Evaluating Bond Strength for 0.600-in. Diameter Steel Prestressing Strand, Grade 270, Uncoated, Used in Prestressed Ground Anchors
This test method describes procedures to establish the relative bond strength of 0.600-in. [15.24-mm] diameter, Grade 270 [1860] steel prestressing strand in cement grout as used in prestressed ground anchors for the purpose of evaluating the effects of manufacturing practices on bond strength.
The test method originated from work that was conducted by the Department of Mining Engineering at Queen’s University in Ontario, Canada in the early 1990’s for the Post tensioning Institute (PTI). The test was formally adopted as ASTM A981 in 1997. Additionally, the acceptance criteria for ASTM A981 were simultaneously published in ASTM A416 as Supplementary Requirement S1. “Bond Strength of 0.600-in. [15.24-mm], Grade 270 [1860] Strand Used in Prestressed Ground Anchors”
RJ Peterman & Associates is accredited to conduct ASTM A981 pullout tests, and has performed over 130 pullout tests of 0.6”-diameter strands from 7 different manufacturing plants (both domestic and international sources).
We are currently using this test methodology to determine the difference in bond that can occur when utilizing different mixers and different sources of cement (including Type IL Cement) and the use of water-reducing admixtures.
We have the ability to batch grout using a conventional grout mixer, a paddle mixer with supplemental agitation, and also a colloidal mixer which allows for mixing and placement of the grout by direct pumping.