CONCRETING IN HOT AND COLD WEATHER CONDITIONSPRESENTED BYPRESENTED BYDIVYA . KDIVYA . K CONCRETING IN HOT AND COLD CONDITIONSINTRODUCTIONHOT WEATHER CONCRETINGEFFECTS OF HOT WEATHER ON CONCRETEPRECAUTIONS COLD WEATHER CONCRETINGEFFECTS OF COLD WEATHER ON CONCRETEPRECAUTIONSA CASEOF COLD WEATHER CONCRETINGCONCLUSIONS INTRODUCTIONWeather is the condition of the air that surrounds the earthThe !eather "a# $e hot or co%d& c%oud# or c%ear& !ind# orca%" And it "a# $rin' frost& rain& sno!& s%eet& or hai% The !eather affects our %i(es in nu"erous !a#s For e)a"*%e& the t#*e of c%othin' !e !ear de*ends %ar'e%# on the !eather The !eather has an enor"ous i"*act on a'ricu%tureFar"ers need c%ear !eather to *%ant and har(est their cro*s Industr#& trans*ortation& and co""unication a%so suffer durin' $ad !eather INTRODUCTIONThe construction of $ui%din's& $rid'es& and roads "a# $e de%a#ed $# rain& sno!& or e)tre"e co%d Concrete so"eti"es $eha(e as a non (ersati%e "ateria% !hen *%aced in e)tre"e conditionsConcretin' in e)tre"e conditions inc%ude concretin' in *%aces of hi'h *ressure&under !ater and a%so in e)tre"e !eather conditions %i+e hot and co%d !eatherThe concrete *%aced at a at"os*heric te"*erature a$o(e ,-o C is considered as hot !eather concretin' INTRODUCTIONCo%d !eather concretin' is concretin' !hen te"*erature is %o! or $e%o! free.in' *oint Hot !eather concretin' "a# $e cha%%en'in' due to acce%erated settin' caused $# heat and hu"idit#At hi'her te"*erature concrete hardens "ore ra*id%# !hich can cause *ro$%e" !ith *%acin' and finishin' INTRODUCTIONThe *roduction of concrete in co%d !eather introduces s*ecia% and *ecu%iar *ro$%e"s& such as de%a# in settin' and hardenin'& da"a'e to concrete in *%astic condition !hen e)*osed to $e%o! free.in' *ointOne area fre/uent%# o(er%oo+ed& or "isunderstood& is the re%ationshi* $et!een te"*erature and concreteDifficu%t !eather does not ha(e to "ean the end of *%acin' concrete Thus !hene(er concrete is to $e *%aced in e)tre"e conditions its *erfor"ance is ad(erse%# affected un%ess a**ro*riate "easures are ta+en to contro% it HOT WEATHER CONCRETING WHAT IS HOT WEATHER CONCRETING 0Hot !eather concretin' is re'arded as the concrete *%aced at an at"os*heric te"*erature a$o(e ,-oC Hot !eather concretin' is an# co"$ination of the fo%%o!in' conditions1Hi'h a"$ient te"*eratureLo! re%ati(e hu"idit#So%ar radiationWind (e%ocit#tending to impair the quality of fresh or hardened concrete or otherwise resulting in abnormal properties. HOT WEATHER CONCRETINGEFFECTS OF HOT WEATHER ON CONCRETEAt hi'her te"*erature certain s*ecia% *ro$%e"s are encountered The# are1Ra*id rate of h#dration 12At hi'h a"$ient te"*erature the settin' ti"e of the ce"ent is reduced considera$%# 2With the resu%tear%# stiffenin' ta+es *%ace !hich "a+es the concrete %ose the !or+a$i%it# HOT WEATHER CONCRETING2The concrete *%aced in hot !eather no dou$t de(e%o*s hi'h ear%# stren'th &$ut !i%% suffer certain %oss of %on' ter" stren'th2The 'ra*h $eside sho!s the effect of te"*erature on one da# and 34 da#s co"*ressi(e stren'th HOT WEATHER CONCRETINGRa*id e(a*oration of "i)in' !ater 12Hot !eather condition is nor"a%%# associated !ith re%ati(e%# %o!er re%ati(e hu"idit# On account of this& the !ater "i)ed !ith the concrete to 'i(e re/uired !or+a$i%it# !i%% $e %ostGreater *%astic shrin+a'e12Ra*id e(a*oration %eads to *%astic shrin+a'e crac+in' and su$se/uent coo%in' of hardened concrete introduces tensi%e stresses HOT WEATHER CONCRETINGLess ti"e for finishin'12In hot !eather&finishin' "ust $e done as ear%# as *ossi$%e after *%acin' In certain cases if ear%# finishin' is not *ossi$%e due to faster stiffenin' and /uic+er e(a*oration of !ater &/ua%it# of finishin' !i%% $e of *oor standardA$sor*tion of !ater fro" the concrete $# the su$ 'rade and for" !or+2In hot !eather re'ions the su$ 'rade is nor"a%%# dr# and a$sor*ti(e HOT WEATHER CONCRETINGCurin' 12In hot !eather co"*arati(e%# ear%# curin' $eco"es necessar# 2Hot !eather re/uires a continuous effort of curin' If there is an# %a*se& the concrete surface dries u* fast and interru*ts the continuous h#dration2Once interru*tion ta+es *%ace & the su$se/uent !ettin' does not fu%%# contri$ute to the de(e%o*"ent of fu%% stren'th HOT WEATHER CONCRETINGDifficu%t# in contro%%in' the air entrain"ent12At hi'her te"*erature it is "ore difficu%t to contro% the air content in air entrained concrete 2This adds to the difficu%t# of contro%%in' !or+a$i%it#2 For a 'i(en a"ount of air entrainin' a'ent& hot concrete entrains %ess air than does concrete at nor"a% te"*erature HOT WEATHER CONCRETINGRECO55ENDED PRACTICES AND PRECAUTIONS 1Te"*erature contro% of concrete in'redients 12The te"*erature of the concrete can $e +e*t do!n $# contro%%in' the te"*erature of the in'redients2The a''re'ates "a# $e *rotected fro" direct sunra#s $# erectin' te"*orar# sheds or she%ters o(er the a''re'ate stoc+*i%esWater "a# a%so $e s*rin+%ed on to the a''re'ate $efore usin' the" in concrete HOT WEATHER CONCRETING2The "i)in' !ater has the 'reatest effect on the te"*erature of the concrete E(en thou'h !ei'ht of !ater used is %ess than other in'redients&the use of co%d "i)in' !ater !i%% effect 'ood reduction of concrete te"*erature2The 'ra*h sho!s effect of co%d !ater at 6oC on concrete te"*erature HOT WEATHER CONCRETING2If the a"$ient te"*erature is (er# hi'h& the use of coo%ed !ater "a# not $e fu%%# effecti(e Use of ice "a# $e "ade as a *art of "i)in' !ater It sha%% $e ensured that ice cr#sta%s shou%d $e co"*%ete%# "e%ted $# the ti"e of "i)in'Pro*ortionin' of concrete "i) 12The "i) shou%d $e desi'ned to ha(e "ini"u" ce"ent content consistent !ith other functiona% re/uire"ents HOT WEATHER CONCRETING2As far as *ossi$%e& ce"ent !ith %o!er heat of h#dration shou%d $e *referred to those ha(in' 'reater fineness and heat of h#dration2Use of !ater reducin' or set7retardin' ad"i)tures are $eneficia% Car$on fi$er reinforced concrete is used in hot !eather concretin'Production and de%i(er# 12The te"*erature of a''re'ates&!ater and ce"ent shou%d $e "aintained at the %o!est %e(e% so that te"*erature of concrete is $e%o! ,-oC at the ti"e of *%acin' HOT WEATHER CONCRETING2The te"*erature of the concrete at the ti"e of %ea(in' the $atchin' *%ant shou%d $e "easured !ith a suita$%e "eta% c%ad ther"o"eter2The *eriod $et!een "i)in' and de%i(erin' shou%d $e +e*t to an a$so%ute "ini"u" $# coordinatin' the de%i(er# of concrete !ith its rate of *%ace"entP%ace"ent and curin' 12The for"!or+&reinforce"ent and su$ 'rade shou%d $e s*rin+%ed !ith coo% !ater 8ust $efore *%ace"ent of concrete HOT WEATHER CONCRETING2S*eed of *%ace"ent and finishin' he%*s "ini"i.in' *ro$%e"s in hot !eather concretin'2I""ediate%# after co"*action& the concrete shou%d $e *rotected to *re(ent the e(a*oration of "oisture $# "eans of !et 'unn# $a's&hessian&etc2Continuous curin' is i"*ortant $ecause the (o%u"e chan'es due to a%ternate !ettin' and dr#in' *ro"ote the de(e%o*"ent of surface crac+in' HOT WEATHER CONCRETING2The $est *ractice is to co(er the concrete !ith "oist co(erin' for a$out 3, hours and then a**%# !ater $# s*ra#in' or $# *ondin'2When the da# te"*erature is (er# hi'h& it is $etter to do the concretin' o*erations durin' the e(enin' ti"eRe"e"$er to *rotect the cre! in hi'h te"*eratures Drin+ *%ent# of f%uids and $e carefu% !ith %on' e)*osure to the sun COLD WEATHER CONCRETINGWHAT IS COLD WEATHER CONCRETING 0An# concretin' done at a te"*erature $e%o! 6oC is ter"ed as co%d !eather concretin'The *roduction of concrete in co%d !eather introduces s*ecia% and *ecu%iar *ro$%e"s& such as de%a# in settin' and hardenin'& da"a'e to concrete in *%astic condition !hen e)*osed to $e%o! free.in' *oint o!in' to the for"ation of ice %enses The %o!est te"*erature e(er recorded on earth !as a "ind7$o''%in' 7934: F ;74u%# 39& 9