23. Mechanical tying of Rebar 1) What is mechanical tying of rebar? It is essential construction method for large scale civil engineering construction such as high-building, bridge, dam, etc and underground building anti-earthquake plan and also special construction. It is a splice method for strong economic quality assurance if folded tying method is impossible in case rebar arrangement with density and rebar diameter is bigger and so by the increase of rebar strength & concrete strength. It is applicable for deformed rebar to use rebar concrete building. In foreign countries, it was verified from 1960 and it is using for Korean construction site from mid-1990. 2) Type of mechanical tying of rebar 3) Screw-type tying of rebar rebar warehouse-in → make rebar screw process drawing → start processing of screw type → deliver to construction site(3~10days from order date) screw type inflation type compression type joint rib cut type taper type others mortar injection type gas compression hydraulic compression type site tie type joint fixed body adhesion type joint rib compressed jack adhesion type process type process type inflation type compression type joint rib cut type taper type inflate of rebar processing part largely by mold (example) rebar 25mm - M30 case screw type bury rebar joint rib by mold (example) rebar 25mm - M25.5 processing screw after deleting rebar joint rib with fixed size (example) rebar 25mm - M26 screw processing with angle of rebar front end prove the confidence after processing of low carbon steel bar(SD300) available for large production prove the confidence after processing of low-mid carbon steel bar(SD300,400) available for large production available for production on construction site prove the confidence after processing of low-mid- high carbon steel bar(SD300,400,500) available for large production available for production on construction site prove the confidence after processing of low carbon steel bar(SD300) available for production on construction site the inflation processing end might has low confidence if it is caused by processing vulcanization of mold in case high carbon steel bar low confidence after binding 2 rebars low confidence in case of bending the compression processing end might has low confidence if it is caused by processing vulcanization of mold in case high carbon steel bar low confidence in case of bending coupler size is 10% longer than inflation & compression type by the deviation of size of rebar joint & rib low confidence of omission & untying for testing tension strength and repeat test case screw type case screw type cut screw type screw processing merit demerit