B tng v va

tcxdvn 329:2004

tcxdvn 329:2004

TCXDVN Tiu chun xy dng Vit nam

TCXDVN 329 : 2004Bin son ln 1

B tng v va xy dng

phng php xc nh pH

Concrete and Mortar - Method for determination of pH

H ni - 2004

B Xy dng--------cng ho x hi ch ngha Vit Nam

c lp - T do - Hnh phc

S:29 /2004/Q-BXD----------

H ni, ngy 10 thng 12 nm 2004

Quyt nh ca b trng B Xy dng

V vic ban hnh TCXDVN 329 : 2004 " B tng v va xy dng

- Phng php xc nh pH "

b trng B Xy dng

- Cn c Ngh nh s 36 / 2003 / N-CP ngy 4 / 4 / 2003 ca Chnh ph quy nh chc nng, nhim v, quyn hn v c cu t chc ca B Xy dng.

- Xt ngh ca Vin trng Vin Khoa hc cng ngh Xy dng ti cng vn s 1067 / CV-VKH ngy 5 / 11 / 2004 v V trng V Khoa hc Cng ngh.

quyt nh

iu 1. Ban hnh km theo quyt nh ny 01 Tiu chun xy dng Vit Nam :

TCXDVN 329 : 2004 " B tng v va xy dng - Phng php xc nh pH "

iu 2. Quyt nh ny c hiu lc sau 15 ngy, k t ngy ng cng bo

iu 3. Cc ng Chnh vn phng B, V trng V Khoa hc Cng ngh, Vin trng Vin Khoa hc cng ngh Xy dng v Th trng cc n v c lin quan chu trch nhim thi hnh Quyt nh ny ./.

Ni nhn:

- Nh iu 3

- VP Chnh Ph

- Cng bo

- B T php

- V Php ch

- Lu VP&V KHCN

B trng b xy dng

Nguyn Hng Qun

Li ni u

Tiu chun xy dng TCXDVN 329 : 2004 B tng v va xy dng - Phng php xc nh pH do B Xy dng ban hnh theo quyt nh s 29 / 2004 / Q-B Xy dng ngy 10 / 12 / 2004.

Bin son ln 1

B tng v va xy dng - Phng php xc nh pH

Concrete and Mortar - Method for Determination of pH

1 Phm vi p dng

Tiu chun ny quy nh phng php xc nh pH ca b tng v va xy dng bng my o pH.

2 Ti liu vin dn

TCVN 6492 : 1999 Cht lng nc - Xc nh pH.

TCVN 4851: 1989 Nc dng phn tch trong phng th nghim.

TCXD VN 262: 2001 B tng nng - Phng php xc nh hm lng clorua trong ct liu v b tng.

3 Nguyn tc th

Tin hnh xc nh pH ca b tng v va thng qua o hiu in th ca in cc khi nhng trong dung dch mu bng my o pH.

4 Thit b v dng c th

4.1My o pH

4.1.1ng h o pH: Vi in tr u vo ln hn 1012 (, c b phn b tr nhit v iu chnh dc theo milivon trn n v pH v chnh xc n 0,01 n v pH.

4.1.2in cc l h in cc t hp (in cc kp) gm c:

in cc ch th: L in cc thy tinh hay cn gi l in cc pH.

in cc so snh: C th s dng in cc calomen bo ha hay in cc Ag/AgCl.4.2Thit b v dng c ly mu

4.2.1 Thit b ly mu b tng dng cc:

My khoan ng ly li b tng, ng knh mi khoan t 50 mm n 150 mm.

My ct ly mu b tng cc.

4.2.2 Thit b ly mu b tng, va dng bt, va dng cc :

My khoan in cm tay, ng knh mi khoan t 10 mm n 16 mm.

Ba, c.

Tha hoc que gt bng thp khng g ly mu b tng, va dng bt t l khoan, giy bng knh hng mu khoan.

Ti ng mu bng polyetylen.

4.3 Thit b v dng c gia cng mu

4.3.1Ba, ci, chy ng hoc gang p v nghin b tng, va dng cc.

4.3.2My nghin c kh nng nghin bt mn qua sng 0,14mm.

4.3.3Sng c 0,14 mm hoc 0,15 mm.

4.3.4Cn k thut c chnh xc n 0,01 g.

4.3.5Cn phn tch c chnh xc n 0,001 g.

4.3.6Cc hoc bnh ng mu bng thu tinh bn kim hoc bng cht do, dung tch ti thiu 50 ml, y bng, c np y.

4.3.7Cc ong dung tch 100ml; 500ml.

4.3.8Bnh nh mc dung tch 1000ml.

4.3.9 Giy ch th pH.

4.3.10 Nhit k c thang chia n 0,5oC.

5Ha cht

5.1Nc ct

Nc dng trong qu trnh th nghim l nc ct theo tiu chun TCVN 4851: 1989 c un si ui kh CO2.

5.2Dung dch m tiu chun

C th s dng cc dung dch m tiu chun ch sn hoc t pha. Khi s dng sn phm ch sn, ch thi hn s dng v cch bo qun ghi sn trn bao b.

Ha cht dng pha cc dung dch m tiu chun c tinh khit khng thp hn "tinh khit phn tch" (TKPT).

Ch thch:

Gi tr pH ca cc dung dch m tiu chun theo nhit v cch pha ch c trnh by chi tit trong ph lc A.

6Chun b mu th

6.1Ly mu

6.1.1Ly mu b tng

Mu b tng c ly dng cc v dng bt theo iu 6.2.1, tiu chun TCXD VN 262 : 2001.

6.1.2Ly mu va

Mu va c ly dng bt, hoc cc.

Dng khoan in cm tay khoan t 6 n 10 mi xung quanh khu vc cn ly mu, trong mt vng khong 0,15 m2. Hng ly bt va ri ra trong lc khoan bng giy bng knh. Khi lng mu va cn ly khng t hn 25 g.

C th ly mu bng ba, c dng cc.

Mu sau khi ly cn c bo qun trong ti polyetylen kn, trnh tip xc vi khng kh v hi m trc khi tin hnh th nghim.

6.2Chun b mu

6.2.1Mu cc hoc li khoan.

Dng ba hoc chy p nh thnh cc ht c kch thc b hn , trn u, p nh n cc ht c kch thc khong 5 mm, rt gn theo phng php chia t n khi thu c khong 25 g mu.

Nghin nh n khi lt ht qua sng c 0,14 mm hoc 0,15 mm thu c mu bt tin hnh xc nh pH.

6.2.2Mu ly dng bt

em nghin nh 25 g mu ly dng bt cho n khi lt ht qua sng c 0,14 mm hoc 0,15 mm thu c mu bt tin hnh xc nh pH.

Ch thch:

1. Mu th dng bt c bo qun trong ti polyetylen kn cho n khi th. Nn th ngay khi c th thu c kt qu chnh xc nht.

2. Thi gian lu mu khng qu mt thng.

7Tin hnh th

7.1Chun b mu o

7.1.1Cn 5 g mu bt b tng v va ( theo iu 6.2.1 v 6.2.2), chnh xc ti 0,01g vo cc hoc bnh c np y c c ra sch v trng bng nc ct (chun b theo iu 4.3.6). Thm vo 50 ml nc ct chun b theo iu 5.1.

7.1.2Khuy hoc lc nh bnh ng mu trong thi gian 5 pht cho bt va v b tng phn tn u trong nc, y np trnh tip xc vi khng kh.

7.1.3Sau 30 pht lc li cc bnh mu mt ln na.

7.1.4 yn bnh mu trong 24 h, thu c mu b tng, va xc nh pH.

7.2Chun my

7.2.1Xc nh pH s b ca dung dch mu b tng bng giy ch th, ghi li gi tr pH o.

7.2.2Trng ra in cc v bnh ng dung dch m tiu chun bng nc ct t nht ba ln. Thm kh nc u in cc bng giy thm hoc khn lau mm. Bnh ng mu c th sy hoc lau kh bng giy thm.

7.2.3 Chn hai dung dch m tiu chun c gi tr pH sao cho pH ca dung dch mu o c mc 7.2.1 nm trong khong pH ca hai dung dch m tiu chun.

7.2.4 Chun my o pH ti hai gi tr pH dung dch m tiu chun chn mc 7.2.3. Quy trnh chun my theo hng dn s dng ca nh sn xut.

7.2.5 Kt qu ca hai ln o ca mt dung dch m chun chnh lch khng qu 0,02 n v pH. Nu vt qu phi tin hnh chun li.

Ch thch :

Khng s dng li cc dung dch m tiu chun dng.

7.3Tin hnh o

7.3.1 Trnh ra, lm sch in cc nh iu 7.2.2 .

7.3.2 Trc khi o, lc nh bnh ng mu chun b iu 7.1, yn 5 pht.

7.3.3Nhng in cc vo mu o, lc trn v nh cho dung dch tip xc ht vi in cc. yn in cc cho n khi gi tr thu c my o khng i. Ghi li gi tr pH .

Ch thch:

Khi nhng in cc vo mu o, u in cc khng c chm vo lp b tng, va lng y bnh.

7.3.4Tip tc o pH ca dung dch mu th hai (mu song song). Kt qu gia hai ln o khng chnh lch qu 0,05 n v pH. Nu vt phi tin hnh lm li.

Ch thch:

1. Khi ra v lau in cc, trnh c ra mnh c th nh hng ti phn cc ca in cc dn ti sai s ca php o.

2. Bo qun in cc v my o pH theo hng dn ca nh sn xut.

8Kt qu th

Gi tr pH ca b tng, va c tnh bng trung bnh cng kt qu o ca hai th nghim tin hnh song song ca cng mt mu, ly chnh xc ti 0,01 n v pH.

9Bo co kt qu

Trong bo co kt qu cn c nhng thng tin sau :

a) K hiu mu, ngy, thng, nm ly mu;

b) Ni ly mu hoc tn cu kin ca cng trnh ly mu;

c) Tn n v th nghim;

d) Ngy, thng, nm th nghim;

e) Tiu chun th nghim (s hiu tiu chun ny);

f) Nhit thc hin th nghim;

g) Gi tr pH ca mu o theo iu 8.

Ph lc A

( Tham kho)Cc dung dch m tiu chun

A.1 Gi tr pH ca cc dung dch m tiu chun theo nhit

Bng A.1 : Gi tr pH ca cc dung dch m tiu chun theo nhit

Nhit C

PhtalatD

PhotphatE

BoraxF

Natri cacbonat /

Natri hidrocacbonatI

Canxi hidroxyt

04,006,989,4610,3213,42

54,006,959,3910,2513,21

104,006,929,3310,1813,00

154,006,909,2710,1212,81

204,006,889,2310,0612,63

254,006,869,1810,0112,45

304,016,859,149,9712,29

354,026,849,109,9312,13

404,036,849,079,8911,98

454,046,839,049,8611,84

504,066,839,029,8311,71

- Cc dung dch m tiu chun trn phi c pha bng nc khng c cha cacbon ioxit. Nc dng trong qu trnh pha ch phi l nc ct theo tiu chun TCVN 4851:1989 c un si ui kh CO2.

- S dng ho cht "TKPT" pha dung dch m tiu chun, cn phn tch chnh xc ti 0,001g

A.2 Cch pha ch cc dung dch m tiu chun

Dung dch C : Phtalat pH= 4,00 25 oC.

Ho tan 10,21 g kali hydro phtalat sy 2 gi 120oC vo nc ct 25oC ( 1oC v pha long thnh 1 lt trong bnh nh mc.

Dung dch D: Dinatri hidro photphat pH = 6,86 25o C. Ha tan 3,55g dinatri hydrophotphat ( sy 120oC trong 120 pht) v 3,39g kali dihidrophotphat vo nc ct 25 oC ( 1oC v pha long thnh 1 lt trong bnh nh mc.Dung dch E: Natri borax (Na2B407.10 H20) 0,01 M; pH = 9,18 25o C.

Ha tan 3,81g natri borax vo nc ct 25 oC ( 1o C v pha long thnh 1 lt trong bnh nh mc.

Dung dch F: Natri cacbonat (Na2C03) 0,025 M v natri hidrocacbonat (NaHC03) 0,025 M; pH = 10,01 25o C. Ha tan 2,64g natri cacbonat ( sy 250o C trong 90 pht) v 2,09g natrihidro cacbonat vo nc ct v pha long thnh 1 lt trong bnh nh mc.

Dung dch I: Canxi hidroxyt (Ca(OH)2); pH = 12,45 25oC.

Chun b dung dch qu bo ho Ca(OH)2 (TKPT) trong l nha, lc k v lc ly phn dung dch bng phu lc.

Bo qun dung dch m trong bnh nha, y nt kn trnh tip xc vi CO2 khng kh. Nu dung dch b vn c phi b i.

Ch thch: Cch pha ch dung dch m tham kho TCVN 6492:1999 v ASTM D 1293-95.

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