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PHN I : GII THIU CHUNG V CNG TRNH
HI GIANG GROUPBIN PHP THI CNG 9
THUYT MINH
BIN PHP T CHC V
GII PHP K THUT THI CNG
cc ni dung ca thuyt minh
phn i :gii thiu chung v cng trnh
i. c im cng trnh
ii. khi lng thc hin
phn II: bin php t chc thi cng
i. cc cn c t chc thi cng cng trnh
ii. cng tc t chc thi cng cng trnh
phn iii: bin php k thut thi cng
1. Bin php thi cng o t, lp t h mng
2. Bin php thi cng, yu cu k thut cng tc ct thp
3. Bin php thi cng, yu cu k thut cng tc lp dng, tho d cp pha
4. Bin php thi cng btng
5. Bin php thi cng cng tc xy
6. Bin php thi cng phn hon thin
7. Bin php thi cng lp t in, nc.
phn iv: bin php bo m k thut thi cng
1. T chc qun l cht lng cng trnh
2. T chc cng tc nghim thu
3. K hoch v tin thi cng
phn v : cng tc an ton lao ng - phng chng chy n v phng chng lt bo
1. Bin php an ton lao ng
2. Bin php phng chng chy n
3. Bin php phng chng bo lt
phn vi : cng tc v sinh mi trng v an ninh trt t
1. Cng tc an ninh trt t
2. Cng tc v sinh mi trngphn vii : ch bo hnh cng trnh
phn viii: kt lun
PHN I
GII THIU CHUNG V CNG TRNH
I. C IM CNG TRNH
1. Tn cng trnh :Nh my knh ni Chu Lai cng sut 700 tn SP/ngyHng mc : H thng nc tun hon .
2. Tn ch u t : Cng ty CP knh ni Chu Lai - TKV.
3. a im xy dng: Tam Hip - Ni Thnh - Qung Nam.
4. Quy m xy dng, gii php k thut cng trnh
H thng nc tun hon bao gm4.1 B nc tun hon V=2400m3Dng hnh ch nht, Chiu di =60 m, chiu rng = 11m, chiu cao b 4,75 m trong phn ni trn mt t l 1m, phn chm trong t l 3,95m.
Mt trn ca np b c l thng hi v ca thm ln xung lm v sinh trong b.
Kt cu ca b cu to nh sau :
* y b : bng BTCT mc 300 dy 450 mm gm cc lp t trn xung:
+ B tng mn mc 250 dy 30mm, dc 3% v hng rnh thu nc+ B tng ct thp y b
+ Btng lt mng mc 100 dy 100mm.+ t t nhin* Thnh b : bng BTCT mc 300 dy 300mm
Thnh ngoi b t cao - 0.500 tr ln lng va xi mng xoa nhn mt dy 20 mm, lp sn xi mng gin n cao dy 50 mm, lp va chng thm dy 20 mm+ B tng ct thp thnh b
+ Trt va XM 75 dy 20mm
Np b: bng b tng ct thp mc 300 dy 150 mm:+ B tng ct thp np b dy 150 mm.4.2 Trm ti ch nca. Gii php mt bng :
Gm c 1 gian dnh cho phng thit b:+ Chiu di :18m, chiu rng: 6,9m, din tch: 124,2m2
+ Chiu cao: 4,6m
Mt gian dnh cho phng iu khin:+ Chiu di :9m, chiu rng: 6,9m, din tch: 62.1m2
+ Chiu cao: 4,6m
Mt gian dnh cho trm nc:+ Chiu di :33m, chiu rng: 6,9m, din tch: 227,7m2
+ Chiu cao: 4,6mb. Kt cu cng trnh
+ Mng bng BTCT.
+ Dm ging mng bng BTCT+ Tng xy gch ng 9x9x19 dy 220 mm+ Mi BTCT ti ch, bn trn lp mi tn mi chiu di bt kII. KHI LNG THC HIN
- Cn c vo khi lng trong H s mi thu ca Ch u t.
- Cn c vo H s bn v thit k thi cng .
----------------------------------------------------------------------
PHN II
BIN PHP T CHC THI CNG
I. CC CN C T CHC THI CNG CNG TRNH
1. Cc cn c
- Hin trng khu t xy dng, iu kin giao thng, c s h tng, a hnh, a cht thy vn, c im cng nh cc iu kin an ninh an ton x hi ca khu vc.
- Quy m v phm vi ca gi thu.
2. Cc tiu chun - quy phm thi cng
Trong qu trnh thi cng, ngoi cc ch dn k thut trong iu kin hp ng v yu cu v cht lng k thut thi cng. Nh thu s m bo tun th theo cc tiu chun c lin quan c k di y:
1.TCVN 5637 1991 Qun l cht lng xy lp cng trnh xy dng - Nguyn tc c bn
2.TCVN 5951 1995 Hng dn xy dng S tay cht lng
3.TCVN 4085 1985 Kt cu gch . Quy phm thi cng v nghim thu
4.TCVN 4459 1987 Hng dn pha trn v s dng va xy dng
5.TCVN 4087 1985 S dng my xy dng. Yu cu chung
6.TCVN 4091 1985 Nghim thu cc cng trnh xy dng
7.TCVN 4447 1987 Cng tc t-Quy phm thi cng v nghim thu
8.TCVN 4452 1987 Kt cu btng v btng ct thp lp ghp. Quy phm thi cng v nghim thu
9.TCVN 4453 1995 Kt cu btng ct thp ton khi. Quy phm thi cng v nghim thu.
10.TCVN 5724 1993Cng tc btng nn mng - qui phm thi cng v nghim thu
11.TCVN 4085 1995 Cng tc xy - qui phm thi cng v nghim thu
12.TCVN 4516 1988 Hon thin mt bng xy dng - quy phm thi cng v nghim thu.
13.TCXD 79 1980 Thi cng v nghim thu cng tc nn mng.
14.TCVN 5841 1991 B cha nc bng BTCT - qui phm thi cng v nghim thu
15.TCVN 5674 1992 Cng tc hon thin trong xy dng - Thi cng v nghim thu.
16.TCVN 5718 1993 Mi v sn BTCT trong cng trnh xy dng. Yu cu k thut chng thm nc
17.TCXD 170 1989 Kt cu thp, gia cng, lp t v nghim thu- Yu cu k thut
18.TCVN 5640 1991 Bn giao cng trnh xy dng. Nguyn tc c bn
19.TCXD 159 1986 Trt trang tr. Thi cng v nghim thu
20.TCVN 567 1992Cng tc sn, trn - qui phm thi cng v nghim thu
21.TCVN 5641 1991 B cha bng b tng ct thp. Quy phm thi cng v nghim thu.
22.TCVN 4519 1988 H thng cp thot nc bn trong nh v cng trnh. Quy phm nghim thu v thi cng.
23.TCVN 5576 1991 H thng cp thot nc.Quy phm qun l k thut.
24.TCVN 5639 1991 Nghim thu thit b lp t xong. Nguyn tc c bn
25.Cc yu cu k thut c qui nh trong h s thit k km theo v cc quy nh k thut hin hnh khc c lin quan.
26.Cc phng php th v phng php ly mu th p dng theo tuyn tp xy dng Vit Nam ( tp X v XI)
27.TCVN 2287 1978H thng tiu chun an ton lao ng. Quy nh c bn
28.TCVN 2291 1978 Phng tin bo v ngi lao ng. Phn loi
29.TCVN 4086 1985An ton in trong xy dng. Yu cu chung.
30.TCVN 4244 1986 Quy phm an ton thit b nng
31.TCVN 5308 1991 Quy phm k thut an ton trong xy dng
32.TCVN 3255 1986 An ton n. Yu cu chung
33.TCVN 3254 1989 An ton chy. Yu cu chung
II. CNG TC T CHC THI CNG CNG TRNH
1. Cng tc nhn mt bng thi cng
Sau khi nhn bn giao mt bng nh thu s nhanh chng trin khai cng vic dn dp, chun b mt bng trin khai thi cng ngay.
Ch u t cng t vn gim st v t vn thit k bn giao mt bng thi cng v cc cc mc, im, trc nh v cng trnh cho nh thu. Trn c s mc chun ca ch u t bn giao, nh thu s tin hnh xy dng mng li nh v chun cho cng trnh, bo qun trong sut qu trnh thi cng,Trc khi tin hnh thi cng cng trnh, nh thu tin hnh nh v cng trnh ra thc a theo bn v thit k. H thng kch thc tim ca li ct c xc nh bng my kinh v, h thng ny c bn gi ln cc vt c nh hoc lm cc mc btng t cch trc bin ca cng trnh m bo khng b x dch trong qu trnh thi cng.
Cao chun ca cng trnh c xc nh trn c s cao chun c bn giao t ch u t. Nh thu s dng my thu bnh xc nh v cao chun ca cng trnh c bn gi vo cc vt c nh bn ngoi cng trnh sau bn chuyn vo cng trnh.
2. T chc cng trng, tng mt bng thi cng
Sau khi nhn mt bng thi cng, nh thu tin hnh t chc cc bin php to ranh gii khu vc thi cng nhm m bo an ton cho cn b cng nhn vin, dn c ang lm vic v sinh sng ti khu vc ny. Cng tc an ton, an ninh cng trng c thit lp bng h thng hng ro tm chc chn, c bin bo hiu, n bo v y nh sng vo bui ti, ban m.
Cn c vo mt bng thi cng thc t ti hin trng, nh thu b tr mt bng t chc thi cng: xy dng cc kho tng, ln tri, h thng cp thot nc cng trng, in thi cng, ng giao thng ni b, xng gia cng ct thp, thit b gin gio vt t p ng cho thi cng.
Nh thu ch ng lm vic vi ngnh giao thng cng chnh v cng an a phng xin php cho cc loi xe my, thit b hot ng trn ng ph, ra vo cng trnh.
a. Ngun in :
Nh thu s lin h vi Ch u t v c quan qun l in khu vc lp t cc thit b in phc v thi cng theo yu cu ca in lc ti in phng v s dng in.
Ti im u in c cng t chia ra lm 02 tuyn :
+ Tuyn 1: phc v in ng lc cho cc my hn, my trn btng, my trn va v cc thit b khc phc v thi cng.
+ Tuyn 2: Phc v cng tc bo v v sinh hot ti cng trng .
Ton b h thng dy dn in u i trn cc ct g cao 3m dc theo hng ro cng trng v phn nhnh n tng ph ti. Trong trng hp phi i ngm bo m an ton th s dng h thng dy cp ngm bc PVC cng sut.
phng tnh hung s c mt in, nh thu b tr 01 my pht in t hnh c cng sut 15KW m bo lin tc c in phc v thi cng v bo v cng trnh.
b. Ngun nc :
Lin h vi ch u t v ngnh nc mua nc, lp ng h thanh ton nc phc v sinh hot v thi cng cng trnh. Ngoi ra, c th dng nc ging khoan thi cng khi xt nghim nc t tiu chun cho php s dng cho thi cng v sinh hot. Xy b cha nc tm cha nc ch ng cho thi cng cng trnh .
c. Thot nc thi cng:
Trong qu trnh t chc thi cng, nc sinh hot, nc ma v nc d trong qu trnh thi cng (nc ngm chng thm sn, nc ra ct liu) c thu v h ga v thot vo mng thot nc ca khu vc qua h thng rnh tm. Ton b rc thi trong sinh hot v thi cng c thu gom vn chuyn i ng ni quy nh m bo v sinh chung v m quan khu vc cng trng
3. T chc nhn lc thi cng
Ngay sau khi tin hnh k kt hp ng v bn giao mt bng, nh thu s huy ng ngay lc lng thi cng, thnh lp ban ch o ti cng ty v ban iu hnh thi cng ti cng trng, b tr cn b k thut, kinh t vt t, an ton vin, iu ng cc t cng nhn theo tin yu cu cng vic.
a. S t chc qun l hin trng thi cng cng trnh:
S b tr ban ch huy cng trng
Quan h ch o cng vicb. Ban iu hnh cng trng:
Cng ty giao nhim v thi cng trc tip thi cng cng trnh cho Ban ch huy cng trng thc hin.
B my qun l thi cng lm vic thng xuyn trc tip ti cng trng gm:
TTH V TNCHC VNGH NGHIPKINH NGHIM
1Nguyn Vn PhcCh huy trngKS. Thy Li10 nm
2Hong Vn VnhCh huy phKS. Kinh T15 nm
3Nguyn BnhK thut trngKS.XD DD&CN05 nm
4Trn Vn Cng CB. K thutKS.XD DD&CN03 nm
5Trn Vn CB. K thutKS. in03 nm
6Trnh Vn DngCB. Vt tTrung cp03 nm
7Nguyn Tng XunTh khoTrung cp03 nm
- Ch huy trng cng trng (K s Thy Li): c trn 10 nm kinh nghim thi cng xy dng c bn v ch huy trng cc cng trnh cng loi, cng cp, c chng ch gim st cht lng cng trnh xy dng.
- Cn b ph trch k thut : l k s xy dng DD &CNc trn 05 nm kinh nghim thi cng cng trnh c bn.
- Cn b k thut thi cng :
+ 01 K s xy dng DD&CN : kinh nghim thi cng trn 03 nm.
+ 01 Trung cp xy dng DD&CN : kinh nghim thi cng trn 05 nm
+ 01 K s in k thut: kinh nghim thi cng trn 03 nm.
Ngoi ra cn c:
+ K ton - thng k: 01 ngi
+ Nhn vin vt t: 01 ngi
+ Nhn vin bo v v th kho cng trnh: 02 ngi
c. Lc lng cng nhn trc tip :
c iu ng b tr ph hp theo tin thi cng. B tr cc t th tham gia xy dng cng trnh nh sau:
- T th n v hon thin:
1 t = 20 ngi
- T th ct thp:
1 t = 10 ngi
- T thi cng in, nc:
1 t = 15 ngi
- S th bnh qun trn cng trng:30 ngi/ ngy
- S th cao nht trong cng trnh: 60 ngi/ngy
Khi b tng dm, sn ton khi c khi lng ln, Nh thu chng ti huy ng thm lc lng nhn cng ti a phng thi cng.
- Thi gian lm vic: 8 gi/1 ca.
- Ngy lm vic: 1 ca. Ring b tng dm, sn ton khi c khi lng ln, Nh thu s b tr chia nhiu ca, kp thay nhau b tng n khi hon thnh mi thi.
y l lc lng th ch yu ca Cng ty, c o to c bn v c tay ngh cao thi cng cng trnh m bo t cht lng k, m thut v tin tt.
d. Qun l nhn lc:
Nhn lc thi cng c b tr mt khu vc trong cng trng, l lc lng cng nhn xy dng ca Cng ty, c o to qua trng dy ngh, trc tip thi cng cc cng tc n, in, nc, c kh, hon thin. Cng ty cam kt iu phi nhn lc m bo thi cng cc hng mc cng vic theo ng tin lp.
Thc hin cng tc ng k tm tr tm vng vi chnh quyn a phng s ti cho s cn b, cng nhn thi cng, nhn vin bo v li cng trng.
m bo an ninh trt t, an ton x hi trn a bn ng qun.
Lp ni quy cng trng v ni quy an ton lao ng, t chc cho cng nhn hc tp v thc hin nghim tc nhng Quy nh ca Ch u t yu cu.4. Thit b my mc phc v thi cng
TTTn thit bVTS lngNc sxCng sut, ti trng
01My trn b tng 350LCi02T. Quc350L
02My trn vaCi02T. Quc150L
03My m diCi8Nht1-1,5 KW
04My m bn t hnhCi1Nht1,2 KW
05My ct st bng in Ci02Nht4 KW
06My hnCi02Nht18 KVA
07My o bnh xch Komatsu 0,65m3Ci02Nht0,7m3
08My ko km bucCi01T. Quc
09My miCi02Nht1 KW
10My khoan b tng Ci02c1 KW
11My pht inCi01Lin X75 KVA
12My un stCi03T. Quc
13My thu bnhCi01Nht
14My kinh v Ci01Nht
15Xe ti t KAMAZCi05Lin X12T
16Tole cp pha nh hnhM23.000Hn Quc
17Gin gio thpB80Vit Nam
18Cy thp chng ADCy3000VN-T.Tin
19My vn thngCi02Nga
20Cu thiu nhiCi 02Vit Nam0,5T
5. T chc cung ng vt t
Ngoi cc yu t nh t chc qun l iu hnh, t chc nhn lc, s dng thit b my thi cng, gii php k thut th vic cung ng vt t cng l mt khu then cht quyt nh n cht lng v tin thi cng cng trnh.
a. T chc cung ng vt t p ng cc yu cu sau:
Vic cung ng vt t cho cng trnh do Cng ty ch ng theo yu cu tin tng hng mc cng vic ca cng trnh. Bao gm:
- Cc loi vt liu xi mng, st thp, gch, sn ,in, nc cc loi: Hp ng qua i l v Nh sn xut c Chi nhnh trn a bn thnh ph Tam K - tnh Qung Nam v cc vng ph cn .
- xy dng c cung ng ti m trn a bn a phng sn xut m bo tiu chun cht lng v vn chuyn ti chn cng trnh.
- Ngun cung cp vt liu ti a phng thc hin ng theo quy nh ca chuyn ngnh qun l xy dng.
- Vt t a vo s dng ng chng loi, kch thc cht lng sn phm theo yu cu h s thit k, h s mi thu ca Ch u t, p ng vi tiu chun k thut v quy phm hin hnh.
- T chc cung ng bo m khi lng cc loi vt t n chn cng trnh ch yu dng phng tin vn ti xe ca Cng ty. Tt c cc loi xe ch vt liu phi c che ph bng bt kn trnh gy nhim mi trng v phi xin giy php khi xe vo ng cm.
b. Bin php t chc cung ng vt t: - Tnh ton khi lng chng loi vt t v lp k hoch cho tng giai on thi cng ph hp theo tin cng trnh. (Ch n cc loi vt t d tr hp l khng b nh hng do thi tit nh: gch, ct, ).
- Kim tra cht lng vt liu, vt t bng cch ly mu th nghim cc ch tiu c l v kch thc hnh hc v c Ch u t ng trc khi cung ng.
- Ton b vt t a vo cng trnh c nhp kho u c nhn mc, xut x ca nh sn xut v xut thi cng theo tin .
- Lp phng n bo qun vt t khi vn chuyn vo kho cng trnh nht l xi mng v st thp, g, cc thit b in, nc.
- Thc hin nghim tc thi gian vt t lu kho theo ng quy nh.
c. Yu cu tiu chun vt t - vt liu xy dng.
Vt t, vt liu a vo xy dng cng trnh phi bo m tiu chun Vit Nam, ng chng loi, cht lng, s lng, mu m, ngun gc xut x ghi trong H s thit k v H s mi thu ca Ch u t yu cu; u c nhn mc ca nh sn xut v nh cung ng c trnh bo cho Ch u t bit kim tra v ly mu th nghim ti hin trng xc nh cht lng trc khi a vo thi cng cng trnh.
d. K hoch v bin php cung ng vt t:
- Thnh lp b phn cung ng vt t phc v cho cng trnh.
- Lp tin cung ng cc loi vt t, vt liu chnh.
Cn c vo tin thc hin cc cng tc xy lp c d tr khi lng vt t cn thit trong thi gian 4 ngy, vi cc loi vt liu nh thp, gch, ct c cung ng v sm hn v c d tr phng xy ra hin tng "st" khan him.
- Chng ti gii quyt vn s dng ti a nhng vt liu sn c ca a phng, nhng phi m bo cc yu cu v quy cch, cht lng vt liu theo quy phm thit k yu cu v ch u t ng .
- Cng tc cung ng vt t l khu then cht quyt nh n cht lng, tin thi cng cng trnh, chng ti ln biu cung ng vt t:
+ Biu tin cy ca ngun vt t.
+ Biu h s an ton v cung ng vt t.
+ Biu nhu cu vt t
+ T xc nh h s an ton cung cp vt t theo tng thi im, tin thi cng trnh trc trc cung cp vt t do cc nguyn nhn gy nh hng n tin thi cng.----------------------------------------------------------------------
PHN III
BIN PHP K THUT THI CNG
- Cn c vo c im cng trnh, khi lng chi tit trong H s mi thu.
- Cn c vo tin yu cu ca Ch u t. Nh thu chng ti chn gii php thi cng chnh xy dng cng trnh nh sau:
1. i vi ton b cng trnh, tin hnh thi cng tun t cc cc hng mc v nghim thu cc cng vic, hng mc thi cng theo giai on k thut.
2. i vi cc hng mc c b tr song song thi cng xen k, nhng khng nh hng n quy trnh quy phm k thut v cht lng cng vic.
3. Phn chia qu trnh thi cng thnh cc giai on nh: thi cng phn mng, b nc, phn thn , phn hon thin.
4. Trong qu trnh thi cng tng cng vic, phn chia theo tng khu vc thi cng cho ph hp vi thc t cng trng, bo m cc yu cu k thut, s dng c ti a lc lng thi cng v kh nng lun chuyn coppha cy chng, cc thit b. Gim ti a cc khong thi gian gin on trn cng trng, nhm m bo tin thi cng, cht lng cng vic v hiu qu kinh t. (C bn v bin php t chc v tin thi cng)
5. T chc cng tc thi cng xy lp chnh kt hp vi mt s cng tc khc nh: Gia cng ca cc loi, trang tr ni tht; thot nc, m bo thi gian thi cng ph hp vi cc yu cu k thut.
6. Dng coppha thp, tm thp, cy chng thp, gin gio khung Tip, coppha g vi nhiu m un khc nhau tin dng trong lp dng v tho d. Gin gio v cy chng s dng bng g v thp nh hnh m bo tin v hiu qu kinh t.
H thng gin gio v cy chng st kt hp coppha cy chng g cho tng loi kt cu cng vic. Trn c s thi cng xong tng giai on dm, sn BTCT ca tng 1, sau tho d coppha, kt hp chuyn gin gio phc v cng tc hon thin.
7. Nguyn tc t chc thi cng:
- Tp trung thi cng nhanh cc khi lng phn th Hng mc: Mng, b nc khung b tng ct thp dm sn , lp mi .
- Cng tc hon thin t trn xung v t ngoi nh vo trong. Kt hp tho cp pha b nc, sn hon thin cng tc trt tng, trn b tng. Tranh th thi gian ma kh tp trung hon thin khi lng cc cng tc thi cng ngoi tri.
- Ch ng tnh ton tp kt vt t, vt liu m bo cht lng, khi lng thi cng.
- Nghim thu tng loi cu kin sn phm n chic mu, sau mi gia cng lp dng theo tin nh.
- Tun th cng tc nghim thu tng hng mc cng vic, tng giai on vi Ch u t v T vn Gim st theo Quy nh nghim thu hin hnh.
8. Phng tin thit b vn chuyn vt liu:
- Ti in loi cng sut 3KW v rng rc dy thng kt hp.
- Vn chuyn ngang: S dng xe ra, xe ci tin, x.
Vic b tr cc my mc thit b thi cng ph hp vi Bin php thi cng tng phn cng vic.1. Bin php thi cng o t, lp t h mng
1.1.Cng tc o t h mng:
Do khi lng o t ln, nn nh thu chn gii php o t bng my kt hp vi sa bng th cng. t o 1 phn c vn chuyn ra khi cng trng v bi thi, mt phn li xung quanh h mng v cc khu t cha khi cng sau ny lp t h mng, tn nn.
My o s o n cch cao thit k ca h mng khong 20 cm th dng li v cho o th cng sa n cao thit k .
Mng c o theo vt thit k trnh st l
Trong qu trnh thi cng lun c b phn trc c theo di kim tra cao h mng.
vic tin hnh thi cng o t c thun li, Nh thu s cho lm cc rnh thu nc dn v h ga thu nc, b tr bm nc c cng sut ln bm nc ngm v nc ma, m bo h mng lun kh ro, dng ng bm dn nc ra ngoi h ga nc thi chung ca khu vc.
H mng o xong c kim tra k cng v nh v tim, ct, a cht ca t. Nu pht hin t c s thay i v a cht s bo co vi bn A, t vn gim st v thit k c kin x l. Nghim thu nn t xong mi tin hnh cng tc tip theo.
* S c thng gp khi o t v bin php x l :
- ang o t, gp tri ma lm cho t b st l xung y mng. Khi tnh ma nhanh chng ly ht ch t sp xung, lc vt t sp l s tin hnh cha li 15cm y h o so vi ct thit k. Khi bc b lp t cha li ny (bng th cng) n u tin hnh lm lp lt mng bng b tng 4x6 ngay kp thi.
- C bin php tiu nc b mt khi gp ma nc khng chy t mt xung y h o. Lm rnh mp h o, quanh h mng trnh nc chy xung h o.
1.2.Cng tc lp t h mng:
Cng tc lp t h mng c thc hin sau khi b tng i mng v ging mng c nghim thu v cho php chuyn bc thi cng. Thi cng lp t h mng bng my kt hp vi th cng. t c lp theo tng t, lng nc v m cht bng my m cc Mikasa n cht thit k.
t lp mng v ct tn nn c chia thnh tng lp dy t 20-25cm, m cht bng my m cc n cht , kt hp m th cng cc gc cnh.
Cng tc lp t h mng nh thu m bo nhng yu cu sau:
+ t khng ln tp cht, vt rn lm nh hng n cng tc m.
+ V sinh h lp, vt b g vn, st vn. Khng lm nh hng n cc kt cu thi cng v thp ch thi cng dm ging, tr.
+ Kim tra m cht ca tng lp t, nu khng t yu cu th phi lm li.
+ Nu trong iu kin thi tit c ma ln nh hng ti lp t m t yu cu th lm li v lp t phi c kim tra li.
+ t lp phi t cao thit k.
+ Thng xuyn c lng nc m bo cc lp ct p c cht u.
+ Lp, m xong t tin hnh nghim thu v lp h s hon cng2. Bin php thi cng, yu cu k thut cng tc ct thp
2.1.Yu cu k thut:
a. Vt liu:
Ct thp trong b tng c s dng l ct thp Lin doanh sn xut ti Vit Nam, c trn th trng thnh ph v vng ph cn.
- Ct thp c p dng v nh gi theo tiu chun Vit Nam TCVN 1651-85 "Thp ct b tng cn nng" v TCVN 4453-95 "Kt cu btng ct thp ton khi. Quy phm thi cng v nghim thu".
- Thp khi a vo s dng thi cng, phi c chng ch ca nh sn xut v phi c kim tra cc ch tiu c l, c giy xc nhn cht lng ca c quan hnh ngh kim nghim vt liu xy dng.
- Ct thp trc khi gia cng phi bo m b mt sch khng c dnh bn t du m, sn hay r st, thnh vy. Thp c ko thng, cong vnh khng c vt qu sai s cho php theo quy phm TCVN 4453-95 .
- Cc loi thp phi c nh gi ng cht lng, ng chng loi, s lng, kch thc gia cng lp t vo ng cu kin theo yu cu ca bn v thit k. Trong qu trnh thi cng nu th trng khng chng loi ct thp cung ng, cn phi thay i chng loi thp Lin doanh m bo tin thi cng, th phi bo cho T vn gim st v Ch u t, khi c s chp thun ng chuyn i bng vn bn mi cung ng cho thi cng tip theo.
b. Bo qun ct thp
- Ct thp c bo qun ring theo tng nhm v c bin php chng n mn, chng han r , ct thp m bo sch, khng dnh bn, du m, sn dnh bm vo, khng c vy st v lp g, khng st so.
- Ct thp c ct gi trong nh kho v xp thnh ng phn bit theo s hiu, ng knh, chiu di v m hiu tin vic s dng. Khng xp ln ln gia ct thp r v cha r. Khi xp ct thp bi ngoi hin trng th k 1 u cao, 1 u thp trn nn cng khng c c mc. Thp k cao hn nn t nht 50 cm, khng xp cao qu 1,2 m v rng qu 2m, c bt che ph kn.
c. Gia cng ct thp
- Ct thp b bp, b gim din tch mt ct do co g, lm sch b mt hoc do nguyn nhn khc gy nn khng qu gii hn cho php l 5% ng knh.
- Dng my ct thp theo phng php c hc, ph hp vi hnh dng v qui cch thit k. Sn phm ct thp ct v un c kim tra theo tng l v vi sai s cho php i vi thp gia cng khng vt qu ch s qui nh trong qui phm. Mi l gm 100 thanh thp cng loi ct un, c mi l ly 5 thanh bt k kim tra.
- Ct thp c un ngui v dung sai un m bo theo tiu chun TCVN 4453-95. Khi un ct thp s tun theo ch dn sau:
+ Ch bt u un cong s c hnh thnh mt on cong phng u, bn knh cong bng 15 ln ng knh ct thp, gc v v tr ch un cong m bo ph hp vi qui nh ca thit k.
+ Mc cong hai u ct thp u hng vo pha trong kt cu. Nu ng knh ca ct thp ai t 6-10 mm th on thng u mc un ca ct ai m bo khng nh hn 60 mm. Nu ng knh ca ct thp ai t 10-12mm th on thng u mc un ca ct ai m bo khng nh hn 80 mm.
+ Ct thp u c un ngui, tuyt i khng un nng.
+ Ct thp sau khi c un cong m bo khng vt qu cc tr s quy nh sau:
STTCc loi sai sTr s sai lch cho php
1Sai lch v kch thc theo chiu di ca ct thp chu lc trong kt cu:
a Mi mt di( 5 mm
b Ton b chiu di( 20 mm
2Sai lch v v tr im un( 20 mm
3Sai lch v chiu di ct thp trong kt cu b tng khi ln:
a Khi chiu di nh hn 10 m( d
b Khi chiu di ln hn 10 m( (d+0,2d)
4Sai lch v gc un ct thp
Sai lch v kch thc mc un( 30
* Ni, hn ct thp:
- Ct thp c t trong vn khun ng v tr thit k, c hn hoc buc theo ng tiu chun TCXD 234-1999 "Ni ct thp c g". Chiu cao ng hn, chiu di mi hn m bo theo thit k, ng hn c chc, y, khng hn chy, hn xong c v sinh ngay. Chiu di ni theo thit k c k s gim st hin trng ghi chp cn thn v c nghim thu trc khi b tng.
- Khi ni ct thp tuyt i khng ni cc v tr chu lc ln v ch un cong. Trong mt mt ct ngang ca tit din kt cu khng ni qu 25% din tch tng ct thp chu lc i vi thp trn trn v khng qu 50% i vi thp c g.
* Phng php ni hn:
- Vic lin kt cc loi thp c tnh hn thp v khng c hn c thc hin tuyt i theo ch dn ca c s ch to.
- Hn ct thp s do th bc cao c kim tra thc t v c chng nhn cp bc ngh nghip. Khi cn thit s c kim tra bng thc nghim mi cho php thi cng.
- Trc khi ni hn lp s b tr mi ni, khng t mi ni hn ca thanh chu ko v tr chu lc ln.
- Ti nhng v tr b tr ct thp dy, khong cch nh hn 1,5 ln ng knh ct thp s khng hn chng ct thp ln nhau m bo khe h cho hn hp va b tng lt qua.
- Khi kim tra hnh dng mt ngoi mi ni hn bng mt thng m bo cc yu cu sau: Mt nhn v u, khng phng bt, khng ng cc, khng chy, khng t qung, khng b gim tit din cc b. Dc chiu di mi hn kim loi ng c, khng c khe nt, ti mt ni tip khng c khe h, ng tim ca hai ct thp trng nhau. Ct thp hn xong ly ba g c ting ku gin.
Kim tra sai s cho php ca kch thc thp so vi thit k v sai s cho php ca mi hn theo cc quy nh trong bng sau:
TTCc loi sai sTr s cho php
1Sai s v kch thc chung ca khung hn phng v li hn phng, cng nh theo di ca cc thanh gia cng ring l.
a - Khi ng knh ct thp nh hn 16 mm
Theo di ca thnh phm( 10 mm
Theo chiu rng hoc chiu cao ca thnh phm( 5 mm
Khi kch thc ca thnh phm theo chiu rng hay chiu cao nh hn 1 m( 3 mm
b - Khi ng knh ct thp t 18 40 mm
Theo di ca thnh phm( 10 mm
Theo chiu rng hoc chiu cao ca thnh phm( 10 mm
Khi kch thc ca thnh phm theo chiu rng hay chiu cao nh hn 1 m( 5 mm
c - Khi ng knh ct thp ln hn 40 mm
Theo di ca thnh phm( 50 mm
2Theo chiu rng hoc chiu cao ca thnh phm
Sai s v khong cch gia cc thanh ngang (thanh ni) ca khung hn, sai s v kch thc ca li hn v v khong cch gia cc b phn phng ca khung khng gian.( 20 mm
( 10 mm
3Sai s v khong cch gia cc thanh chu lc ring bit ca cc khung khng gian vi ng knh thanh l:
a Nh hn 40 mm( 5 d
b Ln hn hoc bng 40 mm( 1 d
4Sai s theo mt phng ca cc li khung hoc cc khung hn khi ng knh ca cc thanh l:
a Nh hn 12 mm( 10 mm
b T 12 ( 25 mm( 15 mm
c - T 25 ( 50 mm( 20 mm
d - T 50 mm tr ln( 25 mm
5Sai lch v v tr ch un ca thanh ct thp( 2 d
6Sai lch tm cc mi ni( 15 mm
7
Sai lch v v tr s vng thi cng cc khung ct thp chu lc so vi thit k.5%
* Phng php ni buc.
- ng knh ca thanh ni buc khng vt qu 25mm .
- Trc khi ni, tin hnh lp h s b tr mi ni, khng t mi ni ti nhng v tr chu lc ln, ch un cong.
- Chiu di cc on ni quy nh nh sau:
TTLoi ct thpChiu di ni buc
Khu vc chu koKhu vc chu nn
Dm v tngCc kt cu khcCt thp c mcCt thp khng mc
1Ct thp trn cn nng40d30d20d30d
2Ct thp c g cn nng40d30d20d
- Ct thp nm trong khu vc chu ko trc khi ni buc u c un u thnh mc cu vi thp trn.
- Dy thp buc dng loi dy thp c ng knh khong 1mm. Mi ni buc t nht l 3 v tr (gia v 2 u).
d. Lp dng ct thp
- Vn chuyn ct thp gia cng n v tr lp dng m bo thnh phm khng h hng v bin dng. Nu trong qu trnh vn chuyn ct thp b bin dng th trc khi lp dng u c sa cha li.
- Ct thp c k vi vn khun bng vin k bng b tng. V tr v loi vin bo h m bo ct thp khng b n mn v ph hp vi tnh cht chu lc sau ny ca cng trnh.
- V tr khong cch, dy lp bo v v kch thc ca cc b phn ct thp u c thc hin theo s vch sn ph hp vi qui nh ca bn v thit k. Ct thp c lp dng m bo khng bin dng v x dch v tr trong qu trnh thi cng. Nhng cu kin st thp c nh t trc vo b tng nh bu lng, cu thang m bo lp t ng v tr thit k quy nh, nu khng cn chn sn th tin hnh t ng tre, na cha l, tuyt i khng lm gy ct chu lc khi thi cng.
- m bo khong cch gia ct thp v vn khun, chng ti s dng nhng vin bo h bng b tng c chiu dy bng lp bo v v c dy thp buc cht vo cu kin k vo gia vn khun v ct thp, khng dng du mu ct thp k. Gia hai lp ct thp c t c gi khong cch gia chng theo ng quy nh ca thit k.
- Lin kt tng thanh thp ti v tr giao nhau c tin hnh bng phng php ni buc hoc hn.
- Sau khi lp dng, cc sai s khng vt qu tr s quy nh trong bng sau:
TTCc loi sai sTr s cho php (mm)
1Sai s v khong cch gia cc thanh chu lc ring bit
a - i vi cc kt cu khi ln( 30
b - i vi ct, dm v vm( 10
c - i vi bn, tng( 20
2Sai s v khong cch gia cc hng ct thp khi b tr nhiu hng theo chiu cao.
a Trong cc dm, khung v bn c chiu dy ln hn 100 mm.( 5
b Trong tng v bn c chiu dy n 100 mm v lp bo v 10 mm.( 3
3Sai s v khong cch gia cc ct ai ca khung( 10
4Sai s cc b v chiu dy ca lp bo v
a Trong cc kt cu khi ln( 20
b Trong mng nm di kt cu v cc thit b k thut khc( 10
c Trong ct, dm v vm( 5
d Trong tng v bn c chiu dy ln hn 100 mm.( 5
5Sai s v khong cch gia cc thanh phn b trong mt hng
a Trong cc tng( 25
b Trong cc kt cu b tng khi ln( 40
6
7Sai s v ct thp ai so vi chiu ng hoc chiu ngang (khng k cc trng hp khi cc ai t nghing theo quy phm).
Sai s v v tr tim ca cc thanh t u khung hn ni ti hin trng vi cc khung khi ng knh ca thanh( 10
a - Bng v ln hn 40 mm( 10
b - Nh hn 40 mm( 5
8Sai s v v tr mi hn ca cc thanh theo chiu di ca b phn
a - cc khung v cc kt cu tng mng( 20
b - cc kt cu khi ln( 50
9Sai s ca v tr cc b phn ct thp ca cc kt cu khi ln (khung, khi, gin) so vi thit k
a Trn bnh ( 50
b Trn chiu cao( 30
e. Kim tra, nghim thu ct thp
Cc sn phm gia cng c thng xuyn t chc kim tra, th nghim m bo theo tiu chun Vit Nam 4453-95 "Kt cu btng ct thp ton khi. Quy phm thi cng v nghim thu". Khi nhp ct thp a vo s dng cho cng trnh, nh thu cng t vn gim st v ch u t s tin hnh nghim thu vt liu loi cc thanh ct thp khng m bo quy cch cht lng. Khi t xong ct thp vo vn khun v trc khi b tng nh thu s t chc nghim thu ni b cng vic xy dng, khi no nghim thu ni b cng vic xong th nh thu mi cng cng t vn gim st v ch u t tin hnh nghim thu ct thp, ch khi no ton b ct thp ph hp vi cc iu kin v sinh sch s, kch thc cc im un, cht lng mi ni, v tr lp t v chiu di lp bo v theo ng thit k mi c php tin hnh b tng. H s nghim thu ct thp bao gm: Chng ch ni sn xut thp, bn v thit k (ghi mi thay i v ct thp trong qu trnh thi cng) kt qu kim tra mu th v cht lng mi hn, cht lng gia cng thp, bin bn nghim thu ni b cng vic xy dng ca nh thu, bin bn nghim thu cng vic xy dng. T vn gim st v cn b k thut thi cng cng kim tra, sau khi c s ng nghim thu ca t vn gim st mi lm cng vic tip theo.
Cng tc nghim thu ct thp c lp thnh bin bn trong ghi s cc bn v thi cng, cc sai s so vi thit k, nh gi cht lng cng tc ct thp v kt lun kh nng b tng km theo bin bn nghim thu ct thp c nhng ti liu sau:
+ Cc bn l lch ct thp v que hn ca nh my sn xut hoc cc bn phn tch ca phng th nghim.
+ Cc bin bn nghim thu ct thp gia cng xng vi cc kt qu th nghim mi hn, th nghim c hc ca ct thp chu lc theo quy nh trong thit k.
+ Cc bin bn th nghim cc mi hn ct thp ti hin trng.
+ Cc bn sao hoc thng k cc vn bn cho php thay i trong bn v thi cng.
Cn c vo cc mc trc c trn sn kim tra chnh xc ca cc thp ch.
Trc khi b tng sn tng di, kim tra thp ch ct tng trn. Thp ch ct, ct ai c buc y , chc chn m bo cng v khng b x dch khi b tng. Ct dc ming trn vn khun c neo chc vo vn khun gi v tr chnh xc trong vn khun, trnh b chuyn v.
2.2. Lp t ct thp mt s kt cu c th :
a . Mng b :
- Xc nh trc, tm mng, cao t li thp mng.
- Lp li thp mng c th gia cng lp buc ti h mng. Li thp c t trn cc con k m bo chiu dy lp bo v.
b . Dng buc ct thp thnh b :
- Kim tra v tr thnh b .
- Dng buc ti ch , bt u t thp mng, t ct thp ng v tr ri ni bng buc hoc hn, lng ct ai t trn xung v buc vi thp ng theo thit k. Ch phi m bo chiu dy lp bo v.
c . Ct thp dm sn.
- Chn mt s mu g k ngang vn khun thp .
- Vi cc thanh ni th phi chn ch c m men un nh nht .
- Dng thc g nh du v tr ct ai vo, nng hai thanh thp chu lc ln chm kht ct ai ri buc, buc hai u vo gia, xong li i 2 thanh thp di ln buc tip.
- Sau khi buc xong ct ai th h khung thp vo vn khun, h t t bng cch rt dn cc thanh g k ra .
3. Bin php thi cng, yu cu k thut cng tc lp dng, tho d cp pha
Gii php cp pha, dn gio cho d n l cp pha, dn gio thp nh hnh. Ngoi ra cn kt hp vi cp pha v cy chng g lp dng cho cc kt cu nh, l.
3.1. Yu cu k thut ca cp pha:
Cp pha v gio c thit k v thi cng phi m bo n nh trong qu trnh b tng, vng chc v mc bin dng m bo trong phm v cho php, n nh, d tho lp, khng gy kh khn cho vic t ct thp, v m b tng.
Cp pha phi c ghp kn, kht khng lm mt nc ximng khi v m b tng, ng thi bo v c b tng mi di tc ng ca thi tit.
Cp pha dm, sn c ghp trc lp t ct thp, cp pha ct c ghp sau khi lp t ct thp.
3.2 Lp t cp pha mt s kt cu c th
a. Lp t vn khun mng .
- Vn khun mng b c lp sau khi lp dng ct thp
- Ghp vn khun theo ng kch thc ca mng c th .
- C nh vn khun bng cc thanh chng cc c .
b. Vn khun thnh.
- Trc tin phi tin hnh mm thnh b cao 50mm to dng dng vn khun. Lu t sn cc thp ch trn nn sn to ch neo cho cp pha thnh.
- Gia cng thnh tng mng c kch thc hp l.
- Ghp cc mng theo kch thc c th ca thnh b.
- Dng gng(bng thp hoc g c nh),khong cch cc gng khong 50 cm - Ch : phi ca s b tng, chn vn khun thnh b c cha l v sinh trc khi b tng.
* Cch lp ghp :
-Vch mt ct thnh ln mt sn, nn .
- Ghim khung c nh chn vn khun bng cc m g t sn trong lng khi mng lm c .
- Dng ln lt cc mng pha trong ri n cc mng pha ngoi ri ng inh lin kt 4 mng vi nhau , lp gng v nm cht.
- Dng di kim tra li thng ng ca vn khun thnh b.
- C nh vn khun ct bng cc dy neo hoc cy chng.
c. Vn khun dm.
Gm 2 vn khun thnh v 1 vn khun y. Cch lp dng nh sau :
- Xc nh tim dm .
- Ri vn lt t chn ct .
- t cy chng ch T , t 2 cy chng st ct, c nh 2 ct chng, t thm mt s ct dc theo tim dm .
- Ri vn y dm trn x ct chng T , c nh 2 u bng cc ging .
- t cc tm vn khun thnh dm, ng inh lin kt vi y dm, c nh mp trn bng cc gng , cy chng xin , bu lng .
- Kim tra tim dm , chnh cao y dm cho ng thit k .
d. Vn khun sn .
- Dng vn khun thp t trn h dn gio khung Tip chu lc bng thp v h x g bng g, dng ti a din tch vn khun thp nh hnh, vi cc din tch cn li th dng kt hp vn khun g.
- Theo chu vi sn c vn dim, vn dim c lin kt bng inh con a vo thnh vn khun dm v dm vn khun dm.
3.3 Kim tra, nghim thu cng tc lp dng cp pha
Sau khi tin hnh xong cng tc vn khun th phi kim tra, nghim thu vn khun theo ni dung sau:
- Kim tra hnh dng kch thc theo bng sau
Cc yu cu cn kim traPhng php kim traKt qu kim tra
Cp pha lp dng:
Hnh dng v kch thcBng mt,
o bng thc Ph hp vi kt cu ca thit k
Kt cu cp phaBng mtm bo cc b phn chu lc ca gio hn ch s lng cc thanh ni
phng gia cc tm ghp niBng mtMc g gh gia cc tm (3mm
kn, kht gia cc tm cp pha, gia cp pha vi mt nnBng mtCp pha c ghp kn, kht, m bo khng mt nc xi mng khi m b tng
Chi tit chn ngm v t snXc nh kch thc, v tr v s lng bng cc phng tin thch hpm bo kch thc, v tr v s lng theo quy nh.
Chng dnh cp phaBng mtLp chng dnh ph kn cc mt cp pha tip xc vi b tng.
V sinh bn trong cp phaBng mtKhng cn rc, bn t v cc cht bn khc bn trong cp pha.
nghing, cao v kch thc cp phaBng mt, my trc c v cc thit b ph hpKhng vt qu cc tr s ghi.
m ca cp pha gBng mtCp pha g c ti nc trc khi b tng.
gio lp dng:
Kt cu gioBng mt, i chiu vi thit k gio gio c lp dng m bo kch thc, s lng v v tr theo thit k.
Ct chng gioBng mt, dng tay lc mnh cc ct chng, cc nm tng ct chngCt chng c k, m v t ln trn nn cng, m bo n nh.
cng v n nhBng mt, i chiu vi thit k gioCt chng c ging cho v ging ngang s lng, kch thc v v tr theo thit k.
- Kim tra cng vng ca h , h chng.
- phng ca mt phi vn khun (b mt tip xc vi mt b tng).
- Kim tra k h gia cc tm ghp vi nhau.
- Kim tra chi tit chn ngm.
- Kim tra tim ct , kch thc kt cu.
- Khong cch vn khun vi ct thp.
- Kim tra lp chng dnh, kim tra v sinh cp pha.
3.4 Cng tc tho d vn khun:
Cp pha gio ch c tho d khi b tng t c cng cn thit kt cu chu c trng lng bn thn v cc ti trng tc ng khc trong giai on thi cng sau.
Thi gian ti thiu cn thit k t khi b tng ti khi tho d vn khun, i vi cc kt cu khc nhau s c tun theo bng sau:
V trNgy i vi b tng xi mng Portland
thng thng
Mt bn dm, tng, ct (cha chu lc)2
Tm (c ct chng bn di)4
D ct chng tm10
Mt di dm (ct chng bn di)10
D ct chng dm14
i vi vn khun thnh thng ng khng chu lc do trng lng ca kt cu nh tng dy, tr ln ch c php tho d khi b tng t c cng m bo gi c b mt v cc gc cnh khng b st m hoc st n. Cng b tng l 25daN/cm2 nh sau:
Nhit trung bnh hng ngy (0C)15202530
Thi gian ti thiu t 25 daN/cm221,511
i vi vn khun chu ti trng (trng lng ct thp v trng lng hn hp b tng mi ) thi gian tho d vn khun da vo kt qu th nghim cng b tng. Trong trng hp khng c kt qu th nghim th s tun theo thi gian ti thiu qui nh sau:
Tn gi kt cu cng trnhCng t c tho vn khunNhit bnh qun hng ngy 0C
15202530
Tm an c khu t 2m tr xung50%7654
Tm an, dm c khu t 2m 8m70%121098
i vi vn khun chu ti trng, tho d vn thnh trc xem xt cht lng b tng, nu cht lng b tng nt r th tin hnh x l b tng t yu cu mi tho vn khun.
Cc kt cu vng, cng xn, sn ch tho y khi cng b tng t mc thit k v c i trng chng lt.
Nhng kt cu sau khi tho d vn khun, i n khi b tng t cng thit k mi cho php chu ton b ti trng thit k.
Khi tho d cp pha, gio trnh gy ng sut t ngt hoc va chm mnh n kt cu b tng.
Cc b phn cp pha, gio khng cn chu lc sau khi b tng ng rn (cp pha thnh dm, tng, ct) c th c tho d khi b tng t cng trn 50%daN/cm2.
Khi tho d cp pha gio cc tm sn b tng ton khi ca nh nhiu tng nn thc hin nh sau:
Gi li ton b gio v ct chng tm sn nm k di tm sn sp b tng
Tho d tng b phn ct chng cp pha ca tm sn di na v gi li ct chng an ton cch nhau 3m di cc dm c nhp ln hn 4m.
i vi cp pha gio chu lc ca 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 cng l 50% (7 ngy) vi bn dm, vm c khu nh hn 2m, t cng 70% (10 ngy) vi bn, dm, vm c khu t 2-8m, t cng 90% vi bn dm, vm c khu ln hn 8m.
4. Bin php thi cng btng
B tng dng cho cng trnh l b tng c trn bng my bng my bm t hnh4.1 Cng tc chun b trc khi :
a. Vt liu .
Tp kt s lng, m bo cht lng, s lng vt liu cha c ti trm trn phi c k hoch cung ng kp thi m bo thi cng lin tc.
Xi mng: Chng loi xi mng v mc ximng s dng phi ph hp vi thit k v cc iu kin, tnh cht, c im mi trng lm vic ca kt cu cng trnh.
Vic bo qun v vn chuyn ximng phi tun theo tiu chun TCVN 2682: 1992-"Ximng pooclng"
Xi mng dng trong cng trnh l xi mng Pooclng PC30, PCB 40 do cc nh my xi mng l quay sn xut , hot tnh th theo phng php nhanh khng di 500daN/cm2.
Vic vn chuyn v bo qun xi mng c tun theo tiu chun TCVN 2682-92 Xi mng Pooclng ng thi m bo tho mn cc yu cu k thut sau:
+ Xi mng dng trong thi cng c chng ch xc nhn ca nh sn xut v vic xi mng m bo cc tiu chun yu cu trong thi gian s dng.
+ Xi mng c gi ti hin trng trong iu kin khng lm thay i cht lng.
+ Bao ng ximng kn, khng rch, thng c t cch nc v thong kh trn mt sn cch mt t hn 300mm v c phng chng nc.
+ Khi cn thit xi mng c th d tr nhng m bo thi gian khng qu 3 thng k t ngy sn xut.
Vic kim tra xi mng ti hin trng s c tin hnh vi cc trng hp sau:
+ Khi thit k thnh phn cp phi b tng.
+ Do mt nguyn nhn no gy ra s nghi ng v cng xi mng khng p ng vi chng nhn ca nh my.
+ L xi mng c bo qun trn 3 thng k t ngy sn xut. Ct: Ct dng lm b tng nng phi tho mn cc yu cu ca tiu chun TCVN1770:1986 "Ct xy dng-yu cu k thut".
Bi cha ct phi kh rc, ng theo nhm ht, theo mc sch bn tin s dng v cn c bin php chng gi bay, ma tri v ln tp cht.
Ct s dng trong cng trnh l loi ct th c mun ln 2,3-2,4, khi lng th tch xp khng nh hn 1.400kg/m3, tp cht hu c cha trong ct th theo phng php so mu m bo sng hn mu chun. Cc ch tiu c l khc ca ct tho mn yu cu k thut ca TCVN 1770-86 " Ct xy dng. Yu cu k thut".
Ct vng sch khng ln bn v tp cht hu c, t l ht c kch thc 5 - 10mm ln khng vt qu 5% khi lng ct.
Thnh phn ht ca ct, i vi ct to v ct va, m bo ph hp vi cc tr s quy nh sau:
ng knh mt sngLng st tch lu trn sng theo % trng lng (%)
50
2,50-20
1,2515-45
0,6335-70
0,31570-90
0,1490-100
Cn c theo m dun ln Mc, ct chia lm bn loi nh trong bng sau:
Loi ctM dun ln nht ca ct (Mc)Lng st tch lu trn sng 0,63 mm theo % trng lng %
Ct to3,5-2,5(50
Ct va2,5-230-50
Ct nh2,0-1,510-30
Ct mn