News Detail

Repair and Recycle

4/21/2016

The themes of repair and recycle were dominant at The Concrete Convention and Exposition, Milwaukee, WI, USA, on Wednesday, April 20, 2016.

Repair was covered extensively in a special session titled, “ACI 562 Concrete Repair Code, Applicability, and Use,” coordinated by ACI Committee 562, Evaluation, Repair, and Rehabilitation of Concrete Buildings

Concrete deteriorates when subjected to many environments and not all concrete repairs are performing satisfactorily due to design, construction, and material selection choices. Each concrete structure is repaired differently, by different people, in different circumstances. ACI 562 “Code Requirements for Evaluation, Repair, and Rehabilitation of Concrete Buildings and Commentary” establishes the required minimum repair practice conditions, and achieves protections, quality assurance, and safety for building structures.

With all this in mind, the “ACI 562 Concrete Repair Code, Applicability, and Use,” session sought to educate on the applicability and use of ACI 562 Code Requirements, and the new ACI/ICRI "Guide to the Code for Evaluation, Repair, and Rehabilitation of Concrete Building” through practical examples. Presenters discussed ACI concrete Repair Code Provisions, with examples of case studies to enable attendees to develop an understanding of the evaluation and analysis of existing buildings.

Presentations:

Structural Repair of a Concrete Parking Garage Using ACI 562-13
Description: Prior to the publication of (ACI 562), an industry standard specific to repair and rehabilitation of existing concrete structures did not exist in the United States. Thus, practitioners frequently refer to codes for new concrete construction that could be more stringent than the code in effect at the time the structure was originally constructed resulting in additional and possibly unnecessary repairs. ACI 562 was developed to provide uniform code provisions and criteria coupled with extensive commentary that engineers can use in this kind of projects.

ACI 562 Construction and Quality Assurance Provisions

Presented By: Jay Paul
Affiliation: Klein & Hoffman Inc
Description: Mr. Paul will present the provisions of Chapters 9&10 of the ACI 562-13 – Code Requirements for Evaluation, Repair and Rehabilitation of Existing Concrete Buildings and Commentary. The presentation will include relevant specifications and case studies.

An Example of Strengthening Repairs with External Post-Tensioning Reinforcement

Presented By: Gene Stevens
Affiliation: JR Harris & Co Structural Engineers
Description: Using ACI 562-13 provisions, two designs and the construction of repairs to strengthen faulty construction in podium slab beams supporting three stories of wood framing in four buildings are explained. The repair construction of the concrete podium beams as completed in the Village Lofts Condominium buildings is examined. Chapter 5 of ACI 562-13 and potential revisions of ACI 562-16 for the applicable equations of Chapter 5 are reviewed in a design example. Details of the construction and strength determination using plastic mechanisms for the beams are noted. The presentation addresses the engineering judgment of when to include fire protection for the beams.

Design Strength Requirements for Externally Applied Reinforcing Systems

Presented By: Tarek Alkhrdaji
Affiliation: Structural Technologies
Description: ASCI 562 include two distinct strength requirements for design of external repair systems: Minimum strength required to prevent failure of the structural members due to damage of the external reinforcement, and minimum strength requirement to prevent failure during a fire event. The first case is intended to guard against failure of the structural member if the external reinforcing system is damaged while the structure is in standard operation conditions. For fire, ACI 562 adopted the load combination for fire in ASCE 7. Fire rating of the repaired member is determined based on reduced material strength that accounts for fire exposure period and effects of fireproofing systems during a fire event.

The new Guide to the Code for Evaluation, Repair, and Rehabilitation of Concrete Buildings provides guidance and assistance to professionals engaged in the repair of concrete buildings. The guide has been developed to serve as an invaluable companion to ACI 562-13. The new guide is separated into two main components: chapter guides that follow the organization of ACI 562, broken down by the corresponding sections and project examples that illustrate the use of the code for real world projects from inception through completion. These two components work together to provide additional information on how to apply the performance requirements in ACI 562 and how the requirements may be applied to a broad range of projects. Published jointly by ACI and ICRI.

A new version of ACI 562 Repair Code is expected to be available in summer 2016.

View ACI Resources on Repair.

Later in the day, the “Recycled Materials to Enhance CLSM Applications and Properties” session provided attendees with an understanding of what recycled materials are used in controlled low-strength materials (CLSM); what properties can be improved with the addition of recycled material content; and examples of applications of CLSM with recycled materials.