CNG N THI VT LIU XY DNG Cu1: CTrc ca VLXD,nh hng ca cu trc vi t/c ca VLXD? a.Cu trc ca VLXD c th hin 3 mc: - CT v m: C th nhn thy = mt thng. - CT vi m: Quan st = cc thit b (knh hin vi). - CT trong hay cu to cht:Quan st =knh hin vi in t,tia Rnghen. b.nh hng ca ctrc ti t/c thuc VLXD : *Cu trc v m: - VL ct c: + C cng , kh nng chng thm chng n mn tt hn cc VL rng cng loi ,khi lng th tch ln. + ht nc thp, cch nhit, cch m km. Vd:Btng nng ,Btng nh c cu to c. - VL cu trc rng: + Cng ,khi lng th tch nh, ht nc cao ,kh nng chng thm ,dn nhit thp. + chng n mn km hn VL c cng loi. . Lng l rng kch thc hnh dng ,c tnh ,s phn b ca chng c a/h ln n t/c VL. VD: Btng kh ,btng bt. - VL c ctrc ht:t/c ph thuc hnh dng ,kch thc ,hm lng c ht . - VL c ctrc si:c cng n nhit v t/c khc ,rt khc theo phng dc v ngang th . VD:G,cc SP t bng khong v bng thu tinh. - VL c cu to dng lp cng l VL liu c t/c d hng . *Cu trc vi m: + Cu to tinh th. + Cu to v nh hnh. Cu to tinh th v v nh hnh ch l 2 trng thi khc ca 1 cht . VD: SiO2 dng tinh th thch anh; dng v nh hnh opan. - Dng tinh th c bn v m ln hn dng v nh hnh. VD: SiO2dng tinh th khng tc dng vi Ca (OH)2 iu kin nhit p sut thng; dng v nh hnh tc dng vi Ca(OH)2 iu kin nhit v p sut thng. - Cc cht c cu to tinh th c nhit nng chy( p sut khng i)v hnh dng hnh hc thuc tinh th mi dng th hnh nht nh. T/c ca n tinh th l t/c d hng => c th to nn VL c tnh ng hng = cch sp xp cc VL gm nhng tinh th khc theo 1 trt t nht nh.

*Cu trc trong : -Cu to nguyn t, phn t hnh dng kch thc ca tinh th lin kt ni b gia chng . C trc bn trong qnh :cng , cng bn nhit v nhiu t/c quan trng khc. - Lin kt cng ho tr : hnh thnh t i in t dng chung trong nhng tinh th thuc c 2 ngun t. - Lin kt cng ho tr c cc: to thnh t 2 nguyn t c t/c khc , cp in t dng chung lch v pha nguyn t c t/c phi kim mnh hn => R ( cng )cao kh chy. - Lin kt ion : l lin kt gia cc nguyn t khi tng tc vi nhau th nhng n t cho nhau => to thnh ion (+) v ion (-) => R , cng thp khng bn nc Nhng VLXD m tinh th gm c lin kt cng ho tr v lin kt ion th t/c rt khc VD: CaCO3 cng kh cao cng li thp. Fenspat : cng v cng kh cao - Lin kt phn t (lin kt vandervan) di tc ng thuc nhit lin kt ny d b ph hu => cc cht c nhit nng chy thp. - Lin kt silicat : l lin kt phc tp to ra nhng t/c c bit ca VLXD. Cu 2: Thnh phn vt cht to nn VLXD ? nh hng ca thnh phn n cc t/c ch yu thuc vt VLXD: I-Thnh phn vt cht to nn VLXD: VLXD c c trng = 3 thnh phn: 1. Thnh phn ho hc : c biu th = % hm lng cc oxit trong VL . i vi kim loi hoc hp kim th thnh ca n c tnh = % cc nguyn t ho hc thnh phn ho hc ca VL c xc nh = cch phn tch ho hc. 2. Thnh phn khong vt : vic xc thnh phn khong vt rt phc tp c bit v mt nh lng v vy phi dng nhiu phng php b tr cho nhau , phn tch nhit vi sai, phn tch quang ph Rnghen , laze. 3. Thnh phn pha : a s VLXD tn ti pha rn nhng trong VL lun cha 1 lng l rng nn ngoi pha rn n cn cha cc kh v pha lng . Ngoi VL rn trong xy dng cn VL rt ph bin trong thi nht do. II-nh hng ca thnh phn n cc t/c ch yu ca VLXD: 1.Thnh phn ho hc : khi thay i thnh phn ho hc th t/c ho hc, t/c thuc VLXD thay i rt ln . Thnh phn ho hc c biu th = % hm cht lng

cc oxit c trong VL . N quyt nh hng lot cc t/c ; tnh chu la , bn sinh vt cc c trng c hc v c c tnh tinh th khc ca VL. 2.Thnh phn khong vt :q tnh cht c bn ca VL. khi thay i thnh phn khong vt th t/c ca VL thay i rt ln. VD: C3S gip xi mng c R cao lm xi mng rn nhanh ; C 3A lm xi mng rn rt nhanh ; khong 3Al2O32SiO2quyt nh t/c thuc VL gm 3.Thnh phn pha gm c : pha rn , pha lng , pha kh , pha nht do ( ho hc btng ) . T l cc pha ny trong VL c nh hng n cht lng : c bit l t/c v m nhit chng n mn , R s thay i thnh phn pha lm cho t/c thuc VL cng thay i VD: Nc cha nhiu trong cc l rng thuc VL=> nh hng xu n t/c nhit , m , R lm ch VL b n ra. Cu 3 : Th no l khi lng th tch , khi lng th tch tiu chun ca VLXD? Trnh by trng thi cu to rng thuc VL ? rng v t/c l rng nh hng ti t/c ntn? Mc ch v ni dng ca phng php xc ch ch tiu ny? 1. nh ngha : Khi lng th tch l khi lng ca 1 n v th tch VL trng thi t nhin (k c l rng). - L rng trong VL gm c l rng kn v l rng h. + L rng h : L l rng thng vi mI trng bn ngoi . Cng 1 th tch l rng nhng VL c l rng h th ht m tt cng thp cch nhit km nhng trong iu kin bng gi cc VL c l hng s b ph hu. + L rng kn : L l rng cch nhit, khng thng vi mI trng bn ngoi . i vi vt liu dng ht cn phn ra l rng trong ht v l rng gia cc ht . VL cha nhiu l rng kn th cch nhit cao R tt. rng ca vt liu dao ng trong phm vi ln t 0 -> 98% . Da vo rng c th phn on ms t/c thuc VL: chu lc ,tnh chng thm ,cc t/c c lin quan ti nhit m . VD: VL c rng ln th R nh , cch nhit , cch m tt , chng thm km , ht nc ln. 2. Cng thc v n v: Cng thc : =G/Vo Trong : : khi lng th tch G :khi lng VL

V0 : th tch t nhin n v : :g/cm3 kg/cm3 T/cm3 G: g kg T V0: cm3 m3 3. Cc yu t nh hng n: + Do cu trc : nu cu trc c cng V0 nhng cc ht thnh phn c khi lng ln dn n tng G ( V0 = const) tng ; ngc li th gim . + Do cu to : nu Vl c cu to nhiu l rng , tng r dn n gim G v V0 = const, ta c gim . + Do thnh phn ho hc , cht khong , pha, th VL s c khi lng khc nhau vng V0 nu tng G -> tng.1 + Do m (W) : cc m khc nhau th c VL khng tng th tch nh btng nhng cng c loi th tch tng gim rt nh ( g) nhng khi lng G li thay i ln nn dn ti thay i. 4. Phng php xc nh : +Vic xc nh G c thc hin = cch cn. +Xc nh V0 tu theo loi VL m dng 1 trong 3 cch sau: Vi VL c kch thc hnh dc : dng cch o. Vi VL khng c kch thc r rng dng phng php chim ch trng trng trong cht lng. Vi VL ri th VL t 1 chiu cao nht nh xung 1 ci ca c th tch bit trc. 5. ngha thc tin : Da vo c th phn on c 1 s t/c ca VLXD. - Nu tng VL c cng R cao , chng thm chng nhit tt - Nu gim VL c cng thp dn nhit km Da vo tnh c phng tin vn chuyn v kho bi cha. Da vo tnh ton c trong lng ca cng trnh. Da vo tnh ton phi hp thnh VL. Cu 4: Khi lng ring ca VLXD: 1. nh ngha : Khi lng ring ca VLXD l khi lng ca 1 n v th tch trng thi hon ton c sau khi sy kh n khi lng khng i nhit = 1050C 1100 C ( v 1000C nc bay hi t do ). 2. Cng thc v n v: Cng thc = G / Va trong :

:khi lng ring G : khi lng kh ca VL. V a : th tch hon ton c ca VL. n v ?o : g/ cm3 kg/cm3 T/ cm3 G : g kg T V0 : cm3 m3 3. Phng php xc nh - VL c + c hnh dng hnh hc xc nh : cn G o c V a + khng c hnh dng hnh hc xc nh : cn G o c Va = phng php nc ri ch VL rng : xc nh phng php bnh t trng + nghin gch v em sy kh + ly khong 100 g bt gch vo cc + dung mI khng tng tc ho hc vi VL vo bnh t trng n vch V1 + dnga thu tinh v giy thm lau sch thnh bnh + gt t t bt gch vo bi bnh t trng n khi nc dng n vch V2 ?o = ( M 1-M2)/ ( V2 - V1) M1: Khi lng bt gch v cc ban u M2:Khi lng v bt gch cn li Cc yu t nh hng :Khi lng ring ca VL ph thuc vo thnh phn v cu trc v m ca n.Nu VL c cu trc c th khi lng ring ln;VL c cu rc rng c khi lng ring nh;Vl c pha lng kh c khi lng ring nh hon cc VL khc .i vi VL rn th khi lung rin khng ph thuc vo thnh phn pha ngha : -Bit ?o ->c th nh gi s b c tnh cht thuc VL VD: Bit ?o thuc xi mng =3,05:3,15 xi mng Pc lng -Dng d thit k thnh phn Btng C th nh gi s b thnh phn khong ho h s truyn nhit ,tnh ht nc, tnh thm nc - ?o ca VL bin i trong 1 phm vi hp c bit nhng loi VL cng loi c ?o tng t nhau do c th dung ?o d phn bit nhng loi vt liu khc nhau -phn on 1 s tnh cht ca VL -tnh ton thnh phan VL trong VL hn hp

Cu 5 : Cu to rng ca VL ? hy giI thch s nh hng ca rng v t/c cc l rng ti cc t/c ch yu ca VLXD ? nh ngha : rng l th tch rng cha trong 1 n v th tch t nhin thuc VL CT tnh ton ? ?=V ?/V0= V0-Va/ V0= 1- (Va) / V0 = 1- (Y0)/ Ya V ? : th tch rng Va: Thtch hon ton c V0 : th tich s t tnhin Y0 : khi lng th tch Ya ; khi lng ring Cch xc nh Vic xc nh rng ca VL c thc hin thng qua tnh ton theo theo CT v cng c th dng phng php bo ho hlilng ngha : rng ca VL dao ng trong phm vi kh rng 0-98% . Da vo rng c th phn on c 1 s t/c thuc VL : chu lc , tnh chng thm , cc t/c c lin quan n nhit m VD: VL c rng ln th R nh cch in m tt chng thm km , ht nc thp ' Cu 6 : Khi lng th tch thuc VLXD'? N : khi lng th tch thuc VLXD l khi lng ca 1 n v th tch trng thI t nhin ( k c l rng ) Cng thc v n v LH : Y0 = G / V0 G : khi lng thuc VL V0: th tch t nhin thuc VL n v :g/cm3 kg/ cm3 T/cm3 Phng php xcnhk - VL c hnh dng nht nh cn G on V0 - VL khng c hnh dng hnh hc c nh : phng php ri ch , hoc cht lng ri ch ( gach) + cn mu c G1 + nhng mu vo pharaphin nng chy ( trch ht nc ) + cn mu sau khi nhng vo pharaphin c G2

+ nc vo ng ong ns vch V1 + nhng mu vo ng ong o c mc ncn vch V2 Y0= G1/Y1-V2-YP ; VP = GP/YOP= G2-G1/0,93 cc yu t nh hng : khi lng th tch thuc VLXD dao ng trong 1 khong rng ph thuc vo cu trc v m thuc VL : VL c ct ckhi lng th tch ln ; VL c cu trc rng ,khi lng th tch nh. Ngoi ra cn chu ph thuc vo MT kh m khc nhau cn pI xc nh ?v tnh cht ngha : da vo khi lng th tch thuc VL c th phn on 1 s t/c thuc n nh cng rng => la chn phng tin vn chuyn tnh ton s lng bn thn kt cu VD : ?o cng thp , rng ln , cch nhit , cch m tt thm ln , ht nc nhiu Cu 7 : Nc trong VLXD v nh hng ca n ti t/c thuc VLKD Da vo mc lin kt gia nc vi VL m hp cht trong VLXD c chia thnh 3 loi + nc ho hc : l noc tham gia thnh phn VL c lien kt bn vi VL . Nc ho hc ch bay hI nhit cao( t0 > 5000) . Khi nc ho hc mt I th t/c thuc VL thay i rt ln ,cu trc thnh phn ho hc b ph hu VD : caslinit ( Al2O3.2SiO2.2H2O) mt nc s mt tnh do + nc ho l ( nc hp th ) : c lin kt kh bn vi VL = lc ht phn t Vanduvan hp = lc ht tnh in b mt (nc mng ) . Nc hp th l nc nm trong cc t bo , trong mnh tinh th ng mao dn mao qun . Nu ng knh l rng d> 1m : nc thm vo ; d > 1 m : nc khng thm vo l rng v trong c y nc hp th . Nc ho l ch thay i lng nc hp th th t/c thuc VLXD thay i c bit l cng + nc t do : gn nh khng c lin kt vi VL nm trong l rng thuc VL . Khi nc t do thay i t/c thuc VL cng thay i . Nu VL ht nc gy ra bin dng th tch Cu 8 m thuc VLXD ? m ( %) l ch tiu nh gi lng nc c tht trong VL ti thi im th nghim W = ( mu-mk) / (mk) . 100 % Phng php xc nh : Cn VL c mu em sy nhit t 1050-> 1100C n khu lng khng i => cn VL tnh ton theo cng thc nh hng thuc m t t/c thuc VL : m thay i dn n thay i t/c

thuc VL c bit l bin dng m ( thay i tch ) . m thuc VL ph thuc vo cu trc v m bn cht ca VL , vo c tnh ca l rng, vo mI trng .Trong cng 1 iu kin mI trng nu VL cng rng th m thuc n cng cao . mI trng khng kh khi p lc hI nc tng ( m tng i thuc khng kh tng ) th m thuc VL tng Cu 9 : Trnh by v ht nc thuc VL nh nghia : ht nc ca VL l kh nng ht nc v gi nc ca n iu kin nhit v p sut thng ht nc c xc nh theo khi lng v theo th tch + ht nc theo khi lng thnh phn ( % ) HP=( m u-mk) / ( mk) . 100 % + ht nc theo th tch Hv = ( Vn/ V0 ) .100 % = [( m u- mk) / ( v0n)] .100% +fn : khi lng ring thuc nc ( =1g/cm3) H0/HP= mk/ (V0 n)=vtc / n=> Hv= (HP. ?otc) / n ht theo khi lng thuc VL rng c th ln hn rng nhng ht nc theo th tch th khing th vt qua rng Phng php xc nh ( ht nc ca gch ) phng php ngm t t : -chia mu gch lm 4 phn , cn mu c G 1 -t mu vo dng c ngm - nc n 1/4 vin gch ngm trong 5 pht dng gi m lau kh v em cn c G2 -t gch ngm n 2/4 trong 5pht lm tng t c G3 -t gch ngm n 3/4 trong 5pht lm tng t c G4 -Ngm ngp bin gch trong 5 pht lm tng tuq c G5 HP( G5-G!) /(G1) .100% ; Hv=HP.?og Cc yu t nh hng : - ht nc ca VL ph thuc vo cu truc v m ca VL ; c tnh ca l rng . VL c c ht nc nh , Vl rng c ht nc nc ln . Cng th tch l rng , nuVL c l rng kn th ht nc nh hn ht nc thucVLc l rng h . Nu ng knh l rng d< 1m nc khng vo trong l rng v thi gian l rng y nc hp th => nu VL c nhiu l rng c d < 1m th ht nc nh -Cu 10 : Th no l trang thI bo ho thuc VLXD ? Phng php lm cho VL bo ho nc v ngha ca pp v ngha ca phng

php ? hy phn bit ht nc bo ho vi ht nc ht nc thng Trng thI bo ho thuc VLXD l trng thI ht nc nc ti a thuc VL trong trng thI cng bc ( trong nc , trong MT pd sut )_ Phng php lm VL bo ho nc :c 2 phng php - phng php nhit : cn mu kh sau un trong nc sI 8 gi ( k t lc sI ) => em cn mu tnh ton theo CT H P= ( GU-GC)/ (GK) . 100% - phng php chn ko : sy kh mu t mu vo trong bnh nc kn ht khng kh sao cho p trong bnh p=20mmHg; ngm n khi bt khi thot ht sau phc hi p= 1atm , ch ht bt kh ly VL ra . em cn VL v xc nh nh ht nc ngha : phng php ny gip nh c ht nc bo ho thuc VL do s tnh c h s bo ho Cbh= HbhV ; 0 =Cbh=1 Cbh= 0 tt c l rng trong VL l kn Cbh= 1 tt c cc l rng l h Phn bit ht nc thng v ht nc bo ho thuc VL : Khi o ht nc thng = cch ngm VL trong noc c nhit t 200-> 250noc ch c th chu vo cc l h Xc nh ht nc bo ho ca VL trong trng thI cng bc => noc c th chu vo ton b l rng thuc VL ( c l rng kn v l rng h ) => ht nc bo ho ln hn ht nc thng => nh hng thuc nc thng Cu 11:KN v cng ca VL XD.GiI thch cc yu t nh hung ti c VLXD v cc phng php xnh chng Cng ca VLXD -Kn:Cng l kh nng ca VL chng li s ph hoi a xut hin trong VL do ngoi lc hay diu kin mI trng -S ca VL khi c ngoi lc tc ng vo VL tu thuc vo cch tc dng ca ngoi lc tho cc phng khc nhau m VL c tng tc S khc nhau :ko ,nn -C 3 loi cng ca VL hay ding :cng chu ko Rk,cng chu nn Rn,cng chu un Ru -trong mi tng tc S ngi ta ly gi tr cc i ca S m VL chu c lm gi tr ca cng VL trong tng tc S * Cc phng php xc nh cng :2 pp a, pp ph hu

-ch to VL theo kch thc tiu chn , dng tI trng tc dng n khi VL b ph hu ta xc nh c R Rnh= Pph/F -ng vi mi loi cng cn xc nh phI ch to mu c hnh dng xc nh cho cc mu th chu theo s tiu chun xc nh tI trng ph hu t tnh cng theo cng thc - v VL ch top khngdng nht nn cng xc nh theo gi tr trung bnh do th nghim phI t 3 mu tr ln b. phng php khng phhu : phng php ny rt thun tin cho vic xc nh cng ca kt kin hoc kt cu trong cng trnh + xc nh cng VL m VL khng b ph hoi c nhiu phng php nhng c 2 phng php hay dng : +phng php bt ny : vi nguyn ld khi cho song bn vo bb mt VL s phn hi trn khc vch ca song tra bng -> R +phng php siu m : cng ca VL gin tip c nh gi qua tc truyn sng siu m v , R = f ( v) 3. Cc yu t nh hng ti cng cng ca VL ph thuc vo 2 yu t : a. do bn thn VL + v mt ct : t vi mi ct th VLL c cng khc nhau V cu to VL - rng : rng tng th R gim v ngc li - t/c ca rng : khi rng khng i th cng ca l rng kn cao hn cng ca l rng h + hnh dng kch thc trng thI b mt mu c nh ti kt q th nghim ; mu lp phng c kch thc nh c cng nn ln hn cng c kch thoqc ln , cng mu lng tr nh hn mu lp phng cng thit din , khi bI trn b mt mu th kt qu cng mu c khi gim I 50% + tc tng tI cng c nh hng ti cng mu :nu tc tng tI nhanh hn tiu chun th kt qu th nghimk s tng ln v bin dng do khng tng kp vi s tng tI trng b. k t nhin - m tng th cng gim - nhit cao th cng km hn bnh thng v nc hp th bay hI lm cho VL co li

Cu 12: Nhit dung ca VLXD ? KhI nim : nhit dung l nhit lng Q (kcal) m VL thu vo khi nung nng cng thc xc nh Q = C.G.(t2-t1) Trong C: nhit dung ring thuc VL (kcal/kg0C) G :khi lng thuc VL (kg) t2,t1: nhit thuc VL sau v trc khi nung nng Nhit dung nhit l nhit lng cn thit nung nng 1 kg VL ln 10C ngha : nhit dung ring ca VL ding tnh ton nhit lng khi gia cng nhit VLXD > Lhi VL hn hp bao gm nhiu VL thnh phn c nhit dung ring l C1,C2,Cnv khi lng t l m1,mn Ch= (m1C1+m2C2+ +mnCn) / ( m1+m2+ +mn) p1 , p2 , , pn : t l tng thnh phn Ch=(p1C1+p2C2++pnCn) / (C1+C2+ +Cn) da vo C la chn VL trong cc trm nhit cc yu t nh hng : khi m thuc VL tng th nhit dung ca n tng ln CW= ( C+ 0,01WCn) /( r + 0,01 W) C,CW,Cn: nhit dung ring thuc VL kh , VL m nc Cu13 : KhI nim c bn v t/c dn nhit ca VLXD ? Bn cht hin tng dn nhit qua VL ; phn tch cc yu t nh hng ti khid nim dn nhit thuc VLXD? T/c dn in ca VLXD l khI nim cho nhit truyn qua thuc VLXD . Khi ch truyn nhit n nh v VL c dng tm phng th nhit lng Q (kcal) truyn qua VL tnh = cng thc : Q= ?(F?tt) /(a) Trong : Q nhit lng truyn qua VL (kcal) ; ? h s truyn nhit (kcal/m0C.h) ; din tch ( m2) ; a dy thuc kt cu ; ? t chnh lch nhit (a) ; t thi gian truyn nhit (h) H s truyn nhit ? = nhit lng Q truyn qua 1 tm tng c F = 1m2; chiu dy a = 1m trong thi gian t = 1h khi nhit chnh lnh nhit 2 bn tm tng l 10C Phn tch cc yu t nh hng ti khI nim dn nhit thuc VLXD : kh nng dn nhit ca Vl ph thuc vo rt nhiu yu t loi VL ct rng v t/cthuc l rng . dn nhit thuc khng kh rt b so vi dn nhit thuc vt rn . V

vy VL cng rngdn nhit cng km ( ch nhit tt ) VL cng nng (?0cng ln) th dn nhit cng tt ?25= Cn bc 2( 0,019? + o,22?0 ) - 0,14 + VL m dn nhit tt hn VL kh . Khi nhit bnh qun gia 2 mt tm tng tng th dn nhit cng ln ? 1= ?0( 1+ 0,002 t ) ?o: h s dn nhit 0oC ?1: h s dn nhit nhit bnh qun t ngha : ngi ta dung h s dn nhit la chn VL cho cc kt cu bao che v tnh ton kt cu bo v cc thit b nhit Cu 14 : Bin dng l g ? th no l bin dng do v bin dng n hi ? hy ni r hin tng t bin v chng ng sut thuc VLXD tnh bin dng ca VLXD l t/c thuc n c th thay i hnh dng kch rthc di s tc dng thuc tI trong bn ngoi ngi ta chia bin dng thnh 2 loi : bin dng do v bin dng n hi + bin dng n n hi l phn bin dng hon ton mt I khi loi b nguyn nhn gy bin dng + bin dng do l bin dng khng mt I khi loi b nguyeen nhn gy bin dng hin tng t bin : l hin tng bin dng tng theo thi gian khi ngoi lc khng i tc dng lu di nn VL rn + nguyn nhn : do trong lng vt rn c 1 b phn phi tinh th c t/c gn ging cht lng . Mt khc bn than mng li tinh th cng c nhng khuyt tt hin tng chng ng sut : nu gi cho bin dng khng i di tc dng thuc ngoi lc ; ng sut n hi s gim dn theo theo thi thi gian l hin tng chm ng sut do 1 phn Vl c bin dng n hi dn dn chuyn sang bin dng do . Nng lng n hi chuyn thnh nhit v mt I Cu 15 : Cng thuc VLXD ? KhI nim : cng VLXD l khI nim chng li cc ng sut XH khi c tc dng thuc ngoi lc v ca mI trng Cng c biu th = cng gii hn Rn=P/F n v : kg/cm2; daN/cm2 ; N/mm2 Ru=M/m phng php xc nh : 2 phng php

+phng php ph hoi mu : ch to mu bo dng trong iu kin tiu chun => em mu I nn un + phng php khng ph hoi mu : phng php ny rt tin li cho vic xc nh cng ca kt cu hoc cu kin cng trnh . Trong cc phng khng ph hoi phng php khng ph hoi dng rng rI nht , cng thuc VL ph thuc c nh gi gin tip qua tc truyn sng siu m thuc n . i vi VL hn hp ( btng ) ngi ta hay dng phng php siu m ngha : da vo cng thuc VL ta c th bit kh nng chu tI trng => la chn VL ph hp vi kt cu cng trnh phn tch cc yu t nh hng n cng ca VLXD : cng ca VL ph thuc vo rt nhiu yu t + bn thn VL ct v thnh phn thuc VL nh ti cng : VL c ct c ,ct dng tinh th lin kt cng ho tr th cng cao , VL c ct rng c lin kt ion th cng thp +k th nghim v mI trng -kch thc mu : cng 1 loi VL kch thc ln th R b , kch thc b th R ln => kch thc t/c thuc VL khi em th nghim 15.15.15cm Rn= a ( P ) / (F ) ; a h s ph thuc vo kch thc ( h s iu chnh ) VD : nu kch thc 10.10.10cm a = 0,19 -tc tI trng : nu tc tng tI trng nhanh hn tiu chun th kt qu th nghim R s tng do bin dng do khng tng kp vi s tng tI trng -b mt mu : nu b mt mu gip th khi th nghim th s khng gip cho kt qu th nghim c chnh xc ; b mt mu nhn -> cng th nghim gim 50% -nhit m : nhit cao c cng cao v khi trng VL n ra , lnh VL co li -k ch to mu : nh hng rt nhiu ti cng k ch to mu thun li VL c tnh ng nht cao => R ln Cu 16 : H s mm v h s phm cht ph thuc VLXD? D thc t thuc cc h s ny ? H s mm : dc trng cho bn nc thuc VL ngi ta dng h s mm km thng qua cng cc mu bo ho nc Rbh v cng ca mu kh Rk Km=Rbh/Rk 0=m =m>0,75:Vl bn nc c th dng cho cc cng trnh thu cng Kmpc) l 1 i lng c trng bng t s gia cng tiu chun Rk v khi lng th tch tiu chun:

.kpc =Rtc/?otc=kg/cm2 Kg/m2 H s phm cht l 1 ch tiu tng i tng qut .Di vi VL bnh thng khi cgn cao th ?o ln -> nng ,cc tnh cht v nhit v m km ,k pc nh cn VL mun c k pc ln th n phI va c kh nng chu lc tt ,va phI nh ,cc t/c v m nht tt Cu 17:Khi nim c bn v Btng dng cht kt dnh v c ?Vit ca cc VL thnh phn trong' Btng? a/Khi nim c bn v Btng dng cht kt dnh v c : Btng l 1 loi nhn to thu c d qu trnh rn chc ca 1 hn hp gm c: cht kt dnh+ dung mI + ct liu b+ ct liu ln +ph gia =hn hp Btng rn chc * Btng chu nn tt ,chu un km: Ru= (1/10:1/5)Rn -> tng kh nng chu un thuc Btng ngi ta thng s dng nguyn VL a phng r tin ,d kim , gi thnh r .c th ch to c nhng loi Btng c cng hnh dng v t/c khc nhau bn vng ,n nh vi nng ma,nhit , m . Tuy nhin Btng cng c nhc im:Nng cch m,ch nhit km,kh nng chng n mn km b/Vai tr ca cc thnh phn VL trong Btng : Trong Btng ct liu ng vai tr l b khung chu lc ,nh hng nhiu n cng ca Btng Cht kt dnh cng nc l thnh phn hot tnh trong Btng bao boc xung quanh ht ct liu,ng vai tr l cht bI trn ,ng thi lp y khong trng gia cc ht ct liu, gn kt cc ht ct liu di dc to thnh 1 khi rn chc c cng cao Cu 18:S nh hng ca XM,ct liu n tnh cng tc ca Be tng ? nh hng ca XM: Loai lng v mc ca XM nh hng n tnh cng tc ca B tng rt ln .Nu hn hp Btng c XM cng vi nc lp y l rng ca ct liu ,bc v bI trn b mt ca chng th lu ng s tng .Tuy nhin v l do kch thc nn lng XM ko th qu nhiu .Nu XM mc cao th mn ca XM ln ,do lng nc bI trn cng nhu .V vy nu s dng XM mc cao th st ca Btng nh . 1 hm lng nht nh th lung dng XM ko nh hng ti st ca Btng nhng nu vt qu gii hn ny th lng dng

XM tng dn n st ca Btng gim (do ni m ma st tng ) nh hng ca ct liu : Ct liu b(ct) v ct liu ln ( si) c ahng n tnh cng tc ca hn hp Btng .Ct cng mn th rng ca Btng cng ln , do Btng nh c do km Hnh dng v c trng b mt ca ct liu tc ng n tnh cng tc .Nu ct liu c dng hnh dng trn trng hnh van ,b mt nhn th hn hp btng c tnh cng tc cao.Nu ct hnh dt ,b mt gip th tnh cng tc thp . Cu 19 :hay trnh by v nuoc xi mang dung ch to b tong? a.xi mng:cht kt dnh cng vi nc l thnh phn hot tnh trong be tong; bao boc xung quanh hat cot lieu; dong vai tro la chat boi tron; dong thoi lap dau khoang trong giua cac hat cot lieu,dong thoi gan ket cac hat cot lieu roi rac thanh mot khoi vung chac co cuong do cao chat luong va luong dung xi mang co anh huong nhiue den chat luong be tong.xi mang dung de che tao phai thoa man tcvn2682-2000. viec lua chon mc ca xi mng la rt quan trong no va m bo t mc thit k ca b tong,va m bo yu cu kinh t.mc ca xi mng bng 1,5n 2 ln mc ca b tong.khng dung c xi mang mc thp ch to b tong mc cao.v khi thit k thnh phn lng dung xi mang se nhiu, co ngt nhiutrong b tong s xut hin nhng vt nt dn n b tong d b n mn,nh huong den tnh bn vng ca b tong.khng dung xi mng mc cao ch to b tong mc thp v khi thiets k thnh phn ca b tong luonwj dung b tong qu t nn khng lp y l rng giu cc ht cot liu, gn kt cootl liu.,be tong bi rong cuong do giam.ben canh do che tao xi mang mac cao gia thanh dat.su dung hop ly be xi mang trong be tong la phai dung luong xi mang toi thieu dung de lien ket.luong xi mang ytoi thieu ohai phu thuoc vao dieu kien thi cong. b.Nuoc: nuoc dung de che yao be tong (rua cot lieu nhao tron va bao duong)phai co dup ham chat de khong anh huong xau den thoi gian ninnh ket va ran chac thuoc xi manh ko an mon cot thep. Nuoc xsinh hoat la nuoc co the dung khong nen dung nuoc o ao ho , dam.nuoc bien co the dung che tao be tong cho nhung ket cau lam viec trong nuoc bien,neu tong ca loai muon trong nuoc khong qua 35g tron 1 lit nuoc. Cau 20:the nao la tinh deo cua hon hop be tong nang?phuong phap xax dinh do ca hn hp b tong nang? Tinh deo hp l ca b tong nng l tnh do hp l ca hn hp b tong sao cho b tongo t c cng v kh nawngthi cng vi nng sut cao t c m thu thuc CT.tnh do hp l thuc b tong ph thuoocjvafo tnh cht lkys thu

ca cng trnh. Ddieuf kin nguyn vt liu thi tit kh hu. B.phng php xc nh do thuc hn hp b tong nng Phng php hnh nn ct c hn hp b vo hnh nn ct chia l, 3 lp, mi lp m 25 ci bng m phi 16, m t ngoi vo trong theo hnh xon trn c lp trn ch lp di 2cm trn phn tng.nhc hnh nn ct vi c cao thuc hn hopwoj b tong suy ra hn hp b tong do v b tong cng SN=0 hn hp b tong cng SN>0 hn hp b tong do u nhc im :phng php ny rt n gin c th s dng nhng vng khng c in nhng khng chnh xc ch dung cho hn hp b tong do. Png php nht k thut: L dng c gm hai hnh tr cungd ng knh v chiu cao lng vo nhau. ng knh trong ca thanh hnh tr trong bng y ln ca hnh nn ct.ton b thit b c t trn bn rung Ngi ta t nn ct vo trong nht k k thut, hn hp b tong vo hnh nn ct chia lm 3 lp mi lp m 25 ci bng dm phi 16 m t ngoi vo trong bng theo hnh trn c,lp trn cch lp di 2cm trnh phn tng. Nhc hnh nn ct ra bm ng h v cho my rung chop n khi hn hp b tng trong 2 hnh tr san bng nhau. Qung thi gian k t khi bt u rung cho n khi hn hp b tng trong 2 hnh tr san bng nhau c trng cho cng chia hn hp; KH :C(SEC).da vo cng chai hn hp b tng t do c bit cng,nu hn howpjc b tng c bit cuwngs th th nghim tht chnh xc. u nhc im:c th s dng cho hn hp b tng cng v do.nhc im :ch s dng c trong phng kt DmaxM100% sau 28 ngy m tho nn xy ra 3 trng hp : Rbtn=1,15Rbyc: t yu cu Rbtn=>1,15Rbyc: thit k li v ko k thut RbtnCu 22: Cng b tng cc yu stoos nh hng n cng ca b tng ? a/Cng b tng : l khi nim chu lc ca mu b tng 15.15.15cm c ch to v dng h trong iu kin chun 28 ngy m rn chc .Trong qu trnh cng rn cng b tng ko ngng tng ln .T 7-14 ngy cng pht trin mnh sau 28 ngy m chm dn v c th tng n hang chc nm sau . R thuc b tng tng theo quy lut logic Rn/R28=lgn/lg28 R28 R Rm 1 1,25 1,75 b. Cc yu t nh hng n cng b tng : Rb: thuc cng ca xi mng thuc c Rx: c thuc xi mng thuc N/X -nh hng ca xi mng ti cng thuc b tng Rh=f(N/X,Rx) Rb1/(N/X) N/X cng ln th Rb cng thp v ngc li RbRx Cng thc Belialeo:Rb=Rx/k(N/X)^(3/2) k:h s ph thuc vo ct liu v phng php xc nh ca xi mng . y l cng thc thc nghim . Cng thc Bolomay: R28=ARx(X/N0,5) -Hn hp b tng cng X/N2,5 R28=A1Rx(X/N-0.5) A,A1: h s ph thuc vo cht lng thuc ct liu Phng php xc nh ca xi mng hn hp b tng do hoc cng nh hng ca ct liu :s phn b gia cc ht ct liu tnh cht cu n (cng hnh dng ca n .b mt,lng l rng h ,t l din tich ) c nh hng n cng thuc b tng -Ct liu c:

+Rcl>>Rb:cng ct liu t nh hng n cng thuc b tng +RclRb:ct liu nh hng rt ln n R thuc b tng ,ct liu rng cng thuc khng nh hng n cng thuc b tng -Hnh dng c trng b mt : +Ct liu c hnh ko c trng ,b mt rt th cng thuc b tng tng (nu mc thuc b tng 300 tr i th dng ct liu ln : dm +Ct liu c hnh dt b mt nhn cng b tng thp -Ct cng mn th lng nc nho trn b tng tng rng cng ln =>b tng nh c cng b -T l C/(CD) V pha phi ca t l ti u , khi tng C/(CD) lng va xung quanh cc ht ct liu tng ln, cc ht ct liu liu b y ra xa nhau n mc chng khng ocnf tc dng tng h vi nhau =>R thuc b tng gim v pha tri ca t l ti u, C/(CD) tng dn n C/(CD) tiu chun lng va s lp y l rng gia cc ct liu y chng ra xa hn vi kt cu hp l =>cng b tng pht trin kh cao. nh hng thuc ph gia:ph gia nh hng ti b tng phn ln do c ch thuc ph gia : khi a ph gia vo s lm gim lng nc vo trn => tng c ca xi mng t tng cng b tng -Ph gia rn nhanh : c tc dng y nhanh qu trnh thu ho ca xi mng nn lm tng nhanh s pht trin ca cng b tng dng h trong iu kin t nhin cng nh ngay trong khi dng h nhit -Ngoi ra ph gia rn nhanh cn c tc dng tng tnh chng thm nc cho b tng -Ph gia trn nghin mn (v c nghin mn hoc vi ct liu ) tng c cho b tng t tng R thuc b tng nh hng ca chn ng : Nu ti trng tng dn th cc cu c thuc hn hp b s giao ng v t sp xp li v thuc mnh lm cho cu trc thuc b tng c chc hn t tng R thuc b tng . Tuy nhin nu cp phi ht khng t th chn ng mi c ngha. Thi gian rn chc : R28n=1 R12j=1,75 cng thuc b tng c th pht trin trong 1 nm 2 nm 10 nm n khi qu trnh thu ho thuc xi mng kt thc. Mi trng rn chc : R thuc b tng cao nht th phi bo dng b tng trong 28 ngy m iu kin tiu chun (t=20 C 5 C ), w=95% -100%.

Nu t=80% W=95% -100% th trong 14h Rb t 70%, R ph thuc b tng sau 28 ngy m (tuy nhin nhit ko qu cao cht kt dnh ko b ph hu ). Cu 23: tnh cng tc thuc hn hp b tng ? a/ Khi nim v phn loi : tnh cng tc ca b tng biu thi kh nng lp y khun nhng vn m bo ng nht trong 1 iu kin m nn xc nh Phn loi : nh gi tnh cng tc thuc hn hp b tng ngi ta s dng 3 ch tiu : - lu ng : c trng cho cng cu trc thuc hn hp. - cng : c trng cho cng cu trc thuc hn hp - gi nc : biu th kh nng tch nc ca hn hp sau khi vn chuyn v m chc khi m nn hn hp b tng do , cc ht ct liu c khuynh hng nhn xung v xch li gn nhau ,nc b p tch ra khi ct liu v ct thp ni ln pha trn v cng vi xi mng chui qua k h chui ra ngoi to thnh nhng l rng lm kh nng chng thm ca nc b tng gim . Mt phn nc tha ng li bn trong hn hp to thnh nhng hc rng , nh hng xu n cu trc thuc b tng .Vic gim lng nc nho trn v nng cao kh nng gi nc thuc hn hp b tng c th thc hin bng cch s dng ph gia hot ng b mt v la chn thnh phn ht thuc ct liu hp l. b. Cch xc nh . c. Cc yu t nh hng n cng tc -nh hng cho lng nc nho trn -Vi lng nc t 0t l din tch b mt ct liu tng => lng nc cn bi trn b mt nhiu hn => tnh cng tc thuc b tng gim xung . -V pha thuc t l ti u :tng C/(CD)nhng hm lng ct dn dn tin ti hm lng =>h s trt gia cc ht ct liu =>tnh cng tc tng . -nh hng ca ph gia : khi a ph gia vao lm vic di c ch ph gia => tnh cng tc thuc hn hp b tng tng . + ph gia a nc : khi ph gia h xi mng cn t nc hn lc lien kt gia cc ht xi mng gim rreex rn trt ln nhau lm lu ng thuc hn hp b tng tng . + Ph gia k nc : khi hp th trn b mt xi mng ph gia ko b thm t to thnahf cc lp mng bao bc xung quanh cc ht xi mng c lhar nng trn trt ln nhau d dng lm cho lu ng tng .

+ Ph gia to bt kh : khi nho trn vi b tng ph gia s cun theo mt lng khng kh . Cc ht khng kh s lm gim sc cng mt ngoi cauir cht lng mt phn cch kh lng . Lng bt kh nh c cc ph gia m c n nh trong cht lng ng thi lm tng th tch thuc h xi mng . Do lu ng thuc hn hp b tng tng ln . -nh hng thuc chn ng : khi cung cp cho cc cu t thuc hn hp b tng mt tn s no chng s dao ng , u tin chng s dao ng quanh v cn bng sau s dao ng cng bc =>ni ma st -thuc hn hp b tng gim v tnh cng tc tng ln . - nh hng thuc thi tit kh hu : nhit cao p sut thp , tc gi ln => nc bay hi tng ln => gim lng nc trong hn hp b tng =>tnh cng tc gim . Cu 24 : ln ca ct liu c nh hng th no n tnh do thuc b tng , phng php xc nh ln thuc b tng ? -* ,ln ca ct liu c nh hng ti tnh do thuc b tng : -Ct liu b : ct cng mn th rng cng ln => b tng nh ,c R b do km -Ct liu ln : nu cp phi kt liu dung cho b tng l cp phi gin on th hn hp b tng cng tnh do km kh thi cng . Nu l cp phi lien tc th hn hp b tng c tnh do d thi cng . -Phng php xc nh ln thuc ct liu : dng boojj sn tiu chun Cu 25 : cc yu cu k thut ca ct liu dung sn xut b tng nng. A. ct thp b (ct): ct dung ch to b tng c th l ct thin nhin hay ct nhn to c ht t 0,14=>5mm: -Ct thin nhin : l loi cu thin nhin l sn phm cu qu trnh vun nt c trc tn ti dng : ct song, ct bin , ct ni . Ct gm c ct vng (ht mu vng hoc xanh ) v ct en . -Ct nhn to : l sn phm thuc qu trnh gia cng ct liu ln ( mt ) -*lng dung ct nh hng n lng dung xi mng cht lng cu ct ph thuc vo thnh phn khong , thnh phn ht v lng ngm tp cht. -Thnh phn ht v ln ca : -* Nc yu cu cu ct : -Xc nh bng cch : ly hn hp X : C =1:2 ,a va ln bn nhy , tm bt ca n .

-Nu Nyc > 7,5 ct nh ,Nyc = 77,5 : ct trung bnh , Nyc rng ln =>b tng c cng b , hn hp b tng c do km -* Lng ngm tp cht : -Ht nh (bi bn st) s lm tng Nyc thuc lng ct v lng dng xi mng trong h b tng ln ht lng nh (lt qua sang N014 ) khng c vt qu 10% ( ring lng trong ht bn st khng c ln qu 3%) . Ht st do s bin i th tch ln do m thay i c th dn n s ph hoi thuc cu trc b tng ln phi khng ch cht ch hn ( khng c ln hn 0,5%) cc tp cht khc nhau cng phi tho mn yu cu quy phm . -Khi ct m th tch cu n b bin i . V vy nu inh lng ct theo th tich th cn phi hiu chnh th tich thuc n theo m thc t . B . Ct liu ln : dm , si . Cu 26: s pht trin ca cng b tng thuc b tng nng? phn tch nh hng ca t l N/X va Rx n cng thuc b tong nng?( cu 6 ) Cu 27: phn tch u nhc im thuc hn hp b tng cng so vi hn hp b tng do? cch xc nh cng do thuc b tng ? Phn tch u nhc im thuc hn hp be tng cng so vi hn hp b tng do: Hn hp b tng cng: u im :lng dng xi mng t ,lng nc dng nho trn t ,cng thuc b tng cao Nhc im :kh thi cng phi m nn nhiu,cn dng chn ng Hn hp b tng do u im :d thi cng khng vn to chn ng Nhc im :tn nhiu xi mng cn nhiu lng nc nho trc vi cung b tng b Cu 28: bin dng ca b tng? Tnh co n thuc b tng trong qu trnh rn chc ? a.bin dng ca b tng?b tng l loi vl n hi do , bin dng ca n gm hai phn:bin dng n hi v bin dng do bin dng n hi tun theo nh lut hc =s.E :ng sut trong b tng s l bin dng tng i E l m un n hi thuc b tng Bin dang n hi :khi ti trng tc dng nhanh vo to ra ng sut khong kn lm Tnh n hi thuocj b tng giai on ny c c trng m dun n hi ban

u: E=10/(1,7+360/2,28) M un n hi thuc b tng tng ln khi lhamf lng ct liu ln cng v m un n hi thuc ct liu tng ln v hm lng xi mng t l X/N gim Biens dng d Xy ra ng sut vt qu 0,2 cng gii hn thuc b tng b =af+ d Dc trng bin dng thuc b tng Ebd = /h= /(dh+hd) b.tnh co n thuc b tng:trong qa trnh rn chc b tng ,cn hin tng co ngt lun xy ra l mt hin tng xu nguyn nhn :do s mt nc cu cc gen xi mng cu trc gen bao gm nhunwng mm tinh th li c bc bng 1 lp nc lien kt .nhiu chui lien kt to thnh mt mng li khng gian.mt li cha y nc. s mt nc lm cho cc mm tinh th xich li gn nhau hn, ng thi cc gen cng dch chuyn lm cho b tng b co. qu trnh cacbonnat ho hidro tron xi mng gim th tch tuyt i ca h xi mng nc Hu qu :co ngt gy ra ng sut co ngt nn trong ct liu ,ct liu v ko trong xi mng l nguyn nhn gy ra nt ; gim cng chng thm v n nh ca b tng ,ca mi trng xm thc.v vy i vi cc cng trnh c chiu di ln trnh nt ngi ta phn on to thnh cc khe co gin . co ngt pht trin mnh trong thi k u t l vi mt nc t do (bay hi,thu ho xi mang) gim dn theo thi gian n mt lc no th tt hn C yu t nh hng :tr s co ngt ph thuc vo lng xi mng , lng nc v t l ct trong hn hp ct liu.d co ngt trong xi mng ln hn trong va v trong b tng Ngoi ra d co ngt ph thuc vo cc ch dng h.khi dng h nhit m co ngt xy ra mng m v nhanh chng hn trong diu kin thng nhng tr s cui cng Cu 29:cc ch tiu nh gi khi lng vi rn trong khng kh 1. linh hot n : linh hot ca vi l tng hm lng CaO v MgO cha trong vi nhng v lng MgO qu t (Cu 30 :nguyn liu v qu trnh sn xut vi rn trong khng kh ?cc bin php nng cao cht lng khi nung voi? Dm bo nhit ln hn 900CCaO +CO2 -42,5 Kcal/kg.thoe l thuyt nhit bng 900C phn ng xy ra nhng khi nung v gii phng ra CO2 mt i

440%kgkltrong vi li nhiu l rng h s truyn nhit gim xung trong li vin nhit nh hn 900C phi nng cao nhit ln ti 100C CaCO3 phn gi hon ton L phi thong thong CO2 thot ra tng tc phn ng xy ra theo chiu thun Nguyn vt liu kch thc ca vin phi ph hp vi cng nghip nung:l gin on ,nghuyn vt liu phi ng thnh bnh xe xen k . vi c th c kch thc nh nhng phi mng :l lien tc thng phi cho ln than vo trong vi, phi nh Cu 31 :cc phng php s dng vi trong xy dng? phn tch cc u nhc im ca tng phng php v kh nng ng dng ca n? Vi c s dng dng chin v vi bt sng Vi chin l vi c ti trc khi dng c thnh phn chnh Ca(OH)2 v 50% l nc :vi sa >50% nc < Ca(OH)2 Trong xy dng dng ch yu l vi nhuyn v vi sa .bt vi chin c dng trong y hc v trong nng nghip u im s dng v bo qun dn gin Bt vi sng :l vi c nghin mn trc khi c s dng(>90% ht lt qua sang 4900 l/cm^2) u im :rn chc nhanh v c cng cao voi chin l do tn dng c lng nhit to ra khi ti to ra phn ng silicat ,khng b nh hng thuc ht non la ,khng mt thi gian ti. Nhc im :kh bo qun ,tn thit b nghin bi vi c th nh hng n sc kho ca cng nhn Cu 32 ln nc tiu chun , thi gian ninh kt hp n nh th tch ca xi mng pooclang? a.khi nim l lng cn thit h xi mng t do tiu chun khong thi gian 24-30% khi lng thuc xi mng nhng lng nc tham gia thu ho 15-20%. phng php th nghim :phng php th dn ly 400g xi mng ,ly lng nc trong khong 23-30% kl xi mng lau bay cho bng gi m xi mng vo to thnh nhng l nh , nc vo trn u trong vng 5 pht xc 1 ln vo khun ,to chn ng ct bng mt t kim vica.th ri kim u

t do trong 30s ,nu kim ri cch y 5-7mm l t tiu chun(d=10 mm)nu khng t phi lm li t u. cc yu t nh hng thnh phn hn hp :trong xi mng c nhiu CaO th xi mng km bn nc cn nhiu nc xy ra phn ng CaO+ H2O hm lng nc yu cu tng thnh phn khong vt : mn ln i mng tc dng vi nc ,cn nhiu nc thi tit kh hu b.thi gian ninh kt n :thi gian ninh kt chia lm 2 thi k Bat dau ninh ket la khoang thoi gian tu khi do nuoc den khi ho xi mang het tinh deo,ung voi luc do kim Vica cam sau tu 1-> 2 mm Phuong phap -------xac dinh;PP thu dan; d=1+-0.1mm -Lay 400g xi mang, lay luong nuoc tieu chuan thuoc xi mang -Lay tay lau chao bang re am -do xi mang vao, tao thanh lo nho,do nuoc vao tron deu -xuc 1 lan do vao khuon to chn ng . ct bng mt ,dt vo kim vica -sau 45 phut th kim,sau d 5 pht li th kim mt ln Cac yu t nh hng +Thnh phn ho hc:Cao lm cho xi mng rn nhanh dn;CaSO4;H2O c tc dng diu chnh thi gian ninh kt cho xmng.Ngoi c cht photphatnitrat canxi,natri,nhom,ng l nhng xhaats lm chm ninh ket.Cc cacbonat v clorua thuc kim loi mm l nhng cht lm tng nhanh ninh kt +Thanh phn khong vt :C3S,C3A:l nhng cht lm cho ximang rn nhanh ,giam thoi gian ninh kt + mn:Tng mn ca xmang c ngha l tng thu ho,gim thi gian ninh kt +thi tit ,kh hu m,nhit d thuc mI trng nh hng qu trnh rn chc Ca ximang v giai on u thuc qu trnh rn chc l thu ho.Neu mI trng m to diu kin d tng tc thu ho Tc d ca cc phn ng thu ho gia cc khoang clanke vi nc lm nhit tng ln=>thi gian ninh ket giam Tinh n nh cua th tch +DN: L kh nng khng b cong vnh ,nt l sau 28 ngy m rn chc v

trong ximang cn hm lng MgO va CaO o dng tinh th t do,C3A qu nhiu, thi tieet v kh hu kjhoong ph hp vI qu trnh rn trc thuc ximang Phng php th nghimLbnh a ximang Ly 450g Xm ly lng nc tiu chun thuc XM nho trn thnh h XM -chia h XM thnh 6 phn bng nhau c d=6-8cm chiu day 1cm Hai mu hp, hai mau luc trong nc sI trong 4h,2 mu bo qun trong ddieuf kin t nhin.Trong su mu ko c mu no cong vnh nt l=> XM n nh th tch +Cc yu t nh hng Thnh phn ho hc : nhiu CaO=> thuwafCaO nm trng thI t do,khi thu ho s gy nt n=>Gim tnh n nh th tch thuc xi ng -Thnh phn khong vt:C3A lm cho xi mng rn rt nhanhto nhiu nhit gy nt n cho xmng.Mt khc C3A + CaSO4.H2 O -> 3CaO.Al2O3.3 CaSO4..H2 O (etricrip) Nu hm lng nhiu qu s gy n th tch -> xi mng nt n -> gim tnh n nh th tch thuc xi mng DDK mI trng :MI trng hanh kh , m thp nhit cao gy mt nc khi thu ho xi mng->Xi mng b cong vnh nt n.Thng thng rwans chc trong mI trng khng kh kh th xi mng b co,cn nu rn chc trong mI trng nc th xi mng b co hoc n cht t Cau33' :Cng d v phng php t mc cho xi mng? DN:cng ca xi mng l kh nng chu lc hay la gii hn cng chu lc chu nn sau 28 ngy m rn chc iu kin tieu chun.Tc pht trin cng thuc xi mng :c nh gi t th nghim mu4.4.16cm cng thuc xi mng ->khng du:trong 3 ngy c th t 40-50% mc Xi mng 7 ngy u 60-70%.Trong nhng ngy sau tng cng cn chm na dn 28 ngy t c mc.Tuy nhien trong nhng iu kin thun li s rn chc xi mng c th ko di hng thng,thm ch hng nm CD gp 2-3 ln cng 28 ngy Cc yu t nh hng:Cng ca xi mng v tc cng ca n ph thuc thnh phn ca clanke, mn ca x mng m v nhit d ca mI trng,thi giam bo qun xi mng -Thnh phn ho hc:nhiu CaO khi thu ho s gy nt n cho xi mng-> cng

giamrtocs pht trin cng ca mi khong l khc nhau,C3S c tng cng la nhanh nht.Sau 7 ngy n dt n 70% cng ca 28 ngy sau th chm laijTrong thi k u n tui 28 ngyC2S pht trin cng chm ch t khoang 15% cua C3S.Thi k sau tc ny tng ln c th ui kp hoc vt C3S. C3A bn thn c cng thp hn nhng li pht trin nhanh thi k u - mn ca xi mng tng th cng tng.C tng mn ca Xi mng ln 1000cm2/g th cng tng ln t 20-25% -MI trng rn chc (t0.) :t0= 80; =95% ch sau 14h cng xi mng tng 75% v nhit tng->ho tan tng->kt tinh nhanh ,Rn chc xi mng nhanh m phI m bo lng nc thu ho ieu kin th nghim:PhI tun th qu trnh -Ch rung P2 xc nh -Phng php cng:Ly t l X/C=1/3 N=(a/4+b) th tch ct/1m2 va a.luwongj ct tiu chn bheej s vi xi mng poc lng b=1 c mu 7.07. 7.07. 7.07-> em mu ko nn -Phng php mm:ly X/C=1/2;N/X=0.5 em nho trn.c mu 4.4.16 dng h trong iu kin t nhin 1 ngy sau em tho khun ngm trong nc.Sau 28 ngy m dem ko nn xc nh R 'Cu 34' :Hin tng n mn xi mng v c phng php bo v a.Hin tng n mn xi mng DDN:Hin tng n mn l hin tuuwowng xi mng b rng cu trc bng gim cng dn ti bijphas hoi Nguyn nhn: S phn gi giu cc thnh phn ca xi mng,s ho tam va ra trI hydroxit canxi Cao+ H2O->Ca(OH)2 l cht b ra tri-> to thnh l rng trong xi mng r b n mn Cc dng n mn -n mn nuwowc ngt l hin tng ra trI cc sn phm thuc qu trnh thu ho,do va p c hc Khi Ca(OH)2 b ra trI 15-30% th cuorngf ca xi mng gim n 40-50% -n mon axit Ca(OH)2 + mui -> Mui mI tan

VD:Mui etrgit nu c hm lng qu cao s gy nt n to ra cc vt nt _> tng kh nng b n mn _n mn sinh vt n mn iin ho y ra cc cng trnh m ti wcs bin hay dng ln dng xung b.Cc bin php bo v Gim thnh phn khong gy n mn (caO t do C3S, C3A) bng cch la chn cc thnh phn nguyn ieeujdeer p ng cc phng php gia cng cho ph hp -Gim thnh phn gy n mn ln nht Ca(OH)2 bng cch tin hnh cacbonat ho(cho tc dng CaO_>CaCO3 hay Silicat trn b mt sn phm Lm tng cu trc Gim lng nc nho trn:dng ph gia siu do hoc ho do Cho vo vt liu ct liu: tro chu Chn cp phi thuc hn hp vt liu hp l nht-> dt cao nht nh s dng bin php to chn ng m li dm hp lLm cho mt vt liu nhn bng howc xt Ngn cn vt liu vI mI trng 'Cu44:'KhI nim c bn v cht kt dnh v c v phn loi chng nh th no?S lc v mt s cht kt dnh hc 1.KhI nim cht kt dnh v c cc cht kt dnh v c l loi vt liu c sn xut t cc loi khonags cht qua khu gia cng nhiu thu dc vt liu mi c nhng c im sau -Khi trn ch kt dnh v c vI dung mI thch howp to ra cht kt dnh (hn hp do) Sau lt qu trnh phc tp th hn hp cht kt dnh t ng rn li -Trong qua s trnh rn chc cc cht ket dnh c kh nng lin kt cc vt liu ri thnh cc vt liu khooisddoongf nht c cng -c cng pht trin theo thi gian 2.Phn loaijDuwaj vo kh nng kt dnh chia lm 3 loi A.Cht kt dnh v c rn trong khng kh:Thnh phn ch yu la CaO CaCO3-> CaO+ CO2 +Cht kt dinh magiee MgCO3-> MgO + CO2 Cht kt dnh thch cao:Thnh phn ch yu la CaSO4 CaSO4.H2O-> CaSO4.(0.5)H2O+1.5 H2O

+thu tinh kng :silicast natri Na2O.nSiO2;silicat kali Ka2O.mSiO2 dn cho cc sn phm chu axit bazow mng chng n mn chng n mn cho v xy dng l nung sn xut xi mng chng axit Cht kt dnh v c rn trong bc KN: la nhng CKDVC c kh nng rn chc v gi c cng lu di khng nhng mI trng kh m cn c mI trng nc Phn loi +VI thu:Thnh phn co khong 2CaSiO2,5CaO.3Al2O3 t do hm lng st 812% +xi mng la m:2CaSiO2,3CaO.Al2O3 , 4CaO.Al2O3. Fe2O3 CaO st t do hm lng 12-20% sn xut t vI nung nhit 120013000 +xi mng poc lng 2CaOSiO2,, 3CaO.Al2O3 3CaOSiO2, 4CaO.Al2O3. Fe2O3 c sn sut t vI v t st v mt s ph gia khc nh CaSO4. nung nhit 1400-15000 +xi mng Alumilat : c c khong 5CaO.Al2O3.dc sn sut t qung booxits v rn rt nhanh,n th tch khi rn chc cng cao 500-600 kg/cm2 c dng cho cc cng trnh bit c.Cht kt dnh v c rn trong mI trng nhit cao ,p suoaat cao khI nim.L nhng cht c kh nng rn chc trong mI trng bo ho v c p sut cao c im:Cht KD ny c 2 thnh phn ch yu CaO va SiO2 v nuwowcsxCaO.ySiO2.zH2O X,y,z ph thuc vo mI trng vi t0c = 174-1900c p=11-17atp, hp cht ny bn +VI tro: vI x, vI xilic,CaO-SiO2 'Cu 45:'Nguyn liu v qu trnh sn xut vI rn trong khng kh?Nhn xt v qu trnh nung vI va cc sn phm ca chng?Bin php nng cao cht lng nung vi? 1.Nguyn liu v qu trnh sn xut a.Nguyn liu +Nguyn liu l nhng loi giu CaCO3 c hm lng CaCO3>92% v tp cht CaCl2=2H2O +Cng thc x=0.02804.V.K.100%/g Trong -g:Khi lng VI cn u tin -k:H s ng lng axit -V:th tich HCL(cm3) -0.02804: lwongj CaO tong ngd vi 1ml HCl 1M b.Nhit tI v tc ti KN:nhit tI l nhit cao nht m phn ng tI vI tiu chun t c trong phng th nghim =Tc tI l khong thi gian t khi nc vo tI (Vi mt lng nht nh)

cho n khi t c nhit trong phng th nghim VI c cu trc hp li v hot tnh ln(Chiu cao) th s c nhit v tc tI nhanh 'Cu 48':Cc loi oxit ca nguyn liu sn xut xi mng poc lng? Tnh cht ca xi mng la do tnh cht cua clanhke quyt nh.M cht lng ca clanke li ph thuc vo thnh phn khong vt ho hc v cng ngh sn xut Thnh phn khong vt ca clanke biu th bng hm lng % ca cc oxit trong clanhke dao ng trong cc gii hn sau +O xit canxi(CaO):63-66% +oxit silic (SiO2):24-24% +oxit nhom (Al2O3):4-8% Oxit st (Fe2O3) Tng cc oxit ch yu ny l 95-97% Cc Oxit khc:MgO,SO3,K2O,TiO2,, Cr2O3, P2O5chim mt t l khng ln v nhiu t c hi n cht lng xi mng Trong qu trinh nung n nhit kt khi,cc oxit ch yu kt hp thnh siliccat,aluminat v alumoferitcanxi dng khoang cht c cu trc tinh th mt s t cuhuyeenr sang dng v dnh hnh Trong thnh phn ho hc ca clanhke thay i th tnh cht ca xi mng cng thay i -Tng CaO th xi mng thng rn nhanh km bn nc -Tng SiO2 th xi mng thng rn chm v bn nc -MgO:l thnh phn ca pha feroaluminat v thu tinh clinhke,Tn ti dng th t do,thu ho rt chm.S thu ho MgO ko di kh lu (n vi nm ) v khi chuyn thnh Mg(OH)2 htif tng th tch ca pha rn.Cho nn nu hm lng MgO>5%s gy mt n nh th tch ca xi mng -CaO t do dng ht, thng c loi clanhke mi nung xong ,hm lng CaO t do 2O; Ka2O) co trong pha feroaluminat ca clinke cng nh dng Sunfat.D trnh xy ra nt n ca kt cu hm lng ca chng phI rt hn ch nkhi dng vi ct liu cha SiO2 v nh hnh(Ct ,) Cu 49Hy trnh by nhng dc im c bn v cng ngh sn xut xi mng poc lng ?Qu trnh sn xut xi mng poocs lng gm nhng giai on no ? 1.Chun b nguyn liu:

Mc ich ca vic chun b nguyn liu gm c khu nghin mn nho trn hp vi t l yu cu m bo cc phn ng ho hc xy ra hon ton cho clinke c chaat lng ng nht C 3 phng php chun b nguyn liu a.Phng php kh -Khu nghin mn nho trn hn hp u thc hin trng thI kh hoc xy - vI v t st c nghin v xy n m 1-2% -Phng php ny ch ph hp vi vI v t st c m thp (10-15%) -Chi ph v nguyn liu t hn phng php owts 1.5-2.5 ln.Phng php ny ang c phat trin b.Phng php ots -Khauu nghin nho trn trng thI lng ,H2O chim 35-40% v nghin trong my nghin bi n mn yu cu (Lng st trn sn bin thin l 8-10%) -t st c khuy to huyn ph st, vI p nh ri b vo nghin chung -Phng php ny tn nguyn liu nhng ng du c.Phng php hn hp: - vI v t st nho trn trng thI lng to thanhf bn phi liu.Nhng bn c kh nc sau khi cho vo nung 2.Nung Mc ch :dng nhit bin i nguyn liu c chun b thn clanke thng qua phn ng tch nc oxit to khoang mi Phng php +L ng :nguyn liu chun b theo phwwong php kh t j s dng,Nhit khng u +L quay Nguyn liu chun b theo phng phap owts Hn hp nguyn liu a vo u cao kh nng c phun t aauf thp S bin i ho l trong l nung ca nguyn liu Phi liu t kh vo l nung n khi to thnh clanhke ra khi l phI trI qua 6 vng nhit a.Vng bay hI (vng saays) nhit thng n 2000c.Nc t do bay hI phi liu ng thnh cc ri v vn ra b.Vng t nng nhit t 200-700 -200-450 Tch nc hp ph v tp cht hu c chy

-450-700 Nc ho hc bay hI c trng l phn ng Al2O3.2SiO2.2H2O=> Al2O3.2SiO2+H2O Vc.Vng canxi ho +700-10000C:Al2O3. 2 SiO2=> Al2O3+2SiO2 Bt u xy ra phn ng fn hu:CaCO3=>CaO+CO2 -1000=>11000C y ra phn ng to khong u tin ca ximng CaO+ Al2O3=>CaO.3 Al2O3 Va 1 phn phn ng :2CaO+2 SiO2=>2CaO. SiO2 d.Vng phng nhit:1100=>13000C -1100=>12000C xy ra phn ng 5CaO.3 Al2O3=>3CaO. Al2O3+2CaO. Al2O3 Phn ng to ra 2CaO. Al2O3 xy ra hon ton -1200=>1300 y ra phn ng CaO++3CaO. Al2O3+Fe2O3=>4CaO. Al2O3. Fe2O3 Bt u c phn ng 2CaO. SiO2+CaO=>3CaO. SiO2 e.Vng kt ni (1300=>1500=>1300) -1300=>1500:phn ng to alit 3 CaO. SiO2 xy ra hon ton C3A;C4AF chy lng ra -1500=>1300: C3A;C4AF kt tinh li f. Vng lm ngui:1300=>2000C(1000C) -1300=>1000: cu trc v thnh phn ca clinke hon ton hnh thnh v hon thin 3.nghin clinke Mc ch imng l cht kt dnh v c rn trong nc v l phn ng b mt do phI nghin mn thu ho ximng c trit Yu cu imng fI c 85% lt qua sng N0 008 (4900 l.cm2)t l din tch 2500=>300cm2/g Cc phng php nghin: +Phng php nghin kh:hay s dng to sn phm ng bao -nhit nghin 80-1200C -Clinke c nghin do s tr st v va p ca vin bi +Phng php nghin t -a clinke ra tn cng trnh nghin vi nc:hiu qu cao,hp v sinh -Phai s dng ngay Cu 50:c tnh c bn ca cc khong vt chnh trong ximng pooclng?Hy

vit cc phng trnh phn ng thu ho ca chng v nu c tnh cc phm thu ho? 1.c tnh c bn ca cc khong vt chng trong ximng pooclng Clinke c 4 khong vt chnh l alit,belit ,aluminatri,canxi v ferluminat a.Alit3 CaO. SiO2(C3S) -Chim 45-60% trong clinke ximng -Kt tinh 6 dng hnh th khc nhau,trong clinekealit c hnh 6 cnh hoc hnh hp ch nht vi kch thc 3-20micrmt -Alit l khong quan trng nht ca clinke n quyt inh cng v cc tnh cht khc nhau ca ximng b.Belit 2 CaO. SiO2(C2S) -Chim 20-30% trong clinke ximng,l loi khong vt quan trong th 2 -C tc rn chem. Nhng t cng cao tui mun -Belit c 5 dng tinh th cu trc ht hoc trn D=20-50micrmt -Khi lng ring ya=2,97-3,28g/cm2 c.Aluminat tricani 3CaO. Al2O3(C3A) -Chim 4-12% trong clinke ximng -Tc rn chc nhanh nhng cng ko ln -D b n mn sunfat,trong ximng bn sunfat thi C3A a=3,04g/cm2 d. ferluminat tetracanxi 4CaO. Al2O3.Fe2O3(C4AF) -chim 10-12% trong clinke ximng - C4AF c tc rn chc trung gian ca alit v belit nn ko nh hng ln ti tc rn chc v s to nhit ca xingmng pooclng -C khi lng ring ln nht ya=3,77g/cm2 -ngoi ra cn c fa thu tinh clinke chim 5-15% bao gm ch yu l CaO,Al2O3,Fe2O3,MgO,K2O,Na2O. 2.Cc phng trnh phn ng thy ho a.khong C3S khi gp nc: 2(3CaO. SiO2)+6H2O= 3CaO. SiO2.H2O+3Ca(OH)2 b.khong C2S V c Ca(OH)2 t C3S tch ra nn C2S th ho chm hn C3S v tch Ca(OH)2 ra t hn 2(2CaO. SiO2)+ H2O= 3CaO. 2SiO2.3H2O+Ca(OH)2 c.khong C3A -Tham gia phn ng rt mnh v nhanh,ban u to ra C4AH0 v C2AH8 l lp

sn phm ko bn lm gim bn nc ca ximng.sau chuyn sang sn phm chnh dng nh(C3AH6) 3CaO. Al2O3+ 6H2O= 3CaO. 2 Al2O3.6H2O -Trong ximng c thch cao -Trong ximng c thch cao CaSO4.H2O nn phn ng tip to Etringit 3CaO. Al2O3+3(CaSO4.2H2O)+26H2O=3CaO. Al2O3. 3CaSO4.32H2O + Etringit n th tch rt mnh t 2-3 ln + Etringit C li khi xy ra trc qu trnh rn chc v ngc li to ra sm=>chin lp cc l rng ca ximng=>tng cng v n nh ca ximng to ra mun nt v bnh thng + Etringit Tc dng vi 3CaO. Al2O3 d to ra mui p 1 sunfat 2( 3CaO. Al2O3)+ 3CaO. Al2O3. 3CaSO4.32H2O+2H2O=>3(2CaO. Al2O3. 3CaSO4.18H2O) d.Khong C4AF 4CaO.Al2O3.Fe2O3mH2O=>3CaO.Al2O3.6H2O+CaO.Fe2O3.nH 2O -CFHn :c n nh tt rt bn c trong thnh phn ca gen ximng -C3AH6:tc dng vi thch cao (CaSO4.2H2O)=> Etringit Cu 51:S rn chc ca ximng pooclng?Hy trnh by r thuyt rn chc ca Baicp? Khi ximng rn chc,cc qu trnh ho l phc tp i km theo cc phn ng ho hc to ra s bin i tng hp,khin cho ximng khi nho trn vi nc lc u ch l h do sau bin thnh cng c cng . gii thch qu chc trnh rn chc ngi ta dung thuyt ca Baileov-Rebinder.Theo thuyt ny qu trnh rn chc ca ximng c chia lm 3 giai on: 1.Giai on ho tan -Xy ra cc qu trnh hyrat v cc mnh vn ximng tip tc phn tn vo trong nc=>qu trnh hyrat xy ra nhanh hn v xut hin cc tinh th=>k keo phn tn 2.Giai on ho keo -Do mi trng phn tn H2O gim i do bay hi v tham gia fn ng hyrat ,cc phn t phn tn tng ko ngng=>mt pha phn tn tng=>khong cch gia cc ht phn t gim,cc ht phn tn xch li v gn vo nhau=>keo ngng t 3.Giai on kt tinh

-Khi hnh thnh h keo ngng t,nc vn tip tc mt i,hnh thnh cc tinh th kt tinh lin kt=>khung ko gian ca pha rn,khung ko gian ngy cng hon thin lm cho c h thng ho cng cng tng ln theo thi gian th qu trnh ny chm dn ri dng li Nhn xt: +Din bin qu trnh rn chc ca ximng cng nh nhng cht kt dnh v c khc gm 3 giai on:3 giai on ny lc u ni tip nhau sau l song song +Phn ng gia ximng v nc l phn ng d pha ch xy ra trn b mt tip xc v phn ng ny ngy cng b ngn li do sn phm ca hyrat ho bm trn ximng lm tc thu ho chm li,tuy nhin qu trnh rn chc ca ximng ra rt di c th l 10 nm.Cng ca ximng pht trin nhanh sau l chm dn +Qu trnh rn chc ca ximng pooclng s ngng i khi xy ra 1 trong cc trng hp sau: -khi ximng thu ho ht -khi nc ht -khi nhit mi trng thu ho thp=>ngng li Bin php ximng rn chc tt -cung cp nc cho h ximng y -gi ximng trong mi trng c m cao -tng nhit qu trnh phn tn thun li(60-800C) thuyt rn chc ca Baicp:2 nh lut ca Baicp -nh lut 1:nu 1 cht c to thnh sau phn ng ho hc l mt cht ho tan m gp mi trng bo ho th trc ht n tn ti h keo sau kt tinh -nh lut 2:Nu 1 cht c to thnh sau phn ng ho hc l 1 cht ko ho tan m gp mi trng bo ho th trc ht n tn ti h keo ngng t v ch c 1 phn nh chuyn sang kt tinh Cu52:Hy trnh by 2 ch tiu c bn lng nc tiu chun v tnh n nh th tch ca ximng poocln 1.Lng nc tiu chun ca XM pooclng Khi nim: Lng nc tiu chun ca XM l lng nc tnh bng % so vi khi lng xm h xm t do tiu chun Ntc=N/X% phng php xc nh do tiu chun c xc nh bng dng c vica h xm m bo cm su ca kim vica(d=10mm)l 35+_3mm th h xm c do tiu chun v lng nc lc l lng nc tiu chun

Cc yu t nh hng -ph thuc thnh phn khong vt v nghin mn,dao ng khong 22-28% -Nu xm c ph gia v c trn v hot tnh th lng nc tiu chun c th ln ti 32-37% -nu xm c ph gia chng m th lng nc gim 2.Tnh n nh th tch xm KN:khi xm rn chc th tch ca n thng thay i.thng thng nu rn chc trong ko kh th xm b co li,trong nc th c th ko co v n ra cht t.nguyn nhn do 2 yu t chnh: -yu t VL:th tch xm thay i do hm lng nc thay i,c s trao i nc gia h xm v mi trng.s trao i do yu t VL v ng u -yu t ho hc:tao khong etrighit l nguyn nhn chnh gy co n cc b to ng sut nhit ln=>kt cu b ph hoi.ngoi ra trong xm cn cha cc tp cht c hi gy ra s thay i th tch ln nh CaO,MgO bin php tng s n nh th tch -H xm trc khi SD:gim hot tnh ca xm -Trn them vo xm cc ct liu tr -dng cc ph gia v c hot tnh kt hp vi cc thnh phn gy mt hot tnh ca xm 'Cu 53:Thi gian ninh kt ca xm? ' ngha ca thi gian ninh kt xong? P2 X c 2 ch tiu ny? KN: -Thi gian ninh kt ca xm c X t h do tiu chun bng dng c vica(d=1mm) -thi gian bt u ninh kt l khong thi gian k t khi xm bt u nho trn vi nc n khi h xm bt u mt tnh do,khi kim vica cm su 38-39mm - thi gian kt thc ninh kt l khong thi gian k t khi xm bt u nho trn vi nc n khi h xm mt h t tnh do,khi kim vica cm su 1-2mm Cc yu t nh hng n thi gian nnh kt -thnh phn khong - nghin mn:gim=>thi gian ninh kt tng v ngc li -ph gia -hot tnh:thi gian ninh kt gim -tr: thi gian ninh kt tng - to thi gian ninh kt bnh thng khi to ra clinke thng ngi ta cho them

3-5% thch cao 2 nc -cc cht ft ft,nitratcanxi,natri v nhm, ng:l cc cht lm chm ninh kt. ng tc dng vi Ca(OH)2 to ra cht xacaratcanxi d tan.s hin din ca cht ny s lm tng ion canxi, c ch qu trnh thu phn ca C3S,qu trnh ninh kt b chm li,hm lng ng ln i khi lm cho b tong ko rn li c -Cacbonat va clorua ca kim loi kim l nhng cht lm tng ninh kt: Khi chng tc dng vi Ca(OH)2 to ra cc lin kt kh tan:Ca(OH)2 +Na2CO3=CaCO3+2NaOH CaCO3 l cht t tan,Ca(OH)2 b tch ra lm cho qu trnh thu phn C3S c tng cng ngha: -khi xm bt u ninh kt n mt tnh do,do khong thi gian ny fi thi cng,thi gian ninh kt cng chm th cng d thi cng.Theo TCVN thi gian bt u ninh kt >=45 -thi gian ninh kt xong l khong thi gian xm t c cng nht nh,thi gian ny fi ngn c th thi cng nhanh,yu cu ko c vt qu 10h