Shotcrete Presentation

8/19/2019 Shotcrete Presentation

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SHOTCRETING

K.V.SUBBA RAO


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Shotcreting

• Shotcreting is a method in concrete or! in hich the

concrete mi" is a##$ied in $a%ers &nder the #ress&re o'com#ressed air

• . Shotcreting is done ith a s#ecia$ &nit( hich consists

o' a mortar g&n or concrete s#ra%er and a com#ressor


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Shotcreting

• A dr% mi" o' cement and aggregate( &s&a$$% sand( is

#re#ared 'or shotcreting.• The com#ressed air 'orces the mi" thro&gh a hose to the

no))$e( moistens it ith ater s#$ied thro&gh another

hose( and then #ro*ects it at high +e$ocit% ,-/0-1/

m2sec3 onto the s&r'ace 4eing shotcreted.


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Shotcreting

• A sing$e shotcrete $a%er is -/0-5 mm thic! and has highmechanica$ strength ,6/01/ meganetons #er s7 m3(densit%( ater tightness( and co$d resistance

• Shotcreting is &sed in 4&i$ding thin8a$$ed rein'orced8concrete str&ct&ra$ com#onents( s&ch as she$$s( +a&$ts(and tan!s( and in #rod&cing the $ining in t&nne$s. It is

a$so &sed 'or h%dra&$ic ins&$ation( 'or 'inishing the *ointso' rein'orced8concrete str&ct&ra$ com#onents( and 'orre#air and strengthening o' concrete and rein'orced8concrete com#onents.


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Shotcreting

• The shotcrete is #$aced $a%er84%8$a%er

• 9or shotcrete #$acing s#ecia$ e7&i#ment are &sed( here4% means o' :dr%: techno$og% the mi"t&re o' cement(

sand and meta$ 4atched in s#eci'ied #ro#ortions is

s7&ee)ed o&t ith #ress&re air 4% means o' '$e"i4$e hose

to the no))$e atomi)er( here the mi"t&re is moist&ri)ed

ith ater. ;hen the :et: techno$og% is &sed( #re#ared

concrete is de$i+ered to the machines


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Shotcreting

• Shotcreting has high strength #ro#erties< resistance o' its

e"tension is -/ #er cent more in com#arison ith

standard concrete. The co+er o' high strength( densit%

and ater#roo'ing ca#acit% is 'ormed 4eca&se o' im#act

$a%ing

• Shotcrete a##$ication a$$os decreasing 'ace thic!ness

and o&t8t&rns< e"c$&ding the necessit% o' 'ormor! and

mechani)ing the concrete or! #rocess tota$$%.


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=ateria$s 'or shotcreting

• Cement

• Sand

• Coarse Aggregates• ;ater

• Chemica$ additi+es

• Com#ressed Air


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=ateria$s 'or shotcreting

• Chemica$ admi"t&res are added 'or acce$eration o'setting and hardening.

• Sodi&m Car4onate > ? Kg #er 5/ Kg 4ag o' cement

• @Sodi&m A$&minate > ? Kg #er 5/ Kg 4ag o' cement

• @Ca$ci&m Car4onate > - Kg #er 5/ Kg 4ag o' cement

• A$ternati+e$%( 'o$$oing additi+es can a$so 4e &sed

• @Ser #$astici)er - 4% eight o' cement

• @ Acce$erator ,sa% sodi&m Si$icate3 5 4% eight o'cement


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Dre#aration o' S&r'ace

• The 'o$$oing #reca&tions are necessar% in #re#aration

o' the s&r'ace 4e'ore the shotcrete is a##$ied

• The s&r'ace sho&$d 4e 'ree 'rom $ose materia$s. It sho&$d4e c$ean to recei+e the shotcrete $a%ers.

• In case the s&r'ace is smooth it sho&$d 4e ro&ghened

ith sand 4$asting. Otherise the s&r'ace co&$d 4e

c$eaned ith air ater *et..


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Dre#aration o' S&r'ace

• The thic!ness o' the shotcrete $a%er 4eing on$% 1 mm

an% &nd&$ations in the s&r'ace more than s&ch thic!nessi$$ ha+e to 4e 4ac!'i$$ed ith either masonr% or $ean

concrete de#ending on the site conditions and

s#eci'ications #rescri4ed.


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=i" o' shotcrete

• Cement 65/ !g 2 m

• Sand --// !g 2 m ,/.1/ m3• Coarse aggregate

• ,5 mm 0 -/ mm si)e3 5// Kg2= ,/./ =3

• Dro#ortion 4% eight -F.66-.--


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A##$ication =ethodo$og%

• S#ra% #ne&matica$$% the 'irst $a%er o' shotcrete o' mmthic!ness

• ;e$ded ire mesh o' -// mm " -// mm " 5 mm isnai$ed ith the he$# o' nai$s. Binding ire is &sed to !ee#the mesh in #$ace.

• The second and 'ina$ $a%er o' mm o' shotcrete is

s#ra%ed #ne&matica$$% o+er the 'irst $a%er.


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Dreca&tions to 4e ta!en

• The 'inished shotcrete $a%er is to 4e !e#t etcontin&o&s$% 'or at $east a ee! a'ter com#$etion.

• There o&$d 4e re4o&nd d&ring the o#erations hichsha$$ not 4e &sed 'or shotcrete.

• The time $ag 4eteen the 'irst $a%er and the second $a%eris to 4e !e#t as minim&m as #ossi4$e.8sa% $ess than

ho&rs.


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Dreca&tions to 4e ta!en

• A'ter com#$eting the shotcrete and a'ter the mi" is set(

the s&r'ace sho&$d 4e thoro&gh$% so&nded 4% a hammer

'or dr&mming areas res&$ting 'rom re4o&nd #oc!ets or

$ac! o' 4ond etc.( hich sho&$d 4e c&t o&t and re#$aced

ith 'resh shotcrete.

• ;here dr% #rocess is ado#ted the *etting o' ater sho&$d

4e s%nchroni)ed ith that o' the concrete mi" 'or a

homogeneo&s shotcrete.

• ;here et mi" is ado#ted the s#eci'ied ater cement

ratio is to 4e strict$% en'orced.


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Shotcreting


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Shotcreting


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Shotcreting


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Shotcreting


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Shotcreting


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Shotcreting

NSRC


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Than! o&

Shotcrete Presentation

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