The project final report is available as NCHRP Report 639.
Background
No protocols or standards currently exist to test the ability of adhesive anchors to resist sustained tensile loads. There is a creep test protocol in the International Conference of Building Officials Acceptance Criteria 58, Acceptance Criteria for Adhesive Anchors in Concrete and Masonry Elements, but it is a pass-fail criteria with one load for a specific time. It does not provide any data that would predict the operational lifetime of an adhesive anchor. ASTM D 2990, Standard Test Method for Tensile, Compressive, and Flexural Creep and Creep Rupture of Plastics, discusses various methods for testing polymers to assess their creep behavior under sustained loads, but it does not address adhesive anchors. With no protocols or standards, public agencies are left to devise their own tests or to conduct no tests.
Objective
The objective of this project is to develop a draft AASHTO standard test method to determine the ability of adhesive anchors to resist sustained tensile load. This test method will build on current methods from AASHTO, ASTM, state DOTs, and other sources and should consider (1) the creep characteristics of the adhesive over the expected life of the structure, (2) site-specific ultimate strength requirements, and (3) the effects of temperature and moisture. For purposes of this project, the term adhesive anchor encompasses systems for anchoring both threaded metal rod and rebar using any commercial adhesives sold for these purposes, irrespective of their specific chemical formulation.
