Class 6 Cement 1

SUBJECT: “Building Materials & Construction” B. Tech. III (Civil! " th Se#ester

SUBJECT TE$C%E: Bhaven '. Tandel $ssistant $ssist ant ro)e ro)essor ssor!! *e+art#ent o) Civil Engineering! S, 'ational Institute o) Technolog-! Surat. nt/ced.svnit.ac.in (012 134"" "526"

PORTLAND CEMENT

PORTLAND CEMENT

 Portland

Cement → Gypsum+Portland Cement Clinker 

 Portland

Cement Clinker → Calcareous  Clayey Materials !"urnin#$

 Paste → P%C% + &ater 

 Mortar

→ P%C% + &ater + 'and

 Concrete

→ P%C% + &ater + 'and + Gra(el

RA& MATER)AL' O* P%C% $ Calcareous Rocks !CaCO, - ./0$ Limestone C1alk  Marine s1ell deposits •

•

•

2$ Ar#illocalcareous Rocks !3405CaCO,5./0$ Cement rock  Clayey limestone Clayey c1alk  •

•

•

,$ Ar#illaceous Rocks !CaCO  5 340$ Clays '1ales 'lates ,

•

•

•



Portland cement is made "y mi6in# su"stances containin# CaCO   7it1 su"stances containin# 'iO 8 Al O 8 *e O  and 1eatin# t1em to a clinker 71ic1 is su"se9uently #round to po7der and mi6ed 7it1 2:; 0 #ypsum% ,

2

2

,

2

,

CL)Nsin# o#ueJs e9nJs calculate t1e compound composition o? t1e P%C% clinkerQ 2

2

,

2

,

C 'K3%4.;3%F:.%;22%2:;%./%: %3,,%K/2%0 C 'K2%.;22%2:4%./33/2%K23%/0 C AK2%;//%:%;F2,%K4%0 ,

2

,

C3A*K,%43,,%KF%30  To

see t1e e??ect o? c1an#e in o6ide composition on t1e c1an#e in compound composition8 assume t1at CaO is ;,%F0  'iO2  is 2,%20 and ot1ers are t1e same%

C,'K34%30 8 C2'K,;%20 8 C,AK40 8 C3A*KF%30 C,' c1an#ed ?rom /2%0→34%30 C2' c1an#ed ?rom 23%/0→,;%20  0

c1an#e in CaO  'iO2 resulted in more t1an 40 c1an#e in C,'  C2' content%

)n?luence o? Compound Composition on C1aracteristics o? P%C%  P%C%+7ater→t1e

compounds in t1e cement under#o c1emical reactions 7it1 t1e 7ater independently8 and di??erent products result ?rom t1ese reactions% C"S

C#S

C"A

C$AF

ate o& eation

Moderate

'lo7

*ast

Moderate

'eat iberation

i#1

Lo7

ery i#1

Moderate

arl* Cementitiou! +alue

Good

Poor

Good

Poor  

,ltimate Cementitiou! +alue

Good

Good

Poor

Poor  

ASTM T*pe - Name o& .C. T*pe 0 1 O..C. T*pe 00 1 Modi&ied

Avera/e Compound Compo!ition C"S

C#S

C"A

C$AF

3F

2/

2



General Purpose

2

*or Moderate ydration

3;

2F

;

eat

T*pe 000 1 'i/h arl* Stren/th /;

/

2



C,'C,A decreased

T*pe 0+ 1 o2 'eat ,4 .C.

3;

/

,

C2' increased

2

Limit on C,A/08 2C,A+C3A*2/0

T*pe + 1 e!i!tant .C.

Sul&ate

3,

,;

3

increased8

o? C2'

 C2'

 C 'H .4:40 o? cement is composed o? t1ese t7o compounds  most o? t1e stren#t1 #i(in#  properties o? cement is controlled "y t1ese compounds% ,

 >pon

1ydration "ot1 calcium:silicates result in t1e same products% 2C '+; → C '   + ,C 2C '+3 → C '   + C ,

,

2

,

2

,

2

,

 Calcium:'ilicate:ydrate

!C:': #el$ is similar to a mineral called @TOERMOR)TE% As a result it is named as @TOERMOR)TE GEL

 >pon

1ydration o? C '  C '8 C also ?orms 71ic1 "ecomes an inte#ral part o? 1ydration  products% C does not contri"ute (ery muc1 to t1e stren#t1 o? portland cement% ,

 C,'

2

1a(in# a ?aster rate o? reaction accompanied "y #reater 1eat #eneration de(elopes early stren#t1 o? t1e paste% On t1e ot1er 1and8 C ' 1ydrates  1ardens slo7ly so results in less 1eat #eneration  de(elops most o? t1e ultimate stren#t1% 2

 i#1er

C,'→1i#1er early stren#t1:1i#1er 1eat #eneration !roads8 cold en(ironments$ i#1er C2'→lo7er early stren#t1:lo7er 1eat #eneration !dams$

 C,AH

is c1aracteristically ?ast reactin# 7it1 7ater  may lead to a rapid sti??enin# o? t1e paste 7it1 a lar#e amount o? t1e 1eat #eneration !*las1: 'et$:!Suick:'et$% )n order to pre(ent t1is rapid reaction #ypsum is added to t1e clinker% Gypsum8 C,A7ater react to ?orm relati(ely insolu"le Calcium:'ul?o:Aluminates%

 Also

Calcium:'ul?o Aluminates are prone !less resistant$ to sul?ate attack  does not contri"ute muc1 ?or stren#t1% T1e cement to "e used in makin# concretes t1at are #oin# to "e e6posed to soils or 7aters t1at contain sul?ates s1ould not contain more t1an /0 C,A%

 C3A*H

T1e 1ydration o? ?errite p1ase is not 7ell understand% *errite p1ase 1as lesser role in de(elopment o? stren#t1% T1e 1ydration products are similar to C,A% Alumina  iron o6ide occur interc1an#e"ly in t1e 1ydration products%