The paper defines full-strength butt welded bar splices and recognises their suitability
 for earthquake-resistant reinforced concrete structures detailed for ductility. Aspects of the successful use of the
pressure-gas process on an eight-storey shear
core building are reported. Essential features
 of a pressure-gas technique developed for
making full-strength butt welds on site are
described. The significance of a band of
 decarburised steel occurring at the weld interface is discussed, and provisions for its control are indicated. The paper gives test methods and criteria for quality control and acceptance purposes, with reference to a detailed Specification and "Statement of Technique and Equipment” under which the technique is now in principle accepted by the New Zealand Ministry of Works. Proving tests using the technique are reported, and a metallurgical report by R. M. Robb on the test welds, including micro-photographs, is appended. The paper concludes by indicating the practicability of making full-strength butt welds of HY60 bars by the pressure-gas process.