507 33 powerpoint-slides ch1 drcs
TRANSCRIPT
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
1/94
Oxford University Press 2013. All rights
Design ofDesign of
ReinforcedReinforcedConcreteConcrete
StructuresStructures
N. Subramanian
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
2/94
Oxford University Press 2013. All rights
Chapter 1Chapter 1
Introduction toIntroduction to
Reinforced ConcreteReinforced Concrete
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
3/94
Oxford University Press 2013. All rights
Concrete is used in nearly every type of construction.
raditionally! concrete has "een pri#arily co#posed ofce#ent! $ater! and aggregates.
Concrete is not a ho#ogeneous #aterial! and its
strength and structural properties #ay vary greatlydepending upon its ingredients and #ethod of#anufacture.
%teel reinforce#ents are often included to increase thetensile strength of concrete& such concrete is calledreinforced cement concrete '(CC) or si#plyreinforced concrete '(C).
As of 200*! a"out +., "illion cu"ic #etres of concrete
-ntroduction
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
4/94
Oxford University Press 2013. All rights
lo"al Annual Consu#ption of%tructural /aterials
Material Unit Weight(g!m"#
Million$onnes
$onnes!%erson
%tructural steel +,0 12 0.1
Ce#ent 10 300 0.
Concrete 200 1!000 2. '0 litres)
i#"er +00 2++ 0.0
4rin5ing$ater
1000 ,132 0.+3 '+30 litres)
Table 1.1 Annual consumption of major structural materials in the world
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
5/94
Oxford University Press 2013. All rights
Case %tudy
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
6/94
Oxford University Press 2013. All rights
1. /oulded to any shape
2. 6asy availa"ility of #aterials 'for #anufacturing concrete)
3. 7o$ #aintenance
. 8ater and 9re resistant
,. ood rigidity
*. :igh co#pressive strength
+. 6cono#ical
. 7o$;s5illed la"our re
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
7/94 Oxford University Press 2013. All rights
1. 7o$ tensile strength 'one;tenth of its co#pressivestrength)
2. (e
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
8/94 Oxford University Press 2013. All rights
Portland ce#ents are also referred to as hydrauliccements! as they not only harden "y reacting $ith$ater "ut also for# a $ater;resistant product. he ra$#aterials used for the #anufacture of ce#ent consistof li#estone! chal5! seashells! shale! clay! slate! silica
sand! alu#ina and iron ore.
$o di?erent processes! 5no$n as dry and wet! areused in the #anufacture of Portland ce#ent!
-n addition! a se#i;dry process is also so#eti#ese#ployed in $hich the ra$ #aterials are ground dry!#ixed $ith $ater! and then "urnt in the 5ilns. /ost
#odern ce#ent factories use either a dry or a se#i;dry
/anufacturing Process ofPortland Ce#ent
/ f i P f
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
9/94 Oxford University Press 2013. All rights
/anufacturing Process ofPortland Ce#ent
Fig. 1.1 Schematic representation of dry process of cement manufacture
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
10/94 Oxford University Press 2013. All rights
Fig. 1.2 Cement, water, fine and course aggregate, chemical and mineral
admitures are combined to form present!day concrete
Concrete -ngredients
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
11/94 Oxford University Press 2013. All rights
Portland Ce#ent
Portland cement (OPC) is the #ost co##on type ofce#ent in general use around the $orld.
Ordinary Portland ce#ent is the #ost i#portant ce#entand is often used! though the current trend is to use PPC.
he speci9c gravity of Portland ce#ent is approxi#ately3.1,.
he silicates C3% and C2% are the #ost i#portantco#pounds and are #ainly responsi"le for the strength of
the ce#ent paste. hey constitute the "ul5 of theco#position.
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
12/94 Oxford University Press 2013. All rights
e# ca o#pos on oOPC
@Ce#ent che#ists use the follo$ing shorthand notation C B CaO! % B %iO 2! A B Al2O3! B e2O3! /
B /gO! : B :2O!
D B Da2O! E B E2O! % B %O3.
S.
No.
Compound Cement
ChemistNotation
(CCN#&
$'pical
Compositionas
Mineral
%hase
1. ricalciu# silicate3'CaO)F%iO2
C3% ,;*, Alite
2. 4icalciu# silicate2'CaO)F%iO2
C2% 1,;30 Gelite
3. ricalciu# alu#inate3'CaO)FAl2O3
C3A ,;10 Alu#inate
. etracalciu# alu#inoferrite'CaO)FAl2O3Fe2O3
CA ,;1, errite
,. ypsu# Ca%OF2 :2O 2;10
Table 1.2 Chemical composition of "#C $%ogue&s Compounds'
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
13/94
Oxford University Press 2013. All rights
he G-% has classi9ed OPC into the follo$ing threerades
33 rade OPC! -% 2*1
3 rade OPC! -% 1121 ,3 rade OPC! -% 122*1+
he nu#"er in the grade indicates 2 day co#pressivestrength of ce#ent in DH##2
Dote 33 grade is not availa"le in the #ar5etI
hree rades of OPC
Ad t f P tl d P l
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
14/94 Oxford University Press 2013. All rights
Advantages of Portland PoJJolanaCe#ent
1. 6cono#ical than OPC as the costly clin5er is replaced"y cheaper poJJolanic #aterial
2. Converts solu"le calciu# hydroxide into insolu"lece#entitious products! thus i#proving per#ea"ility
and dura"ility
3. Consu#es calciu# hydroxide and does not produce as#uch calciu# hydroxide as OPC
. -#proves pore siJe distri"ution and reduces #icro;
crac5s at the transition Jone due to the presence of9ner particles than OPC
,. (educes heat of hydration and ther#al crac5ing
*. :as high degree of cohesion and $or5a"ility in
concrete and #ortar
4i d t f P tl d
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
15/94 Oxford University Press 2013. All rights
1. he rate of develop#ent of strength is initiallyslightly slo$er than OPC.
2. he e?ect of reducing the al5alinity #ay reduce theresistance to corrosion of steel reinforce#ent.
4isadvantages of PortlandPoJJolana Ce#ent
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
16/94 Oxford University Press 2013. All rights
Portland %lag Ce#ent
P%C is o"tained either "y inti#ateinter;grinding of a #ixture ofPortland ce#ent clin5er and
granulated slag $ith the additionof gypsu# or calciu# sulphate or
"y an inti#ate and unifor#
"lending of Portland ce#ent and9nely ground granulated slag.
A t P t %
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
17/94
Oxford University Press 2013. All rights
1. UtiliJation of slag ce#ent in concrete not only lessens
the "urden on land9lls& it also conserves a virgin#anufactured product 'OPC) and decreases thee#"odied energy re
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
18/94
Oxford University Press 2013. All rights
. he lighter colour of slag ce#ent concrete also helpsreduce the heat island e?ect in large #etropolitanareas.
,. -t has lo$ heat of hydration and is relatively "etterresistant to soils and $ater containing excessivea#ounts of sulphates and is hence used for #arine
$or5s! retaining $alls! and foundations.
A vantages o Port an % agCe#ent
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
19/94
Oxford University Press 2013. All rights
Aggregates
he 9ne and coarse aggregates occupy a"out *0=+, percent of the concrete volu#e '+0=,> "y #ass) and hencestrongly inKuence the properties of fresh as $ell ashardened concrete! its #ixture proportions! and the
econo#y.
Aggregates #ust "e clean! hard! strong! and dura"le&they should "e free fro# coatings of clay! a"sor"edche#icals! and other 9ne #aterials that could a?ect thehydration and "ond of the ce#ent paste.
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
20/94
Oxford University Press 2013. All rights
Aggregates are co##only classi9ed into 9ne and coarse
aggregates. )ine aggregates generally consist ofnatural sand or crushed stone $ith particle siJe s#allerthan a"out , ##. Coarse aggregates consist of one ora co#"ination of gravels or crushed stone $ith particle
siJe larger than , ##.
4epending on the source! they could "e eithernaturall' occurring 'gravel! pe""les! sand! etc.) or
s'ntheticall' manufactured '"loated clay aggregates!sintered Ky ash aggregate! etc.).
4epending on the "ul5 density! aggregates can either
"e normal *eight '1,20=1*0 5gH#3
)! light*eight3
Classi9cation of Aggregates
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
21/94
Oxford University Press 2013. All rights
AggregatesS. No. )actors In,uence on Concrete %ropert'
1. %peci9cgravityHPorosity
%trengthHA"sorption of $ater
2. Crushing strength %trength
3. Che#ical sta"ility 4ura"ility
. %urface texture Gond grip
,. %hape 8ater de#and 'strength)
*. radation or particlesiJedistri"ution
8ater de#and 'strength)! cohesion!"leeding! and segregation
+. /axi#u# siJe of
aggregate
%trength and $ater de#and
. Presence of deleterious#aterials such as dust!clay!silt! or #ud
8ater de#and 'strength)! cohesion!"ond! and dura"ility
Table 1.( Factors of aggregates that may affect properties of concrete
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
22/94
Oxford University Press 2013. All rights
8ater8ater plays an i#portant role in the $or5a"ility!
strength! and dura"ility of concrete.
oo #uch $ater reduces the concrete strength! $hereastoo little $ill #a5e the concrete un$or5a"le.
he $ater used for #ixing and curing should "e cleanand free fro# inLurious a#ounts of oils! acids! al5alis!
salts! sugars! or organic #aterials! $hich #ay a?ect theconcrete or steel. -n general! sea $ater should not "eused for #ixing or curing concrete.
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
23/94
Oxford University Press 2013. All rights
Che#ical Ad#ixturesChe#ical ad#ixtures are #aterials in the for# of
po$der or Kuids that are added to the concretei##ediately "efore or during #ixing in order to i#provethe properties of concrete.
he co##on types of ad#ixtures are as follo$s
1. Accelerators
2. (etarders
3. 8ater;reducing ad#ixtures
. Air entraining ad#ixtures
,. Corrosion inhi"itors
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
24/94
Oxford University Press 2013. All rights
/ineral Ad#ixtures/ineral ad#ixtures are inorganic #aterials that also
have poJJolanic properties. hese very 9ne;grained#aterials are added to the concrete #ix to i#prove theproperties of concrete '#ineral ad#ixtures) or as areplace#ent for Portland ce#ent '"lended ce#ents).
%o#e of the #ineral ad#ixtures are listed as follo$s
1.ly ash
2. round granulated "last furnace slag
3.%ilica fu#e
. (ice hus5 ash '(:A)
,. :igh;reactivity /eta5aolin ':(/)
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
25/94
Oxford University Press 2013. All rights
Concrete /ix
Concrete #ix design is the process ofproportioning various ingredients
such as ce#ent! ce#entitious
#aterials! aggregates! $ater! andad#ixtures opti#ally in order to
produce a concrete at #ini#al cost
and $ill have speci9ed properties of$or5a"ility and ho#ogeneity in thegreen state and strength and
dura"ility in the hardened state.
ropor on ng o oncre e
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
26/94
Oxford University Press 2013. All rights
he #ain o"Lective of any concrete #ix proportioning#ethod is to #a5e a concrete that has the follo$ingfeatures
1. %atis9es $or5a"ility re
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
27/94
Oxford University Press 2013. All rights
/ix Proportioning Procedure
1. Calculate the target #ean co#pressive strength for#ix proportioning.
2. %elect the $Hc ratio.
3. %elect the $ater content.
. Calculate the content of ce#entitious #aterial.
,. 6sti#ate the proportion of coarse aggregate.
*. -dentify the co#"ination of di?erent siJes of coarseaggregate fractions.
+. 6sti#ate the proportion of 9ne aggregate.
. Perfor# trial #ixes.
ropor on ng o oncre e
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
28/94
Oxford University Press 2013. All rights
ropor on ng o oncre e/ixes
S. No. Nominal Ma-imum Sie of
/ggregate0 mm
Ma-imum Water Content0
g
1. 10 20
2. 20 1*
3. 0 1*,Table 1.) *aimum water content per cubic metre of concrete for nominal maimum si+e of
$angular' aggregateNominal
Ma-imumSie of
/ggregate0mm
olume of Coarse /ggregate %er Unit olume of $otal/ggregate for Di2erent 3ones of )ine /ggregate (for
*!c Ratio 4 5.6#
3one I 3one III 3one II 3one I
10 0.,0 0. 0.* 0.
20 0.** 0.* 0.*2 0.*0
0 0.+, 0.+3 0.+1 0.*
Table 1. -olume of coarse aggregate per unit olume of total aggregate for different +ones of
fine aggregate
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
29/94
Oxford University Press 2013. All rights
:ydration of Ce#ent
8hen Portland ce#ent is #ixed $ith $ater! a series ofche#ical reactions ta5es place! $hich results in thefor#ation of ne$ co#pounds and progressive setting!hardening of the ce#ent paste! and 9nally in the
develop#ent of strength. he overall process is referredto as ce#ent hydration.
:ydration involves #any di?erent reactions! oftenoccurring at the sa#e ti#e. 8hen the paste 'ce#ent and$ater) is added to aggregates 'coarse and 9ne)! it acts asan adhesive and "inds the aggregates together to for#
concrete.
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
30/94
Oxford University Press 2013. All rights
7eat of h'dration8 8hen Portland ce#ent is #ixed$ith $ater! heat is li"erated as a result of the exother#icche#ical reaction. his heat is called the heat ofhydration. he heat generated "y the ce#entNs hydration
raises the te#perature of concrete. A very highte#perature rise $ill result in the crac5ing of theconcrete.
/ineral ad#ixtures 'e.g.! Ky ash)! can signi9cantlyreduce the rate and a#ount of heat develop#ent. curing$ith $ater helps to control te#perature increases and is
"etter than other curing #ethods.
:ydration of Ce#ent
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
31/94
Oxford University Press 2013. All rights
ypes of Concrete 4epending on $here it is #ixed! concrete #ay "e
classi9ed as site9mi-ed concreteor read'9mi-ed(factor'9mi-ed# concrete (RMC#.
Concrete $ithout reinforce#ent is called plainconcrete and $ith reinforce#ent is called RCCor RC.
4epending on the strength it #ay attain in 2 days!concrete #ay "e designated as ordinar' concrete!standardor normal strength concrete (NSC#!high9strength concrete 7SC! and ultra9high9
strength concrete (U7SC#.
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
32/94
Oxford University Press 2013. All rights
Concrete $ith enhanced perfor#ance characteristics iscalled high9performance concrete (7%C#. Self9compacting concrete (SCC#is a type of :PC! in$hich #axi#u# co#paction is achieved using special
ad#ixtures and $ithout using vi"rators.
8hen 9"res are used in concrete! it is called :bre9
reinforced concrete ()RC#. :igh;perfor#ance (Csare called ductile :bre9reinforced cementitiouscomposites (D)RCCs#& they are also called ultra9high9performance concretes (U7%Cs# or
engineered cementitious composites (;CCs#.
ypes of Concrete
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
33/94
Oxford University Press 2013. All rights
(eady;#ixed Concrete
(eady;#ixed concrete is a type of concrete that is#anufactured in a factory or "atching plant! "ased onstandardiJed #ix designs! and then delivered to the $or5site "y truc5;#ounted transit #ixers.
/ost of the (/C plants are located in seven large citiesof -ndia! and they contri"ute to a"out 30=*0 per cent of
total concrete used in these cities. he fraction of (/C tototal concrete "eing used is 2., per cent. (/C is "eingused for "ridges! Kyovers! and large co##ercial andresidential "uildings.
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
34/94
Oxford University Press 2013. All rights
/d+antage
his type of concrete results in #ore precise #ixtures!$ith strict
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
35/94
Oxford University Press 2013. All rights
4e9nition of :igh;perfor#anceConcrete
:igh;perfor#ance concrete #ay "e de9ned as any
concrete that provides enhanced perfor#ancecharacteristics for a given application.
AC- has adopted the follo$ing "road de9nition of :PC
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
36/94
Oxford University Press 2013. All rights
he :PCs are #ade $ith carefully selected high;
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
37/94
Oxford University Press 2013. All rights
%ropert' Criteria that ma' be speci:ed
:igh strength +0=10 /Pa at 2=1 days
:igh early co#pressivestrength
20=2 /Pa at 3=12 hours or 1=3 days
:igh early Kexural strength 2= /Pa at 3=12 hours or 1=3 days
:igh #odulus of elasticity /ore than 0 Pa
A"rasion resistance 0=1 ## depth of $ear
7o$ per#ea"ility ,00=2000 Coulo#"s
Chloride penetration 7ess than 0.0+> Cl at * #onths%ulphate attac5 0.10> or 0.,> #axi#u# expansion at *
#onths for#oderate or severe sulphate exposures
7o$ a"sorption 2=,>
7o$ di?usion coeMcient 1000 101 #Hs(esistance to che#icalattac5
Do deterioration after 1 year
7o$ shrin5age %hrin5age strain less than 0.0> in 0 days
7o$ creep 7ess than nor#al concreteTable 1./ 0esired characteristics of #Cs
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
38/94
Oxford University Press 2013. All rights
%elf;co#pacting Concrete
%CC is a highly $or5a"le concrete that can Ko$ throughdensely reinforced and co#plex structural ele#ents underits o$n $eight and ade
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
39/94
Oxford University Press 2013. All rights
%elf;co#pacting Concrete%everal ne$ tests have evolved for testing the suita"ility
of %CC 'see ig. 1.3 in the follo$ing slide). heyessentially involve testing the follo$ing
1. lo$a"ility 'slu#p Ko$ test)
2. illing a"ility 'slu#p Ko$ test! Q;funnel! and Ori#et)
3. Passing a"ility '7;"ox! R;ring! $hich is a si#plersu"stitute for U;"ox)
. (o"ustness
,. %egregation resistance or sta"ility 'si#ple colu#n"ox test sieve sta"ilit test
lf i
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
40/94
Oxford University Press 2013. All rights
%elf;co#pacting Concrete
Fig. 1.( Tests on self!consolidating concrete $a' Slump flow test $b' !bo $c' 3!ring $d' -!funnel
$e' 4!flow test
ruc ura g $e g
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
41/94
Oxford University Press 2013. All rights
ruc ura g $e gConcrete
%78C is #ade $ith light$eight coarse aggregates such
as natural pu#ice or scoria aggregates and expandedslags& sintering;grate expanded shale! clay! or Ky ash&and rotary;5iln expanded shale! clay! or slate.
Advantages
1. he use of %78C allo$s us to reduce the dead$eightof concrete ele#ents! thus resulting in overall
econo#y.2. %eis#ic perfor#ance is also i#proved "ecause the
lateral and horiJontal forces acting on a structureduring an earth
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
42/94
Oxford University Press 2013. All rights
-nternal Curing
An e?ective techni
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
43/94
Oxford University Press 2013. All rights
i"re;reinforced Concrete
i"res are added to concrete to control crac5ing caused"y plastic shrin5age and drying shrin5age.
he addition of s#all closely spaced and unifor#ly
dispersed 9"res $ill act as crac5 arresters and enhancethe tensile! fatigue! i#pact! and a"rasion resistance ofconcrete.hey also reduce the per#ea"ility of concrete.
hough the Kexural strength #ay increase #arginally!9"res cannot totally replace Kexural steel reinforce#ent.
i" i f d C t
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
44/94
Oxford University Press 2013. All rights
i"re;reinforced Concrete
Fig. 1.) Fibres used in concrete $a' 0ifferent types and shapes of steel fibres
$b' Fine fibrillated polypropylene fibres $c' 5lass fibres
4uctile i"re;reinforced
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
45/94
Oxford University Press 2013. All rights
4uctile 9"re;reinforced ce#entitious co#posite is a"roader class of #aterials that has properties andsuperior perfor#ance characteristics co#pared toconventional ce#entitious #aterials such as concrete and
(C.
4(CCs have uni
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
46/94
Oxford University Press 2013. All rights
Classi9cation of Ce#entitious/aterials
Fig. 1. Classification of cementitious materials
4uctile i"re;reinforced
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
47/94
Oxford University Press 2013. All rights
;ngineered Cementitious Composites6CC are a special type of :P(CC that has "een #icro;structurally tailored "ased on #icro;#echanics.
6CC is syste#atically engineered to achieve highductility under tensile and shear loading.
Gy e#ploying #aterial design "ased on #icro;#echanics! it can achieve #axi#u# ductility in excess ofthree per cent under uniaxial tensile loading $ith only t$o
per cent 9"re content "y volu#e.
4uctile i"re reinforcedCe#entitious Co#posites
4uctile i"re;reinforced
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
48/94
Oxford University Press 2013. All rights
Ultra9high %erformance ConcreteU:PCis a high;strength! high;sti?ness! self;consolidating! and ductile #aterial! for#ulated "yco#"ining Portland ce#ent! silica fu#e!
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
49/94
Oxford University Press 2013. All rights
Slurr' In:ltrated )ibrous Concrete(SI)C?N#
%-COD is produced "y in9ltrating ce#ent slurry into
pre;placed steel 9"res 'single plain or defor#ed 9"res) ina for#$or5. -t has to "e noted that it does not contain anycoarse aggregates "ut has a high ce#entitious content.
Slurr' in:ltrated mat concrete (SIMC?N# is si#ilarto %-COD! "ut uses pre;placed 9"re #at instead of steel9"res.
4uctile i"re reinforcedCe#entitious Co#posites
t
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
50/94
Oxford University Press 2013. All rights
erroce#enterroce#ent is a thin (C #ade of rich ce#ent #ortar
'ce#ent to sand ratio of 13) "ased #atrix reinforced $ithclosely spaced layers of relatively s#all dia#eter $ire#esh! $elded #esh! or chic5en #esh.
Fig. 1./ Ferrocement
t
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
51/94
Oxford University Press 2013. All rights
erroce#ent
he #ortar #atrix should have excellent Ko$characteristics and high dura"ility. he use of poJJolanic#ineral ad#ixtures such as Ky ash ',0> ce#entreplace#ent $ith Ky ash is reco##ended) and use of
superplasticiJers $ill not only per#it the use of $ater="inder ratio of 0.0=0., "y #ass "ut $ill also enhancethe dura"ility of the #atrix.
Applications of ferroce#ent include "oats! "arges! $atertan5s! pipes! "iogas digesters! septic tan5s! toilet "loc5s!and #onolithic or prefa"ricated housing.
P l C t
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
52/94
Oxford University Press 2013. All rights
Poly#er Concrete%ol'mer concrete is o"tained "y i#pregnating
ordinary concrete $ith a #ono#er #aterial and thenpoly#eriJing it "y radiation! "y heat and catalyticingredients! or "y a co#"ination of these t$o techni
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
53/94
Oxford University Press 2013. All rights
(einforcing %teel%teel reinforce#ents are provided in (CC to resist tensile
stresses. he
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
54/94
Oxford University Press 2013. All rights
(einforcing %teel
%teel reinforce#ent used in concrete #ay "e of thefollo$ing types
1. /ild steel and #ediu# tensile steel "ars '/% "ars)
2. :igh;yield strength;defor#ed steel "ars ':S%4 "ars)
3. :ard dra$n steel $ire fa"ric
. %tructural steel confor#ing
Corrosion of (e"ars
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
55/94
Oxford University Press 2013. All rights
Corrosion of (e"ars
he pri#ary factors controlling the corrosion rate ofsteel re"ars"are the availa"ility of oxygen! electricalresistivity and relative hu#idity of the concrete! p:! andprevailing te#perature.
Car"onation is another cause for corrosion. Car"onation;induced corrosion often occurs in "uilding facades that
are exposed to rainfall! are shaded fro# sunlight! andhave lo$ concrete cover over the reinforcing steel.
Corrosion of (e"ars
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
56/94
Oxford University Press 2013. All rights
Corrosion of (e"arsCorrosion can also occur $hen t$o di?erent #etals are
in contact $ithin concrete.
8hen corrosion ta5es place! the resulting rust occupies
#ore than three ti#es the original volu#e of steel fro#$hich it is for#ed creating tensile stresses in theconcrete! $hich can eventually cause crac5ing!dela#ination! and spalling of cover concrete.
he presence of corrosion also reduces the e?ectivecross;sectional area of the steel reinforce#ent and leads
to the failure of a concrete ele#ent and su"se
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
57/94
Oxford University Press 2013. All rights
/itigating Corrosion
/itigation #easures to reduce the occurrence of corrosioninclude the follo$ing
1. 4ecreasing the $Hc or $Hc# ratio of concrete andusing poJJolans and slag to #a5e the concrete less
per#ea"le2. Providing dense concrete cover using controlled
per#ea"ility for#$or5 'CP)! thus protecting thee#"edded steel re"ars fro# corrosive #aterials
3. -ncluding the use of corrosion;inhi"iting ad#ixtures. Providing protective coating to reinforce#ent
,. Using of sealers and #e#"ranes on the concretesurface
/itigating Corrosion
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
58/94
Oxford University Press 2013. All rights
/itigating Corrosion
ollo$ing reinforce#ents can "e used to #itigatecorrosion
1.)usion9bonded epo-'9coated reinforcing barsused in (C "ridges $ith a satisfactory perfor#ance
@.Aal+anied reinforcing bars $hose protectiveJinc layer does not "rea5 easily and results in "etter
"ond
".Stainless steel bars $hose initial cost is high "utthe life cycle cost is lo$er
/itigating Corrosion
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
59/94
Oxford University Press 2013. All rights
/itigating Corrosion
B. )ibre9reinforced pol'mer bars ()R% bars# areara#id 9"re 'A(P)! car"on 9"re 'C(P) or glass9"re '(P) reinforced poly#er rods. hey are non;#etallic and hence non;corrosive.
6. asalt bars are #anufactured fro# continuous"asalt 9la#ents and epoxy and polyester resins
using a pultrusion process o?ering a corrosion;resistant alternative to steel reinforce#ent.
Concrete /ixing! Placing!
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
60/94
Oxford University Press 2013. All rights
Concrete /ixing! Placing!Co#pacting! and Curing
he #ixing of #aterials should ensure that the #ass"eco#es ho#ogeneous! unifor# in colour andconsistency. /achine #ixing is to "e adopted for "etter
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
61/94
Oxford University Press 2013. All rights
Concrete /ixing! Placing!Co#pacting! and Curing
he concrete should "e deposited and co#pacted"efore the co##ence#ent of initial setting of concreteand should not "e distur"ed su"se
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
62/94
Oxford University Press 2013. All rights
(e#oval of or#s-t is advantageous to leave for#s in place as long as
possi"le to continue the curing period.
he vertical supporting #e#"ers of for#$or5 'shoring)should not "e re#oved until the concrete is strong
enough to carry at least t$ice the stresses to $hich theconcrete #ay "e su"Lected to at the ti#e of re#oval offor#$or5.
%ince the #ini#u# stripping ti#e is a function ofconcrete strength! the preferred #ethod of deter#iningstripping ti#e in other cases is to "e deter#ined "ased onthe tests of site cured cu"es or concrete in place.
8or5a"ility of Concrete
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
63/94
Oxford University Press 2013. All rights
8or5a"ility of Concrete8or5a"ility #ay "e de9ned as the property of the
freshly #ixed concrete that deter#ines the ease andho#ogeneity $ith $hich it can "e #ixed! placed!co#pacted! and 9nished.
he #ain factor that a?ects $or5a"ility is the $atercontent 'in the a"sence of ad#ixtures). he otherinteracting factors that a?ect $or5a"ility are aggregatetype and grading! aggregateHce#ent ratio! presence of
ad#ixtures! 9neness of ce#ent! and te#perature.
8or5a"ility should "e chec5ed fre
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
64/94
Oxford University Press 2013. All rights
8or5a"ility of Concrete
Fig. 1.7 Slump testing $a' Typical mould for slump test $b' *easuring slump $c' Types of slump
Co#pressive %trength
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
65/94
Oxford University Press 2013. All rights
Co#pressive %trength
Co#pressive strength at a speci9ed age! usually 2days! #easured on standard cu"e or cylinder speci#ens!has traditionally "een used as the criterion for theacceptance of concrete.
his is very i#portant for the designer "ecause concreteproperties such as stress=strain relationship! #odulus of
elasticity! tensile strength! shear strength! and "ondstrength are expressed in ter#s of the uniaxialco#pressive strength.
Cu"e and Cylinder ests
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
66/94
Oxford University Press 2013. All rights
Cu"e and Cylinder ests1. he concrete is poured in the cu"e or cylinder #ould in
layers of ,0 ## and co#pacted properly "y either hand or avi"rator so that there are no voids.
2. he top surface of these speci#ens should "e #ade evenand s#ooth "y applying ce#ent paste and spreading
s#oothly on the $hole area of the speci#en.
3. he test speci#ens are then stored in #oist air of at least 0per cent relative hu#idity and at a te#perature of 2+TC
2TC for 2 hours. After this period! the speci#ens are #ar5edand re#oved fro# the #oulds and 5ept su"#erged in clearfresh $ater! #aintained at a te#perature of 2+TC 2TC untilthey are tested.
Cu"e and Cylinder ests
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
67/94
Oxford University Press 2013. All rights
Cu"e and Cylinder ests
. hese speci#ens are tested "y a co#pression testing#achine after + days of curing or 2 days of curing.
,. he average of three speci#ens gives the co#pressivestrength of concrete.
Cu"e and Cylinder ests
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
68/94
Oxford University Press 2013. All rights
Cu"e and Cylinder ests
Fig. 1.8 Cube testing and failure of concrete cubes $a' Cubes in testing machine $b' Failure ofconcrete cubes
actors A ect ng Co#press ve
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
69/94
Oxford University Press 2013. All rights
g p%trength
1. $Hc or $Hc# ratio 'inversely related to concrete
strength and directly lin5ed to the spacing "et$eence#ent particles in the ce#ent paste)
2. ype of ce#ent
3. Use of supple#entary ce#entitious #aterials
. ype of aggregates
,. Vuantity and
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
70/94
Oxford University Press 2013. All rights
g p%trength
*. /oisture and te#perature conditions during curing
+. Age of concrete
. (ate of loading during the cu"e or cylinder test 'the#easured co#pressive strength of concrete increases$ith increasing rate of loading)
. %iJe of speci#en
%tress=%train Characteristics
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
71/94
Oxford University Press 2013. All rights
%tress=%train Characteristicsypical stress=strain curves of nor#al $eight concrete of variousgrades! o"tained fro# uniaxial co#pression tests! are sho$n in ig.1.10. %uch a #athe#atical de9nition of stress=strain curve is re
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
72/94
Oxford University Press 2013. All rights
ensile %trength
Concrete is very $ee5 in tension! and direct tensilestrength is only a"out =11 per cent of co#pressivestrength for concretes of grade /2, and a"ove.
he use of poJJolanic ad#ixtures increases the tensilestrength of concrete. Although the tensile strength ofconcrete increases $ith an increase in co#pressive
strength! the rate of increase in tensile strength is of thedecreasing order.
ensile %trength
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
73/94
Oxford University Press 2013. All rights
ensile %trength
Eno$ledge of tensile strength is re
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
74/94
Oxford University Press 2013. All rights
ensile %trength
Shear StrengthPure shear is a rare occurrence& usually a co#"ination ofKexural and shear stresses exists! resulting in a diagonaltension failure.
ond Strength
he co##on assu#ption in (C that plane sections re#ain
plane after "ending $ill "e valid only if there is perfect"ond "et$een concrete and steel reinforce#ent. Gondstrength depends on the shear stress at the interface"et$een the reinforcing "ar and the concrete and on the
geo#etry of the reinforcing "ar.
/odulus of 6lasticity
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
75/94
Oxford University Press 2013. All rights
/odulus of 6lasticity
he #odulus of elasticity of concrete is a 5ey factor for
esti#ating the defor#ation of "uildings and #e#"ers as$ell as a funda#ental factor for deter#ining the modularratio.he SoungNs #odulus of elasticity #ay "e de9nedas the ratio of axial stress to axial strain! $ithin the elastic
range.
8hen linear elastic analysis is used! one should use thestatic #odulus of elasticity.Qarious de9nitions of #odulus
of elasticity are sho$n in ig. 1.11 'in the follo$ing slide).
he dyna#ic #odulus of elasticity of concretecorresponds to a s#all instantaneous strain. -t has to "e
used $hen concrete is used in structures su"Lected to
Qarious 4e9nitions of /odulus
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
76/94
Oxford University Press 2013. All rights
of 6lasticity of Concrete
Fig. 1.11 -arious definitions of modulus of elasticity of concrete
4yna#ic /odulus
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
77/94
Oxford University Press 2013. All rights
he dyna#ic #odulus of elasticity of concretecorresponds to a s#all instantaneous strain.
Used $hen concrete is used in structures su"Lected todyna#ic loading.
4eter#ined "y the non;destructive electro;dyna#ic#ethod.
4yna#ic /odulus
PoissonNs (atio
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
78/94
Oxford University Press 2013. All rights
Poisson s (atio
%oisson>s ratio is de9ned as the ratio of lateral strain tothe longitudinal strain! under unifor# axial stress.
8idely varying values (ange of 0.1,=0.2,.
Goth D%C and :%C use 0.2.
or light$eight concretes -t has to "e deter#ined fro#
tests.
reng un er o# ne
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
79/94
Oxford University Press 2013. All rights
g%tresses
%tructural #e#"ers are usually su"Lected to aco#"ination of forces! $hich #ay include axial force!
"ending #o#ents! transverse shear! and t$isting#o#ents.
Any state of co#"ined stress acting at any point in a#e#"er #ay "e reduced to three principal stresses
acting at right angles to each other on an appropriatelyoriented ele#entary cu"e in the #aterial.
8hen one of these three principal stresses is Jero! a
reng un er o# ne
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
80/94
Oxford University Press 2013. All rights
g%tresses
-n #ost of the situations! only the uniaxial strength
properties are 5no$n fro# si#ple tests.
:o$ever! the strength of concrete for "iaxial state of
stress has "een esta"lished experi#entally "y Eupfer! etal. ig. 1.12 'in the follo$ing slide) sho$s that under"iaxial tension! the strength is close to that of uniaxialtension.
8hen one principal stress is tension and other isco#pressive! the concrete crac5s at a lo$er stress than it
$ould have in uniaxial tension or co#pression.
reng un er o# ne
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
81/94
Oxford University Press 2013. All rights
g%tresses
Fig. 1.12 Strength of concrete in biaial stress
%hrin5age 6?ects
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
82/94
Oxford University Press 2013. All rights
%hrin5age 6?ects
he total shrin5age strain in concrete is co#posed of thefollo$ing
1. Autogenous shrin5age! $hich occurs during the
hardening of concrete
2. 4rying shrin5age! $hich is a function of the#igration of $ater through hardened concrete
%hrin5age 6?ects
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
83/94
Oxford University Press 2013. All rights
%hrin5age 6?ects
he #ost i#portant factors that inKuence shrin5age inconcrete are as follo$s
1.ype and content of aggregates
2.$Hc ratio
3.6?ective age at transfer of stress
.4egree of co#paction
,.6?ective section thic5ness
*.A#"ient relative hu#idity
+.Presence of reinforce#ent
e#perature 6?ects
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
84/94
Oxford University Press 2013. All rights
e#perature 6?ectsConcrete expands $ith rise in te#perature and
contracts $ith fall in te#perature. o li#it thedevelop#ent of te#perature stresses! expansion Lointsare to "e provided.
e#perature stresses #ay "e critical in the design ofconcrete chi#neys and cooling to$ers. (oof sla"s #ayalso "e su"Lected to ther#al gradient due to solar
radiation.
he coeMcient of ther#al expansion depends on the
type of ce#ent and aggregate! ce#ent content! relative
Creep of Concrete
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
85/94
Oxford University Press 2013. All rights
Creep of ConcreteCreep in concrete is the gradual increase in defor#ation
'strain) $ith ti#e in a #e#"er su"Lected to sustainedloads. he creep strain is #uch larger than the elasticstrain on loading 'creep strain is typically t$o to fourti#es the elastic strain).
Creep occurs under "oth co#pressive and tensilestresses and al$ays increases $ith te#perature. :%Cs
creep less than D%Cs.
he #ain factors a?ecting creep strain are the concrete
#ix and strength! the type of aggregate used! curing!
Creep of Concrete
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
86/94
Oxford University Press 2013. All rights
Creep of Concrete
Fig 1.1( Typical creep cure
Don;destructive esting
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
87/94
Oxford University Press 2013. All rights
Don destructive estingDon;destructive tests are used to 9nd the
strength of existing concrete ele#ents.
Fig. 1.1) ;on!destructie testing
Don;destructive esting
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
88/94
Oxford University Press 2013. All rights
Don destructive esting
hey are classi9ed as follo$s1. :alf;cell electrical potential #ethod to detect the
corrosion potential of reinforcing "ars in concrete
2. %ch#idtH(e"ound ha##er test to evaluate thesurface hardness of concrete
3. Car"onation depth #easure#ent test to deter#ine
$hether #oisture has reached the depth of thereinforcing "ars! there"y leading to corrosion
Don;destructive esting
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
89/94
Oxford University Press 2013. All rights
Don destructive esting
. Per#ea"ility test to #easure the Ko$ of $ater throughthe concrete
,. Penetration resistance or 8indsor pro"e test to#easure the surface hardness and hence the strength ofthe surface and near;surface layers of the concrete
*. Cover#eter test to #easure the distance of steelreinforcing "ars "eneath the surface of the concrete andthe dia#eter of the reinforcing "ars
Don;destructive esting
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
90/94
Oxford University Press 2013. All rights
Don destructive esting
+.(adiographic test to detect voids in the concrete andthe position of prestressing ducts
. Ultrasonic pulse velocity test #ainly to #easure the
ti#e of travel of ultrasonic pulse passing through theconcrete and hence concrete
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
91/94
Oxford University Press 2013. All rights
10. o#ographic #odelling! $hich uses the data fro#ultrasonic trans#ission tests in t$o or #ore directions! todetect voids in concrete
11. -#pact echo testing to detect voids! dela#ination!and other ano#alies in concrete
12. round penetrating radar or i#pulse radar testing to
detect the position of reinforcing "ars or stressing ducts
13. -nfrared ther#ography to detect voids! dela#ination!and other ano#alies in concrete and also to detect $ater
entry points in "uildings
Don destructive esting
4ura"ility of Concrete
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
92/94
Oxford University Press 2013. All rights
4ura"ility of Concrete4eteriorating concrete structures not only a?ect the
productivity of the society "ut also have a great i#pacton our resources! environ#ent! and hu#an safety.
he deterioration of concrete structures is due to the
#ain e#phasis given to #echanical properties and thestructural capacity and the neglect of construction
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
93/94
Oxford University Press 2013. All rights
u a" y o Co c e e)actors /2ecting the Durabilit' of Concrete
1.6nviron#ent
2.Concrete cover to the e#"edded steel
3.Vuality and type of constituent #aterials
.Ce#ent content and $Hc ratio of concrete
,.4egree of co#paction and curing of concrete
*.%hape and siJe of #e#"er
:ADE SOUI
-
7/21/2019 507 33 Powerpoint-slides Ch1 DRCS
94/94
:ADE SOUI
ADS VU6%-OD%W