Description

AASHTO MP 18M/MP 18 – Standard Specification for Uncoated, Corrosion-Resistant, Deformed and Plain Alloy, Billet-Steel Bars for Concrete Reinforcement and Dowels

AASHTO MP 18M/MP 18-15 covers uncoated, corrosion-resistant, deformed and plain chromium alloyed, billet-steel concrete reinforcement and dowel bars in cut lengths or coils, where corrosion-resistant performance may be essential. The standard sizes and dimensions of deformed bars and their number designations shall be those listed in Table 2 for millimeter-kilogram bars [Table 3 for inch-pound bars].

Note 1 – For coils of deformed bars, the capacity of industrial equipment limits the maximum bar size that can be straightened.

Note 2 – The degree of corrosion resistance needed for reinforcement or dowel bars is dependent on both the project’s environmental conditions and the concrete in which they are embedded.

Bars are of three minimum yield levels: 420 MPa [60,000 psi], 520 MPa [75,000 psi], and 690 MPa [100,000 psi], designated as Grade 420 [60], Grade 520 [75], and Grade 690 [100], respectively.

Hot-rolled plain rounds, in sizes up to and including 50 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]

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 – The weight for plain rounds smaller than 10 mm [3/8 in.] in diameter shall be computed on the basis of the size in ASTM A510/A510M.

Note 4 – When welding of the material listed in this specification is required, it should be in conformance with AWS D1.4 Structural Welding Code – Reinforcing Steel and the applicable sections of AWS D1.6 Structural Welding Code – Stainless Steels. If the material is not addressed in these specifications, the manufacturer of the steel should be contacted to obtain a welding procedure for the particular application.

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.