Reinforcing bars that are installed into hardened concrete using an adhesive product are referred to as “post-installed” reinforcing bars. The installation process consists of drilling a hole into a concrete member, injecting an adhesive into the hole, and inserting the reinforcing bar into the hole such that the adhesive, when cured, will bond to both the concrete and the bar. The bond that develops between the adhesive and bar, and the adhesive and concrete, permits load applied to the bar to be transferred into the concrete member. Post-installed reinforcing bars that have been evaluated via an accepted test program can be designed for a strength that exceeds the load being applied (also referred to as “strength design”) or designed to yield using cast-in reinforcing bar design provisions. 

The International Code Council Evaluation Service (ICC-ES) writes what are known as “acceptance criteria”, to permit evaluation of products for recognition under the International Building Code (IBC). IBC recognition is provided via an ICC-ES evaluation report which is also known as an “ESR”. In Canada, recognition under the NBC is provided via an Evaluation Listing for Canada (ELC). The ESR or ELC indicates compliance “in the opinion of ICC-ES” with the model building code.

The ICC-ES acceptance criteria for evaluation of adhesive anchor systems is titled Acceptance Criteria for Post-Installed Adhesive Anchors in Concrete Elements (AC308). As the NBC and the Canadian Standards Association (CSA) standard titled Design of Concrete structures (CSA A23.3) require adhesive anchors to be evaluated per ACI 355.4, AC 308 is used to execute the evaluation in accordance with ACI 355.4. Evaluation per AC308 not only permits recognition under the NBC, it also provides data and provisions that can be used for design with the Canadian Standards Association (CSA) standard titled Design of Concrete structures (CSA A23.3). CSA A23.3 includes provisions for designing reinforced concrete members such as beams, slabs and columns; and for anchoring into a concrete member. CSA A23.3 provisions for reinforced concrete member design are predicated on the use of cast-in reinforcing bars. CSA A23.3 provisions for anchoring into a concrete member are predicated on the use of cast-in anchors such as headed bolts and AWS D1.1 headed studs, or post-installed mechanical anchors and “adhesive anchor systems”. An adhesive product is one component in an overall “adhesive anchor system” consisting of the adhesive product, the anchor element (e.g. reinforcing bar), and the approved installation procedure. Reinforcing bars evaluated per AC308 can be post-installed as part of an adhesive anchor system in which the bars are designed using CSA A23.3 anchoring-to-concrete provisions (e.g. CSA A23.3 Annex D provisions). Reinforcing bars evaluated per AC308 can also be post-installed as part of an adhesive anchor system in which the bars are designed using development provisions (e.g. CSA A23.3 Chapter 12 provisions)*. Therefore, satisfying the criteria of an AC308 test program permits adhesive product recognition under the NBC, and establishes product-specific data and parameters that permit an adhesive product to be used (e.g. with a reinforcing bar) for design with CSA A23.3 provisions. The product-specific data and design parameters derived from testing per AC308 test programs are given in an ICC-ES Evaluation Report (ESR) or an Evaluation Listing for Canada (ELC) can be furnished for design in accordance with CSA A23.3. For design of adhesive anchors with development length provisions, reference the adhesive product’s ESR. ELC’s provide compliance with relevant Canadian standards. Because ACI 355.4 do not provide requirements for adhesive anchors being used for development of reinforcement, the ELC relevant provides no data*.  

The test programs outlined in AC308 Table 3.2 are used to evaluate an adhesive anchor system for use with CSA A23.3 anchoring-to-concrete provisions. Testing per Table 3.2 is noted in Section 6 of the adhesive anchor ESR.

AC308 Table 3.2 testing establishes design parameters such as the types of anchor elements that can be used with the adhesive, permissible concrete condition (cracked, uncracked, normal weight, lightweight), and load conditions (static, seismic). Table 3.2 testing also establishes installation parameters such embedment depth limits, minimum concrete edge distance, minimum anchor spacing, minimum concrete member thickness, and hole cleaning provisions. 

The test programs outlined in AC308 Table 3.8 are used to evaluate an adhesive anchor system for post-installing reinforcing bars designed per CSA A23.3 development and splice provisions*. 

Installation parameters such maximum embedment depth, injection method, and hole cleaning are evaluated to determine if a post-installed reinforcing bar installed per these parameters performs equivalent to a cast-in bar; thereby permitting the post-installed reinforcing bar to be designed for yield using CSA A23.3 development and splice provisions in the same manner as a cast-in bar is designed using these provisions.

*The evaluation of a post-installed reinforcing bar system as an alternative to cast-in-place reinforcing bars using the development length provisions of ACI 318 and CSA A23.3 is outside of the scope of ACI 355.4. The suitability of this application is evaluated under ICC-ES Acceptance Criteria AC308, Table 3.8.

Additional Resources
 
Design Guides
Hilti Post-installed Reinforcing Bar Design Guide
Hilti Post-installed Reinforcing in Fire Conditions Design Guide

Design Software
PROFIS Engineering
           
Hilti Post-Installed Rebar White Papers
* Post-installed Reinforcing Bar Design Options: An Overview
* Interface Shear Transfer Design using the Hilti Method for Post-installed Rebar Design
* Design for Yield using Anchoring-to-Concrete Provisions for Post-installed Reinforcing Bar Design
* Extension Design using CSA A23.3-19 Provisions for Post-installed Reinforcing Bar
* Structural Joint Design using CSA A23.3-19 Provisions for Post-installed Reinforcing Bar
* Designing Rebar in Fire-rated Concrete-to-concrete Connections: Frequently Asked Questions
* Designing Post-installed Rebar for Fire Conditions using PROFIS Engineering Whitepaper