TCVN_4453_1995_Ket Cau Be Tong Va Be Tong Cot Thep Toan Khoi - Quy Pham Thi Cong Va Nghiem Thu

Tiu chun vit nam tcvn 4453 : 1995

Tiu chun bt buc p dng tng phn

Kt cu b tng v b tng ct thp ton khi r Quy phmthi cng v nghim thu.

check and acceptance

1.

1.1. Tiu chun ny p dng cho vic thi cng b tng do cc t chc xy dng thc hin. Cc cng trnh c cng tc thi cng b tng do n|c ngoi u t| hoc lin doanh gp vn, nu khng c cc ch dn k thut ring cng p dng tiu chun ny.

cht l|ng thi cng cc kt cu b tng v b tng ct thp ton khi nhm m bo cht l|ng, an ton v v sinh mi tr|ng ca khu vc xy dng cng trnh.

1.3. Tiu chun ny ch p dng cho vic thi cng cc kt cu b tng v b tng ct thp ton khi bng b tng nng thng th| ch hn hp b tng1800kg/m3 r 2500kg/m3) |c trn ngay ti cng tr|ng hoc b tng ch trn sn (b tng th|ng phm) vn chuyn t cc trm trn b tng tp trung.

a) Cc kt cu lm bng cc loi b tng t ong, b tng ct liu rng, b tng siu nng v b tng chu ha cht;

b) Cc kt cu thi cng bng ph|ng php b tng trong n|c, b tng va dng;

c) Cc kt cu b tng ng sut tr|c;

d) Cc kt cu c bit khc quy nh ring theo thit k;

2. Cc tiu chun trch dn

TCVN 5574 : 1991: Tiu chun thit k b tng ct thp

TCVN 2737 : 1990: Tiu chun thit k - Ti trng v tc ng.

TCVN 4033 : 1985: Xi mng pooclng r puzolan.

TCVN 4316 : 1986: Xi mng pooclng r x l xo.

TCVN 2682 : 1992: Xi mng pooclng.

TCVN 1770 : 1986: Ct xy dng r Yu cu k thut.

TCVN 4506 : 1987: N|c cho b tng v va r Yu cu k thut.

TCVN 5592 : 1991: B tng nng r Yu cu bo d|ng m t nhin.

TCVN 3106 : 1993: B tng nng r Ph|ng php th st.

TCVN 3118 : 1993: B tng nng r Ph|ng php xc nh c|ng nn.

TCVN 5718 : 1993: Mi bng v sn b tng ct thp trong cng trnh xy dng - Yu cu chng thm n|c.

1


TCVN 1651 : 1985: Thp ct b tng.

3. Cp pha v gio.

3.1.1. Cp pha v gio cn |c thit k v thi cng m bo cng, n nh, d tho lp, khng gy kh khn cho vic t ct thp, v m b tng.

b tng, ng thi bo v |c b tng mi d|i tc ng ca thi tit.

3.1.3. Cp pha v gio cn |c gia cng, lp dng sao cho m bo ng hnh dng v kch th|c ca kt cu theo quy nh thit k.

loi cp pha gio tiu chun |c s dng theo ch dn ca n v ch to.

3.2. Vt liu lm cp pha v gio.

do. gio c th s dng tre, lung v b|ng.

Chn vt liu no lm cp pha gio u phi da trn iu kin c th v hiu qu kinh t.

3.2.2. G lm cp pha gio |c s dng ph hp vi tiu1075 : 1971 v cc tiu chun hin hnh, ng thi c th s dng c loi g bt cp phn.

chuyn nhiu ln i vi cc loi kt cu khc nhau.

3.3. Thit k cp pha v gio.

3.3.1. Cp pha v gio phi |c thit k m bo cc yu cu ca mc 3.1, s liu

3.3.2. Cp pha vm v dm vi khu ln hn 4m phi |c thit k c vng thi cng. Tr s vng |c tnh theo cng thc:

1000

3Lf

Trong : L l khu , tnh bng m.

3.3.3. Cc b phn chu lc ca gio nn hn ch s l|ng cc thanh ni. Cc mi ni khng nn b tr trn cng mt mt ct ngang v v tr chu lc ln.

Cc thanh ging cn |c tnh ton v b tr thch hp n nh ton b h gio cp pha.

3.4. Lp dng cp pha v gio.

a) B mt cp pha tip xc vi b tng cn |c chng dnh;

b) Cp pha thnh bn ca cc kt cu t|ng, sn, dm v ct nn lp dng sao

v gio cn l|u li chng (nh| cp pha y dm, sn v ct chng);

2


c) Tr chng ca gio phi t vng chc trn nn cng, khng b tr|t v khng b bin dng khi chu ti trng v tc ng trong qu trnh thi cng.

thun li cho vic kim tra tim trc v cao ca cc kt cu.

3.4.3. Khi n nh cp pha bng dy chng v mc neo th phi tnh ton, xc nh s l|ng v v tr gi n nh h thng cp pha khi chu ti trng v tc ng trong

3.4.4. Trong qu trnh lp dng cp pha cn cu to mt s l thch hp pha d|i khi c ra mt nn n|c v rc bn c ch thot ra ngoi. Tr|c khi b tng, cc l ny |c bt kn li.

3.5. Kim tra v nghim thu cng tc lp dng cp pha v gio.

3.5.1. Cp pha v gio khi lp dng xong |c kim tra theo cc yu cu bng 1, cc sai lch khng |c v|t qu cc tr s ghi trong bng 2.

Bng 1 r Cc yu cu kim tra cp pha, gio.

1 2 3

Cp pha lp dng

chiu di thch hp k

Kt cu cp pha Bng mt m bo theo quy nh ca iu 3.3.3.

ni 3mm

kn, kht gia cc tm cp pha, gia cp pha v mt nn

Bng mt Cp pha |c ghp kn, kht, m bo khng mt n|c xi

Chi tit chn ngm v t sn Xc nh kch th|c, v tr v s l|ng bng cc ph|ng tin thch hp

m bo kch th|c, v tr v s l|ng theo quy nh

Chng dnh cp pha Bng mt Lp chng dnh ph kn cc mt cp pha tip xc vi b tng.

cc cht bn khc bn trong cp pha

nghing, cao v kch Bng mt, my trc c v cc Khng v|t qu cc tr s

m ca cp pha g Bng mt Cp pha g |c t|i n|c tr|c khi b tng

gio lp dng

Kt cu gio Bng mt, dng tay lc mnh cc ct chng, cc nm tng ct chng

gio |c lp dng m bo kch th|c, s l|ng v v tr theo thit k

3


Ct chng gio Bng mt, dng tay lc mnh cc ct chng, cc nm tng

Ct chng, |c k, m v t ln trn nn cng, m

cng v n nh Bng mt, i chiu vi thit k gio

Ct chng |c ging cho v ging ngang s l|ng, kch th|c v v tr theo thit k.

3.5.2. Vic nghim thu cng tc lp dng cp pha gio |c tin hnh ti hin tr|ng, kt hp vi vic nh gi xem quy nh bng 1 v ccsai lch khng v|t qu cc tr s ghi trong bng 2.

Tn sai lch Mc cho php, mm

1. Khong cch gia cc ct chng cp pha, cu kin chu un v khong cch gia cc tr ging n nh, neo v ct chng so vi khong cch thit k.

a) Trn mi mt di 25

b) Trn ton b khu 75

chng so vi chiu thng ng hoc nghing thit k

a) Trn mi mt di 5

b) Trn ton b chiu cao ca kt cu:

- Mng 20

- T|ng v ct tm sn ton khi c chiu cao d|i 5m 10

- T|ng v ct tm sn ton khi c chiu cao trn 5m 15

- Dm v vm 5

3. Sai lch trc cp pha so vi thit k

b) T|ng v ct 8

c) Dm x v vm 10

4. Sai lch trc cp pha tr|t, cp pha leo v cp pha di ng so vi trc cng trnh 10

3.6. Tho d cp pha gio

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3.6.1. Cp pha gio ch |c tho d khi b tng t c|ng cn thit k kt cu chu |c trng l|ng bn thn v cc ti trng tc ng khc trong giai on thi

hoc va chm mnh lm h| hi n kt cu b tng

3.6.2. Cc b phn cp pha gio khng cn chu lc sau khi b tng ng rn (nh| cp pha thnh bn ca dm, ct t|ng) c th |c tho d b tng t c|ng

2

3.6.3. i vi cp pha gio chu lc ca cc kt cu (y dm, sn, ct chng), nu khng c cc ch dn c bit ca thit k th |c tho d khi b tng t cc gi tr c|ng ghi trong bng 3.

3.6.4.khi c|ng b tng t mc thit k v c i t|ng trng chng lt.

3.6.5. Khi tho d cp pha gio cc tm sn b tng ton khi ca nh nhiu

a) Gi li ton b gio v ct chng tm sn nm k d|i tm sn sp b tng;

b) Tho d tng b phn ct chng cp pha ca tm sn pha d|i na v gi li

3.6.6. i vi cc cng trnh xy dng trong khu vc c ng t v i vi cc cng trnh c bit, tr s c|ng b tng cn t tho d cp pha chu lc do thit

3.6.7. Vic cht ti tng phn ln kt cu sau khi tho d cp pha gio cn |c tnh ton theo c|ng b tng t, loi kt cu v cc c tr|ng v ti trng trnh cc vt nt v cc h| hng khc i vi kt cu.

thc hin khi b tng t c|ng thit k.

chu lc (%R28) khi ch|a cht ti

Loi kt cu

thiu cn t tho d cp pha, %R28

c|ng tho cp pha cc ma v vng kh hu - bo d|ng b tng

TCVN 5592 : 1991, ngy

Bn, dm, vm c khu nh hn 2m 50 7

Bn, dm, vm c khu ln hn 8m 90 23

Ch thch:

1) Cc tr s ghi trong bng ch|a xt n nh h|ng ca ph gia.

5


2) i vi cc kt cu c khu nh hn 2m, c|ng ti thiu ca b tng t tho d cp pha l 50% R28 nh|ng khng |c nh hn 80N/cm

2.

4.1. Yu cu chung.

4.1.1. Ct thp dng trong thit k b tng ct thp phi m bo cc yu cu ca thit k, ng thi ph hp vi tiu chun thit k TCVN 5574 : 1991 oKt cu b tng

4.1.2. i vi thp nhp khu cn c cc chng ch k thut km theo v cn ly mu th nghim kim tra theo TCVN 197: 1985 oKim loi r Ph|ng php th kop v

4.1.3. Ct thp c th gia cng ti hin tr|ng hoc ti nh my nh|ng nn m bo mc c gii ph hp vi khi l|ng thp t|ng ng cn gia cng.

4.1.4. Khng nn s dng trong cng mt cng trnh nhiu loi thp c hnh dng v

4.1.5. Ct thp tr|c khi gia cng v tr|c khi b tng cn m bo:

a) B mt sch, khng dnh bn t, du m, khng c vy st v cc lp g;

khc khng v|t qu gii hn cho php l 2% |ng knh. Nu v|t qu gii hn ny th loi thp |c s dng theo din tch tit din thc t cn li;

c) Ct thp cn |c ko, un v nn thng.

4.2. Ct v un ct thp.

4.2.1. Ct v un ct thp ch |c thc hin bng cc ph|ng php c hc.

4.2.2. Ct thp phi |c ct un ph hp vi hnh dng, kch th|c ca thit k. Sn

thanh thp cng loi ct v un, c mi l ly 5 thnh bt k kim tra. Tr s sai lch khng v|t qu cc tr s bng 4.

Bng 4 r Kch th|c sai lch ca ct thp gia cng

Cc sai lch Mc cho php, mm

1. Sai lch v kch th|c theo chiu di ca ct thp chu lc

a) Mi mt di 5

b) Ton b chiu di 20

2. Sai lch v v tr im un 20

3. Sai lch v chiu di ct thp trong kt cu b tng khi ln:

a) Khi chiu di nh hn 10m + d

4. Sai lch v gc un ca ct thp 30

5. Sai lch v kch th|c mc un + a

Trong : d) |ng knh ct thp;

6


a) Chiu dy lp b tng bo v ct thp.

4.3. Hn ct thp

bo cht l|ng mi hn theo yu cu thit k.

Khi chn ph|ng php v cng ngh hn phi tun theo tiu chun TCXD 71 : 1977 oCh dn hn ct thp v chi tit t sn trong kt cu b tng ct thpp. Vic

dn ca c s ch to.

4.3.2. Khi hn i u cc thanh ct thp cn nng bng my hn t ng hoc bn t

4.3.3. Hn im tip xc th|ng |c dng ch to khung v l|i ct thp c |ng knh nh hn 10mm i vi thp ko ngui v |ng knh nh hn 12mm i vi thp cn nng.

ch dn c bit th thc hin theo quy nh sau:

a) i vi thp trn trn hn tt c cc im giao nhau;

cc im cn li gia cch mt hn mt theo th t xen k;

c) i vi khung ct thp dm, hn tt c cc im giao nhau.

4.3.5. Hn h quang |c dng trong cc tr|ng hp sau:

a) Hn ni di cc thanh ct thp cn nng c |ng knh ln hn 8mm;

b) Hn tt c cc chi tit t sn, cc b phn cu to v lin kt cc mi ni trong lp ghp.

a) B mt nhn, khng chy, khng t qung, khng thu hp cc b v khng c bt;

4.3.7. Lin kt hn |c tin hnh kim tra theo tng chng loi v tng l. Mi l gm 100 mi hn hoc 100 ct thp loi khung, loi l|i hn. Nhng l sn phm ny |c kim tra theo nguyn tc sau:

a) nh|ng khng t hn 5mu th ko v 3 mu th un;

b) Tr s cc sai lch so vi thit k khng v|t qu cc gi tr trong bng 6 i

Bng 5 r Sai lch cho php i vi sn phm ct thp.

Tn sai lch Mc cho php

1 2

theo di ca cc thanh gia cng ring l.

7


a) Khi |ng knh thnh ct thp khng qu 16mm

Bng 5 - kt thc

- Theo di ca sn phm 10mm

- Theo chiu rng (hoc chiu cao) ca sn phm 5mm

3mm

b) Khi |ng knh thnh ct thp 18mm r 40mm

- Theo chiu di ca sn phm 10mm

- Theo chiu cao (hoc chiu rng) ca sn phm 10mm

- Khi kch th|c ca sn phm theo chiu rng hoc chiu cao khng ln hn 1m

5mm

- Theo chiu di ca sn phm 50mm

- Theo chiu cao ca sn phm 20mm

s v kch th|c ca l|i hn v v khong cch gia cc b phn ca khung khng ging

10mm

khung khng gian vi |ng knh ca thanh l:

- Nh hn 40mm 0,5d

- Bng v ln hn 40mm 1d

knh ca cc thanh:

- Nh hn 12mm 10mm

- T 12mm n 24mm 15mm

- T 20mm n 50mm 20mm

- Ln hn 50mm 25mm

5. Sai lch v v tr ch un ca thanh 2d

7. Sai lch v vng cc khung ct thp chu lc so vi thit k 5%

Bng 6 r Sai lch cho php i vi mi hn

1 2

1. S x dch ca |ng ni tm ca 2 thanh np trn i vi trc ca thanh |c ni (khi c thanh np v |ng hn v mt bn)

0,1d v bn ca mi hn

2. Sai lch v chiu di ca cc thanh m v thanh np 0,5d

3. X dch thanh np so vi trc ca mi hn c khun 0,1d

8


4. X dch thanh np so vi trc ca mi hn theo h|ng dc (tr cc mi hn c thanh np t lch) 0,5d

6. X dch tim ca cc thanh mi ni

Bng 6 r Kt thc

a) Khi hn c khun 0,10d

b) Khi hn c cc thanh np trn 0,10d

c) Khi hn i u 0,10d

7. Sai s v chiu di ca cc mi hn cnh 0,5d

8. Sai s v chiu rng ca cc mi hn cnh 0,15d

9. Chiu rng chn mi hn khng bm vo thp gc khi hn bng

40mm 0,1d

10.Chiu su vt lm cho tia h quang thp tm v thp hnh khi hn

11. S l|ng l rng v x ngm vo trong mi hn

- Trn b mt mi hn trong di khong 2d 3 ch

Khi d nh hn hoc bng 16mm

Khi d ln hn 16mm

12. |ng knh trung bnh l rng v x ngm vo mi hn

2 ch

3 ch

- Trn mt mi hn

- Trong tit din mi hn

Khi d t 16mm tr xung

1,5mm

1,0mm

4.4. Ni buc ct thp:

4.4.1. Vic ni buc (ni chng ln nhau) i vi cc loi thp |c thc hin theo quy nh ca thit k. Khng ni cc v tr chu lc ln v ch un cong. Trong mt

thp chu lc i vi thp trn trn v khng qu 50% i vi thp c g.

4.4.2. Vic ni buc ct thp phi tha mn cc yu cu sau:

khng |c nh hn 250mm i vi thp chu ko v khng nh hn 200mm i vi thp chu nn. Cc kt cu khc chiu di ni buc khng nh hn cc tr s bng 6;

thp c g khng un mc;

9


c) Dy buc dng loi dy thp mm c |ng knh 1mm;

d) Trong cc mi ni cn buc t nht l 3 v tr ( gia v hai u).

Trong mi tr|ng hp vic thay i ct thp phi |c s ng ca thit k. Tr|ng hp s dng ct thp x l ngui thay th ct thp cn nng th nht thit phi |c s ng ca c quan thit k v ch u t|.

4.6. Vn chuyn v lp dng ct thp.

4.6.1. Vic vn chuyn ct thp gia cng m bo cc yu cu sau:

a) Khng lm h| hng v bin dng sn phm ct thp;

b) Ct thp tng thanh nn buc thnh tng l theo chn loi v s l|ng trnhnhm ln khi s dng;

c) Cc khung, l|i ct thp ln nn c bin php phn chia thnh tng b phn

Chiu di ni buc

Dm hoc t|ng

Kt cu khc u ct thp c mc

u ct thp khng

c mc

Ct thp c g cn nng

Ct thp ko ngui

40d

45d

30d

35d

-

20d

20d

30d

4.6.2. Cng tc lp dng ct thp cn tha mn cc yu cu sau:

b) C bin php n nh v tr ct thp khng bin dng trong qu trnh b tng;

c) Khi t ct thp v ct pha ta vo nhau to thnh mt t hp cng th cp pha

nh ca thit k.

4.6.3. Cc con k cn t ti cc v tr thch hp tu theo mt ct thp nh|ng khng ln hn 1m mt im k. Con k c chiu |c lm bng cc loi vt liu khng n mn ct thp, khng ph hu b tng.

Sai lch chiu dy lp b tng bo v so vi thit k khng v|t qu 3mm i vi lp b tng bo v c chiu dy a nh hn 15mm v 5mm i vi lp b tng bo

4.6.4. Vic lin kt cc thanh ct thp khi lp dng cn |c thc hin theo cc yu cu sau:

10


a) S l|ng mi ni buc hay hn dnh khng nh hn 50% s im giao nhau, theo th t xen k;

hn dnh 100%.

4.6.5. Vic ni cc thanh ct thp n vo khung v l|i ct thp phi |c thc hin theo ng quy nh ca thit k. Khi ni buc khung v l|i ct thp theo ph|ng

nh|ng khng nh hn 25mm.

Mc b tng

Mc 150 Mc 200

Vng chu ko

Vng chu nn

Vng chu ko Vng chu nn

Ct thp c g cn 20d 20d 25d 15d

Ct thp trn cn nng

Ct thp ko ngui v rt ngui

35d

40d

25d

30d

30d

35d

20d

25d

Ch thch: d- |ng knh ca ct thp chu lc.

4.6.6. Chuyn v ca tng thanh thp khi ch to hoc khi lp dng khung l|i ct thp

thn thanh . Sai lch cho php i vi ct thp lp dng |c quy nh bng 9.

Tn sai lch Mc cho php, mm

1. Sai s v khong cch gia cc thanh chu lc t ring bit:

a) i vi kt cu khi ln. 30

c) i vi bn, t|ng v mng d|i cc kt cu khung

2. Sai s v khong cch gia cc hng ct thp khi b tr nhiu hng theo chiu cao:

20

thit b k thut.

b) Dm khung v bn c chiu dy ln hn 100mm.

20

5

3. Sai s v khong cch gia cc ct thp ai ca dm, ct, khung v dn ct thp. 10

11


4. Sai lch cc b v chiu dy v lp bo v.

a) Cc kt cu khi ln (chiu dy ln hn 1m)

c) Ct dm v vm

d) T|ng v bn chiu dy ln hn 100mm.

10

5

10mm.

5. Sai lch v khong cch gia cc thanh phn b trong mt hng.

a) i vi bn t|ng v mng d|i kt cu khung.

3

25

6. Sai lch v v tr cc ct thp ai so vi chiu ng hoc chiu ngang (khng kt cc tr|ng hp khi cc ct thp ai t nghing vi thit k quy nh).

40

10

Bng 9 - Kt thc

1 2

7. Sai lch v v tr tim ca cc thanh t cc u khung hn ni tihin tr|ng vi cc khung khc khi |ng knh ca thanh:

a) Nh hn 40mm. 5

8. Sai lch v v tr cc mi hn ca cc thanh theo chiu di ca cu kin.

a) Cc khung v cc kt cu t|ng mng. 25

9. Sai lch ca v tr cc b phn ct thp theo trong kt cu khi ln (khung, khi, dn) so vi thit k:

50

b) Theo chiu cao. 30

4.7.1. Kim tra cng tc ct thp bao gm cc phn vic sau:

a) S ph hp ca cc loi ct thp |a vo s dng so vi thit k;

tr|c khi gia cng. Tr s sai lch cho php i vi ct thp gia cng ghi bng 4;

c) Cng tc hn: bc th, thit b, que hn, cng ngh hn v cht l|ng mi hn. ct thp gia cng hn theo bng 5

v cht l|ng mi hn theo bng 6.

d) S ph hp v vic thay i ct thp so vi thit k.

- S ph hp ca ph|ng tin vn chuyn i vi sn phm gia cng.

12


- Chng loi, v tr, kch th|c v s l|ng ct thp lp dng so vi thit k; Tr s sai lch cho php i vi cng tc lp dng ct thp |c quy nh

- S ph hp ca cc loi thp ch v chi tit t sn so vi thit k;

- S ph hp ca cc loi vt liu lm con k, mt cc im k v sai lch chiu dy lp b tng bo v so vi thit k. Chiu dy lp b tng bo v ct

4.7.2. Trnh t, yu cu v ph|ng php kim tra cng tc ct thp thc hin theo quy nh bng 10.

4.7.3.ca iu 4.7.1. v bng 10 nh gi cht l|ng cng tc ct thp so vi thit k tr|c khi b tng.

4.7.4. Khi nghim thu phi c h s bao gm:

a) Cc bn v thit k c ghi y s thay i v ct thp trong qu trnh thi cng v km bin bn v quyt nh thay i;

b) Cc kt qu kim tra mu th v cht l|ng thp, mi hn v cht l|ng gia

c) Cc bin bn thay i ct thp trn cng tr|ng so vi thit k;

d) Cc bin bn nghim thu k thut trong qu trnh gia cng v lp dng ct

e) Nht k thi cng.

Bng 10 - Kim tra cng tc ct thp.

Yu cu kim tra

Ph|ng php

kim tra

Kt qu

kim tra

Tn s

kim tra

1 2 3 4

Theo phiu giao hng, chng ch v quan st g ct thp

C chng ch v ct thp |c cung cp ng yu cu

Mi ln nhn hngCt thp

th|c kp c kh ng |ng knh yu cu hng

Th mu theo TCVN 197 : 1985, TCVN 198 : 1985.

m bo yu cu theo thit k Tr|c khi giao hng

Mt ngoi ct thp

Bng mt B mt sch, khng b gim tit din cc b

Tr|c khi giao hng

13


Ct v un Bng mt m bo quy trnh k thut Khi gia cng

Ct thp o bng th|c c Sai lch khng v|t qu cc tr Mi l, 100 thanh

kim tra

Thit b hn m bo cc thng s k thut Tr|c khi hn v theo nh k 3

Bc th: Hn mu th t tiu chun bc th hn theo quy nh

Tr|c khi thc hin cng tc hn.

Bng mt, o bng Mi hn m bo yu cu theo Sau khi hn v khi

Th nghim mu m bo cht l|ng. Nu mt mu khng t phi kim tra li vi s l|ng mu gp i

Mi l 100 mi hn, ly 3 mu kim tra c|ng

Kim tra bng siu m theo TCVN 1548 : 1985

Mi hn m bo cht l|ng theo yu cu

Khi cn thit hoc khi nghi ng

1 2 3 4

Thp ch v chi tit t sn

Xc nh v tr, kch th|c v s l|ng

m bo cc yu cu theo quy nh ca thit k

Tr|c khi b tng

thch hp

Ni buc ct thp

Bng mt, o bng th|c

Chiu di ni chng, m bo theo yu cu ca bng 7 v bng

Trong v sau khi lp dng

Lp dng ct thp

Bng mt, o bng th|c c chiu di thch hp

- Lp dng ng quy trnh k thut.

Khi lp dng v khi nghim thu

kch th|c ng theo thit k.

- Sai lch khng v|t qu cc tr s ghi bng 9

th|c 4.6.3. thp.

Chiu dy lp b tng bo v

Bng mt, o bng th|c

m bo tr s sai lch theo iu 4.6.3 hoc theo quy nh

Khi lp dng v khi nghim thu

Thay i ct thp

Kim tra bng tnh ton

Ct thp thay i ph hp vi cc quy nh ca thit k

Tr|c khi gia cng ct thp.

5. Vt liu sn xut b tng.

5.1. Yu cu chung

5.1.1. Cc vt liu sn xut b tng phi m bo yu cu k thut theo cc tiu chun

14


5.1.2. Trong qu trnh l|u kho, vn chuyn v ch to b tng, vt liu phi |c |c bo qun, trnh nhim bn hoc b ln ln c ht v chng loi. Khi gp cc

l|ng.

5.1.3. Cc loi vt liu khng hon ton ph hp tiu chun hoc khng cp trong tiu chun ny, ch s dng sn xut b tng, nu c lun c khoa hc v cng

|c s ng ca ch u t|.

5.2. Xi mng

5.2.1. Xi mng s dng phi tha mn cc quy nh ca cc tiu chun:

- Xi mng poclng TCVN 2682 : 1985.

- Xi mng poc r lng Pufzlan TCVN 4033 : 1985.

- Xi mng poclng - x ht l cao TCVN 4316 : 1986.

Cc loi xi mng c bit nh| xi mng bn sunft, xi mng t ta nhite. dng theo ch dn ca thit k.

5.2.2. Chng loi v mc xi mng s dng phi ph hp vi thit k v iu kin, tnh

5.2.3. Vic s dng xi mng nhp khu nht thit phi c chng ch k thut ca n|c sn xut. Khi cn thit phi th nghim kim tra xc nh cht l|ng theo tiu chun Vit Nam hin hnh.

5.2.4. hin tr|ng nht thit phi tin hnh trong cc tr|nghp.

a) Khi thit k thnh phn b tng;

c) L xi mng |c bo qun trn 3 thng k t ngy sn xut.

5.2.5. Vic vn chuyn v bo qun xi mng phi tun theo tiu chun TCVN 2682 ;

5.3. Ct.

5.3.1. Ct dng lm b tng nng phi tha mn cc yu cu ca tiu chun TCVN 1770 : 1986 oCt xy dng r Yu cy k thutp.

Ch thch: i vi cc loi ct c ht nh (m un ln d|i 2), khi s dng phi tuntheo tiu chun 20 TCVN 127 : 1986 oCt mn lm b tng v va xy dngp.

- Th nghim kim tra cht l|ng ct |c tin hnh theo cc tiu chun t TCVN 337 : 1986 n TC

- Nu dng ct vng bin hoc vng n|c l th nht thit kim tra hm l|ng Cl- v SO4

--. Nu dng ct m, ct i th cn phi kim tra c hm l|ng Silic v nh hnh.

dng v cn c bin php chng gi bay m|a tri v ln tp cht.

5.4. Ct liu ln.

dm p t si thin nhin. Khi s dng cc loi ct liu ln ny phi m bo

15


cht l|ng theo quy nh ca tiu chun TCVN 1771 : 1986 o dm, si dm, si dng trong xy dngp.

thnh nhm c kch th|c ht ph hp vi nhng quy nh sau:

a) i vi bn, kch th|c ht ln nht khng |c ln hn 1/2 chiu dy bn;

b) i vi cc kt cu b tng ct thp, kch th|c ht ln nht khng |c ln

c) i vi cng trnh thi cng cp pha tr|t, kch th|c ht ln nht khng qu 1/10 kch th|c cnh nh nht theo mt ct ngang ca kt cu;

3

dm v si khng v|t qu 120mm. Khi dng my trn c th tch nh hn 0,8m2, kch th|c ln nht khng v|t qu 80mm;

e) Khi vn chuyn b tng bng my bm b tng, kch th|c ht ln nht khng

dm;

f) Khi b tng bng ng vi voi, kch th|c ht ln nht khng ln hn 1/3

5.5. N|c

N|c dng trn v bo d|ng b tng phi m bo yu cu ca tiu chun TCVN 4506 : 1987 oN|c cho b tng v va r Yu cu k thutp.

o d|ng b tng. Khng dngn|c thi ca cc nh my, n|c bn t h thng thot n|c sinh hot, n|c ao h cha nhiu bn, n|c ln du m trn v bo d|ng b tng.

5.6.1. tit kim xi mng hoc ci thin cc c tnh k thut ca hn hp b tng v b tng, c th dng cc loi ph gia thch hp trong qu trnh ch to b tng.

Vic s dng ph gia phi m bo:

a) To ra hn hp b tng c tnh nng ph hp vi cng ngh thi cng;

b) Khng gy nh h|ng n tin thi cng v khng tc hi ti yu cu s dng ca cng trnh sau ny;

5.6.2. Cc loi ph gia s dng phi c chng ch k thut |c cc c quan qun l Nh n|c cng nhn. Vic s dng ph gia cn tun theo ch dn ca ni sn xut.

Cc cht n vo b tng phi m bo khng nh h|ng n tui th ca b tng v khng gy n mn ct thp.

Khi s dng cc cht n phi thng qua th nghim c c s kinh t k thut,

Ch thch:

1) Cht n l nhng cht khong mn c th thm vo b tng ci thin mt s tnh

2) C hai loi cht n: cht n dng tr v cht n c hot tnh (bt x qung tro nhit in, bn puzlane).

16


6. Thi cng b tng

6.1. Chn thnh phn b tng (bt buc p dng).

trnh hoc tng b phn cng trnh, trn c s quy nh mc b tng ca thit k thnh phn b tng |c chn nh| sau:

a) i vi b tng mc 100 c th s dng bng tnh sn ghi ph lc C;

b) i vi b tng mc 150 tr ln th thnh phn vt liu trong b tng phi |c thit k thng qua phng th nghim (tnh ton v c mu th nghim).

6.1.2. Thit k thnh phn b tng

thc hin. Khi thit k thnh phn b tng phi m bo cc nguyn tc:

a) S dng ng cc vt liu s dng thi cng;

cng trnh, hm l|ng ct thp, ph|ng php vn chuyn, iu kin thi tit. Khi chn st ca hn hp b tng thit k cn tnh ti s tn tht st trong thi gian l|u gi v vn chuyn. st ca hn hp b tng ti v tr

Bng 11 - st v cng ca hn hp b tng ti v tr

st Loi v tnh cht ca kt cu

m my m tay

Ch s cng

S

bng

- Mt |ng v |ng bng, nn nh, kt cu khi ln khng hoc t ct thp (t|ng chn, mng block e.)

0 r 20

-

20 r 40 35 r 25

- Kt cu khi ln c tit din ln hoc trung bnh

- Kt cu b tng ct thp c mt ct thp dy c, t|ng mng, phu sil, ct, dm v bn tit din be cc kt cu

50 r 80 80 r 120 12 r 10

- Cc kt cu bng b tng bm 120 - 200

6.1.3. Hiu chnh thnh phn b tng ti hin tr|ng.

Vic hiu chnh thnh phn b tng ti hin tr|ng |c tin hnh theo nguyn tc khng lm thay i t l N/X ca thnh phn b tng thit k.

Khi ct liu m cn gim bt l|ng n|c trn, gi nguyn st yu cu.

ng thi thm n|c v xi mng gi nguyn t l N/X.

6.1.4. Tu thuc quy m v mc ca cng trnh m xc nh cc loi h s th nghim

6.2. Ch to hn hp b tng

17


6.2.1. Xi mng, ct, dm hoc si v cc cht ph gia lng ch to hn hp b tng |c cn theo khi l|ng. N|c v cht ph gia cn ong theo th tch. Sai s cho

6.2.2. Ct ra xong, kh ro mi tin hnh cn ong nhm gim l|ng n|c ngm trong ct.

6.2.3. chnh xc ca thit b cn ong phi kim tra tr|c mi t b tng. Trong

6.2.4. Hn hp b tng cn |c trn bng my. Ch khi no khi l|ng t mi trn bng tay.

Bng 12 r Sai lch cho php khi cn ong thnh phn ca b tng

theo khi l|ng

Xi mng v ph gia dng bt

Ct, dm, hoc si

1

3

trong ct liu m.

6.2.5. Trnh t vt liu vo my trn cn theo quy nh sau:

a) Tr|c ht 15% - 20% l|ng n|c, sau xi mng v ct liu cng mt n tc phn n|c cn li;

b) Khi dng ph gia th vic trn ph gia phi thc hin theo ch dn ca ng|i sn xut ph gia.

dng trn. Trong tr|ng hp khng c cc thng s k thut chun xc th thi gian t nht trn u mt m b tng my trn c th ly theo cc tr s ghi bng 13.

Bng 13 - Thi gian trn hn hp b tng (pht)

(mm) D|i 500 T 500 n 1000 Trn 1000

Nh hn 10 2,0 2,5 3,0

trn 50 1,0 1,5 2,0

6.2.7. Trong qu trnh trn trnh hn hp bm dnh vo thng trn, c sau 2 gii lm vic cn vo thng trn ton b ct liu ln v n|c ca mt m trn v quay

18


my trn khong 5 pht, sau cho ct v xi mng vo trn tip theo thi gian quy nh.

Tr|c khi trn cn t|i m sn trn chng ht n|c t hn hp b tng. Th t trn hn hp bng th cng nh| sau: Trn u ct v xi mng, sau cho v trn u thnh hn hp kh, cui cng cho n|c v trn u cho n khi |c hn hp

6.3. Vn chuyn hn hp b tng.

6.3.1. Vic vn chuyn hn hp b tng t ni trn n ni cn m bo cc yu cu:

tng, b chy n|c xi mng v b mt n|c do gi nng.

b) S dng thit b, nhn lc hn hp v ph|ng tin vn chuyn cn b tr ph hp vi khi l|ng, tc trn, v m b tng;

xc nh bng th nghim trn c s iu kin thi tit, loi xi mng v loi ph gia s dng. Nu khng c cc s liu th nghim c th tham kho cc tr s ghi bng 14.

Bng 14 - Thi gian l|u hn hp b tng khng c ph gia

Nhit (0C) Thi gian vn chuyn cho php, pht

Ln hn 30

20 r 30

30

45

5 r 10 90

6.3.2. Vn chuyn hn hp b tng bng th cng ch p dng vi c ly khng xa qu 200m. Nu hn hp b tng b phn tng cn trn li tr|c khi vo cp pha.

6.3.3. Khi dng thng treo vn chuyn hn hp b tng th hn hp b tng vo thng treo khng v|t qu 90 r 95% dung tch ca thng.

6.3.4. Vn chuyn hn hp b tng bng t hoc thit b chuyn dng cn m bo cc quy nh ca iu 6.3.1. v cc yu cu sau:

;

b) Nu vn chuyn bng thit b chuyn dng va i va trn th cng ngh vn chuyn |c xc nh theo cc thng s k thut ca thit b s dng.

6.3.5. Khi dng my bm b tng vn chuyn phi m bo cc yu cu sau:

a) Thnh phn v st ca hn hp b tng cn |c th nghim v bm th nhm m bo cht l|ng b tng v iu kin thi cng, ng thi ph hp vi

b) Khi thi cng trong thi tit nng, mt ngoi ng cn che ph hoc sn trng hn ch bc x mt tri lm nng b tng.

19


6.3.6. Khi vn chuyn hn hp b tng bng bng chuyn phi m bo cc yu cu d|i y:

chuyn cao su. Bng chuyn dng phng ch s dng khi chiu di |ng vn chuyn d|i 200m;

b) Gc nghing ca bng chuyn khng v|t qu cc tr s bng 15. Mt bng

c) Tc vn chuyn ca bng chuyn khng v|t qu 1m/s. Tc vn chuyn ca cc bng chuyn trong h thng khng chnh lch nhau qu 0,1m/s;

b tng |c ri u v lin tc trn bng chuyn. Chiu dy ca lp b tng trn bng chuyn ph thuc vo sc chu ti cho php ca tng loi bng chuyn;

chuyn vo cp pha cn thc hin qua ng phu h|ng hn hp b tng ri thng ng.

Bng 15 r Gc nghing gii hn ca bng chuyn ().

st Khi vn chuyn b tng Khi vn chuyn b tng

(mm) ln cao

Nh hn 40 15 12

40 r 80 15 10

6.4. v m b tng

6.4.1. Vic b tng phi m bo cc yu cu:

v ct thp.

b) Khng dng m di dch chuyn ngang b tng trong cp pha;

quy nh ca thit k.

6.4.2. trnh s phn tng, chiu cao ri t do ca hn hp b tng khi khng v|t qu 1,5m.

ng vi voi. Nu chiu cao ri trn 10m phi dng ng vi voi c thit b chn ng.

0,25m trn 1m chiu cao, trong mi tr|ng hp phi m bo on ng d|i cngthng ng.

6.4.4. Khi dng mng nghing th mng phi kn v nhn. Chiu rng ca mng khng

m bo hn hp b tng khng b tc, khng tr|t nhanh sinh ra hin t|ng phn tng. Cui mng cn t phu thng ng h|ng hn hp b tng ri

20


thng ng vo v tr v th|ng xuyn v sinh sch va xi mng trong lng mng nghing.

a) Gim st cht ch hin trng cp pha gio v ct thp trong qu trnh thi cng x l kp thi nu c s c xy ra;

b) Mc y hn hp b tng vo cp pha phi ph hp vi s liu tnh ton

c) nhng v tr m cu to ct thp v cp pha khng cho php m my mi m th cng;

hp ngng b tng qu thi gian quy nh (bng 18) phi i n khi b tng t 25 daN/cm2 mi |c b tng, tr|c khi li b tng phi x l lm nhm mt. b tng vo ban m v khi c s|ng m phi m bo

6.4.6. Chiu dy mi lp b tng phi cn c vo nng lc trn, c| li vn chuyn, kh nng m, tnh cht ca kt cu v iu kin thi tit quyt nh, nh|ng khng v|t qu cc tr s ghi trong bng 16.

Bng 16 - Chiu dy lp b tng

Ph|ng php m Chiu dy cho php mi lp b tng, cm

m di 1,25 chiu di phn cng tc ca m

m mt: (m bn)

- Kt cu khng c ct thp v kt cu c ct thp n

20

12- Kt cu c ct thp kp

m th cng 20

Khi b tng mng cn m bo cc quy nh ca iu 6.4.1. B tng mng ch |c ln lp m sch trn nn t cng.

Ct c chiu cao nh hn 5m v t|ng c chiu cao hn 3m th nn lin tc.

Ct c kch th|c cnh nh hn 40cm, t|ng c chiu dy nh hn 15cm v cc ct c tit din bt k nh|ng c ai ct thp chng cho th nn b tng lin tc

Ct cao hn 5m v t|ng cao hn 3m nn chia lm nhiu t b tng, nh|ng phi bo m v tr v cu to mch ngng thi cng hp l.

Kt cu khung nn b tng lin tc, ch khi cn thit mi cu to mch ngng, nh|ng phi theo quy nh ca iu 6.6.4.

21


6.4.10. b tng dm, bn.

Khi cn lin tc b tng dm, bn ton khi vi ct hay t|ng, tr|c ht

ngt ban u, mi tip tc b tng dm v bn. Tr|ng hp khng cn b tng lin tc th mch ngng thi cng ct v t|ng t cch mt d|i ca dm v bn t 2cm r 3cm.

cc kt cu t|ng t c kch th|c ln (chiu cao ln hn 80cm) c th ring tng phn nh|ng phi b tr mch ngng thi cng thch hp theo quy nh ca iu 6.6.5.

6.4.11.

Cc kt cu vm phi b tng ng thi t hai bn chn vm n nh vm, khng bn thp bn cao. Nu c mch ngng thi cng th mt phng ca mch

Vm c khu d|i 10m nn b tng lin tc t chn vm n nh vm.

Vm c khu ln hn 10m th c 2m r 3m c mt mch ngng vung gc vi trc cong ca vm, rng 0,6m r 0,8m. Cc mch ngng ny |c chn lp bng b

6.4.12. b tng t|ng trn c xy vm ca t|ng hm phi m bo cc quy nh sau:

40c th dng li, b tng c thi gian co ngt v sau thi cng vm.

b) Phn b tng tip gip gia t|ng v chn vm cn |c x l m bo yu cu theo quy nh ca thit k.

6.4.13. ng bng sn bay phi m bo cc yu cusau:

a) b tng lin tc ht ton b chiu dy mi lp b tng;

nh th khe co gin nhit m |c t theo hai chiu vung gc cch nhau 4m r 6m, chiu rng khe 1cm r 2cm v c chiu cao bng chiu dy kt cu;

c) Thi gian ngng b tng gia hai lp phi ph hp vi iu 6.8.2.

6.4.14. m b tng.

Vic m b tng phi m bo cc yu cu sau:

a) C th dng cc loi m khc nhau, nh|ng phi m bo sao cho sau khi m

b) Thi gian m ti mi v tr phi m bo cho b tng |c m k. Du hin nhn bit b tng |c m k l va xi mng ni ln b mt v b kh

c) Khi s dng m di, b|c di chuyn ca m khng v|t qu 1,5 bn knh tc dng ca m v phi cm su vo lp b tng tr|c 10cm;

d) Khi cn m li b tng th thi im m thch hp l 1,5 gi - 2 gi sau khi

mt ln nh| sn mi, sn bi, mt |ng t e. khng m li cho b tng khi ln.

22


6.5. Bo d|ng b tng (bt buc p dng)

6.5.1. Sau khi b tng phi |c bo d|ng trong iu kin c m v nhit cn

b tng.

6.5.2. Bn d|ng m

Bo d|ng m l qu trnh gi cho b tng c m cn thit ninh kt v

TCVN 5592 : 1991 oB tng nng r yu cu bo d|ng m t nhin)p.

Thi gian bo d|ng m cn thit khng |c nh hn cc tr s ghi trong bng

nh| rung ng, lc xung kch, ti trng v cc tc ng c kh nng gy h| hi khc.

Vng kh hu

tng m

Vng A H IV r IX

X r III

50 r 55

40 r 50

3

4

Vng B

Vng C

Kh

M|a

Kh

II r VII

VIII r I

XII r IV

55 r 60

35 r 40

70

4

2

6

M|a V r XI 30 1

Rth BD r C|ng bo d|ng ti hn;

Tct BD - thi gian bo cn thit

Vng B (Pha ng Tr|ng Sn v t Din Chu n Thun Hi)

Vng C (Ty Nguyn v Nam B)

6.6.1. Yu cu chung

Mch ngng thi cng phi t v tr m lc ct v mmen un t|ng i nh,

6.6.2. Mch ngng thi cng nm ngang:

- Mch ngng thi cng nm ngang nn t v tr bng chiu cao cp pha.

- Tr|c khi b tng mi, b mt b tng c cn |c x l, lm nhm, lm o lp b tng mi bm cht vo lp b

tng c, m bo tnh lin khi ca kt cu.

23


6.6.3. Mch ngng thng ng.

Mch ngng thi cng theo chiu thng ng hoc theo chiu nghing nn cu to

Tr|c khi lp b tng mi cn t|i n|c lm m b mt b tng c, lm nhm b mt, ra sch v trong khi phi m k m bo tnh lin khi ca kt cu.

Mch ngng ct nn t cc v tr sau:

a) mt trn ca mng

b) mt d|i ca dm, x hay d|i cng xn dm cn trc.

c) mt trn ca dm cn trc.

6.6.5. Dm c kch th|c ln v lin khi vi bn th mch ngng thi cng b tr cch

6.6.6. Khi b tng sn phng th mch ngng thi cng c th t bt k v tr no nh|ng phi song song vi cnh ngn nht ca sn.

ngng thi cng b tr trong khong 1/3 on gia ca nhp dm.

Khi b tng theo h|ng song song vi dm chnh th mch ngng thi cng b tr trong hai khong gia ca nhp dm v sn (mi khong di 1/4 nhp).

6.6.8. cha, cng trnh thu li, cu v cc bphn phc tp ca cng trnh, mch ngng thi cng phi thc hin theo quy nh ca thit k.

6.7.1. Cc mi v sn c lp b tng chng thm n|c u phi |c thi cng ng theo yu cu ca TCVN 5718 : 1993 oMi bng v sn b tng ct thp trong cng trnh xy dng r Yu cu chng thm n|cp.

thng gc. i vi mi khng c lp chng nng, khe co gin phi t cch nhau 6m r 9m. i vi mi c lp chng nng m bo yu cu k thut, khong cch khe co gin khng v|t qu 18m.

6.8. Thi cng b tng khi ln

6.8.1. Cc kt cu b tng v b tng ct thp |c gi l khi ln khi kch th|c cnh nh nht khng d|i 2,5m v chiu dy ln hn 0,8m.

chnh lch nhit gia mt ngoi v trong lng khi b tng trong qu trnh ng rn.

Ch thch: Cc bin php khng ch nhit phi thc hin theo cc ch dn ca thit k. Tr|ng hp thit k khng ch dn c th hn ch bt ng sut nhit bng cc binphp sau:

a) Dng ph gia ha do gim l|ng xi mng

c) Dng ph gia chm ng kt;

24


d) Lm lnh ct liu v trn b tng bng n|c nhit thp;

e) t cc |ng ng dn nhit t trong lng b tng ra ngoi bng n|c lnh;

g) Che ph quanh khi b tng bng vt liu cch nhit gi ng u nhit trong khi b tng;

chia khi cn xc nh c th c tnh n iu kin thi cng, vt liu b tng, iu kin thi tit v c im kt cu.

6.8.2. Khi thi cng b tng khi ln phi thc hin nhng quy nh sau:

khi phi |c nh xm m bo tnh lin khi;

b) Vic b tng khp kn cc khi chn |c thc hin sau khi cc khi

chc thi cng;

c) i vi mng chu ti trng ng nn b tng lin tc, khng c mch ngng thi cng. Tr|ng hp cn c mch ngng ph hp vi iu kin thi

d) B tng phi lin tc thnh nhiu lp c chiu dy u nhau, ph hp vi c tr|ng ca my m s dng v theo mt ph|ng nht nh cho tt c cc lp.

hin khi c thit k thi cng v cc ch dn v cng ngh b tng bc thang;

phi qua th nghim, cn c vo nhit mi tr|ng, iu kin thi tit, tnh cht ca xi mng s dng v cc nhn t khc quyt nh.

Ch thch:

khng c iu kin th nghim.

2) Nu thi gian tm ngng v|t qu thi gian quy nh trong bng 18 th phi x l b mt b tng.

Bng 18 - Thi gian ngng cho php khi b tng khng c ph gia (pht)

Nhit trong khi

khi b tng, 0C

Xi mng

Poclng

Xi mng Poclng r X xi mng Puzolan

Ln hn 30 60 90

10 r 20 135 180

Khi x l cn thc hin nh| sau:

25


- C|ng ca lp b tng bn d|i ch|a t n 25daN/cm2 th khng |c lm cng tc chun b trn mt lp b tng khc;

-

st lm nhm mt b tng;

- Tr|c khi b tng lp trn, mt b tng x l phi v sinh sch, ht kh n|c v ri mt lp va xi mng ct vng dy 2cm r 3cm.

xem xt kh nng khng ch vt nt v nhit. Trnh tho cp pha khi c s chnh lch nhit gia khi b tng v nhit mi tr|ng. Khng tho cp pha khi c lung gi lnh. Khi nhit trong lng b tng v nhit mi tr|ng chnh lch nhau qu 15 C r 20pha.

6.8.4. Nhng kt cu khi ln khng c ct thp hoc c t ct thp c th n thm

l|ng theo yu cu thit k.

Khi thi cng b tng c n thm hc cn m bo cc quy nh sau:

a) Kch th|c cnh nh nht ca kt cu khi ln |c n hc phi ln hn

Kch th|c ln nht ca hc khng |c ln hn 1/3 kch th|c nh nht ca khi . c dng thoi dt khng |c s dng. C|ng ca hc

b) hc |c xp th|a cch u trong khi b tng theo mi pha vi khong cch khng nh hn 30cm. B tng nm trong vng chu ko khng |c n thm hc;

hc thch hp, sao cho hc c nhit t|ng |ng vi nhit ca hn hp b tng ngay sau khi trn.

6.8.5. Bo d|ng b tng khi ln

Nhim v ch yu ca vic bo d|ng b tng khi ln l khng ch s chnh lch nhit gia b mt b tng v trong lng khi b tng nhm hn ch vt nt v nhit. Vic bo d|ng ny phi cn c vo iu kin thc t m p dng cc bin

a) Dn nhit t trong lng khi b tng ra ngoi bng |ng ng vi n|c c nhit thp hoc bng khng kh lnh;

b) Bao ph b mt b tng gi cho nhit ca khi b tng |c ng u t

c) Khng tho d cp pha tr|c by ngy.

6.9. Thi cng b tng trong thi tit nng v trong ma m|a.

cao hn 300C. Cn p dng cc bin php phng nga v x l thch hp i vi vt liu, qu trnh trn, , m v bo d|ng b tng khng lm tn hi n cht l|ng b tng do nhit cao ca mi tr|ng gy ra.

6.9.2. Nhit ca hn hp b tng t my trn nn khng ch khng ln hn 300C vkhi khng ln hn 350C.

26


6.9.3. Vic khng ch nhit hn hp b tng c th cn c vo iu kin thc t p dng nh| sau:

trn v bo d|ng b tng;

b) Thit b, ph|ng tin thi cng, bi ct , ni trn v ni b tng cn |c che nng;

c)

d) Dng ph gia ha do c c tnh ph hp vi mi tr|ng nhit cao;

e) b tng vo ban m hoc sng sm v khng nn thi cng b tng vo 0

6.9.4. Khi thi cng b tng khi ln trong thi tit nng phi m bo cc quy nh ca phn 6.8.

6.9.5. cn m bo cc

a) Phi c cc bin php tiu thot n|c cho bi ct, , |ng vn chuyn, ni trn v ni b tng;

b) Tng c|ng cng tc th nghim xc nh m ca ct liu kp thi iu

thnh phn chn;

c) Cn c mi che chn trn khi khi tin hnh thi cng b tng d|i tri m|a.

6.10.1. Qu trnh thi cng b tng bng cp pha tr|t |c thc hin theo nhng quy nh sau:

b tng to chn tr|c khi tr|t vi chiu cao 70cm r 80cm, chia lm hai lp

- Lp th nht |c vo cp pha vi chiu cao 35cm r 40cm;

- Lp th hai |c tip theo, khi lp th nht |c v m xong trn

Sau b|c nng u tin, qu trnh v tr|t |c thc hin lin tc. Lc ny mi lp b tng |c vi chiu cao ph hp vi cc bin php thi cng.

6.10.2. Vic nng cp pha theo chu k |c thc hin theo tc tr|t xc nh trong nh|ng phi m bo khi tr|t l b tng th c|ng b

tng t t 15N/cm2 r 25N/cm2.

6.10.3. Kim tra thng bng ca sn thao tc, sai s tim trc v thng ng ca cp

m bo yu cu k thut.

6.10.4. B mt b tng cn |c gi m theo ch bo d|ng ca TCVN 5592 : 1991.

6.11. Hon thin b mt b tng.

6.11.1. Trong mi tr|ng hp, b mt b tng phi |c hon thin tha mn yu cu v cht l|ng, phng v ng u v mu sc theo quy nh ca thit k.

Vic hon thin b mt b tng |c chia lm 2 cp:

b) Hon thin cp cao.

27


6.11.2. Hon thin thng th|ng:

Sau khi tho cp pha, b mt b tng phi |c sa cha cc khuyt tt v hon

mt b tng khi o p st bng th|c 2m khng v|t qu 7mm.

6.11.3. Hon thin cp cao i hi phng nhn khi kim tra bng th|c 2m, g gh khng v|t qu 5mm v phi m bo ng u v mu sc.

1) Trng thi b mt b tng |c hon thin y l nhng kt cu m b mt b tng khng tri hoc khng bao ph b mt.

php khc nhau tu theo mc khuyt tt v tnh cht kt cu. Khi sa cha cc khuyt tt nh| r, x|c, h thp, nt e. c th thc hin theo cc ph|ng php truyn thng (trt, v, phun va xi mng, c ty v xoa nhn b mte.). Khi to

b mt.

3) Cc b mt hon thin cp cao th|ng |c thc hin theo ph|ng php xoa mi bng my hoc bng th cng tu theo quy m, din tch b mt kt cu v theo quy

7. Kim tra v nghim thu.

7.1. Kim tra

7.1.1.cp pha gio, ct thp, ch to hn hp b tng v dung sai ca cc kt cu trong cng trnh.

7.1.2. Kim tra cp pha gio |c thc hin theo cc yu cu ghi bng 1.

7.1.4. Kim tra cht l|ng b tng bao gm vic kim tra vt liu, thit b, quy trnh sn xut, cc tnh cht ca hn hp b tng ng cng. Cc yu cu kim tra ny

7.1.5. st ca hn hp b tng |c kim tra ti hin tr|ng theo cc quy nh sau:

a) i vi b tng trn ti hin tr|ng cn kim tra ngay sau khi trn m b tng u tin.

b) n b tng (b tkim tra mi ln giao hng ti ni b tng.

c) Khi trn b tng trong iu kin thi tit v m vt liu n nh th kim tra

d) Khi c s thay i chng loi v m vt liu cng nh| khi thay i thnh phn cp phi b tng th phi kim tra ngay m trn u tin, sau kim tra thm t nht mt ln trong mt ca.

m theo TCVN 3105 : 1993.

7.1.7. Cc mu th nghim xc nh c|ng b tng |c ly theo tng t, mi t gm

3105 : 1993. Kch th|c vin mu chun 150mm x 150mm. S l|ng t mu |c quy nh theo khi l|ng nh| sau:

28


a) i vi b tng khi ln c 500m3 ly mt t mu khi khi l|ng b tng trong mt khi ln hn 1000m3 v c 250m3 ly mt t mu khi khi l|ng

t khi d|i 1000m3;

b) i vi cc mng ln, c 100m3 b tng ly mt t mu nh|ng khng t hn mt t mu cho mt khi mng;

c) i vi b tng mng b my c khi ln hn 50m3 ly mt t mu nh|ng

d) i vi khung v cc kt cu mng (ct, dm, bn, vme) c 20m3 b tng ly mt t mue;

kt cu n chic c khivn ly mt t mu;

f) i vi b tng nn, mt |ng (|ng t, |ng bnge) c 200m3 b tng ly mt t mu nh|ng nu khi l|ng b tng t hn 200m3 vn phi ly mt t

g) kim tra tnh chng thm n|c ca b tng, c 500m3 ly mt t mu nh|ng nu khi l|ng b tng t hn vn phi ly mt t mu.

7.1.8. trnh sau khi kim tra tuc ti hin tr|ng |c coi l t yu cu thit k khi gi tr trung bnh ca tng t mu khng |c nh hn mc thit k v khng c mu no trong cc t mu c c|ng d|i 85% mc thit k.

Bng 19 r Cc yu cu kim tra cht l|ng b tng

tra tra

1 2 3 4

1. Vt liu

Xem phiu giao hng ph hp vi n t hng

Mi ln giao hng

Xi mng Th nghim xc nh Ph hp vi TCVN

2682 : 1992Theo iu 4.2.4.

theo TCVN 4029 : 1985

Xc nh bn Ph hp vi TCVN - Ln giao hng u

bn ca ct liu theo tiu chun hin hnh

TCVN 1770 : 1986 (ct)

- Khi c nghi ng

- Khi thay i ct liu

Xem phiu giao hng Ph hp vi n t Mi ln giao hng

Ph gia v cht n Th nghim mu b tng c ph gia (hoc cht n)

Ph hp vi yu cu k thut

Khi c nghi ng

N|c

Th nghim phn tch ha hc

N|c khng c cc cht c hi, ph hp vi

Khi khng dng n|c sinh hot cng cng.

29


TCVN 4506 : 1987 Khi c nghi ng, khi thay i ngun n|c

My trn n chic

H thng trm trn Cc thng s k thut Khng c s c khi vn hnh

Tr|c khi s dng sau theo nh k

Thit b cn ong xi mng

Thit b cn ong Cc thng s k thut m bo chnh xc Tr|c khi s dng, sau

Thit b cn ng phu gia cht n

Thit b v dng c

Thit b dng c th st

kim tra thch hp theo quy nh

Thit b vn chuyn Cc thng s k thut Khng c s c khi s Tr|c khi s dng sau v my m b tng

dng theo nh k.

3. Hn hp b tng trn trn cng tr|ng

TCVN 3106 : 1993 nh theo quy nh ca iu 7.1.5.

ng nht ca So snh cc mu th nh gi s ng Khi c nghi ng

khc nhau tng

chng thm n|c

Th nghim theo TCVN 3116 : 1993

So snh vi chng thm n|c quy nh

Theo quy nh ca thit k

3118 : 1993 ko quy nh iu 7.1.7.

C|ng ko khi un

Th mu theo TCVN 3119 : 1993

So snh vi c|ng ko quy nh

- Khi cn thit

4. Hn hp b tng trn sn s dng trn cng tr|ng

Hn hp b tng Bng mt So snh vi trng thi thng th|ng

Mi ln giao hng

3118 : 1993 nn quy nh iu 7.1.7.

C|ng ko khi un

Th mu theo TCVN 3119 : 1993

So snh vi c|ng ko quy nh

- Khi cn thit

5. Qu trnh trn, to hnh v bo d|ng

- T l pha trn vt liu

Bng thit b o l|ng (ti ni trn)

- m bo t l trn theo quy nh.

- t l N/X

Quy trnh trn o l|ng vt liu, thi m bo chnh xc Ln trn u tin sau theo thi gian thch

30


gian trn theo bng 12, m bo thi gian trn theo quy nh.

hp

Vn chuyn hn hp b tng

nh gi st v ng nht (ti ni b tng)

Hn hp b tng khng b phn tng, m bo st quy nh

Mi ln vn chuyn

thut theo 6.4.

Bng mt B tng |c m cht theo iu 6.4.14 m b tng Mi ln m b tng

nh

Bng 19 r (Kt thc)

1 2 3 4

Bo d|ng b tng Bng mt Ph hp vi TCVN 5592 : 1991

Mi kt cu

Tho d cp pha Thi gian v c|ng Ph hp vi iu 3.6.2 Mi kt cu

pha gio

Cc khuyt tt Bng mt |c sa cha m bo theo yu cu k thut

Mi kt cu

B mt kt cu Bng mt Khng c cc khuyt tt Mi kt cu

ng nht Theo 20 TCN 17 : 1989

Xc nh ng nht - Khi c nghi ng

Dng sng bt ny va siu m theo 20 TCN 171 : 1989

So snh vi c|ng nn quy nh C|ng nn ca

b tng

- Khi th mu khng t c|ng

cu t- S l|ng mu th khng theo quy nh

o thch hp bng 20

7.2. Nghim th:

7.2.1. Cng tc nghim thu |c tin hnh ti hin tr|ng v phi c y cc h s sau:

b) Cht l|ng b tng (thng qua kt qu th mu v quan st bng mt ti hin tr|ng);

vi thit k;

d) Bn v hon cng ca tng loi kt cu;

31


e) Cc bn v cho php thay i cc chi tit v cc b phn trong thit k;

f) Cc kt qu kim tra c|ng b tng trn cc mu th v cc kt qu kim

g) Cc bin bn nghim thu ct thp, cp pha tr|c khi b tng;

h) Cc bin bn nghim thu nn mng;

j) S nht k thi cng.

7.2.2. Dung sai cho php.

thp ton khi so vi thit k, khng v|t qu cc tr s ghi trong bng 20. Cc sailch ny |c xc nh theo cc ph|ng php o c bng cc thit b v dng c chuyn dng.

Bng 20 r Cc sai lch cho php khi thi cng cc kt cu b tng

v b tng ct thp ton khi.

Tn cc sai lch Mc cho php, mm

1. lch ca cc mt phng v cc |ng ct nhau ca cc mt phng so vi |ng thng ng hoc so vi nghing thit

a) Trn 1m chiu cao kt cu;

b) Trn ton b chiu cao kt cu;

5

20

- T|ng trong cp pha c nh v ct lin vi sn

- Kt cu khung ct

- Cc kt cu thi cng bng cp pha tr|t hoc cp pha leo

15

10

1/500 chiu cao cng trnh

1. lch ca mt b tng so vi mt phng ngang;

a) Tnh cho 1m mt phng v bt c h|ng no

100mm.

5

2. Sai lch trc ca mt phng b tng trn cng, so vi thit k khi kim tra bng th|c di 2m p st mt b tng.

3.8

4. Sai lch tit din ngang ca cc b phn kt cu

5. Sai lch v tr v cao ca cc chi tit lm gi ta cho cc kt cu thp hoc kt cu b tng ct thp lp ghp

8

5

32


Ph lc A

S liu thit k cp pha gio cho cc kt cu b tng

A.1. Khi thit k cp pha gio phi tnh ton vi cc tr s ti trng tiu chun sau y:

a) Khi l|ng th thc ca cp pha gio xc nh theo bn v thit k. Khi l|ng th tch ca g kh phn loi theo TCVN 1072 : 1971 nh| sau:

3 3

- Nhm IV t 550kg/m3 n 610kg/m3

- Nhm V t 500kg/m3 n 540kg/m2.

- Nhm VI 3

b) Khi l|ng n v th tch ca b tng nng thng th|ng tnh bng 2500kg/m3.

- i vi cc loi b tng khc tnh theo khi l|ng thc t.

c) Khi l|ng ca ct thp, ly theo thit k, tr|ng hp khng c khi l|ng c th

d) Ti trng do ng|i v dng c thi cng:

- Khi tnh ton cp pha sn v vm th ly 250daN/m2.

;

- Khi tnh ton ct chng cc kt cu ly 100daN/m2.

Ch thch:

dng c thi cng l 130daN do xe ci tin ch y b tng l 350daN;

2. Nu chiu rng ca cc kt cu cp pha ghp li vi nhau nh hn 15mm th lc tp trung ni trn |c phn u cho hai tm k nhau.

e- Ti trng do m ru .

A.1.2. Ti trng ngang.

a) Ti trng gi ly theo TCVN 2336 : 1990 i vi thi cng ly 50% ti trng gi

b) p lc ngang ca b tng mi vo cp pha xc nh theo bng A.1.

c) Ti trng do chn ng pht sinh khi b tng vo cp pha ca kt cu xc

Bng A.1 r p lc ngang ca hn hp b tng mi

Ph|ng php m Cng thc tnh ton p lc ngang ti a, daN/m2

Gii hn s dng cng thc

P = . H H R

1. m di

2. m ngoi

P = (0,27V + 0,78)k1.k2P = . H

V 0,5 khi H 4

V 4,5 khi H 2R1

33


P = (0,27V + 0,78)k1.k2 V 4,5 khi H 2m

Cc k hiu trong bng ny:

P r p lc ngang ti a ca hn hp b tng tnh bng daN/m2;

H - chiu co mi lp hn hp b tng tnh bng m;

V - tc hn hp b tng tnh bng m/h;

1

v m ngoi R1 = 1,0m;

k1 - h s tnh n nh h|ng st ca hn hp b tng.

-

- i vi b tng c st 4cm r 6cm th k1 = 1,0.

- i vi b tng c st 8cm r 12cm th k1 = 1,2;

k2 - h s k n nh h|ng nhit ca hn hp b tng

- Vi nhit 80C, k2 = 1,15;

- Vi nhit 80C r 110C, k2 = 1,1;

- Vi nhit 120C r 170C, k2 = 1,0;

- Vi nhit 180C r 270C, k2 = 0,95;

- Vi nhit 280C r 320C, k2 = 0,9;

- Vi nhit t trn 330C, k2 = 0,85;

Bng A.2 - Ti trng ng khi b tng vo cp pha

(daN/m2)

bng my v ng vi voi hoc trc 400

trc tip t cc thng c:

- Dung tch nh hn 0,2m3

- Dung tch 0,2m3 r 0,8m3200

400- Dung tch ln hn 0,8m3 600

A.2. Khi tnh ton cc b phn ca cp pha theo kh nng chu lc, cc ti trng tiuchun nu trong A.1 phi |c nhn vi h s v|t ti quy nh trong bng A.3.

34


Bng A.3

1. Khi l|ng th tch ca cp pha gio

2. Khi l|ng th tch ca b tng v ct thp

1,1

1,2

4. Ti trng o m chn ng

5. p lc ngang ca b tng

6.

1,3

1,3

1,3

pha

- Khi xt n ti trng tm thi ca cc ti trng hu ch v ti trng gi, tt c cc

- Khi tnh ton cc b phn ca cp pha gio v mt bin dng, cc ti trng khng |c nhn vi h s qu ti.

cc tr s sau:

a) i vi cp pha ca b mt l ra ngoi ca cc kt cu: 1/400 nhp ca b phn cp pha;

pha;

c) vng n hi hoc ln ca g chng ct pha: 1/1000 nhp t do ca kt cu

A.4. Tnh ton n nh chng lt ca cp pha v gio phi xt n tc ng ng thi ca ti trng gi v khi l|ng bn thn. Nu cp pha |c lp lin vi ct thp th phi tnh c khi l|ng ct thp, h s v|t ti i vi ti trng gi ly bng 1,2 v

Ngoi ra, h s an ton v n nh chng lt khng |c nh hn 1,25.

Ct thp ca cc kt cu b tng ct thp

B.1.1. Ct thp trong cc kt cu b tng ct thp |c phn loi nh| sau:

a) Theo cng ngh ch to: Thp cn nng v thp cn ngui;

thp trong kt cu b tng ng sut tr|c;

c) Theo hnh dng: Ct thp trn v ct thp c g;

B.1.2. Tnh cht c hc ca ct thp |c c tr|ng bng tr s gii hn chy, c|ng

35


B.1.3. Mt s loi thp dng trong kt cu b tng ct thp sn xut trong n|c v n|c ngoi bng sau:

Bng B.1 r Tnh cht c hc ca thp Vit Nam

theo tiu chun TCVN 1651 : 1985.

Nhm ct thp

|ng knh ct thp, mm

Gii hn chy daN/cm2

C|ng cc hn daN/cm2

dn di t|ng i, %

Th nghim un ngui c- dy trc un d-

thp

Khng nh hn

CI 6-10 2200 3800 3800 C = 0,5d 1800

CII

CIII

CIV

10-40

6-40

10-32

3000

4000

6000

5000

6000

9000

5000

6000

9000

C = 3d 1800

C = 3d 900

C = 5d 450

Bng B.2 r Tnh cht c l ca thp Lin X (c) theo GOST 5781 : 1975

Gii hn chy

daN/cm2

C|ng cc hn daN/cm2

dn di tr|ng i

%Th nghim un nguiNhm ct |ng

thp, mm Khng nh hn

|ngknh un

Gc un

AI 6-22 2400 3800 3800 C = 0,5d 1800

AIII

AIV 6-40

10-32

4000

6000

6000

9000

6000

9000

C = 3d

C = 5d 900

450

Ch thch: i vi ct thp c |ng knh ln hn 40mm, |c php gim tiu chun v dn di t|ng i. Khi |ng knh tng ln 1mm, dn di t|ng i |c gim 0,25%

B.2. X l ct thp.

B.2.1. tit kim ct thp dng ct thp x l ngui trong cc kt cu b tng ct thp.

ngui, dng loi ct thp trn cn nng.

b) Ct thp rt ngui phi c b mt trn khng g, sai lch |ng knh khng qu 0,1mm.

36


Mc Tiu chun

NF (Php)

A35-015

Fe E 215

(215)

Fe E 235

(235)

Fe E400

(400)

Fe E 500

(500)

BS (Anh)

4449

4461

Gr 250

(250)

Gr.460/425

(


Ct liu v quy cch Mc xi Xi Ct si N|c

(kg)

Ct liu nh M1 = 2,1 r 3,5

Ct liu ln c ht Dmax = 10mm PC 30 265 615 1260 195

Ct liu nh M1 2,1, = 3,5


Ct liu nh M1 = 2,1 r 3,5

Ct liu nh M1 = 2,1 r 3,5


Ph lc D

H s tnh i kt th nn v c|ng cc vin mu b tng c

Hnh dng v kch th|c mu, mm H s tnh i

100 x 100 x 100

150 x 150 x 150

200 x 200 x 200

0,91

1,00

1,05

300 x 300 x 300 1,1,0

Mu tr

71,4 x 143 v 100 x 200 1,1,6

200 x 400 1,24

Bng C - Bng tnh sn thnh phn vt liu cho 1m3

b tng nng mc 100

38


Lc Niu tn

caniutn

N

daN

9,81N = 1daN

1 daN = 10N

- ng sut, c|ng vt liu, m un n

hi.

caniutn trn centimet vung

daN/cm2 9,81N/cm2 1daN/cm2

- p sut Niu tn/mt vung N/m21N/m2 = 0,1daN/cm2

9,81N/m2 1daN/m2

1N/m2 = 0,1daN/m2

caniutn trn mtvung

Pascal

daN/m2

Pa

1daN/m2 = 10N/m2

1Pa = 1N/m2

1bar = 105 Pa

tmtphe at 1at = 0,98 1bar

Mmem un, m men xon

cnniutn mt daNm, KNm 9,81 NM 1daNm

Ti trng phn b trn mt di

caniutn trn mt daN/m 9,81N/m = 1daN/m

Ph lc E

Bng chuyn i mt s n v o l|ng hp php

n v hp phpi l|ng

Tn gi k hiu

Chuyn i n v

39

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TCVN_4453_1995_Ket Cau Be Tong Va Be Tong Cot Thep Toan Khoi - Quy Pham Thi Cong Va Nghiem Thu