Sloped for drainage level surfaces is spccitied

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Unformatted text preview: of finish to IX applied shall bc as follows: a) I;iltish (rl ( screeded finish ) .- shall apply to unformed surtaccs that are to 1~ covered by backfill or by concretcb and surfaces of subfloors which will bc cove’red by concrete floor topping. Finish U1 is also used as tlkc first stagr for Finishes U2 and U3. Finishing operations shall consist of sufficient levelling and screeding to produce even uniform surfaces. Surface irregularities, measured as dcscribcd under 4.16.1 shall not exceed 1 cm ( or ) in ). surlaces b) Finish U2 (jEo&d $nish) - shall’ apply to unformed not permanently concealed by backfill or concrete or unformed surfaces for which Finshcs Ul and U3 are not specified, and shall crete 28 IS : 457 - 1957 include floors. of sumps, tops of walls, parking areas, parapet walls, sdrfaces of gutters, sitlcwalks :md outside entrance slabs. Finish U2 is also used as the second stngc for Finish U3. Floating may be performed by use of hand- or power-driven equipment. Floating shall bc started as soon as the screeded surface has stiffened sufficiently, and shall IX, tl:c> minimum necessary to produce a surface that is frc,c from srrcccl marks and is uniform in If Finish II3 ih to bc al~l~lic~:l,floating shall be continued texture. until a small amount of mortar \\itllout excess water is brought to the surface, so as to permit cffcctivi: trowelling. Surface irregularities, measured as tlcscribcd under 4.16.1 shallkot exceed O-5 cm ( or $ in ). Joints and etlgcs of gutters, sidewalks, entrance slabs, and other joints ant! cclgcs shall be tooled where necessary. c) Finish U3 ( trowelled jinish ) -- shall apply to unformed surfaces, such as slabs to be covcrtxtl with built-up roofing or membrane water-proofing and stair treads. \Thcn the floated surface has hardened suf?iciently to prcvcnt exct’ss of fine material from being drawn to the surface. steel trowelling shall he started. Steel trowelling shall be performed with firm pressure, so as to flatten the sandy texture df the floated surface and produce a dense uniform surface, free from blemishes and trowel marks; light steel trowelling will be permissible on surfaces of slabs to be covered with built-up roofing or membrane waterproofing, in which light trowel marks are not considered objectionable. Surface irregularities measured as described under 4.16.1 shall not exceed 0.5 cm (or & in). 5. FORMS FOR CONCRETE 5.1 General-Forms shall I)r usrd whcrcvrr nrcessary to confine conAll exposed conrrtstc surfaces having slopes crete and shape it as required. Where of one to one or stccpcr shall I )t’ formed, u111css othc;rwist~ clirectcd. the character of the natural material cut into to receive a concrete structure is such that it can be trimmed to the prcscrihed lines, the use of forms shall not be r:~cluiretl. The forms sl~all Ilave sufficient strength and rigidity to hold the concrete ant1 to witllstand the nrcessary pressure, ramming, and vibration Lvithont excessive deflection...
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