AASHTO MP 18M/MP 18

Abstract

This specification covers uncoated, corrosion-resistant, deformed and plain alloy, billet-steel concrete reinforcement and dowel bars in cut lengths or coils, where corrosion-resistant performance may be essential (Notes 1 and 2). The standard sizes and dimensions of deformed bars and their number designations shall be those listed in Table 2 [Table 3]. <br><strong>Note 1</strong>&#8212;For coils of deformed bars, the capacity of industrial equipment limits the maximum bar size that can be straightened. <br><strong>Note 2</strong>&#8212;The degree of corrosion-resistance needed for a specific use is dependent on both the project's environmental conditions and its application. <br>Comparative corrosion performance data in accordance with Section 11 and Annex A shall apply only when specified by the purchaser. <br>Bars are of three minimum yield levels: 420 MPa [60000 psi], 520 MPa [75000 psi], and 690 MPa [100000 psi], designated as Grade 420 [60], Grade 520 [75], and Grade 690 [100], respectively. <br>Hot-rolled plain rounds, in sizes up to and including 50.8 mm [2 in.] in diameter in coils or cut lengths, when specified for dowels, spirals, and structural ties or supports shall be furnished under this specification in Grade 420 [60], Grade 520 [75], and Grade 690 [100] (Note 3). <br>For ductility properties, test provisions of the nearest nominal diameter deformed bar size shall apply. Those requirements providing for deformations and marking shall not be applicable (Note 3). <br><strong>Note 3</strong>&#8212;The weight for plain rounds smaller than 9.5 mm [³/₈ in.] in diameter shall be computed on the basis of the size in ASTM A 510. <br><strong>Note 4</strong>&#8212;Welding of the material in this specification should be approached with caution since no specific provisions have been included to enhance its weldability. When the steel is to be welded, a welding procedure suitable for the chemical composition and intended use or service should be used. <br>This specification is applicable for orders in either SI units (as Specification MP 18M) or in inchpound units (as Specification MP 18). SI units and inch pound units are not necessarily equivalent. Inch-pound units are shown in brackets in the text for clarity, but they are the applicable values when the material is ordered to MP 18.