13.1 Provisions given Part 6 ‘Structural Design, Section 5 Concrete, Subsection 5A Plain and Reinforced Concrete’ of the Code shall apply. In addition, the provisions given in 13.1.1 and 13.1.2 shall also apply.
13.1.1 Jointing of Butted Assemblies
13.1.2 The joints of butted assemblies shall be made of either cement grout or cement mortar or concrete. Cement grouting shall be used for joints up to 12 mm
thick. For joints thicker than 12 mm and up to 75 mm, cement mortar shall be used. The mortar which may be made of one part cement and one-and-a-half parts sand shall be of a dry consistency and shall be packed hard in layers so that it rings true. Where joints exceeding 75 mm are encountered, the joint shall be made up of concrete. Use of epoxy may be permitted with the approval of engineer-in-charge.
13.1.2.1 The stressing operations may be carried out in case of mortar joints immediately after placing the mortar but the stress in the mortar shall not exceed . In the case of grouted joints and concrete joints the allowable stress in the first 24 h after placing of the grout or concrete in the joint shall approximate as closely as possible to the strength of the grout or concrete used.
13.1.3 The holes for the prestressing tendons shall be accurately located and shall be in true alignment when the units are put together.
13.1.4 Full tensioning shall not be carried out until the strength of the concrete or mortar in the joint has reached twice the stress at transfer.