3. concrete brief insight

8/9/2019 3. Concrete Brief Insight

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CONCRETEBRIEF INSIGHT


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AIM : TO MIX MATERIALS IN MEASURED AMOUNTSTO MAKE CONCRETE THAT IS EASY TO:

• TRANSPORT • PLACE• COMPACT • FINISH

The amount of eachmaterial (i.e cement,

ater an!a""re"ate#$ affect#

the %ro%ertie# ofhar!ene! concrete.


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AGGREGATES• Aggregates are of two as!" t#$es:

• COARSE & cru#he! roc', "ra el or #creenin"# %!&e "r's(e)

ro"&* gra+e% or s"ree,!,gs • FINE & fine an! coar#e #an!# an! cru#her fine# %!&e

f!,e a,) "oarse sa,)s a,) "r's(er f!,es-• Aggregates s(o'%) e:

GRADED STRONG . HARD CHEMICALLY INACTI/E

Ro',)e) aggregates g!+e a 0orewor&a %e 0!1-

A,g'%ar aggregates 0a&e "o,"rete(ar)er to $%a"e* wor& a,) "o0$a"t*

't "a, 0a&e "o,"rete stro,ger .


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2ATER2ater i# mi)e! ith the cement %o !er to form a %a#te hich hol!# thea""re"ate# to"ether li'e "lue.

ADMIXTURES are mi)e! into the concrete to "(a,ge or a%ter !ts$ro$ert!es , i.e the time concrete ta'e# to #et an! har!en, or it#

or'a*ilit+.


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HO2 THE 3ROCESS 2ORKS Meas're) a0o',ts of t(e "oarse a,) f!,e

aggregates are 0!1e) toget(er

A 0eas're) a0o',t of "e0e,t i# a!!e! an! mi)e! in. Enou"h water i# a!!e! to 0a&et(e 0!1 wor&a %e . All the material# are then mi)e! to"ether ell. The cement %o !eran! ater form a %a#te hich *on!# the a""re"ate# to"ether li'e "lue.


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T(e fo'r 0a!, $ro$ert!es of "o,"rete are:

2ORKABILITY * COHESI/ENESS* STRENGTH a,) DURABILITY

THE 3RO3ERTIES OF CONCRETE ARE ITSCHARACTERISTICS OR BASIC 4UALITIES


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2ORKABILITYmean#

How eas# !t !s to 3LACE* HANDLE* COM3ACT a,) FINISH a "o,"rete 0!1-

2or&a !%!t# !s affe"te) #:• The amount of cement %a#te & The cement %a#te i# the #oft or li ui!

%art of the concrete mi).• The a""re"ate "ra!in" & -ell "ra!e!, #mooth, roun!e! a""re"ate#

im%ro e the or'a*ilit+ of a mi).•

-ater Cement ratio & maintain a%%ro%riate -/C ratio

To 0a&e a 0ore wor&a %e 0!1:• 0#e -ELL 1RA2E2 a""re"ate#.• 0#e an A2MI3T0RE• Pro%er -/C ratio

NOTE:NE4ER TR5 TO MA6E A MI3T0RE MORE-OR6A7LE 75 80ST A22IN1 MORE -ATER7ECA0SE THIS LO-ERS THE STREN1THAN2 20RA7ILIT5 OF CONCRETE.


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STRENGTH AND DURABILITY

2e%% 0a)e "o,"rete !s a ,at'ra%%# stro,g a,) )'ra %e 0ater!a%- It i#

DENSE, rea#ona*l+ 2ATERTIGHT , a*le to re#i#t chan"e# inTEM3ERATURE, a# ell a# ear an! tear from 2EATHERING .


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STRENGTH AND DURABILITY ARE AFFECTED BY:

• COM3ACTION & i# remo in" the air from concrete.• CURING & i# 'ee%in" concrete !am% for a %erio!, to allo it to reach

ma)imum #tren"th.• 2EATHER & -armer eather ill cau#e concrete to ha e a hi"her earl+

#tren"th.• TY3E OF CEMENT & 2ifferent t+%e# of cement ill affect concrete

%ro%ertie# i.e ho uic'l+ or #lo l+ concrete "ain# #tren"th.• 2ATER TO CEMENT RATIO & Too much ater an! not enou"h cement

mean# concrete ill *e ea'er an! le## !ura*le.


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3RO3ORTIONING OF MIX


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TRANS3ORTING AND 3LACING CONCRETE

-hen tran#%ortin" an! %lacin" concrete,A/OID

– 2ELA5 – SE1RE1ATION an! –

-ASTA1E


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THE SLUM3 TEST The #lum% te#t i# !one to ma'e #ure a concrete mi) i# or'a*le.The mea#ure! #lum% mu#t *e ithin a #et ran"e, or tolerance, from the tar"et #lum%.


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THE SLUM3 TEST


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2OS AN2 2ONTS


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IT IS 2ORSE TO UNDER5/IBRATE THAN TO O/ER5/IBRATE CONCRETE


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FINISHING CONCRETE

• 2ater t(at a$$ears o, t(es'rfa"e of t(e "o,"rete !s"a%%e) BLEED 2ATER-

• E1"ess %ee) water "a, ere0o+e) # )ragg!,g a"rosst(e s'rfa"e of t(e "o,"rete -


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EDGING AND GROO/ING


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CURING CONCRETE


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3. concrete brief insight

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