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<br />Adequate' compressor oapacities fOr the dry-mix
<br />process, based on a hose 'Ienl!th of 150 feet and the
<br />nozzle not more tha.n .25" feet ab9vc the' delivery
<br />equ(pmenr, are'as .shown belcJw. .
<br />
<br />The. pressure in the. delivery equipment for the
<br />qry-mix .process shaH be maintained at not less than
<br />35 psi for hose jengths up to 100 feet and shall be
<br />increased by at least 5 psi for each additional 50
<br />feet of hose, and by at least 5 psi for each 25 feet
<br />that the nozzle: is raised above the delivery
<br />equipment. The water for the dry-mix process shall
<br />be maintained at a uniform pressure of at least 15
<br />psi greater than the pressure at 'the nozzle. The
<br />contractor shall furnish, install.,. and maintain in
<br />satisfactory operation suitable pressure gages for
<br />indicating air and water pressures.
<br />
<br />If the contractor proposes to use the wet. mix
<br />process (aU' ingredientS for th~ shoterete, including
<br />water'l .thoroughly mixed befo're beiog fed-into the
<br />delivery equipment, the mixture being metered into.
<br />th.e delivery hose and conveyed by compress~d ai~
<br />to' the nozzle), ne snaIl' demonstrate to the
<br />satisfaction of the contracting officer that: (1) The
<br />equipment proposed for use is capable of mixing
<br />and delivering high-quality. low:slump mixture with
<br />reliability; and (2) the air' compressor- .used is
<br />capable of maintaining a clean air adequate for
<br />sufficient nozzle velocity and 'for operation of a
<br />bl,?w pipe for clearing away rebound.
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<br />Care shaH be taken to prevent the formation of sa~d
<br />pockets, and should sand pockets be formed, they
<br />snaU 'be. removed j.mmediately 'and replaced wi\.n
<br />suitable shotcrete at tile expense of the Contractor.
<br />Unless otherwise directed by the contracting off~cer,
<br />any snQtCtete whkh shows e\J\dence o~ o:.\oughing Or
<br />separation shall be removed and replaced by and at
<br />the expense of the contractor and to the satisfaction
<br />of the contracting officer. Hand .patching will not ~e
<br />permitted. The length or area of the section' fo'r
<br />which shotcrete is to be applied in one continuous
<br />operation shall be subject to approval.
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<br />SPECIFI€ATIONS NO. DC,6!14G:. .
<br />(SUPPLlifMeN.-FAC'NOTICE ,t(e.' 3)
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<br />When work ~s .to b~ "Suspended at the end' of~
<br />or, . otherw.ise,.. for. a F'e~iod over 30 minut.
<br />shote~e\.e shan be stoped to 'a. thin edge;':'
<br />ptactlcable, and, beforEFworKis resumed, the'~' ~~~.
<br />of the shotcrete. upon. or: against which'. $h'
<br />shotcrete is to be placed shall be thcil" -g~ly
<br />cleaned, 'roughened ,f, 'in the' opinion" \~t.~'~
<br />contracting officer, roughening is necessat.' f~~?
<br />shall 'be moistened. thoroughly. There shal ~~o
<br />free moisture on the previously placed sh:. ~iet(~
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<br />contracting officer may consider neceSSI:.tto.
<br />prevent injury to or the formation of Object-i. a~l~
<br />coatings on completed shotcrete surfac .;l,by.
<br />particles of rebound from subsequent ':ope : _ I,O:ns,
<br />and to avoid or minimize accumulations of ~e '!:H''ld,
<br />Reuse' of rebound will not be perm.tte<F5~nd
<br />rebound accumulations shall be removecF'and
<br />disposed of as approved by the contracttng o.~~'cer..
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<br />e. Protection and curing..-.On cornPletiob/:. of
<br />placement and as s~on as the shotcrete .Iast' ~b"Te.'d
<br />has hardened sufficiently, the' shotcrete; -s~Il'';be
<br />cured by membrane curing or 'by water cu[iti~?at
<br />the option of the contractor.' I f water cure /\the
<br />concrete shall be kept continuously moist: :1':. .at
<br />least 14 days after being placed by sprin~.
<br />spraying or by other methods approved.
<br />contracting officer. Membrane curing, if use,
<br />be by application of sealing compou.
<br />accordance with the procedures. c'ontained r;..: the
<br />Seventh Edition of the' Bureau of Recta': ticn
<br />Concrete Manua\. . , .'
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<br />Sealing compound, if used for curln1J shotcret~~:~hall
<br />be w\iite-Pig~~ryted. compoi.J~' ,'\'conforl1)iAA':. t,o
<br />Bureau of Re.'i!itnallon "Sp..', ~on for sealln.9
<br />Compound fer ..:Curing Cone .,....l~ dated Jtfu~.:l., ,I
<br />1961 .'. f~'. .\'!,. .
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<br />Water for curing shall meet the requiremef.Jts of
<br />.these specifications for water used for ~i)(i.ng
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<br /> Maximum size of Operating air pressur~>,
<br />Compressor capacity clm Hose diameter (inches) nozzle tip (inches) available at compressorpsi
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<br />250 1 3/4 40 ~ .
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<br />315 1 and 1/4 1 45 '..('
<br />365 1 and 1/2 1 and 1/4 55 ~~ .
<br />500 1 and 5/B 1 and 1/2 65 .. ,
<br />600 1 and '3/4 1 and 5/B 75 .- ...j.'.
<br />750 2 1 and 3/4 85 Jf.:'
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