Mill scale occurs ti the time the reinforcing bars m manufactun:d (rolled) and resulrs from cooling the hot meal. Loose rus, ar. d scale is usua ly re moved when the bars are handled and loodcd in the fabric.-. ating shop_, or in ll!ll®d!!Jg_;irul honil)mg at tho. J®'il JC Thtli Jiill_ni>t <!illl><le """"~ the bars ls normal and docs noc have an harmful dl"tt. :l on hor. d! Rust improves bond because ru~t increases the roughness of the surface. Only when the height of deformations or the weight of tbc reinforcing bars is,... duccd below tho minimum would rust bo considered harmful, os per ASTM requirements. Reinforcing bars: with rust or mill scale or a oombinatioo of both are considered to he occ:eplllblc without clconing or brushing, provided d1. at the minimum dimensions. including height of defomu11iom, and weight of a cleaned sample arc not Jc,s than ASTM specilicatioo requirements. Reinfon::ing bars should be wiloaded 311d stored in such a manuer that they will be lccpt free of mud. Arry mud coating on tho hors should be washed ol T before they arc placcd. Oc. casiona lly, reinforcing bars become covered with machine oil or grease. which mus, be removed before p L:tcing. Removal may be done by wiping with solvcllls. Sometimes in oiling forms, a slight ovco:spray of form oil gets on the reinforcing bars. Oil prcscnl on the ban; in <1uanlities sullicicnl IO decrease bond must be~ before placing.,,,.,,,ieto. HOISTING Power equipment is normally required co raise or 10"tt reinforcing bars from one level to another or to bridge obs12cles that prevent the hors from being carried mnnunlly. The typo of hoisting cquipmont will depend on: I) The size of the projec~ 2) Whether in a coog,cstcd area or an open :uea; and 3) Th<o height oflhe strucrore. l'ho moot commonly used types of hoisting equipment ore illustrated in Fig. 8-2. Tower cranes should also be included wi1h a note that m many areas NCCCO (National Commission for the Certificat ion of Crane Operators) cer­ tifications arc nccdcd for crane signo. lina and rigging. Placil1g Relnf O<Cll>g Baro-10th Edition 8--3 Section 609 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 6-9