liu vi bt khong v bitum. Thnh phn ca b tng asphalt c th c thit k theo tiu chun Vit Nam v tiu chun ca Vin Asphalt Hoa K. Thnh phn hn hp vtliukhongtheocctiuchunnyvcnbnlgingnhau.Tuynhin,vn lng bitum ti u cn c nhng im cha thng nht.Cc tnh cht ca b tng asphalt ph thuc vo nhit thi cng v nhit khai thc. Theo cc ti liu quc t th b tng asphalt c th khai thc nhit t 500C n +600C. Ccgii php tng cng n nh nhit ca b tng asphalt cn c bit lu khi s dng b tng asphalt trong iu kin kh hu nhit i. Trong qu trnh khai thc b tng asphalt chu nh hng ca cc yu t nhit v thi tit nn n b gi i, nt n, b mi mn v bin dng lm gim tui th khai thc ca b tng asphalt. Tui th trung bnh ca cc lp ph mt ng bng b tng asphalt khong 10 n 15 nm. Trong iu kin thit k, thi cng, bo dng v khai thc hp l th tui th ti a c th t n 20 nm. Yucuvthnhphnhnhp,tnhchtcabtngasphaltvphngphp thit k thnh phn c ghi r trong tiu chun TCVN v TCN GTVT. C th tham kho tiu chun 912884 hoc 2.05.0285 hoc 1280184 ca Nga; tiu chun ca Vin Asphalt Hoa K. Btngasphaltcsdngxydngkhong50%ccconngtrn ton th gii v khong 15% cc con ng Vit Nam. B tng asphalt cn c th s dng lm va h, khu vui chi gii tr, cng trnh th thao v cc cng trnh thu li. B tng asphalt chyu c mu en nhng trong iu kin yu cu cng c th ch to b tng asphalt c mu khc. 1. 2. PHN LOI B TNG ASPHALTB tng asphalt l vt liu khongbitum c cht lng cao. Ngoi ra cn c cc loi hn hp khc nh: vt liu nha macadam, nha cp phi c, nha cng cao, nha ht mn (va asphalt), hn hp to nhm, nha thm nc. S khc nhau c bn gia hn hp asphalt v nha l cp phi ca hn hp. Cp phi ct liu trong asphalt thng bao gm ct liu ln, ct liu mn v bt . Trong cc hn hp nha thng t s dng bt . Cc hn hp to nhm v nha thm nc thng s dng cc cp phi gin on. B tng nha cn c th c ch to t cc loi bitum polyme hoc cc loi nh tng bitum. Cng ca b tng asphalt thay i t 115MPa v ph thuc vo nhit . B tng asphalt c th c phn loi theo cc yu t sau: Theocctiuchunquctv22TCN24998caBGiaothngvntiqui nh nh sau: Hn hp b tng asphalt v b tng asphalt c phn loi theo cc c im sau: Theo nhit thi cng: Hn hp b tng asphalt trong lp ph mt ng c chia ra loi nng, m v ngui. Hn hp nng c ri v bt u lm c khi nhit khng nh hn 120oC. Hn hp ny thng dng bi tum c qunh 40/60, 60/70 v 70/100. Hn hp m c ri v bt u lm c khi nhit khng nh hn 900C v thng dng bitum lng s 1, 2, 3. Hn hp ngui dng bi tum lng c nht 70/130 c ri nhit khng kh khng nh hn 5oC v c gi nhit thng. Theoc(hocrngd):Theochtiurngdbtngasphaltc chia lm 3 loi: loi c c rng 25%, loi rng c rng 612% v loi rt rng c rng 1225% theo th tch. Theo ln ca ht ct liu: Theo ng knh ln nht ca ht vt liu khong c chia ra 3 loi: loi ln (Dmax 40mm), loi trung bnh (Dmax 20mm) v loi nh (hn hp ht nh v hn hp ct Dmax 5mm).Theo tiu chun M b tng asphalt chia lm 21 loi k hiu l s Lam v c ch tiu ph l a, b, c, d...V d Ia,..., IId... Vi Dmax l 2,5 in, 1,5 in, 1 in, 0,5 in v 3/8 in, Dmin l mt sng s No200 (0,071 mm). Theo hm lng gia dm (hoc si) v ct: B tng asphalt nng hoc m, ccchialm3loi:loiAnutldmhnhpctliutrongkhong5065%; loi B: 3550%; loi C: 2035%; loi D: b tng asphalt ct thin nhin; loi G:btngasphaltctnghin.Btngasphaltnguicchialm2loi:BN: 3550%; CN: 2035%. B tng asphalt ct ri ngui c k hiu: DN v GN.Theochtlngcavtliuvtnhchtcl:Btngasphaltcnchiara loisau: I, II, v III: B tng asphalt c v nng. I,II: B tng asphalt nng rng v rt rng. I,II: B tng asphalt ngui. Vcbncchphnloibtngtheocctiuchunlthngnhttuycquy nh khc nhau v n v o kch thc htct liu v k hiu loi b tng. Theo tiu chun Vit Nam v Nga n v o l mm, tiu chun Anh, M l in. 1.3. CC YU CU CHUNG I VI B TNG ASPHALT B tng asphalt l mt loi vt liu c bit vi cc tnh cht thay i nhiu theo nhit ca mi trng v theo ma. Vo ma h nhit b tng tronglp ph mt ng c th t 50600C, cng ch cn 11.5MPa, b tng asphalt tr nn do v cthbchy.Vmangcngtt1015MPa,btngasphalttrnnn hi thm tr c th dn. Trongcnmmctitrngchuynngtrnmtnglkhngi.Nh vy vic thit k thnh phn b tng, thit k kt cu mt ng, thit k cng ngh thi cnglmtbitonrtlphctpmboyucuthayitrngthingsut bin dng trong cc iu kin thay i nhit khc nhau. Bi ton c gii quyt bng cch la chn dng, kiu, vt liu, kt cu mt ng hp l c xt n s ph hp giaiukinvntivkhhu.Btngasphaltcnmboccyucuvcng , n nh, bin dng nhit cao v chng li s ph hoi do nt nhit thp. Khi m bo c cc yu t trn b tng asphalt c th t tui th t 15 n 20 nm. 1.4. KT CU MT NG B TNG ASPHALT Kt cu mt ng t ch yu gm mt s lp: lp mt, mng v lp nn mng. Hnh 1.1 m t mt mt ct ngang in hnhca mt con ng. Cc lp kt cu mt ng b tng asphalt m t hnh 1.2. Kt cu mt ng c kh nng phn b hiu qu ti trng xe, m bo kh nng chu ti, tui th, chi ph u t xy dng v bo dng hp l.Kt cu mt ng c thit k m bo di tc dng ca ti trng xe ng sut trn mt ng v nn ng khng vt qu cc gii hn cho php. Ngy nay ti trng trc xe thit k thng t 1013 tn, trong tng lai c th n 15 tn. Ti trng camybaycthphttrinn25tn.Cctcngcamitrngnhm, lng ma, mc nc ngm, cc iu kin kh hu cng nh hng ln n cht lng mt ng. Lpmtngthngbaogm2lp:lptrnthngcgillpo(lp mt). Lp ny thng s dng b tng asphalt c ht nh. Lp di thng s dng b tngasphaltrinnghocmrngvhtln.Lptrncamtngphimbo kh nng chng li bin dng di tc dng ca ti trng xe, khng thm nc bo v lp di ca mt ng. Trong nhng con ng c bit c th s dng cc lp bitum rng thm nc hoc cc lp matt asphalt cng.Hnh 1.1. Mt ct ngang ng t in hnh Mt ng b tng asphalt l loi mt ng chnh trong giao thng th, ngoi th, ng cao tc v ng nhiu xe chy. Hnh 1.2.Cu to cc lp mt ng t Lp mng l b phn kt cu chnh trong kt cu mt ng phn b ti trng m bo cc lp di khng b qu ti. y l lp chu lc chnh, c kh nng chng li bin dng d v s ntgydo mi v ng sut pht sinh do chnh lchnhit .Lp mng c th chia ra lm 2 lp: lp mng trn v lp mng di (lp cp phi dm tiuchun).Lpmngtrnthngsdngccvtliudnhkt,lpmngdis dngvtliucgiacng.Ccvtliudnhktbaogmbtngasphaltcrng cao,vtliukhongbitum,ccvtliuhocnnmngcgiacngbngcht dnh kt v c. Lp gia cng gm c dm, ct, vt liu khong t cc i hoc cc snphmchtthicngnghip.Tngmngcngcthsdngccloibtng ngho.Lp nn mng ca kt cu mt ng c bn gm 2 lp: lp nn trn thng bng vt liu ht c cht lng tt, lp nn di l t t nhin hoc t c gia c nhm to lp lp mt tt ca nn ng. i khi cng b sung mt s lp: lp ph nn c th bng t t nhin hoc ct liu ht th c gia c vi v xi mng.Lp thot nc t do to thnh mt lp thot nc ra khi mt ng bng dc ngang lp ny c th dng ct vi tiu chun k thut m bo. CU HI N TP 1.Khi nim v phn loi b tng asphalt 2.Cc yu cu chung i vi b tng asphalt 3.Kt cu mt ng b tng asphalt Chng 2 CHT KT DNH BITUM 2.1.KHI NIM V PHN LOI BITUM LM NG 2.1.1. KHI NIM Nhng loi vt liu nh bitum, gurng, nh tng, nha mu l cc cht kt dnh hu c. Chng c th dng cng, qunh, lng (thnh phn ch yu l hirccbon cao phn t v mt s hp cht khc), c kh nng trn ln v dnh kt cc vt liu khong, tothnhvtliunhntocnhngtnhchtvtl,chcphhpxydng ng t v sn bay. Cc cht kt dnh hu ccn c dng lm vt liu lp, cch nc, chng thm v bo v cc p nc, cc cng trnh kin trc, lm nn, gia c nn ngst,snththao,nguatvmt.Chtdnhkttrongbtngasphalt thng s dng bitum du m qunh hoc lng, nh tng bitum hoc bitum polyme. 2.1.2.PHN LOI Bitum c cc loi sau: Bitumdumsnphmcuicngcaqutrnhchngctdum,cnhiu M, Nga v Trung ng.Bitumdusnphmkhichngdu.ducthchan12%bitum. Bitum du c sn xut Php v Thu S. Bitum thin nhinloi bitum thng gp trong thin nhin dng tinh khit hay ln vi cc loi . c khai thc ti cc m u tin Ty Ban Nha. Nhtngbitum:lmtloibitumlngbaogmcchtbitumphntntrong mi trng nc v cht nh ho. Bitum polyme ci tin: l loi bitum ci tin c thm thnh phn polymehu c hocccchtpolymetomu.Bitumpolymectnhnnhnhithoctomusc cho cng trnh. Gi thnh ca bitum polyme cao nn c s dng trong cc cng trnh ng cao cp, c cc yu cu c bit. Bitumrnvbitumoxi ho:nhit2025oClmtchtrnctnh ginv tnh n hi, nhit 180200oC th c tnh cht ca mt cht lng. Bitum qunh: nhit 2025oC l mt cht mm, c tnh do cao v n hi khng ln lm. Bitum lng: nhit 2025oC l cht lng v c cha thnh phn hyrcacbon d bay hi, c kh nng ng c li sau khi thnh phn nh bay hi, v sau c tnh cht gn vi tnh cht ca bitum qunh. 2.2. THNH PHN V CU TRC CA BITUM 2.2.1. THNH PHN CU TO CA BITUMBitum du m l mt hn hp phc tp ca cc hp cht hyrcacbon cao phn t (metan,naftalen,ccloimchvng).Bitumcmuen,hotanctrongbenzen (C6H6),cloruafooc(CHCl3),disunfuacacbon(CS2)vmtsdungmihuckhc, cc nhm chc nng c cha lu hunh, nit v nguyn t xy. Bitum cng cha mt s lng nh kim loi nh niken, st, magi, canxy di dng mui hu c.Thnh phn ho hc ca bitum du m nh sau: C = 8288%;S = 06%; N = 0,51%;H = 811%; O = 01,5%. Datrncslthuytvnhmhohcngitachiabitumdumthnh3 nhmchnh(nhmchtdu,nhmchtnha,nhmasphalt)vccnhmph.Nhn chung,cthtchthnhphnhohccabitumthnhhainhmasphaltvmaltel. Nhmccmaltelcthchiarathnhccchtboho,ccchtnha,ccchtthm (phn loi theo tiu chun Anh). Nhmchtdu(thm)gmnhnghpchtcphntlngthp(300600), khng mu, khi lng ring nh (0,910,925).Nhm cht du lm chobitum c tnh lng. Nu hm lng ca nhm ny tng ln, tnh qunh ca bitum gim. Trong bitum nhm cht du chim khong 4560%.Nhm cht nha gm nhng hp cht c phn t lng cao hn (600900), khi lngringxpxbng1,munusm.Ncthhotantrongbenzen,etxng, clorofooc. Nhm cht nha trung tnh (t l H/C = 1,61,8) lm cho bitum c tnh do. Hmlngcantng,docabitumcngtngln.Nhaaxit(H/C=1,31,4) lm tng tnh dnh bm ca bitum vo . Hm lng ca nhm cht nha trong bitum du m vo khong 1530%. Nhm asphalt rn, gin gm nhng hp cht c phn t lng ln (100030000), khi lng ring 1,101,15, c mu nu sm hoc en, khng b phn gii khi t. Khi nhit ln hn 300oC th b phn gii ra kh v cc, t l H/C = 1,1. Asphalt c th ho tan trong clorofooc, ttraclorua cacbon (CCl4), khngho tan trong te, du ho v axtn (C3H5OH). Tnh qunh v s bin i tnh cht theo nhit ca bitum ph thuc ch yu vo nhm ny. Hmlngnhmasphalttnglnthtnhqunh,nhithommcabitum cng tng ln. Hm lng ca nhm asphalt trong bitum vo khong 1025%. Nhmcacbenvcacbit.Tnhchtcacacbengngingnhchtasphalt,ch khc l khng ho tan trong benzen v trong CCl4, ho tan c trong isunfuacacbon, khi lng ring ln hn 1. Cacbit l mt cht rn dng mui, khng ho tan trong bt c dung mi no. Hm lng ca cc cht ny trong bitum nh hn 1,5%, lm bitum km do. Nhmaxitasphaltvanhyrit.Nhmnylnhngchtnhaho(nhaaxit) mangcctnh(gmnhngphntcchagccacbxynCOOH),nlthnhphn hottnhbmtlnnhtcabitum,dhotantrongrucn,benzen,clorofoocv khhotantrongetxng.Axitasphaltckhilngringnhhn1,munusm, hmlngtrongbitumnhhn1%.Khihmlngtngln,khnngthmtv cng lin kt ca bitum vi b mt vt liu khong dng ccbonat tng ln. Nhm parafin (cc cht no) l nhng hyr cacbua bo dng chui thng hoc phn nhnh c phn t lng trung bnh, bao gm cc cht parafin v khng thuc dng parafin.Papafincthlmgimkhnmgphntnvhotancaasphaltvotrong ccnhmkhc,cthlmgimtnhngnhtcabitum.Nutlparafintngln, nhithomm,tnhgincabitumnhitthpstngln,bitumholng nhitthphnsovibitumkhngchaparafin.Tlcaparafintrongbitumdu m n 5%. Tnh cht ca bitum ph thuc vo thnh phn v tnh cht ca hn hp cc nhm cu to ho hc. Da vo nhm cu to ho hc c th chia bitum du m thnh 3 loi: loi 1, loi 2 v loi 3. Bitum loi 1 c nhm asphalt > 25%, nha < 24% v dung dch ccbon > 50%. Bitum loi 2 c hm lng nhm cu to ho hc tng ng l > 18%; >36%v 50 9 4 M un cng ti thiu 400C: thigianchutisau1000 giy vimcx 2,5.104s1,kN/m2 > 3 n nh bo qun: skhcnhauvimmm nh xungysau7ngybo qun trong mt thit b hnh tr 1600C, 0C < 5< 5 Hm lng polyme, %7,0 1,06,0 1,0 CARIPHALTE DM c pht trin s dng trong hn hp b tng asphalt lu nng cht v hn hp b tng asphalt ci tin lp nn lm bng b tng ngho v mt ng b tng c b nhit gy ra mt s dch chuyn lp b tng dn n hin tng nt phn hi ti b mt ng. CARIPHALTE DA c pht trin s dng trong hn hp nha thot nc v hn hp ri lp to ma st. Ccyutvkthutchititcahailoichtlinktnycchititho bng 2.13. Quan h gia nht v nhit ca CARIPHALTE DM v bitum qunh 50 cho thy r l nhit cao ca con ng, v d 600C, CARIPHALTE DM cng hn ng k so vi bitum 50 v do chng bin dng tt hn. nhit thp, < 00C, CARIPHALTE DM do hn bitum 50 v do chng nt tt hn. Mccithinkhnngchngbindngckimtrabngccthnghim vt ln bnh xe do c phng th nghim ng b v vn ti (TRRL) v Shell Research Limited thc hin, c trnh by bng 2.14. R rng l c mt s tng ln ng k v khnngchngbindng,tngtvikhnngchngbindngcabitumchuti nng(HD)cphttrinchuyndngchngbindng.Nhnguimny c khng nh qua cc cuc kim nghim ton din trn thc a. docahnhpbitumcnhlngbngthnghimrobindng khngidoTRRLvShellResearchLimitedtinhnh.Thnghimmic Shell ResearchLimited thc hin trn hn hp b tngasphalt lu nng thi cng 50C vitnsl50Hzchothyvimtphmvirngvtitrngtcnglnmuth nghim CARIPHALTE DM, tui th ro ca mt ng nng ln t nht l 3 ln. Bng 2.14. So snh mc vt ln bnh xe ca mt ng c ri bng asphalt lu nng lm t bitum 50, HD40 v CARIPHALTE DM Cc c tnh ca cht lin kt Cht lin kt Kim ln 250C, dmm im mm (IP), oC ln vt bnh xe 450C mm/h 50 pen HD40 CARIPHALTE DM 56 42 34 52 68 90 3,2 0,7 0,7 2.5.8. CC BITUM POLYME CHU NHIT Ccchtpolymechunhitcsnxutbngcchtrnhaithnhphnlng, thnh phn u l cht nha v phn cn li cha cht lm cng. Hai thnh phn ny kt hp vi nhau v mt ho hc to ra mt cu trc 3 chiu vng chc. Hp cht nha 2 thnhphnnykhitrnvibitumsthhinccctnhnitricaccchtnha chu nhit hn l cc c tnh ca bitum. Cc loi hp cht nha chu nhit 2 thnh phn ny c pht trin khong 30 nm trc y v hin nay ang c ng dng rng ri bc ph b mt v lm cc cht dnh kt. Nhng s khc nhau c bn gia bitum (mt cht do nhit) v cc bitum polyme chu nhit l nh sau: Khi hai thnh phn trong bitum polyme chu nhit c trn th thi gian s dng sn phm ny s b gii hn, thi hn ny ph thuc nhiu vo nhit , nhit cng cao th thi hn s dng cng ngn. Sau khi mt sn phm chu nhit c s dng n tip tc c lu ho v tng cng v sc bn, tc lu ho trn mt ng ph thuc vo nhit mi trng. Khinhittnglnbitumbmmravchy,ccbitumpolymechunhitt mn cm vi nhit hn v trong thc t khng b tc ng ca s thay i nhit trn ng. Bitumpolymechunhitlmtvtliunhi,khngthhinctnhnht chy, n nh vi ho cht, dung mi, nhin liu v du. Ba loi bitum polyme chu nhit c bit n ph bin l: Shell grip/spray grrip; Erophalt; v Sheliepoxy asphalt. Cc loi ny c s dng rng ri trn th gii t nm 1986. Tuy nhin, Vit Nam ang trong giai on nghin cu.2.5.9. TIU CHUN 22TCN319042004 GTVT V BITUM POLYME C th tham kho tiu chun k thut vt liu bitum polyme dng cho ng t v sn bay c quy nh theo 22TCN 319042004 GTVT. Bng 2.15. Tiu chun k thut vt liu bitum polyme cho ng t v sn bay (22TCN 319042004) Tr s tiu chun theo mc bitum polyme TTCc ch tiu n v PMBI PMBIIPMBIII 1Nhithomm(phngphp vng v bi), min oC607080 2 kim ln 250C0.1mm50704070 3Nhit bt la, min oC230 4Lngtnthtsaukhiunnng 1630C trong 5 gi, max %0.6 5T l kim ln ca nha ng sau khiunnng1630Ctrong5giso vi kim ln 250C, min %65 6Lnghotantrong trichloroethytylen, min %99 7Khi lng ring 250Cg/cm31.001.05 8 dnh bm vi , mincp cp 4 9nhi(250Cmukodi 10cm), min %606570 10 n nh lu tr (gia nhit 1630C trong48gi,saikhcnhitho mm ca phn trn v di ca mu), max oC3.0 11nht1350C(nhtkPa.s3.0 Brookfield), max 2.6.NH TNG XY DNG NG (22TCN 3542006) 2.6.1. KHI NIM V PHN LOI NH TNG 2.6.1.1. Khi nim Nh tng l mt h thng keo phc tp bao gm hai cht lng khng ho tan ln nhau. Trong , mt cht lng phn tn trong cht lng kia di dng nhng git nh li ti, gi l pha phn tn, cn cht lng kia gi l mi trng phn tn. cho nh tng c n nh ngi ta cho thm vo cht nh ha (cht ph gia hot tnh b mt). Cht nh ha s hp ph trn b mt cc git bitum hay gurng, lm gim sc cng b mt mt phn chia ca bitum hay gurng vi nc. ng thi n to ra trn b mt ccgit bitum mt mng mng ktcu bn vng, c tc dng ngn cn s kt t ca chng, lm cho nh tng n nh. Nhtngbitumlmthpchtgmhaithnhphndthcbnlbitumv nc,cgilhaiphancvphabitum.Bitumcphntntrongncdi dngcchtringrcngknht0,15micrn.Cchtbitumcgitrng thi l lng tch in v c n nh bng cht nh ho. 2.6.1.2. Phn loi nh tng Cn c vo c trng ca pha phn tn v mi trng phn tn, nh tng c chia ra hai loi: Nu pha phn tn l bitum, cn mi trng phn tn l nc th gi l nh tng dunc (DN), hay cn gi l nh tng thun. Nu pha phn tn l nhng git nc, cn bitum hay gurng l mi trng phn tn, th gi l nh tng ncdu (ND), hay cn gi l nh tng nghch. Theo kh nng trn ln ca nh tng vi vt liu khong chia nh tng ra lm ba loi: 1, 2, 3 (theo quy phm 1865981Nga). Cn c vo cht nh ha, nh tng c chia ra lm cc loi sau: Nhtnganionhottnh(nhtngkim)dngchtnhhalnhngmui kimcaaxitbo,axitnaftalen,nhahaynhngaxitsunfua,pHcanhtngt 912. Nhtngcationhottnh(nhtngaxit)dngchtnhhalccmuica cc cht amniac bc bn, iamin, v.v., pH trong nh tng ny mn trong gii hn t 26. Nh tng trung tnh (khng sinh ra ion)l nh tng dng cht nh ha khng sinh ra ion nh opanol (cao su tng hp), plyizbutilen v.v. pH bng 7. Nh tng l loi bt nho khi dng cht nh ha dng bt v c nhbt vi ti, t st do, trpen, iatmit. Thutnganionvcationchccintchbaoquanhcchtbitum.Hin tng ny bt ngun t mt quy lut c bn v in. Cc in tch cng du y nhau, cc in tch khc du ht nhau. Nu dng in chy qua mt dung dch nh tng cha ht bitum tch in m, chng s di chuyn v pha ant. Bi vy nh tng ny c gi l nh tng anion. Ngc li cc ht bitum c tch in dng s di chuyn v pha catt. Nh tng l cc ht trung tnh s khng di chuyn ti bt k cc cc no. Nh tng trung tnh rt him khi c s dng trong xy dng ng. 2.6.2. VT LIU CH TO NH TNG 2.6.2.1. Cht kt dnh chtonhtng,cthdngccchtktdnhhucnhbitumdum loi c, loi lng v gurng than xy dng ng. Khi dng cht nh ha dng bt (bt vi ti, t st) thc th dngcc loi mc thp (s 13), cn khixy dng mt ng nhng vng kh hu nngdng cc loi mc cao (bitum mc s5). 2.6.2.2. Nc Nc dng ch to nh tng khi dng cht nh ha anion hot tnh th phi l nc mm (nc c cng khng ln hn 3 mili ng lng gam/lt). 2.6.2.3. Cht nh ha Cht nh ha l cht hot tnh b mt, nhng phn t ca n bao gm phnkhng mangcctnhlnhnggchyrccbua,vphnmangcctnh.Chtnyckh nnghpthtrnbmtgitbitumhaygurnglmchonhtngnnh.Khi gc hyr cacbua (nhm khng mang cc tnh), l nhm k nc, nn n lun lun n pha c cc tnh nh hnhng vo bitum; cn nhm c cc tnh, l nhm a nc, th hngvonc.Docutrcphntcachthottnhbmtkhngixngnh vy,nnlpbmt,chngnhhngphhpviquylutcnbngcctnh,v lm gim sc cng b mt mt phn chia gia nc v bitum, tc l n lm gim s khc nhau v sc cng b mt ca bitum v nc. Cht nh ha c chia ra cc loi anion hot tnh, cation hot tnh v loi khng sinh ra ion. Chtnhhoanionhottnhbaogmcxphngcaccaxitbo,axitnha, axit naftalen v cc axit sunfua naftalen. Cht nh ho cation hot tnh l nhng mui ca cc hp cht amniac bc bn, cc amin bc nht, bc hai v cc mui ca chng; cc iamin v.v. Nhm khng sinh ra ion bao gm cc hp cht khng ho tan trong nc, ch yu l cc te. Ngoinhngloichtnhhadnghuctrnra,khichtonhtngcn dng cht nh ha dng bt v c. Nhng cht nh ha dng bt v c hay dng l vi bt, vi ti, t st, t hong th. Trongthctxydngng,ngdngrngrinhtlnhngchtnhha anion hot tnh, ch to nh tng thun. 2.6.3. CC CH TIU K THUT NH TNG LM NG 2.6.3.1. nht Nhtnglmngcncnht hplmbokhisdngcthnho trn vi vt liu khong hoc phun c ln bmtvtliukhongbngccthit b phun.nhtcanhtngthngc xc nh bng nht k tiu chun (xem mc 2.4.2)haynhtkEngler.nhtcanh tng thng dao ng trong phm vi sau: C320= 550 sec. Tng nht ca nh tng bng cch tng t l bitum, thay i dung dch nh ho hoc gim nht ca bitum. Hnh 2.11. m tmiquanhgianhtcanhtng vi hm lng ca bitum. 2.6.3.2. phn tch Nhtngsaukhithicngphitch ncnhanhvdnhbmttvibmtvt liukhongvt.Hnh2.12.mtqutrnh phntchvdnhbmvibmtvtliu khong ca nh tng. Hnh2.12.Smtqutrnhphntchvdnhbmvibmtvtliu khong ca nh tng. phn tch c xc nh bng h s: Hnh2.11.nhtcanhtng (Engler)lmthmcatcchy vi cc hm lng bitum khc nhau. 100,%NNP21 =(2.6) trong :N1lng nha cn li sau khi th nghim N2lng nha trn mt si trc khi th nghim.Th nghim c tin hnh nh sau: Nhng si c ng knh t 6 n 12mm vo nh tng trong 2 pht, ngoi khng kh 30 pht, ra mu trong nc 15 pht P = 10050, %,phn tch nhanh P = 1050, %,phn tch va P nh hn 10, %, phn tch chm. 2.6.3.3. Tnh n nh khi vn chuyn v bo qun Tnh n nh khi bo qun c trng cho kh nng ca nh tng bo ton c cc tnh cht khi nhit thay i, ngha l n khng lng ng, khng to thnh lp v v bo ton tnh ng nht trong mt khong thi gian nht nh. Tnh n nh thng c xc nh sau 7 v 30 ngy bo qun (theo tiu chun 1865981 Lin X c). Cc loi nh tng c thnh phn khc nhau c th n nh trong lc bo qun nhit t +3oC n +40oC trong 30 ngy. Tnh n nh khi vn chuyn hay khi chu tc dng ca ngoi lc c xc nh bng kh nng ca nh tng bo ton tnh cht khi chuyn ch v khi thi cng. xc nh tnh n nh khi bo qun v khi vn chuyn, ly nh tng bo qun sau 7 ngy v 30 ngy cho chy qua sng c kch thc l sng 0,14mm. Yu cu l lng st trn sng khng qu 0,1% theo khi lng v m bo cc tnh cht khc theo tiu chun Nh nc. Tnh n nh khi vn chuyn c kim tra theo cc tnh cht ca bitum sau 2 gi vn chuyn phi m bo cc yu cu k thut. Nh tng c nht cao, t l cht nh ho cao, c kch thc ht ng u s n nh khi bo qun. 2.6.3.4. Tnh dnh bm ca mng chtdnh kt vi b mt vt liu khong Tnhdnhbmckimtrabngtrsbmtcadmvncncph nh tng sau khi ra cc mu th sau khi nhng vo nh tng bng nc nhit 100oC. Tr s b mt phi khng nh hn 75% (vi nh tng anion) v khng nh hn 95% (vi nh tng cation). 2.6.3.5 Tnh cht phn cn li sau khi chng ct Sau khi chng ct nhit 360oC, cho phn dung mi bay hi ht, tnh cht ca phn cn li phi ph hp vi tiu chun nh vi bitum lng. 2.6.4. THNH PHN CA NH TNG VIT NAM Vitnambcunghincuthnhcngmtsnhtngthunloi kim,dngchtnhhoanionhottnhnhxphngbt,dugai,dus,dutru, v.v. thnh phn ca nh tng nh sau: 50% bitum s 5 + 50% nc + (0,51)% x phng bt + (0,10,15)% NaOH. 50% bitum s 5 + 50% nc + (0,51,2)% du thc vt + (0,20,3)% NaOH. Ngoi ra, khi cn ch to nh tng c th tham kho thnh phn nh tng ca Nga (Tiu chun 1865981), ca M ASTM, v.v. 2.6.5. CC YU CU V NH TNG CA M (EMULOIFIED ASPHALT) M c nhiu loi nh tng nha, ch yu thng dng trong xy dng ng l nh tng anion (AEA) v nh tng cation (CEA). Mi loi nh tng nha c chia ra nhiu cp theo tc phn tch v nht. Ccyu cu v tnh cht c lca nh tng c ghi trong bng 2.16. Bng 2.16. Cc yu cu k thut ca nh tng. . Cp Phn tch nhanh Phntch va Phn tch chm Cc ch tiu RS1RS2MS2SS1SS1h K hiu th nghim (1)(2)(3)(4)(5)(6)(7) 1nhtFurol 77oF, scc 20 100100+2010020100 22TCN2542006 2nhtFurol 122oF, scc 75400 cngquy nh tng t (1)(2)(3)(4)(5)(6)(7) 3B nha sau khi ct,%theokhi lng 54+62+62+57+57+ 4Lngng5 ngy,khcnhau gialptrnv lp di, % 33333D224T59 5 kh nh: Khidng35ml 0,02N CaCl2,% 60+50+ 2.6.6. NG DNG CA NH TNG BITUM LM NG 2.6.6.1. Nh tng bitum lm ng Hn hp nh tng bitum ct liu c sn xut v s dng Php t nhng nm 50vcsdngphbinchuu,chuPhi,Mchonngynay.Chngloi hn hp ch yu l nha nh tng c s dng lm lp mng trn ca ng b. Tuy nhin, mt s loi hn hp c sn xut t nh tng bitum dnh cho ri lp trn ca mt ng cng c p dng thnh cng. Mt vn quan trng khi s dng nh tng bitum trong hn hp lm ng l cn to ra rng tng i cao nc c th thot nhanh trong qu trnh m nn v khi con ng i vo hot ng. Hn na bn ca mt ng c gia cng vi hnhpnhtngctliuchnhthnhtngichm.Vchaildonym Khidng50ml ca0,01N CaCl2,% 30 6Thnghimry (phntrnry No20),% 0,100,100,100,100,10 7Th nghim trn vi ximng, % 2,02,0D5T49 8Thnghimtrn bnhasaukhi trngctnh tng nha: kimln, 77oF, 100g, 5s 100200100200 100200 100200 4090D2042T44 hotan trong Trichloroithylene, % 97,5+97,5+97,5+97,5+90,5+D113T51 kodi, 77oF, cm 40+40+40+40+40+ 9Hmlng bitum,% 60+65+65+57+57+ 10Hmlng du, % 3312 cchnhpnhtngctliuchphhpviccconngchutinh.Dovy, loi vt liu ny ch c s dng rt hn ch. Trcy,cchnhpnhangktchmhoccsnxutvivics dng mt phm cp bitum lng vi nhiu loi du pha khc nhau. Cc vt liu ny ch yu c s dng cho vic duy tu sa cha ng. S pht trin ca cc nh tng ph ct liu to ra mt s loi hn hp nh tngct liu dng cho nhng mc ch c th trong xy dng ng giao thng. Mt ng dng khc canh tng bitum trong hn hp lm ng l khi phc mt ng theo phng php trn ngui ti ch. My lm ng lin hp c s dng bc lp mt ng, ri nghin lp bc mt ng thnh cc ht ct liu theo kch c yucuvsnglcloibcchtkhngngkchthc.Sauctliutich cphunmtlpnhtng,saumilnphunnhtngthitbolpctliu c s dng nh tng bm dnh u vi ct liu. Qu trnh phun v o li khong t 2 n 3 ln. Tip theo, xe lu trng lng 810 tn c s dng m nn lp nh tngct liu v cui cng mt ng c lng mt hn hp mn chng thm. Nhtngbitumcngcsdnglmlpdnhbm.lmtkthut c p dng m bo s lin kt bm dnh gia cc lp ca mt ng. 2.6.6.2. Cc ng dng khc ca nh tng bitum. C th s dng nh tng lm n nh t, chng thm, lp ph bo v, trm khe cc khe h v lm lp chng thm. CU HI N TP 1.Khi nim v phn loi bitum lm ng 2.Thnh phn v cu trc ca bitum 3.Cc tnh cht ca bitum du m qunh xy dng ng 4.Thnh phn v cc tnh cht ca bitum lng lm ng 5.Cc loi bitum ci tin lm ng 6.Thnh phn v cc tnh cht ca nh tng xy dng ng Chng 3 CT LIU CHO B TNG ASPHALT 3.1. M U Ctliungvaitrrtquantrngtronghnhpbtngasphalt.Nchim khong92n96%tngkhilngvtliutrongbtngasphaltvchimkhong trn30%githnhcaktcumtng.Vvy,nnhhngkhnhiutigi thnh ca kt cu mt ng. Ct liu chyu ca b tng asphalt l dm (hoc si), ct (ct t nhin hoc ct nghin), bt vi, cc ct liu nhn to (si keramdit, x l cao, xi mng), hoc cc vt liu thi khc.3.2. PHN LOI V PHNG PHP SN XUT CT LIU. 3.2.1. PHN LOI Ct liu bao gm cc loi ct, si, nghin, x, hay thnh phn vt liu khong khc. Chng c th c nho trn vi nhau v s dng cng vi cht kt dnh hu c to thnh vt liu b tng asphalt. Ct liu c th phn loi theo ngun gc t nhin hay nhn to. Ct liu t nhin c ly t nhin v trong qu trnh khai thc, sn xut khng lm thay i bn cht ca chng, ch s dng cch nghin, o, sng hay ra. Trong nhm ny, dm, si v ct l ph bin nht, mc d c th c thm bt, v s, qung st, v vi. Ct liu nhn to bao gm x l cao, t st nung, ct liu nh, v cc vt liu thi. Theongknhlnnht,ctliucchiara2loi:htmnvhtln.Loi htlnlhtphnlnnmtrnsngNo8(2.36mm).Loihtmnphnlnltqua sng 2.36 mm.Kch thc cc mt sng, mm, cho ct liu b tng asphalt nh sau: 50; 37,5; 25; 19; 12,5; 9,5; 4,75; 2,36; 1,18; 0,6; 0,3; 0,15; 0,075.Tu theo loi b tng asphalt c th dng cc ng knh ln nht khc nhau v c thnh phn cp phi ht khc nhau c quy nh theo cc tiu chun k thut. Theo tiu chun Chu u EN 130432002 kch thc c sng ghi bng 3.1.Bng3.1.Ccloicsngphnloiccchtctliuchobtngasphalt (EN 130432002) B sng c bn, c sng, mmLoi 1, c sng, mmLoi 2, c sng, mm (1)(2)(3) 0 1 2 (1) 0 1 2 (2) 0 1 2 (3) 4 8 4 5.6 (5) 8 11.2 4 6.3 (6) 8 10 12.5 14 16 31.5 (32) 63 16 22.4 (22) 31.5 (32) 45 63 16 20 31.5 40 63 Thnh phn ht c quy nh theo EN 93311997 ph thuc vo t l d/D (trong D v d l ng knh c sng ln v nh nht ca b sng), v c quy nh bng 3.2 v 3.3. Bng 3.2. Cc yu cu v thnh phn ht ct liu Lng lt sng theo khi lng, % Ct liu C sng, mm 2D1.4D Ddd/2 K hiu 100100909901002GC90/10 10098100909901505GC90/15 10098100909902005GC90/20 10098100859901502GC85/15 10098100859902005GC85/20 ThD >2 10098100859903505GC85/35 Ht mnD21008599GF85 Hn hp D45 v d=0 100 100 98100 98100 9099 8599 GA90 GA85 Bng3.3.Ccgiihnchungvdungsaichocpphihnhphtthtic sng trung gian. Gii hn phn trmlt theo khi lng D/d C sng trung gian, mm Gii hnDung sai K hiu 258015G25/15 4.750 0.82 0.41 dy ca mng mng bitum khi c tnh theo cng thc l thuyt sau: SAF1b1b 100bT = trong : T- dy ca mng bitum, mm B khi lng ring ca bitum, kg/m3 SAF t din tch b mt ca ct liu, m2/kg b - hm lng bitum, % Din tch b mt ca ct liu c tnh bng cch nhn tng phn trm lng lt qua l sng vi t din b mt tng ng. Khi ct liu gm cc kch c ht khc nhau th c th tnh ring cho tng c ht.Vcutrccabitumtronglpmngtrnbmtcahtvbtcgii thch theo nhiu l thuyt khc nhau. Theo tc gi I.A. Rbev cho rng c mt lc dnh bm ca lp mng ny vi b mt ca . Theo tc gi Karolev lp bitum ny gm c lp bitum t do, lp bitum cng v gia l lp bitum c trn vi bt (cht lin kt asphalt). Theo cc tc gi M cho rng lp bitum trn b mt khong bao gm 2 vng,mtvngthmvovtliuvmtvnghiuqutonnlclinkt vi .Cng , khi lng ring v do ca bitum trong lp ph trn b mt ca vt liu khong s to nn kh nng dnh bm vi b mt ca ht. Chiu dy lp ph bitum ph thuc vo ln ca cc ht. Theo I.B. Karolev trn cc ht c ng knh nh hn 0.071mmthchiudycamngbitumkhong0.2um,cntrncchtdmth chiudycamngbitumt10-20um.Trnbmtcavtliukhongctcng vic m ln th chiu dy ca mng bitum thng nh hn 10um. Thnhphnbtphntnmnhcthlmthayicutrcbitumtronglp mngbngcchsdngthmccphgiadngkeo.nginnhtlhximng nc. Bitum c kt dnh tt i vi hu ht vt liu lm ng vi iu kin cc vt liuphisch,khvkhngcbibm,lcdnhbmphthucvonhtca bitum.Khinhtcabitumcngcaoththigianlmtctliucnglu.Khi bitum dnh kt tt vi cc ht ct liu th s dnh kt t b suyyu ngoi tr s can thipcanc.Khictcngcancsgyhintngkhngktdnhkhic nc. Nu ct liu l cc axt a nc, nc c tc dng lm gim lc dnh kt v c kh nng thm nhp vo gia mng bitum v ct liu, lm tch bitum ra khi ct liu.

CU HI N TP 1.Trnh by v cu trc ca vt liu khong trong b tng asphalt. 2.Trnh by v cu trc ca bitum trong b tng asphalt. Chng 6 CC TNH CHT CA B TNG ASPHALT 6.1.KHI QUTCc tnh cht ca hn hp b tng asphalt v b tng asphalt m nn lm mt ng bao gm tnh cht lin quan n c tnh th tch v tnh cht c hc. c tnh th tch ca b tng asphalt bao gm cc ch tiu: rng d (VIM), rng ct liu (VMA), rng lp y nha (VFA). Cc gi tr ny phi nm trong gii hnquynhmbolpbtngasphaltckhnngchngbindng,chngchy bitumditcngcatitrngxevyutnhitmitrng,hnchsxm nhp ca nc vo hn hp trong qu trnh khai thc. xcnhccchtiuctnhthtchcabtngasphalt,cnthitphith nghim v tnh ton cc ch tiu sau: Cc ch tiu lin quan n t trng ca vt liu thnh phn: t trng ca ct liu th(dm),ttrngcactliumn(ctthinnhin,ctxayt),ttrngca bitum, t trng ca bt khong. Cc ch tiu lin quan n t trng ca hn hp b tng asphalt:t trng biu kincactliutronghnhpbtngasphalt,ttrngkhicahnhpbtng asphalttrngthiri(cham),ttrngkhicahnhpbtngasphaltkhi cmnn,ttrnglnnhtcahnhpbtngasphalttrngthiri(cha m). Cctnhchtchccabtngasphalt:baogmccchtiulinquann cng ca hn hp b tng asphalt sau khi m nn nhm m bo cho kt cu lp b tng asphalt c cng v bn sau khi xy dng v trong qu trnh khai thc di tc ng ca ti trng xe chy v cc yu t mi trng. Khi ti trng bnh xe tc dng xung mt ng, c hai ng sut c truyn ti mt ng b tng asphalt: ng sut thng ng v ng sut nm ngang. Vi ng sut thng ng sinh ra bin dng ln ca kt cu mt ng v gy ra ng sut ko ln nht di y lp vt liu b tng asphalt. Hn hp b tng asphalt v vy cn phi bn chc vkhnngnhichnglingsutnnvngnkhngchoxuthinbin dng vnh cu.B tng asphalt phi c cng ko chng li cc ng sut ko sinh ra y lp b tng asphalt v c n hi chng li cc tc ng ca ti trng m khng sinh ra hin tng nt mi.Cng vi cc tc ng ca ti trng v mi trng, mt ng b tng asphalt s dndnbhhngtheobahnhthcchnhdiyphthucvocchchuti trng xe chy v iu kin mi trng, l: Bin dng vnh cu; Nt mi; Nt do nhit thp. xc nh cc tnh cht c hc ca b tng asphalt, trn th gii ty theo truyn thng, ty theo phng php thit k b tng asphalt v ty theo iu kin pht trin ca tng nc m c nhiu phng php th nghim khc nhau c p dng cho mi nc. Trongqutrnhphttrin,nhiuphngphpthnghimchccabtngasphalt cbsungchophhpviiukinlmviccamtngbtngasphalt,v cng c khng t phng php c loi b do t c p dng. Nhn chung cc phng php th nghim c hc ca b tng asphalt hin nay thng s dng m hnh ti trng trng phc, nhm m phng cc tc ng do ti trng v yu t mi trng (nhit , m) gy ra trn lp mt ng b tng asphalt. Cc tnh cht c hc ca b tng c th phn theo cc nhm sau: Cctnhchtchcphcvchothitkhnhpbtngasphalt:ctin hnh phc v vic thit k la chn hm lng nha ti u cho hn hp b tng asphalt. Mu b tng asphalt thit k va phi tho mn cc tnh cht lin quan n c tnh th tch, va phi tho mn cc tnh cht c hc c quy nh tng ng vi phng php .Phngphpthitkbtngasphaltcpdngkhphbintrnthgiiv c bit nhiu Vit Namc th k n l:Phng php thit k Marshall; Phng php thit k Hveem; Phng php thit k theo Lin bang Nga (Lin x c); Phng php thit k Super Pave. Cctnhchtchccabtngasphaltphcvchotnhtanktcu:tu thucccphngphptnhtonthitkktcumtngkhcnhau,trongquy nh cc ch tiu c hc ca b tng asphalt cn thit phc v tnh ton xc nh chiu dy cn thit ca lp b tng asphalt mt ng di tc dng ca ti trng xe chy v cc yu t mi trng. Phn nhm cc phng php th nghim c hc ca b tng asphalt theo phng ca lc tc dng trn mu th c cc loi: Th nghim vi lc tc ng theo phng ng knh ca mu hnh tr trn; Th nghim vi lc tc ng dc trc mu hnh tr trn; Th nghim vi lc tc ng 3 trc trn mu hnh tr trn; Th nghim ct; Th nghim ko; Th nghim ko un trn mu hnh dm. Phn nhm cc phng php th nghim c hc theo kiu tc dng ca lc th c cc loi: Th nghim vi lc gia ti tnh; Th nghim vi lc gia ti ng, nhiu chu k gia ti. Diytrnhbymtstnhchtchccabtngasphaltvccphng php th nghim lin quan c s dng kh ph bin trn th gii v Vit Nam hin nay v nh hng cho tng lai. 6.2. CC TNH CHT C HC 6.2.1. N NH V DO MARSHALL (CC CH TIU C HC T CC TNHCHTNYCSDNGCHOPHNGPHPTHITK MARSHALL (22TCN 6284, AASHTO T245)) n nh Marshall: l gi tr lc ln nht tc dng ln mu ti thi im mu b ph hoi (S). do Marshall: l gi tr bin dng ln ca mu th nghim ti thi im mu b ph hoi (F). n nh v do Marshall ca mu b tng asphalt m nn l hai ch tiu c hc chnh dng trong phng php thit k Marshall. Hai ch tiu ny c xc nh thng qua th nghim Marshall. ThnghimMarshallcthchintrnmubtngasphalthnhtrtrnc ngknhD=101,6mm;chiucaoH=63mm,cchtotiphngthnghim hoc mu khoan t mt ng. Mubtngasphaltctrnnhitquynh,ctomutrongkhun Marshall vi s chy m v nhit quy nh. Sau khi ngm mu trong nc c nhit 60oCtrongkhongthigian3040pht,muclyravtvothitb Marshall th nghim (Hnh 6.1).Lc nn c tc 50,8mm/pht tc dng dc theo phngngsinhchotikhimub ph hoi. Hnh 6.1. Th nghim xc nh n nh, do Marshall Trong trng hp mu th nghim c chiu cao khc vi chiu cao tiu chun, nnhMarshallbnglncalcphhoimunhnthmvihshiuchnh chiu cao. n nh, do Marshall cng c th c s dng xc nh gi tr m un n hi ca b tng asphalt theo cng thc thc nghim ca Nijboer nh sau: FS1.6 E0dh,60 =(kG/cm2)(6.1) Trong :S: n nh Marshall (KN). F: do Marshall (mm). Hng dn thit k hn hp b tng asphalt theo Marshall ca Vin Asphalt, kt qu thit k (v chn c hm lng bitum ti u) phi tho mn ccyu cu v c tnhthtchvchtiuchc(nnh,do)tngngvilnggiaothng theo quy nh Bng 6.1. Bng 6.1. n nh, do vi b tng asphalt thit k theo Marshall Giao thng nhGiao thng vaGiao thng nng Lp mt & Mng trn Lp mt & Mng trn Lp mt & Mng trn Cc ch tiu k thut yu cu ca hn hp b tng asphalt theo MarshallMinMaxMinMaxMinMax S ln m nn 35 x 250 x 275 x 2 n nh (Stability), KN 3,45,58,0 do, mm3,27,23,26,424 6.2.2.NNHHVEEM(CHTIUCHCTTNHCHTNYC SDNGCHOPHNGPHPTHITKHVEEM(ASPHALT INSTITUTE)) nnhHveemlmtchtiuquantrngtrongthitkhnhpbtng asphalt theo phng php Hveem. Th nghim xc nh n nh Hveem c thc hin trn mu hnh tr trn c ng knh D = 101.6mm, chiu cao H=63.5mm ch b theo phng php Hveem, hoc khoan t mt ng.Musaukhicbodngtrongtsynhit603oCtrongkhongthi gian t 34 gi, c ly ra v t vo v tr th nghim (Hnh 6.2). Tin hnh gia ti cho mu to ra mt p lc hng ban u tc dng ln mu l 34.5kPa. Sau cho my nn hot ng, tc dng ti theo phng dc trc mu vi tc khng i l 1.3 mm/pht. Ghi li ln ca p lc hng ng vi thi im ti trng thng ng tc dng ln mu t 13.4 kN, 22.3kN v 26.7kN.NGAYSAU,GIMTITCDNGLNMUTHEOPHNG DCTRCXUNGCN4.45KN,PLCHNGTCDNGLNMU XUNG CN 34.5 KPA. DNG BM THU LC QUAY TAY TNG DN PLCHNGTCDNGLNMU.MCHNHXCSVNGQUAY P LC HNG TC DNG LN MU TNG T 34.5KPA N 690 KPA, TTNHCCHUYN V TNG NG. Hnh 6.2. Th nghim n nh Hveem nnhHveemlmtgitrkhngcthnguynvcxcnhtheo cng thc: 0.222hPvP.DhP22.2S+=(6.2) Trong :D :Chuynvtngngvisvngquayplchngtcdng ln mu tng t 34.5 kPa n 690 kPa. Pv :plctcdnglnmutheophngdctrc(thngly Pv =2.76 MPa ng vi ti trng tc dng ln mu l 22.3kN). Ph : p lc hng tc dng ln mu ng vi thi im xc nh Pv. TheoquynhcaHveem,hnhpbtngasphaltkhithitkphicn nh ln hn ccgi tr30, 35, 37 tng ng vi lnggiao thng nh, trung bnh v nng.Bng6.2.araquynhkthuttngngviccloibtngasphaltkhi thit k theo Hveem. Bng 6.2. Yu cu k thut vi b tng asphalt thit k theo Hveem Loi hn hp b tng atphaltTiu chun thit k b tng asphalt theo Hveem ABEFG n nh Hveem3735353535 dnh bm Hveem10010010050100 rng d, %24,524,524,524,524,5 . 6.2.3.CNG CHU NN, TNH N NH NC V N NH NHIT CA B TNG ASPHALT (CC CH TIU C HC T CC TNH CHT NY PHCVCHOPHNGPHPTHITKCALINBANGNGA,22TCN 24998) Tnh cht cng chu nn, tnh n nh nc v tnh n nh nhit ca b tng asphalt c nh gi thng qua cc ch tiu: Cng chu nn gii hn; H s n nh nc; H s n nh nhit. Theo tiu chun 22TCN 6284 Quy trnh th nghim b tng nha, th nghim cthchintrnmuhnhtrtrncngknhDbngchiucaoH(viD= 50.5mm, 71.5mm hoc 101.6mm tu theo c ht ln nht ca b tng nha) c ch b bng phng php p tnh hoc khoan v t hin trng. Mtlcnnctc30.5mm/phttcdngdctrcmuchotikhimub ph hoi (Hnh 6.3.), ln ca lc ph hoi mu c s dng tnh cng chu nn gii hn. Hnh 6.3.M hnh th nghim cng chu nn gii hn Th nghim c thc hin 3 trng thi:PTm gia tiPTm gia tiMu th nghim Mu kh (khng ngm nc) nhit 20oC, k hiu l Rnk20 Mu bo ho (ngm nc) nhit 200C, k hiu l Rnbh20 Mu kh nhit 500C, k hiu l Rnk50. Cngchunngiihncabtngasphalt(Rn)ctnhtheocngthc (6.3): FPRn = (daN/cm2)(6.3) Trong :P: Ti trng ph hoi mu (daN). F: Din tch mt ct ngang mu (cm2). Cn c vo cng chu nn gii hn ba trng thi khc nhau nh gi n nh nc v n nh nhit ca b tng asphalt thng qua h s n nh nc v h s n nh nhit, v c xc nh theo cc cng thc sau: H s n nh nc c tnh theo cng thc: Kn = Rnbh20/ Rnk20 H s n nh nhit c tnh theo cng thc: Kt = Rnk50/ Rnk20 Theo 22 TCN 24998, hn hp b tng atphalt cht khi thit k phi tho mn cc yucuvctnhthtch(rngd)vcctnhchtchctheoquynh (Bng 6.3). Bng 6.3. Yu cu v cc ch tiu c l ca b tng asphalt cht Yu cu i vi b tng nha loi TT Cc ch tiu III 1 rng ct liu khong, % th tch15191521 2 rng cn d, % th tch3636 3 ngm nc, % th tch1,53,51,54,5 4 n, % th tch, khng ln hn0,51,0 5 Cng chu nn, daN/cm2, nhit +) 20oC khng nh hn3525 +)50oC khng nh hn1412 6H s n nh nc, khng nh hn0,900,85 7 H s n nh nc, khi cho ngm nc trong 15 ngy m; khng nh hn 0,850,75 8 n, % th tch, khi cho ngm nc trong 15 ngy m, khng ln hn 1,51,8 6.2.4. CNGCHUKOGINTIP(PCH),CNGCHUCT (CCCHTIUCHCTCCTNHCHTNYPHCVCHO PHNG PHP THIT K SUPER PAVE) Theo phng php Super Pave (M), cc ch tiu c hc phc v cho thit k hn hp b tng asphalt bao gm cc ch tiu cng (kh nng lm vic) ca hn hp b tng asphalt v d bo kh nng lm vic thc t ca mt ng b tng asphalt trn c s k t qu ca cc ch tiu s hc sau: Kogintip(IDT)xcnhmunnhivhspotxng(22TCN 27401, ASTM D4123, AASHTO TP31); Ct (SST), c s dng xc nh c tnh bin dng vnh cu (vt hn ln bng xe) v nt do mi. 6.2.4.1. Th nghim ko gin tipBao gm cc th nghim sau: Cng t bin, nt do nhit; Cng , nt mi. Trong th nghim ny p lc nn c t vo mu hnh tr theo mt phng ca ng knh do vy gin tip gy ra ng sut ko theo phng ngang (Hnh 6.4; 6.5).Th nghim c thc hin nhit 5oC, 30oC (hoc 25oC) v 40oC vi cc tn stcdngtitrngbng0.33Hz,0.5Hzv1.0Hz.lncatitrngtrngphc clachnsaochogitrtvokhongt1050%gitrtitrngphhoi nhittngng(thngsdnglntitrngvigitrtrongkhong135N/mm tnh theo chiu di ca mu). Hnh 6.4.M hnh th nghim ko gin tip Hnh 6.5. Thit b th nghim ko gin tip Mu th nghim c ch to trn dng c mxoay, c th dng cc mu hnh tr ch to theo Marshall hoc cc mu khoan trc tip t mt ng. Cho ti trng tc dng lp mt s ln cho n khi thy biu cc bin dng ca cc ln ti trng tc dng lp u nh nhau. y l giai on s b lm mu tip xc tt vi tm truyn ti trng, c cc bin dng n nh. Tip tc cho ti trng trng phc tc dng, khong t 50 n 200 ln, cho n khi bin dng n hi ca nhng ln tc dng k nhau u n nh. Sau khi cc bin dng n hi n nh di tc dng ca ti trng trng phc k nhau th o v ghi li cc bin dng n hi ngang v ng tng ng vi t nht 3 chu k tc dng ti trng k nhau v ly tr s trung bnh. Tnh ton m un n hi E v h s poisson ca mu b tng asphalt tng ng vi nhit , thi gian tc dng, tn s tc dng lc theo cc cng thc sau: ( ) 0.27 H t.PERIiRI+ = (6.4) ( ) 0.27H t.PERTTRT+ = (6.5) 0.27VH 3.59IIRI=u (6.6) 0.27VH 3.59TTRT=u (6.7) Trong :ERI : M un n hi tc thi, MPa. ERT : M un n hi tng hp, MPa. uRI :H s poisson tc thi. uRT : H s poisson ton b. P : Ti trng tc dng trng phc, N. t : Chiu cao mu, mm. HI : Bin dng ngang n hi tc thi ca mu, mm. HT : Bin dng ngang ton b ca mu, mm. VI : Bin dng ng n hi tc thi ca mu, mm. VT : Bin dng ng ton b ca mu, mm. Cc quy nh vi cc loi th nghim: cng t bin, nt do nhit v cng , nt mi nh sau: a). Th nghim cng t bin, nt do nhit Nhit th nghim cho th nghimcng t bin nhgi kh nng chu nt do nhit ca hn hp b tng asphalt nhit 0oC hoc thp hn. Ba nhit in hnh c s dng tnh ton l: 0, 10 v 20oC, trong t nht phi s dng 2 nhit th nghim. Gi tr nhit in hnh c s dng l 5 oC v 15oC. Sau khi duy tr nhit th nghim khng i trong cc mu th nghim thi gian, cn bng li ton b h thng o v tc dng mt lc tnh c cng nh trc nhng khng tc ng ln mu. Ti trng nh trc c s dng cho th nghim t bin phi to ra chuyn vnganggia50v200microstrains(um)trong60giyutin.Nugii hntriviquinh,cnphidngngaythnghimvhiuchnhti trng.Theo di tt c cc bin dng ngang v bin dng thng ng trn cc hng camutrongthigiantcdngti.Titrngsctcdngvichuk 1000 giy. Saukhititrngnhtrcctcdngquachuk1000giy,phitc dng thm ti trng ln mu vi tc gia ti ca pttng 12.5mm/pht. Tt cccchuynngngang,thngngvtitrngphictheodicho n khi ti trng bt u gim (gim 10% so vi gi tr ln nht). b). Th nghim cng , nt mi Nhitthnghimsdngchothnghimphntchntmikhngvt qu 20oC. Saukhiduytrnhitkhngitrongccmuthnghimtrongkhong thi gian hp l, cn bng li ton b h thng o. Tcdngmtlclnmumc50mmchuynngthngng/phtca pttngTtcccchuynngngang,thngngvtitrngphic theodichonkhititrngbtugim.Thnghimscdngli cngnhanhcngttkhititrngbtugimngnkhngchohhng thit b LVTD do s ph hoi bt ng ca mu. 6.2.4.2. Th nghim ctBao gm cc th nghim sau (Hnh 6.6): Th nghim ct ti trng trng phc vi t l ng sut khng i. Th nghim ct ti trng trng phc chiu cao khng i. Th nghim ct n gin chiu cao khng i. MucngknhD=152mm,chiucaoH=50mm,cchbtrongphng bng phng php m xoay hoc khoan v t hin trng.Mu th nghim c dnh lin 2 u vi 2 tmcao su trn b mt 2 tm gia ti bng cht kt dnh (thng dng epoxy). Vinhngthnghimcthchinnhitnhhn40oC,trckhith nghim, mu c t vo trong t sy nhit th nghim trong khong thi gian 2 gi. Vi nhng th nghim c thc hin nhit ln hn hoc bng 40oC, trc khi th nghim, mu c t vo trong t sy nhit th nghim trong khong thi gian t nht l 2 gi nhng khng vt qu 4 gi. Mu th nghimLc tc dng(duy tr mu chiu cao c nh)Tm gia tiTm gia tiPhn lcBin dng ct tch luLc tc dngp lc hngMt bnMt ngMu th nghimCc tm cao su Hnh 6.6. M hnh th nghim ct ca SuperPave Trong qu trnh th nghim, mu th nghim c t trong bung nhit ca thit b th nghim, bung nhit ny c kh nng to ra v duy tr nhit quy nh trong sut qu trnh th nghim. a). Th nghim ct chiu cao khng i Tc dng ln mu mt ng sut ct c ln 7kPa vi s chu k l 100. Sau tngngsutcttcdnglnmuvitcl70kPa/giyvgitrongkhongthi gian 10giy. Sau 10 giy,gim ng sut ct xung cn 0 vi tc 21kPa/giy. Tip tc ghi s liu thm 30 giy na sau khi ti trng v 0. Th nghim c thc hin cc nhit 4oC, 20oC v 40oC.Kt qu th nghim thu c l ng sut dc trc, ng sut ct v bin dng ct. b). Th nghim ct ti trng lp vi t l ng sut khng i Tcdnglnmungthimtngsutdctrcvngsutctcdngna hnh sin c ln sao cho t l gia ng sut dc trc v ng sut ct l khng i v bng t 1,2 n 1,5 ln.Nhit chn th nghim l nhit trung bnh ca 7 ngy trong nm o su mt ng l 50,8 mm. Tcdnglnmungthimtngsutdctrcvngsutctcdngna hnh sin vi s chu k l 100, thi gian tc dng 0.1 giy, ngh 0.6 giy vi ng sut tc dng dc trc khng vt qu 7kPa. Tip theo, cho ti trng tc dng vi s chu k l 5000 chu k.Kt qu th nghim thu c l ng sut dc trc, ng sut ct v bin dng ct. c). Th nghim ct ti trng lp vi chiu cao khng i Tcdnglnmumtngsutctcdngnahnhsinvischukl100, thi gian tc dng 0.1 giy, ngh 0.6 giy vi ng sut tc dng dc trc khng vt qu 7kPa.Tiptheo,tcdnglnmumtngsutctcdngnahnhsincln 70kPavischukl5000,thigiantcdng0.1giy,ngh0.6giy.Nhitth nghim l nhit trung bnh ca 7 ngy trong nm o su50, 8mm. Kt qu th nghim thu c l ng sut dc trc, ng sut ct v bin dng ct. 6.2.5. CC CH TIU C HC PHC V THIT K KT CU 6.2.5.1. M un n hi (22TCN2112006) M un n hi ca b tng asphalt c xc nh bng th nghim trn mu hnh tr trn c chiu cao bng mt na hoc bng ng knh (thng s dng mu c kch thc D = H = 10cm) theo m hnh nn dc trc n hng t do,gia ti bng ti trng tnh v bo dng mu cc iu kin khc nhau tu theo yu cu th nghim, c th: 300C khi tnh cng theo tiu chun ln n hi. 100C (vi lp b tng asphalt c chiu dy di 6cm), 150C (vi lp b tng asphaltcchiudyt712cm)khidngtnhtoncngtheotiuchunchu ko un. 600C khi dng tnh theo iu kin trt. Mucnnvichgiatimtlnviplcp=5daN/cm2vcgi nguyn cho ti khi bin dng n nh (khi tc bin dng ch cn 0.01mm/pht). Sau d ti v i bin dng hi phc cng t c n nh nh trn th c ng h o bin dng xc nh tr s bin dng n hi. M un n hi (Eh) c xc nh theo cng thc (6.8): l D4pHE2dh= (daN/cm2)(6.8) Trong :p : p lc nn mu (daN/cm2). H: Chiu cao mu (cm). D: ng knh mu (cm). L: Bin dng n hi (cm). 6.2.5.2. Lc dnh n v v gc ni ma st (22TCN 2112006) Th nghim c thc hin trn mu hnh tr trn ng knh 30 cm ch b bng cch gia lc tnh hoc t mu khoan mt ng (Hnh 6.7). Th nghim c thc hin nhit 10150C trn my ct phng vi tc ct 0.1cm/pht trn t nht l 3 mu ging nhau tng ng vi nhng p lc thng ng (p) khc nhau (ti trng ln nht khng vt qu ng sut c th xy ra trong kt cu mt ng).ng vi mi gi tr p lc p ta s thu c mt gi tr cng chng ct (), t ta xc nh c tr s lc dnh n v (c) v gc ni ma st () theo phng trnh sau: = c + p.tg (daN/cm2)(6.9) Trong :: Sc chng ct gii hn (daN/cm2). p: p lc thng ng khi th nghim ct phng (daN/cm2). Hnh 6.7.Mhnh th nghim ct tnh xc nh c, 6.2.5.3. Cng ko un gii hn (22TCN 21106) Th nghim c thc hin trn mu dm c kch c khng nh hn 4x4x16 (cm), chbtrongphngbngcchgiatitrngtnhcln300daN/cm2hocctmu dm t mt ng (Hnh 6.8). p Trckhithnghim,mucbodngtrongbnnhnhitnhit 15oC trong khong thi gian 2 gi. Thnghimuncthchinbngcchtmulnhaigitacchnhau 14cm (mt gi c nh, mt gi di ng), phn gi tip xc vi mu c dng mt tr vi bn knh 5mm. Cht ti gia mu trn khp b ngang mu thng qua tm m bng kim loi dng mt tr trn bn knh 10mm hoc c dng mt phng dy 8mm.Hnh 6.8.M hnh th nghim cng ko un Gia ti vi tc nn m bo to ra vng cho mu l 100200mm/pht cho tikhimubphhoi.Trongqutrnhgiati,theodivngcadmbngcc ng h o bin dng t y gia dm v c hai gi ( loi tr bin dng cc b ca dm ti gi). ln ca ti trng ti thi im mu b ph hoi c s dng tnh cng ko un gii hn (Rku) theo cng thc (6.10): 2ku2bh3PlR =(daN/cm2)(6.10) Trong :P: Ti trng ph hoi mu (daN). L: Khong cch gia hai gi ta (cm). b, h : Chiu rng v chiu cao mu (cm). 6.2.5.4.Cngpch(22TCN21193,ASTMD4123,TiuchunTrungQuc, Tiu chun Lin Bang Nga) Th nghim ny phc v cho tnh ton cng chu ko un gii hn ca b tng asphalt theo cng thc Rku = KRech (vi K l h s tng quan thc nghim) phc v thit k kt cu mt ng theo 22TCN 21106. Hin nay, quy trnh tnhton thit k ktcu mt ng mmca TrungQucJTJ01497,caLinBangNga218.046.01cngsdngcngpchthay cho cng ko un gii hn. Theo tiu chun 22TCN 21106, th nghim c thc hin nhit 10oC hoc 15oC; theo tiu chunASTM D4123, th nghim c thc hin nhit tng ng Phb vi nhit th nghim ko gin tip ti trng trng phc xc nh m un n hi v h s poisson (5oC, 25oC, 30oC hoc 40oC). MhnhthnghimcnuHnh6.9vHnh6.10.Lcnntheophng ng sinhgyra trnmu vi tc 50.8mm/pht cho n khi mu b ph hoi. lncalctithiimmubphhoi(P)csdngtnhtoncngp ch theo cng thc (6.11): dh2PRech=(daN/cm2)(6.11) Trong :P:Lc ph hoi mu (daN). d, h: ng knh v chiu cao mu (cm). Hnh 6.9. M hnh th nghim p ch Hnh 6.10. Th nghim xc nh cng p ch Tm gia tiTm gia tiMu th nghimPP6.2.6. BIN DNG VNH CU VT HN LN BNH XE Ccthnghimmphngcsdngthnghimccctrngbindng vnh cu (vt hn bnh xe), nt mi v nt do nhit thp ca vt liu b tng asphalt.CcthitbthnghimmphngthngckiumphngvtbnhxeLWT (Loadedwheeltester),vhinnaytrnthgiicnhiuloithitbthnghimm phng, cc loi thit b ny c phn thnh 2 nhm: Th nghim trong phng; Th nghim ti hin trng.Trong , cc th nghim m phng ngoi hin trng tng i phc tp, i hi phi xy dng nhng on ng th nghim tn km, thi gian th nghim lu hn so viccthnghimmphngtrongphng.Dovytrongthcthinnaythngs dng cc th nghim m phng trong phng. Trn th gii hin nay thng s dng cc loi thit b th nghim m phng trong phng ch yu sau: Thit b Asphalt Pavement Analyzer (APA); Thit b Hamburg Wheel Tracking Device (HWTD); Thit b French Rutting Tester (FRT). u, nhc im ch yu ca 3 loi thit b k trn c th hin Bng 6.4.Nhnchung,nguynllmvicvthnghimxcnhvthnlnbnhxe ca 3 thit b nu trn l tng ng. Thit b APA c p dng ph bin hin nay M. Sau y nu chi tit v thit b v phng php th nghim ca APA. 6.2.6.1. Gii thiu v thit b APA APA l thit b c thit k th nghim ccc trng vt hn ln, c trng mi ca b tng asphalt. C ch hot ng ca thit b l m phng hot ng ca bnh xe t tc ng ln mt ng thng qua cc bnh xe chuyn ng c chu k trn ng cao su p lc tc ng ln b mt ca tp mu b tng asphalt Bng 6.4. So snh u, nhc im ch yu ca thit b APA, HWTD v FRT TTThit b APAThit b HWTDThit b FRT 1c s dng rng rit c s dng, ch yu c Rt t c s dng, ch yu Php 2Thi gian th nghim ngnThi gian th nghim di Thi gian th nghim ngn 3C th th nghim ng thi t 3 n 6 mu C th th nghim ng thi 2 mu C th th nghim ng thi 2 mu 4C th thc hin c 3 th nghim sau: a. Th nghim vt hn ln C th thc hin c 2 th nghim sau: a. Th nghim vt hn Ch thc hin c 1th nghim sau: a. Th nghim vt hn bnh xe b. Th nghim nh gi h hng ca b tng nha di tc dng ca mc. Th nghim mi ln bnh xe b. Th nghim nh gi h hng ca b tng nha di tc dng ca m ln bnh xe Cc thng s c bn ca thit b APA: Kch thc: Di x Rng x Cao = 1800 x 1000 x 2000 mm Khi lng: 1500 kg in nng: 220V, 60Hz, 40A B cha nc n nhit: 132 lt Tnh nng k thut ca thit b APA: Nhit ca bung cha mu v b cha nc t 472oC, c bc iu khin l 1oC. C kh nng gia ti c lp trn 3 bnh xe vi ti trng quy nh. p lc trong ng cao su c th iu chnh v duy tr c mc quy nh. C kh nng th nghim ng thi trn ba mu dm hoc 6 mu hnh tr. Cthitbmchuk,tngdngthnghimkhitnschukth nghim yu cu. 6.2.6.2. Th nghim vt hn bnh xe (AASHTO TP63) Th nghim c thc hin iu kin: Ti trng tc dng ca bnh xe th nghim l 578N; p lc trong ng cao su l 896kPa. Nhit th nghim ly tng ng vi cp nha s dng (theo tiu chun phn loi nha ca Superpave). Th nghim c thc hin trn 6 mu hnh tr c ng knh D =150mm, chiu cao H= 752mm hocmu c ng knh D =150mm, chiu cao H =1152mm hoc trn3muhnhdmcchiurngB=125mm,chiucaoH=752mm,chiudiL = 300mm. Nu l mu hnh tr khoan v t hin trng,yu cu chiu cao ti thiuH = 50mm ( Hnh 6.11, Hnh 6.12, Hnh 6.13). i vi mu hnh tr ch b trong phng, c th m nn bng thit b m xoay SGC(SuperpaveGyratoryCompactor)hocthitbmrung(VibratoryCompactor), mu ch b phi t rng d bng 4.00.5%. ivimuhnhdmchbtrongphng,mnnbngthitbmrung (Vibratory Compactor), mu ch b phi t rng d bng 5.00.5%.

Hnh 6.11. Nguyn l th nghim vt hn bnh xe trn thit b APA Trckhithnghim,mucttrongtnhitnhitthnghimtrong khong thi gian 6 gi. Sau t mu vo v tr th nghim, v cho thit b hot ng vi s chu k bnh xe tc dng ln mu l 8000. Sau khi kt thc qu trnh th nghim, thit b s t ng o xc nh chiu su vt hn bnh xe. Hnh 6.12. Bphn gia ti ca thit b APA

HLc tc dngMu th nghimng cao su p lc caonh 6.13. Mu sau khi th nghim vt hn bnh xe trn thit b APA 6.2.6.3. Th nghim nh gi bn ca b tng asphalt di tc ng ca m Trc khi th nghim, mu c chun b theo trnh t sau: Xc nh bo ho nc: t cc mu th nghim vo trong bnh ht chn khng sau nc ct vo ngp mu ti thiu l 25.4mm. Cho my ht chn khng hot ng cho n khi p sut dcnlitrongbnht1367kPa,gitrngthinytrongkhongthigian510 pht. Sau cho p sut trong bnh tr li trng thi bnh thng v tip tc ngm mu trong bnh trong khong thi gian t 510 pht na. Lymurakhibnhhtchnkhng,laukhbmtvcnxcnhkhi lng mu bo ho b mt sau tnh th tch nc hp ph vo mu theo cng thc:NHP = Gs Gt (cm3) Trong : Gs : l khi lng mu bo ho b mt sau khi ht chn khng (g). Gt : l khi lng mu bo ho b mt trc khi ht chn khng (g). Tnh bo ho nc theo cng thc:BHN = 100NHP/RD, (%) (6.12) Trong:RDltngthtchcclrngtrongmu,ctnhtheo rng d v th tch mu. + Mu t yu cu nu c bo ho nc nm trong phm vi t 5580% + Nu mu c bo ho nc 80% th phi b mu i v s dng mu khc. Dngmtmnhnilngmngbcknmu,sautmubcknnilng vo trong mt ti nilng khc c cha 10ml nc v buc cht u li. t ti nilng ngmunyvotbodngcnhitkhngkhl183oCtrongkhongthi gian t nht l 16 gi. Saulymurakhitbodngvtmuvotrongbbodngcha nc c nhit bng nhit th nghim trong khong thi gian 241 gi.Trnh t th nghim hon ton ging vi trnh t th nghim vt hn bnh xe, ch c mt s im khc bit sau y: Ti trng tc dng ca bnh xe th nghim l 450N; p lc trong ng cao su l 830kPa. Cc mu ch b trong phng phi c rng d bng 7.01.0%. Nhit nc th nghim c ly bng nhit tng ng vi cp nha thp hn cp nha PG ang s dng. Ktquthnghimlchiusuvthnlnsau8000chuktcdngcabnh xe. 6.2.6.4. Th nghim mi Thnghimcthchinvititrngbnhxetcdngl1113N.Trongth nghimny,ccbnhxetcdngtrctiplnmu(khngsdngccngcaosu) (Hnh 6.14, Hnh 6.15, Hnh 6.16).Th nghim c thc hin trn 3 mu hnh dm c chiu rng B=125mm, chiu cao H=752mm, chiu di L=300mm c ch b trong phng th nghim bng cch s dngthitbmrung(VibratoryCompactor);muthnghimcmnnt c rng d bng 71%. Sau khi ch b, mu c ho gi theo trnh t sau: tmuthnghimvotsynhit855oCtrongkhongthigian 1200.5 gi. Sau ly mu ra khi t sy, ngui mu n nhit phng th nghim. Sau khi mu c ho gi, tin hnh th nghim mi theo trnh t sau: tmuvotrongtbodngcnhitkhngkhl20oCtrongkhong thi gian 4 gi. Ly mu ra khi t bo dng v t vo v tr th nghim. Cho thit b hot ng vi ti trng bnh xe tc dng ln mu l 1113N vi s ln tc dng ca bnh xe l 50000 chu k; trong trng hp mu b ph hoi trc khi t 50000 chu k gia ti th phi ghi li s chu k tc dng gy ph hoi mu.Kt qu th nghim l s chu k tc dng ca bnh xe lm cho mu b ph hoi s csdngthitkktcumtnghoctnhtontuithmicabtng asphalt. Hnh 6.14.M hnh th nghimmi Mu th nghim1113 N Hnh 6.15. Bphn gia ti th nghimmi trn thit b APA Hnh 6.16.Mu sau khi th nghim mi trn thit b APA 6.3.Cctnhchtlinquannctnhthtchcahn hp b tng asphalt ri mt ng6.3.1. Tng quan Ccctnhvthtchcahnhpbtngasphaltrimtngnhrng d, rng ct liu khong, rng lp y bitum v hm lng bitum hu ch th hin kh nng phc v ca mt ng. Mc ch ca qu trnh m nn mu b tng asphalt trong phng th nghim nhm m phng cht ca hn hp b tng asphalt ngay sau khi ri hoc sau mt s nm phc v, v c th c xc nh bng cch so snh cc c tnhcamunguyndnglyvthintrngviccctnhcamuctrong phng. Cn thit phi th hin r cc nh ngha v qu trnh phn tch c trnh by ctharaccquytnhthhinshiubitvviclachnhnhpbtng asphaltkhithitk.Nhngthngtinycthcpdngchohnhpbtng asphalt c m nn trong phng hay c vi mu nguyn dng ly v t hin trng. 6.3.2. Cc nh ngha Hnh 6.17. Cc nh ngha v cc loi t trng Ct liu khong c cha cc l nh li ti v c kh nng thm nc cng nh thm bitum vi cc mc khc nhau. T l phn trm v thm nc/ thm ca bitum voctliulkhcnhauivitngloictliu.C3phngphpxcnht trng ca ct liu c quan tm l: t trng khi ASTM, t trng biu kin ASTM v t trng c hiu. S khc nhau gia cc t trng ny xut pht t nhng nh ngha khc nhau v th tch ct liu. Hnh 6.17. minh ho v t trng khi, t trng biu kin, t trng c hiu, rng d, hm lng bitum c hiu trong hn hp b tng asphalt.Cc nh ngha v cc loi t trng nh sau: T trng khi (Sb) l t l gia khi lng cn trong khng kh ca mt n v th tch ct liu c tnh thm nc (gm c cc l rng c tnh thm nc v cc l rng khng c tnh thm nc) mt nhit xc nh chia cho khi lng cn trong khng kh c cng mt ca mt th tch tng ng nc ct khng c bt kh mt nhit xc nh. Ttrngbiukin(Sa)ltlgiakhilngcntrongkhngkhcamt n v th tch ct liu khng c tnh thm nc mt nhit xc nh chia cho khi lngcntrongkhngkhccngmtcamtthtchtngngncct khng c bt kh mt nhit xc nh. T trng c hiu (Sc) l t l gia khi lng cn trong khng kh ca mt n vthtchct liuctnhthmnc(loitrcclrngctnhthm bitum)mt nhit xc nh chia cho khi lng cn trong khng kh c cng mt ca mt th tch tng ng vi nc ct khng c bt kh mt nhit xc nh. Cc nh ngha v rng ct liu, hm lng bitum c hiu, rng d v lngbitum lp ch rng (Hnh 6.18) nh sau: L rng c kh nng thm nc nhng khng c lp y bi nha(Phn ct liu ca t trng ct liu)L rng c kh nng thm nc (Phn ct liu ca t trng khi, khng ca t trng biu kin)L rng c kh nng thm nha (hp ph nha)Nha c hiuCt liu rng dVbaVfaVmaVbVmm VmbVscVsbCtliukhongNhaKhng khVbaVfaVmaVbVmm VmbVscVsbCtliukhongNhaKhng khVbaVfaVmaVbVmm VmbVscVsbCtliukhongNhaKhng kh . Hnh 6.18. Cc loi th tch trong mu b tng asphalt sau khi c m ln. Trong :Vma th tch ca cc l rng trong ct liu khong Vmb th tch khi ca hn hp c m ln Vmm th tch ca hn hp ri mt ng khng k cc khe rng Vfa th tch bitum lp l rng (c hiu) Va th tch cc khe rng Vb th tch bitum Vba th tch bitum thm nhp vo ct liu Vsb th tch ct liu khong (theo t trng khi) Vsc th tch ct liu khong (theo t trng c hiu) rng ct liu (VMA) l th tch cc khe rng ti gia cc ht ct liu trong hn hp, n bao gm rng d v hm lng bitum c hiu. c xc nh theo % ca tng th tch mu. Hm lng bitum c hiu (Pbc) l tng hm lng bitum c trong hn hp tr i phn bitum b mt i do thm vo ct liu. rngd(Va)ltngthtchcacctikhnhnmgiaccctliu cbaobcbitumctronghnhpsaukhiluln.Xcnhtheo%th tch ca hn hp. Hm lng bitum lp y l rng (VFa) l phn th tch ca cc khe rng gia cc ct liu c chim ch bi bitum. Vin Asphalt khuyn rng tr s VMA nn tnh theo t trng khi ca ct liu v t trng c hiu s l c s tnh rng d trong hn hp. rng ct liu v rng d c tnh theo % ca hn hp. Hm lng bitum lp l rng l phn trm ca rng ct liu c lp y bi bitum c hiu. Tu theo hmlngbitumlbaonhiumncthctnhlphntrmcakhilng bitum so vi tng khi lng ca hn hp hay l phn trm ca khi lng bitum so vi tng khi lng ca ct liu c trong hn hp. V rng d v rng ct liu th hin theo th tch, chng khng th xc nh cbngcchcn,dohnhpbtngasphaltphicthitkhocphntch da trn c s th tch.6.3.3. PHN TCH HN HP B TNG ASPHALT SAU KHI M NN Nhngcng vic th nghim v nhng tnh ton cn thit cho phn tch hn hp b tng asphalt nh sau: 6.3.3.1. Cc ch tiu xc nh qua th nghim 1.Xc nh t trng ca ct liu th (AASHTO T85 hoc ASTM C127) v ca ct liu mn (AASHTO T84 hoc ASTM C128). 2.Xcnhttrngcabitum(AASHTOT228hocASTMD70)vcabt khong (AASHTO T100 hoc ASTM D854). 3.Tnh ton t trng biu kin ca ct liu trong hn hp. 4.Xc nh t trng khi ca hn hp trng thi ri. 5.Xcnhttrngkhicahnhpkhicluln(theoASTMhoc ASTM D2726). 6.3.3.2. Cc ch tiu xc nh qua tnh ton 1.Tnh ton t trng c hiu ca hn hp ct liu vi cc hm lng bitum. 2.Tnh ton t trng ln nht ca hn hp cc hm lng bitum khc nhau. 3.Tnh ton kh nng hp ph bitum ca ct liu. 4.Tnh ton hm lng bitum c hiu trong hn hp. 5.Tnh ton rng trong vt liu khong. 6. Tnh ton % rng d trong hn hp sau khi lu ln. 7. Tnh ton rng lp y bitum. 6.3.4. CCH XC NH CC CH TIU 6.3.4.1.T trng (biu kin) ca ct liu AASHTO T85 Ctliutnghpbaogmccloictliuth,ctliunhvbtkhong. Chng c cc t trng khc nhau v t trng biu kin ca ct liu tng hp c tnh theo cng thc sau: nn2211n 2 1sbGP...GPGPP ... P PG+ + ++ + += (6.13) Trong : Gsb t trng ca ct liu tng hp; P1, P2, P3,..., Pn phn trm ca cc loi ct liu, tnh theo khi lng; G1,G2,G3,...,Gnttrngcaccloictliuctrongctliutng hp.6.3.4.2. T trng c hiu ca ct liu Datrnttrnglnnhtcabtngasphalt,GmncxcnhtheoASTM D2041, t trng c hiu ca ct liu, Gse bao gm tt c cc khe h gia cc ht ct liu tr nhng khe h thm bitum, Gse c xc nh theo cng thc sau: bbmnmnb mnseGPGPP PG+=( 6.14) Trong : Gse t trng c hiu ca ct liu Gmn t trng ln nht ca hn hp (khng c rng cn d) Pmn phn trm theo khi lng ca hn hp trng thi ri=100 Pb hm lng bitum theo ASTM D2041 tnh bng % theo tng khi lng ca hn hp. Gb t trng ca bitum Ch : Lng bitum hp ph vo ct liu lun nh hn lng nc hp ph vo ct liu. Do tr s ca t trng c hiu ca mt loi ct liu lun nm gia t trng khi v t trng biu din.6.4.4.3. Ttrnglnnhtcahnhpbtngasphaltngvicchmlngbitum khc nhau. Trong thit k hn hp b tng asphalt vi cc ct liu bit trc th vic xc nh t trng ln nht, Gmm, ng vi cc hm lng bitum khc nhau l cn thit xc nh rng d tng ng vi tng hm lng bitum . T trng ln nht ng vi mi hm lngbitum khc nhau c xc nh theo ASTM D2041. Sau khi tnh ton t trng c hiu ca ct liu t t trng ln nht v tr s trung bnh ca Gse, t trng ln nht ng vi mi hm lng bitum c th tnh ton c theo cng thc sau: bbsesmnmnGPGPPG+= (6.15 ) Trong : Gmn t trng ln nht ca hn hp ri mt ng (khng c rng cn d) Pmn phn trm theo khi lng ca hn hp vt liu khong Ps hm lng ct liu, % theo trng lng hn hp . Pb hm lng bitum, % theo trng lng hn hp Gse t trng c hiu ca ct liu Gb t trng ca bitum 6.4.4.4. Lngbitum hp ph Lng bitum hp ph thng c xc nh theo % trng lng ca ct liu hn ltheotngtrnglngcahnhp.LngbitumhpphPbacxcnhtheo cng thc sau: sbse sbsb seba.G.G GG G100 P= (6.16) Trong : Pba lng bitum hp ph Gse t trng c hiu ca ct liu Gsbt trng khi lng ca ct liu Gb t trng ca bitum 6.4.4.5. Hm lng bitum c hiu trong hn hp b tng asphalt Hmlngbitumchiucahnhpbtngasphaltltnghmlngbitum trilngbitummtidohpphvoctliu.Nlmtphncahmlng bitum to nn lp ph bn ngoi ca cc ht ct liu v n l lng bitum chi phi cc c tnh c l ca hn hp b tng asphalt v theo cng thc sau: sbab beP100PP P = (6.17) Trong : Pbe hm lng bitum c hiu xc nh theo % trng lng hn hp Pb hm lng bitum xc nh theo % trng lng hn hp Pba lng bitum hp ph xc nh theo % trng lng ct liu Ps hm lng ct liu xc nh theo % trng lng hn hp 6.4.4.6. rng ct liu trong hn hp, % rngctliuVMAcxcnhlrnggiacchtctliutronghn hp bao gm rng d v hm lng bitum c hiu, c xc nh theo % ca tng th tch VMA v c tnh ton trn c s t trng khi ca ct liu v c xc nh theo % th tch ca khi hn hp. Do VMA c th c tnh ton bng cch ly th tch khi ca hn hp tr i th tch khi ca ct liu. Phng php tnh ton nh sau: a. Nu xc nh theo % khi lng ca hn hp. sbs mbGP G100 VMA = (6.18) Trong : VMA rng ct liu khong % ca th tch khi Gsb t trng biu kin ca ct liu hn hp Gmb t trng khi ca hn hp b tng asphalt Ps hm lng ct liu % ca tng trng lng hn hp b. Nu xc nh l theo % khi lng ca ct liu. 100P 100100GG100 VMAb sbmb = (6.19) Trong : Pb hm lng bitum tnh theo % trng lng ca ct liu 6.4.4.7. rng d trong hn hp, % rng d trong hn hp b tng asphalt c tnh theo cng thc sau: 100GG1 Vmnmba = (6.20) Trong : Gmm t trng ln nht ca hn hp Gmb t trng khi ca hn hp 6.4.4.8. rng lp y bitum, % rnglpybitumVFAl%carngctliubbitumchimch, khng bao gm lng bitum b hp ph, c xc nh theo cng thc sau: VMAV VMA100 VFAa =(6.21) Trong : VMA rng ca ct liu Va rng d CU HI N TP 1.Trnh by khi qut chung v cc tnh cht ca b tng asphalt. 2.Cc tnh cht c hc ch yu ca b tng asphalt. 3.Trnh by cc tnh cht lin quan n c tnh th tch ca b tng asphalt. Chng 7 THIT K HN HP B TNG ASPHALT THEO MARSHALL 7.1. MCCHCHUNGCACNGTCTHITKHNHPBTNG ASPHALT Thit k hn hp b tng asphalt l la chn c cp phi ct liu hp l v hm lng bitum ti u v mt kinh t m vn tho mn ccyu cu k thut. Hn hp b tng asphalt la chn nhm tho mn cc tnh nng sau: hm lng bitum nhm m bo cho mt ng b tng asphalt lm vic lu di. cng nhm tho mn cc yu cu giao thng m khng b bin dng. rng d ca hn hp sau khi lu ln v cho php mt ng c m nn thm nh ti trng ca cc phng tin giao thng chy trn ng, nh sginncabitumdonhitgiatngnhngmtngkhngbchy bitum hay mt mt bn. rng d ln nht c gii hn nhm hn ch kh nng thm ca khng kh c hi v m vo trong hn hp. cng tc vic ri hn hp c hiu qu m khng lm phn tng vt liu cng nh khng lm gim bn v kh nng lm vic ca kt cu. ivihnhpasphaltlmlpphtrncngthctliuphic nhm v cng to ra kh nng khng trt hp l trong nhng iu kin thi tit bt li. Cthtmlilthitkbtngasphaltlqutrnhthnghimlachnra hmlngbitumtiutronghnhpbtngasphaltnhmthomn2yut:tnh cht lin quan n c tnh th tch v tnh cht c hc theo quy nh ca phng php thit k. Cc phng php thit k b tng asphalt c s dng kh ph bin trn th gii nh: phng php ca Nga, Marshall, Hveem, Superpave nhn chung u tun th nguyntcthitktrn.Nhnchungccnguynlxcnhctnhthtchcacc phng php l ging nhau, khc nhau chyu l tiu ch v cc ch tiu c hc c th hin qua cc phng php th nghim (tham kho chng 6). 7.2. PHM VI P DNG CA PHNG PHP MARSHALL Cc khi nim v phng php thit k hn hp b tng asphalt theo phng php Marshall c Bruce Marshall a ra. Qua qu trnh nghin cu v pht trin, phng php ny ngy cng hon thin v n c chun ho bi ASTM v c hng dn bi Vin asphalt Hoa K. PhngphpMarshallnguynbnchcpdngivihnhpbtngasphaltnngvicpphictliucngknhlnnht(theosngvung)25mm (ng knh ln nht danh nh 19mm). Phng php Marshall sau khi ci tin c pdngchochnhpvicpphictliucngknhlnnhtn38mm. Phng php Marshall ci tin s dng khun ci v chy m ln hn so vi Marshallnguyn bn. Phng php Marshall c dng cho thit k trong phng cng nh kim sot ti hintrngcahnhpbtngasphaltc(cht)trnnngcpphilintc.Hm lng bitum c la chn thng tng ng vi rng d nm trong khong t 35%.rngd4%ltrsthngcsdngtrongnhgibanu.Tuynhin cng c th thay i cht t khi phn tch cc kt qu th nghim. Phng php Marshall u tin c p dng kh ph bin M, v cc nc ang pht trin cng nh Vit Nam hin naydo c nhngu im ni bt nh : gi thnh trang thit b th nghim khng ln, trnh ca cc nhn vin ti nghim khng ihicao,kinhnghimvthitkhnhpctchlu,cctiliuhngdnv thit k hn hp (ca Vin Asphalt M, AASHTO, ASTM) chi tit v c cp nht.7.3. CC CH TIU K THUT QUY NH THEO MARSHALL Theo hng dn thit k hn hp b tng asphalt theo phng php Marshall ca Vin Asphalt, mu thit k (v chn c hm lng bitum ti u) phitho mn cc yu cu v c tnh th tch v ch tiu c hc ( n nh, do) tng ng vi lng giao thng theo quy nh Bng 7.1. Bng7.1.YucukthutvibtngnhathitktheoMarshall(Vin Asphalt) Giao thng nhGiao thng vaGiao thng nng Lp mt & Mng trn Lp mt & Mng trn Lp mt & Mng trn Cc ch tiu k thut yu cu ca hn hp b tngasphalt theo MarshallMinMaxMinMaxMinMax S ln m nn 35 x 250 x 275 x 2 n nh (Stability), KN 3,45,58,0 Giao thng nhGiao thng vaGiao thng nng Lp mt & Mng trn Lp mt & Mng trn Lp mt & Mng trn Cc ch tiu k thut yu cu ca hn hp b tngasphalt theo MarshallMinMaxMinMaxMinMax do, mm3,27,23,26,424 rng d, %353535 rng lp y nha,% 808065786575 rng ct liu nh nht, % Theo Bng 8.2. Bng 7.2. rng ct liu nh nht C ht danh nh ln nht rng ct liu nh nht, % rng d thit k,% mmin.3.04.05.0 (1)(2)(3)(4)(5) 1.18No.1621.522.523.5 (1)(2)(3)(4)(5) 2.36No.819.020.021.0 4.75No.416.017.018.0 9.53/814.015.016.0 12.51/ 213.014.015.0 19.03/ 412.013.014.0 25.01.011.012.013.0 37.51.510.011.012.0 502.09.510.511.5 632.59.010.011.0 Phng php Marshall nguyn bn s dng cc mu th nghim hnh tr trn tiu chuncchiucao64mm,vngknh102mm.Ccmunycchunbtheo ngccthtctiuchunvlmmng,nhotrn,vmnnhnhpctliubitum.HaintctrngchnhcaphngphpthitkhnhptheoMarshallcc phn tch v cht rng v th nghim n nh do trn cc mu th nghim sau khi c m cht. Mt s Tiu chun thit k theo Marshall ca cc nc, v ca Vit Nam c sa iquynhcaBng7.1.theohnglcbbt(vdbrnglpynha) hoc thm (v d ch tiu n nh cn li) ch tiu, hoc thay i thng s quy nh tngngvichtiu(vdtnggitrnnh,thunhhocgimgitr do).Vicmmuvischy75x2tngngvimtngclnggiaothng nng c p dng ph bin hin nay. 7.4.TM TT TRNH T THIT K HN HP THEO MARSHALL Vic thit k theo phng php Marshall c tin hnh theo cc bc sau: 1.Kim tra cht lng cc vt liu thnh phn: tt c cc vt liu (ct liu ln, ct liu nh, bt , bitum) s dng ch to b tng asphalt u phi tho mn cc ch tiu c l theo quy nh ca cc Tiu chun p dng hoc ca ch dn k thut ca d n (Chng 2).2.Phi trn cc ct liu thnh phn a ra t nht mt hn hp ct liu (ct liu ln, ct liu nh, bt ) c cp phi nm trong gii hn ca ng bao cp phi hn hp ct liu quy nh theo quy nh ca cc Tiu chun p dng hoc ca ch dn k thut ca d n (Chng 4).3.Xcnhctnhthtch(rngd,rnglpybitum,rngct liu) trn c s th nghim v tnh ton trn vt liu thnh phn, trn hn hp btngasphaltchamnn,mnnvicchmlngbitumkhc nhau (Chng 6). 4.Xc nh n nh, do ca mu b tng asphalt m nn vi cc hm lng bitum khc nhau (Chng 6).5.Phn tch cc kt qu th nghim quyt nh la chn hm lng bitum ti u tho mn tt c cc quy nh (Bng 7.1).7.4.1.TRNHTTHNGHIM,TNHTONCCTNHCHTVCTNH TH TCH 1.Xc nh t trng khi ca ct liu th (AASHTO T85 hoc ASTM C127) v ca ct liu mn (AASHTO T84 hoc ASTM C128). 2.Xcnhttrngcabitum(AASHTOT228hocASTMD70)vcabt khong (AASHTO T100 hoc ASTM D854). 3.Tnh ton t trng khi ca ct liu.4.Xc nh t trng ln nht ca hn hp b tng asphalt trng thi ri. 5.Xc nh t trng khi ca hn hp b tng asphalt m nn (theo ASTM D1188 hoc ASTM D2726). 6.Tnh ton t trng c hiu ca ca ct liu. 7.Tnhtonttrnglnnhtcahnhpbtngasphaltcchmlng bitum khc nhau. 8.Tnh ton kh nng hp ph bitum ca ct liu. 9.Tnh ton hm lng bitum c hiu trong hn hp. 10.Tnh ton rng ct liu khong. 11.Tnh ton % rng d trong hn hp sau khi m nn. 12.Tnh ton rng lp y bitum. 7.4.2. TRNH T TH NGHIM XC NH N INH, DO MARSHALL Cnphichunb6(hoctnhtl5)tmuthnghim(mitmugm3 mu) ng vi cc hm lng bitum trnh lch nhau 0.5%, vi t nht hai t mu c hm lngbitumlnhnvhaitmuchmlngbitumnhhngitrhmlng bitum thit k mong i. V th, mi mt hn hp thit k theo Marshall cn phi chun b 18 mu (t nht 15 mu) th nghim. Tin hnh trn, gia nhit, m nn hn hp trong khun Marshall. Gia nhit cho munnhitthnghim601oCbngcchngmtrongbnncnnhittrong thi gian 401 pht. Lau sch mt trong ca khun nn. Vt mu ra khi bn nc n nhit v nhanh chng t vo khun nn, a khun nn vo v tr th nghim trn my nn, g ng h o do v iu chnh kim ng h v 0.Gia ti cho mu v quan st ng h o lc, o bin dng ca mu. Khi ng h o lc t gi tr ln nht (v bt u c xu th gim) th ghi li gi tr lc ng thi ghi li s c trn ng h o bin dng. Xc nh gi tr n nh, do Marshall ca mu (Chng 6). Thi gian th nghim t khi ly mu b tng asphalt ra khi bn n nhit n khi c gi tr lc ln nht khng c vt qu 45 giy. 7.4.3. XC NH HM LNG BITUM TI U Thngquaccbiuthitlpbiuthquanhgiahmlngbitumvi: rngd,rnglpybitum,nnh,do(tnhtrungbnhcho3mu).i chiuviquynh(Bng7.1)tmrakhonghmlngbitumthomntngch tiu.Sauxcnhmin(khong)hmlngbitumthomnttcccchtiuv la chn 1 gi tr hm lng bitum trong khong , l hm lng bitum ti u. Gi tr hm lng bitum ti u c th c ly l trung bnh cng ca cc gi tr hm lng bitum tho mn tng ch tiu. Minh ho v cch xc nh hm lng bi tum ti u qua Th d 1. Th d 1 Ktqutrungbnhcacctmu(3mu)btngasphaltmvi75x2chy, vi 5 hm lng bitum phc v thit k b tng asphalt c thng k Bng 7.3. Bng 7.3.Kt qu th nghimSTT Hm lng nha (% theo khi lng hn hp) Khi lng th tch (g/cm3) rng ct liu VMA (%) rng d VA (%) n nh Marshall (kN) do Marshall (mm) Ct 1Ct 2Ct 3Ct 4Ct 5Ct 6Ct 7 14.02.38015.26.58.12.8 24.52.39514.95.08.73.0 35.02.41014.84.09.03.5 45.52.40615.63.28.53.8 56.02.40016.12.87.54.4 CncccgitrtrongBng7.3,tinhnhvccbiuquanh(Hnh7.1)nh sau: Hm lng bi tum n nh Marshall(Ct 2 v Ct 6).Hm lng bi tum do ( Ct 2 v Ct 7).Hm lng bi tum rng d (Ct 2 v Ct 5). Hm lng bi tum rng ct liu (Ct 2 v Ct 2). Hm lng bi tum rng lp y bitum nh nht (Ct 1 v Ct 4). HmlngbitumTtrngkhicabtngasphalthockhilungth tch(Ct1vCt3).(Quanhnykhngphcvchothitkhnhpb tngasphalt,mnhmxcnhgitrTtrngkhicabtngasphalt tngngvihmlngbitumthitktnhrachtmnnhin trng).CncthHnh7.1,datrnccbiuquanhgiahmlngbitumv cc ch tiu k thut tng ng (Bng 7.1) xc nh hm lng bitum tho mn tng ch tiu(Hnh7.1),sauxcnhhmlngbitumtiuthomnttcccchtiu (Bng 7.4) (l khong hm lng bitum).Cnciukinthctdn,chn1gitrnmtrongkhong.lhm lng bitum ti u. Vi hm lng bi tum ti u xc nh, cn c biu quan h hm lng nhat trng khi hn hp (hoc khi lng th tch), xc nh t trng khi tng ng lm c s xc nh cht lu ln hin trng. Hnh 8.1.Biu quan h gia hm lng bitum v cc ch tiu k thut Bng 7.4. Tn ch tiu T trng khiKhi lng th tch rng ct liu VMA (%) rng d VA (%) n nh Marshall (kN) do Marshall (mm) Gi tr quy nhKhng quy nh1517 3.06.0 Min. 824 Phmvihmlng bitumthamntng ch tiu (% khi lng hn hp) 5.056.0 4.135.2 4.05.764.05.6 Phm vi hm lng bitum tha mn tt c cc ch tiu (% khi lng hn hp) Xcnhttrng khithitk tngngvi hmlngbitum ti u 5.055.2 7.5. KHUYNH HNG V QUAN H CA CC S LIU TH NGHIM nhy ca cc tnh nng k thut hn hp b tng bitum theo hm lngbitum trn cc biu c th theo cc khuynh hng sau: ng cong n nh Marshall v ng cong T trng khi tng dn theo hm lng bitum n gi tr ln nht v sau gim dn. ng cong do Marshall tng theo hm lng bitum. ng cong rng d gim khi hm lng bitum tng. ng cong rng ct liu gm n gi tr nh nht sau tng theo hm lngbitum ng cong rng lp y bng bitum tng khi hm lng bitum tng. 7.6.LA CHN THIT K CUI CNG Hn hp asphalt cui cng c la chn (vi hm lng bitum ti u) thng l hn hp kinh t nht tho mn tt c cc yu cu k thut. Tuy nhin, hn hp asphalt khng phi thit k tho mn ti u mt c tnh c bit no . Nhng hn hp c n nh Marshall cao mt cch khng bnh thng th cn c xem xt bi v mt ngsdngloihnhpnythngkmbnvntsmditcdngcalu lng xe ln. Tnh hung ny c bit nghim trng nhng ni m vt liu lp mng trn (base) v t nn (sugrade) bn di mt ng yu gy ra vng mt ng cao di tc dng ca cc phng tin giao thng. Hm lng bitum thit k c chn sao cho tho mn tt c cc c tnh ca hn hp. Vic la chn hm lng bitum thit k c th c hiu chnh trong phm vi hp ny m bo sao cho hn hp c cc c tnh ph hp vi cc yu cu k thut ca d n. Cc c tnh khc c yu cu k thut khc i vi tng trng hp khc nhau, ph thuc vo giao thng, kt cu, kh hu, thit b thi cng v cc nhn t khc. Do , qutrnhhiuchnhlkhnggingnhauiviccmtngvcchnhp.Sau y l mt s vn cn phi xem xt trc khi chnh thc ho hm lng nha thit kcui cng: nh hng ca ca rng ct liu. Nn trnhcc hm lng bitum nm phatngbnphicangcongVMAmnnchnimlncnpha triimthpnhtcangcongtrnhxuhngchybitumdotha lmgimcctipxcgiaccctliuvthmtrgyvtbnhxebdn ng. Tuy nhin nu la chn qu li v pha tri hn hp s qu kh c th sy ra hin tng phn tng v rng d qu cao.nhhngcarngd.rngdt36%lphmvithchhp c la chn theo kinh nghim nhiu nm. Phm vi rng d thng t c trong thit k l khong 4% v rng d ngoi cng trng sau khi thi cng xong khong 8%. Nu rng d cui cng nh hn 3% th mt ng c th b ln hoc b dn ng. Nu rng d cui cng ln hn 5% trong phng th nghim v ln hn 8% ngoi cng trng th c th xut hin gin, nt sm, bong bt, trt. Nn la chn hm lng bitum ph hp vi phm vi xp x v pha tri ca phm vi trung bnh cho php. nh hng ca rng lp y bitum (VMA). Yu cu k thut VMAgip ngithitktrnhchnhpcgitrVMAnmphmvibincho php. VMA cng hn ch rng d cho php ca hn hp. nhhngcarnglpybitum(VFA).Tcdngchnhcachtiu VFA l n gii hn tr s ln nht ca VFA v hm lng bitum, trnh c nhng hn hp d b ln di tc dng ca giao thng nng. nh hng ca mc m nn: cng mt hm lng bitum , c rng d v rng ct liu u gim khi mc m nn tng ln. Trong phng phpthitkMarshallcbamcmnncdngmphngtnh trng lm vic thc t ca hn hp b tng asphalt mt ng. Vic la chn mc m nn s dng chn trong phng th nghim khi thit k hn hp l rt quan trng. V do , hn hp b tng asphalt phi c thi cng m nn ngoi hin trng vi cc thit b m nn tng ng t c cht ban u tng ng vi mc m nn trong phng. nh hngca ma thicng: Thi cng mt ng b tng asphalt voma hthngcnhmlngbitumnhhn,trongkhithicngmtngb tng nha vo ma xun hoc cc ma khc th cn hm lng bitum ln hn m bo qu trnh lu ln c tt do vic lu ln c lin quan n nhit . Bt k mt s thay i no v hm lng bitum trong hn hp cho d l rt nhuphimbothomncctiuchunkthutnhnutrn. Chnh v vy, vic xc nh hm lng bitum theo khong (khng theo gi tr trung bnh) c u im l d xc nh c gi tr hm lng bi tum thit k cui cng bng cch dch v cn di hay cn trn ca khong . nhhngcalngxeluthng:Slngvhotngcaccphng tin giao thng c th nh hng n quyt nh cui cng nhm iu chnh hmlngbitumthitk.Nunhtnhhnhgiaothngthctvocn thphoccncaocabngphnloigiaothngdnglachnmc m nn trong phng th nghim v yu cu k thut, th hm lng bitum c th cn c hiu chnh l tng ng. Nhng khu vc c giao thng nng hn cn mt hm lng nha nm trong phm vi cho php nh hn. Trong trng hp hn hp c dng lm lp ph tng cng ti v tr ng vng, ni m ktongchutcngtptrungcaccphngtingiaothng(tnh phn dng cao, tc rt chm, nhiu cp khc nhau) th phi ch thm nttcccgiaiontrongqutrnhsnxut.Nnlachnhmlng nhathitktcndicaphmviyucukthutvccyucum nn ban u phi tho mn. Trong thi gian mt ng b tng asphalt ang ngui, hn ch cc phng tin giao thng i ln mt ng.7.7. PHNG PHP TH NGHIM MARSHALL CI TIN c p dng vi loi b tng asphalt c c ht ln nht (theo sng vung) khng vt qu 38mm. Th tc tin hnh theo cc trnh t nu i vi th nghim Marshall nguyn bn, ngoi tr mt s iu chnh nh sau: Khun c mu c ng knh trong 152,4 0,2mm. Trnglngbaml10,20,02kg,ngknhmtml 149,4 0,2mm, chiu cao ri ca ba l 4572mm. Chiu cao tiu chun ca mu m l 95,2mm.Thitbthnghimccitinphhpvithnghimmukchthc ln. S c m tng 1,5 ln so vi th nghim Marshall nguyn bn (Bng 7.1). GitrtiuchunthitkMarshallvnnhtng2,25ln,vdo tng 1,5 ln so vi quy nh ca th nghim Marshall nguyn bn. CU HI N TP 1.Mc ch chung ca cng tc thit k hn hp b tng asphalt. 2.Ni dung thit k hn hp b tng asphalt theo phng php Marshall. 3.Cc ch tiu k thut ca b tng asphalt theo Marshall. 4.Phngphpthnghimnhgiccchtiukthuttheophngphp Marshall. Chng 8 THIT K HN HP B TNG ASPHALTTHEO CNG CHU NN LN NHT (TIU CHUN NGA) 8.1.KHI NIM CHUNG Thit k thnh phn b tng asphalt nhm chn ra thnh phn theo khi lng ca hn hp ct liu, bitum v ph gia tho mn cc yu cu k thut ca d n. Thnh phn, cc tnh cht vt l c hc, tnh cht khai thc (cng v c) tnh n nh nc, tnh n nh nhit, n nh trt, bn nc ca b tng asphalt cnphiphhpvicciukinkhaithccthcquinhtrongtiuchun. iu kin khai thc c th l ti trng hin ti, tng lai v iu kin kh hu. Mt s khi nim c bn hng dn thit k thnh phn hn hp b tng asphalt nh sau: Lng dm trong hn hp cng ln th cng tng bn trt ca b tng asphalt.Bindngtrtdophttrinccvngmngvvyccvng mng khi chu ti trng nng m dng hn hp c lng dm cao. Bitum c nht (dnh kt) cng thp th bn nn cng cao v vy nhng vng kh hu n i (pha bc) s dng bitum c dnh kt thp, cc vng nng(phanam)sdngbitumcnht(tnhqunh)cao(kim ln thp). c v cng b tng asphalt thay i theo s thay i hm lng bt khong trong hn hp b tng asphalt. Thnhphnbtngasphaltcthlachntheohngdncacctiu chun ph hp vi cc iu kin khai thc thc t. Lng bitum ti u trong hn hp c th xc nh theo hai phng php: +Phngphpthcnghim:Thnghimtrnccmuthvthnhphnvi lng bitum khc nhau. Xc nh lng bitum p ng yu cu cng ti a v rng cn li ph hp vi yu cu ca tiu chun d n. + Phng php kt hp tnh ton v thc nghim xc nh lng bitum trong hn hp tho mn rng cn li ca b tng asphalt v tiu chun thit k. 8.2.LA CHN DNG HN HP V THNH PHN HN HP Khi la chn dng v mc ca hn hp cn xt n qui lut v kch thc ht vt liu khong (chn ng knh ht ln nht thch hp ca ct liu). Khi ti trng ln v ph hp vi ng cp I (s xe ngy m ln hn 7.000). Yu cu b tng asphalt c n nhtrt cao. Khi cn chn hn hp loi A (nhiu dm) mc I. Trn ng (cp IV) c th chn hn hp loi B (t dm) mc II hoc III.Phhpvilutcachthayloivmccahnhpcthchntheobng 8.1. Bng 8.1.Loi v mc ca hn hp b tng asphalt theo cp ng Cp ngLoi v mc ca hn hp I, II III IV A1, B1 B2, C2, G G, , G1 Khilachnloivmccahnhpcnlachnthnhphnlngvbt khong thch hp. Hnhpbtngasphaltthngcchialm3loiphthucvoyucus dng: hn hp dng cho lp mt, lp chu lc, v lp mng. Ct liu c kch c ln thng c dng lp mng, v lp mt s dng cc ct liu nh. Cho d hn hp thit k l loi no th thit k, sn xut v xy dng vn phi m bo to ra mt mt ng c kh nng lm vic hp l. Vic la chn loi hn hp b tng asphalt cn ph thuc vo cp giao thng nng, va v nh. Cp giao thng cphntheolulngxe/ngym.TheotiuchunVitNamcchialm nhng loi ng chnh nh sau: ng cao tc, tc > 80km/h; lu lng xe bnh qun ngy m > 20.000 xe ng cp I cp II, V > 100km/h; > 6.000 xe ngy m ng cp III, V > 80km/h; > 3.000 xe ngy m ng thnh ph, V> 80km/h; > 1.200 xe ngy m. Cn c vo mc giao thng v cp ng c th chn cc tiu chun v thnh phn hn hp b tng asphalt khc nhau. Hn hp dng cho lp mt cn m bo tnh n nh v lu bn p ng c lu lng giao thng v chu c tc ng bt li ca khng kh, nc v thay i nhit . ng knh ln nht ca ct liu thng t 1020mm.Hn hp lm cho lp chu lc c D = 2040mm. nhng ng c ti trng xe ln v hay b ma nn s dng cp phi ht trung lm lp mt. Hn hp dng cho lp mng thng s dng D ln.Hn hp b tng ct thng s dng ct nghinhoc ct t nhin.Loi hn hp nycnnhkhngln,thngdngchomtngchutitrngnh,vah, khu gii tr v khng dng trong trng hp ng c lu lng xe ln. ng cp IV c th s dng loi b tng nha ct hoc b tng nha ri ngui. Th d: La chn thnh phn ca , ct v bt khong cho hn hp loi B, lng dm3552%vlngbtkhongt612%(ltquasng0.071mm)vivtliu c ghi bng 8.2. Theo phng php la chn thnh phn vt liu khong trnh by Chng 6 Lng D =520mm l 50/95 = 47.5%, chn D = 45%. Bt khong B = 9/75 = 12% Ct: 100 4512 = 43% Kim tra s ph hp vi thnh phn ht tiu chun ghi bng 8.2. Thnhphnkhongcahnhpthitkphhpvithnhphnhtchophp trong tiu chun Bng 8.2. Thnh phn vt liu v kt qu tnh ton Lng, %, lt qua sng kch thc, mm Vt liu201052.51.250.630.310.140.071 dm 520mm100575 Ct sng1007640251241 Bt khong100988375 Hnhptheo tiu chun 95 100 75 100 50 65 38 52 28 39 20 29 14 22 9 16 6 12 dm 45%4525.62.3 Ct sng 43%434343432410.75.11.720.43 Bt khong 12%12121212121211.89.99.0 Thnhphnhn hp chn 10080.657.3554622.716.911.629.43 8.3.LA CHN PHNG PHP THIT K V YU CU K THUT Phng php thit k v cc yu cu thit k l phn chnh trong yu cu k thut ca d n ng. Cc hng sn xut hoc ch u t l nhng ngi c trch nhim v quyn hn la chn phng php thit k v cc yu cu k thut. Khi ccyu t trn c quyt nh th ngi k s thit k phi c trch nhim thc hin v tun th theo ng cc yu cu v ch dn k thut. Tu theo loi d n c th la chn phng php thitkvccyucukthuttheotiuchunVitNamhoctiuchunquct (thngltiuchunASTMhocBS).Trnthgiithngsdngphngphp Marshall.Ccyucukthutcabtngasphalttheocctiuchuncthxem Chng 6 ca gio trnh ny. Nga thit k thnh phn b tng asphalt thng dng tiu chun CH 912884. 8.4. XC NH LNG BITUM TI U Lngbitumtiullngbitumtronghnhpngvicngbtng asphaltlnnhtvrngcnlikhngvtquccgiihnquinh(theotiu chunNga)cxtnvngkhhu.Ngoiracnxemxtnccquynhvkhi lng ring ca b tng asphalt, rng ca hn hp vt liu khong ph hp vi cc tr s yu cu. Cng ca b tng asphalt bin i theo mc tng khi lng ca bitum trong hn hp cho n khi bitum lp y cc l rng ca vt liu khong iu kinnhitvchmchtnhtnh.Lngbitumtiugimkhiplcm nn v nhit khi m nn hn hp tng ln. Lng bitum ti u c th tham kho cc s liu ghi bng 8.3. Lngbitumthngbinituthucvohnhpchayrng,ctliulnhay nh.xcnhchnhxclngbitumtiutinhnhchtomtshnhpt thnhphnkhongclachn,lngbitumthayitheomc0.5%,xcnh ccgi tr trung bnh trn cc mu th theo ccch tiu qui nh, l c s xc nh lng bitum ti u. Bng 8.3.Lng bitum ti u cho cc loi hn hp b tng asphalt. Dng ca hn hpMc hn hpLoi b tngLng bitum, % Ht nh, ri nngA B B B c c rng rt rng 56 5.56.5 4.56 2.53.5 B tng ctG, D c rt rng 79 46 xcnhlngbitumtiuchobtngasphaltctthnhphnvtliu khong c la chn ch to 5 hn hp vi hm lng bitum l 5, 5.5, 6, 6.5 v 7% vmihnhpchto12muvthnghim xcnhcngchunndctrc 200C, khi lng th tch, khi lng ring, rng ca hn hp vt liu khong. Cng c xc nh khi nn cc mu th trn my. Cc ch tiu vt l c xc nh theo phng php v cng thc Chng 6 Cng,rngcahnhpvtliukhongvrngcnlil3chtiu chnh la chn hm lng bitum ti u. Cc ch tiu trn ng vi cc hm lng bitum c v trn cc biu Hnh 8.1. Trn biu ny cho thy ng vi mi ch tiu u c mt lng bitum ti u. Lng bitum ti u tho mn 3 ch tiu trn l tr s trung bnh ca 3 lng bitum ti u cc b (B1, B2, B3) Ngoi ra, hm lng bitum ti u phi tho mn cc tnh cht khc hoc cc yu cu khc m d n quy nh.Thdvlachnthnhphnbitumtiuphhpviyucucngchu nn500Cllnnht,rngcahnhpvtliukhongt1516%,khilng ring ca b tng asphalt t 2.602.61g/cm3, rng cn li l 3% Cc kt qu th nghim c ghi bng 8.4. Bng 8.4.Kt qu th nghim v tnh ton v cc tnh cht c hc v vt l Cc tnh cht mu th vi hm lng bitum, % Cc tnh cht c hc v vt l 5.05.56.06.57.0 rng ca hn hp vt liu khong, % rng cn li % Khi lng ring, g/cm3 Cng 500C, MPa Cng 200C, MPa n nh nc ht nc 16.9 4.20 2.59 1.20 2.51 0.85 1.50 15.7 3.30 2.60 1.40 3.03 0.90 1.20 15.2 2.60 2.60 1.42 3.92 0.93 1.00 16.2 2.00 2.601 1.50 3.00 0.95 0.80 17.9 1.40 2.587 0.82 2.12 0.98 0.50 Hnh 8.1. Biu quan h gia lng bitum v cc ch tiu k thut Btoi u= (B1+B2+B3)/3 Bti u= (5.56+5.53+5.93)/3=5.67 % Vilngbitumtiul5.67%,tratrnbiuB4thomnrngcnli ca b tng asphalt l 3%. Nunhrngcnlikhngphhpvilachnthcthtnhgnng lng bitum theo cng thc sau: BoKrd rKV VB =trong : Bkhilngbitum%,tnhtheokhilngccactliu (100%); VrK rng vt liu khong ca mu th nghim, %; Vrd tr s rng cn li (d) ca b tng asphalt; B khi lng ring ca bitum 20oC, g/cm3; 0K khi lng th tch ca vt liu khong. Khi lng bitum (%) tnh theo khi lng ton b ca b tng asphalt (100+B) c k hiu l Pb c tnh theo cng thc sau: 100 +=100 BBPb , % trong : B khi lng ca bitum, % theo 100% l vt liu khong Chto3muthvxcnhrngcnlicabtngasphalt.Nunh rng cn li ph hp vi quy nh th c th s dng kt qu tnh trn. CU HI N TP 1.Khi nim chung ca cng tc thit k hn hp b tng asphalt theo tiu chun ca Nga. 2.Ni dung cng tc la chn thnh phn vt liu khong theo tiu chun ca Nga. 3.Ni dung cng tc la chn hm lng bitum ti u theo tiu chun ca Nga. Chng 9 CH TO HN HP B TNG ASPHALT 9.1.KHI QUT V CNG NGH CH TO B TNG ASPHALT Mc ch ca vic ch to l to ra mt hn hp b tng asphalt ng nht trong cchtctliulncphntnuvtrnbmtcacchtcbclp bitum. Chtlngcavicchtonhhngncng,nnhnccab tng asphalt. Cht lng ca lp bitum trn b mt ca ht khong c th lm tng hoc gimcctnhchtkthutcabtngasphalt.Nuvictrncchtlngthpth cng c th gim n 2%. Nhit khi trn b tng asphalt thng t 120 1600C tu theo lng v loi bitum c s dng. Trong hn hp b tng asphalt thng c chia ra lm 3 pha: cng dm; lngbitum; khkhng kh. Lc dnh bm tt nht ca bitum trn b mt xut hin trong iu kin sau:k > b + bk trong : ksc cng b mt ca bsc cng b mt ca bitum bk sc cng b mt ca vi bitum (25 40 epg/cm2)Thi gian nho trn cng nh hng n cht lng ca hn hp b tng asphalt. Cng ngh ch to b tng asphalt chia ra cc giai on sau: Chun b; Sy nng nguyn liu, trn kh, gia cng bitum; Trn hn hp. Cng ngh ch to b tng asphalt hon ton ph hp vi cc nguyn tc ca cng nghlthuytcktvtliunhnto.Tuynhincngnghnycmtsim khc nhau khi ch to cc dng b tng asphalt khc nhau. 9.2. CHUN B Chunbvct:vctclmschbngnc(cthratrongmy hoc ra trn bng truyn) v vn chuyn n kho cha. Ct v cgia nhit n nhit t 140 1600C i vi hn hp b tng asphalt nng v 100 1200C i vi hn hp b tng m. C 3 dng sy nng ct liu, gm: loi cc thng sy ngn cho tng m; thng sy hnh tr quay; v thp sy. Sng phn loi ct liu thnh 4 loi theo ng knh ht c cha cc thng cha ring.Chun b bt : bt sau khi nghin nh c kim tra cht lng v sau c cha xil ring, khng cn gia nhit. Chun b bitum: bitum c gia nhit trong thit b c bit. i vi bitum qunh nhitt1401600C,cnivibitumlngt901000C.Qutrnhgianhit bitum m bo t ti nht c th nho trn v dnh bm tt vi vt liu khong.9.3. TRN B TNG ASPHALT 9.3.1. PHN LOI TRM TRN Theo tnh nng sn xut c th c 3 dng trm trn:Trm trn chu k (theo tng m) sy nng gin tip; Trm trn chu k sy nng trc tip; Trm trn lin tc sy nng trc tip. Ccloitrmnycthclptcnhhoclptdingtrncng trng.Loicnhthnglcctrmtrnln.Theonngsuttrnthcccloi trmtrn:rtlncngsut200400T/gi;loiln80150T/gi;loitrungbnh4060T/gi; loi nh di 30T/gi. 9.3.2. TRM TRN CHU K SY NNG GIN TIP Vi cc trm trn chu ksy nnggin tip, ct liu v bitum c chun b trn thnh tng m t 300 5000kg, thi gian trn t 50 80 giy. Qu trnh hot ng ca loi trm trn ny nh sau: Hnh 9.1. Trm trn chu k sy nng gin tip Vn chuyn ct liu bng xe hoc bng truyn n b phn rang sy l mt thng quay ln bng kim loi c t nghing t 2 100 theo trc ca thng. u t bng nhin liu gas hoc du phn thp nht ca thng to ra lung hn nng i qua thng vthotraucaocuithng.Ctliunguiiquathngquaytcatrnc chuyndnqualungkhnngvbnungnngkhonggiavraphncuica thngtrnccgunng.Nhitcactliuthngl1600C.Vtliucvn chuyn thng ng n b sng ca thp, ct liu c phn chia thnh nhm theo c ht xc nh v c lu tr trong cc thng gi nhit. Vt liu c ly ra t mi thng c nh lng v np vo phu theo trnh t t c ht ln nht n c ht nh nht. Mi loi ct liu c phnring theoyu cucho tng m trn theo cng thc thit k.Bitumsaukhicgianhitclugitrongbnchavcdnvo my trn thng qua mt van nh lng. Ct liu sau khi nh lng xong c vo my trn. My trn thng l mt loi bn cu c hai trc quay c lp cnh trn xin gc vi trc. Bitumscchovotrongqutrnhtrnhnhp.Thigiantrnthngt 30 60 giy, thi gian ny m bo c cc ht ct liu bc u bitum v cc c ht ct liu c phn b u trong hn hp. Hn hp trn xong c x trc tip vo t chuyn dng vn chuyn ra cng trng.Trmtrnhotngtheochuk(tngm)doctliucgianhittrckhi trn (cp nhit gin tip) nn d dng v iu chnh c cht lng ca hn hp. Loi trm trn ny ph hp vi vic thi cng ng v sn bay. N c t c nh v c cng sut t 100 400T/gi Hnh 9.2.S cu to trm trn chu k sy nng gin tip 1 .Ct liu ngui; 2.nh lng ct liu ngui; 3 .Bng truyn;4 .Nung ct liu; 5 .Ht bi ct liu; 6 .ng khi;7 .Bng truyn; 8.Sng; 9 .thng cha;10 .Cn; 11 .Thng trn;12 .Thng cha bt khong t nhin;13 .Thng cha bitum nng; 14 .nh lng bitum Hnh 9.3. Trm trn uc lp t phc v xy dng sn bay 9.3.3. TRM TRN CHU K CP NHIT TRC TIP Loitrmtrnny,cpphictliunguicnhlngtheotngmtb phn cp liu ngui v c vo thng sy rang kh v sy nng ri c x vo my trn trn vi bitum. b phn cp liu ngui, cp phi ct liu ngui theo t l nhsncvophukimtratrnglngtrckhirangsy.Tlctliu khng c thay i trong sut qu trnh v do vy vic iu khin cp liu ngui phi rtchnhxc.Tphunhlngccctliucchovothngsytngmmt. Thctthigiannungsymtmkhngn.Sauctliucchovomytrn thng thng trn vi bitum. Loitrmtrnnyltrmtrnchukcpnhittrctipvhnhpctliu nguicxcnhthnhphntrckhigianhit.Chngchophpthayinhanh chng cc ch tiu k thut hn hp v khng b hn ch bi dung lng thng cha ct liu nng. Cng sut ca trm c th t t 50 200T/gi. Tuy nhin kho ct liu c m ln hn 2% th dng trm trn ny s khng kinh t (vi yu cu sy kh vt liu). Do vy loi trm trn ny thch hp vi cc loi vt liuyu cu nhit va v thp nh dm trn bitum hn l nhng hn hp c hm lng ct cao nh b tng nha. 9.3.4. TRM TRN LIN TC CP NHIT TRC TIP Cc trm trn ny cung cp cc hn hp vt liu khongbitum m khng dng h thng cc thng cha ct liu nng, phu nh lng v thng trn. V nguyn tc h thngcpctliunguigingnhmttrn.Tuynhintrmtrnthngquaytrm trn lin tc cp nhit trc tip th ct liu c cp lin tc t cc thng cp ct liu ngui. Thnh phn cp phi ct liu phi chnh xc bi bt k mt sai st no v t l cp liu s ch c pht hin khi cc mu ca hn hp vt liu trn xong c phn tch phng th nghim. Cc thng cp liu ngui ct liu vo cc bng ti, cc bng ti ny ln lt cc ct liu vo bng truyn ti. Vic phi cp liu c thc hin mi cu cn cho phpbiuthtccadngctliu(lmgimmctliu)vdovychophp tnh ton c lng ct liu mn v bitum cn thm vo. Thngquayycdngkhcvithngquaycctrmtrnchukcp nhit gin tip 2 im c bn l: 1) u t t u cui ca thng quay v do vy ctliuchyvotheongnla;v2)hnhdngcaccbungbntrongthngquay phc tp hn. Hnh 9.4.Mt trm trn thng quay Hnh 9.5.S trm trn lin tc theo cng ngh Turbin 1.Thng cha ct liu ngui; 2.Bng truyn; 3 . Thng cha bt ; 4. b phn cp bitum; 5.Vi phun; 6. ng khi;7.Sil cha hn hp trn; A.Nung nng ct liu;B.Trn. Bn trong thng quay c hai khu vc. Khu vc th nht rang sy v cp phi ctliu.Khuvcthhaitrnctliunngvibitum.Khuvctrncbov bng mn chn ngn la hoc thit b lm tngmt ca mn ct liu bo v ct liu c bc nha ( trn xong) khi bc x nhit t l sy. Bitum c phun vo thng quay ti im khi u ca khu vc hai. Tc ca dng bitum t l vi dng ct liu v c khng ch hoc bng cc bm nh trc cc tc khc nhau hoc bng cc van c m khc nhau. Sovicctrmtrnkhclngkhixcatrmtrnloinychbng10%lng bi thi ra ca cc loi trc y. iu ny t c l do lng bi kh sinh ra vng rang sy c hp th bi hn hp cp liu bitum vng trn.Cc trm trn ny gi l trm trn lin tc cp nhit trc tip v cc ct liu c rang sy lin tc trc khi trn vi bitum. Loi trm trn ny kh s dng mt cch linh hot v i hi nhng thay i ln nu mun thay i dng hn hp cn nho trn. Tuy nhinvictnghoiukhinbngmytnhbcukhcphccnhng vn ny. Loi trm trn ny tng i n