Mason contractors are often asked to take on additional jobsite tasks. One common add-on is performing concrete repair. But with the cost of building repairs — especially facades — escalating, mason contractors must approach these projects with greater preparation. Some repair experts suggest that façade repair is 10 times as expensive as that of repair of concrete parking garage deck.
As a result there's been a big push to formalize common repair techniques and material selection. If concrete repair is not something you normally do, you’ll probably be surprised by how much attention it has been given recently.
Spurred by the International Concrete Institute’s Vision 2020, the concrete industry has invested millions of dollars focused on improving the field repair durability. Much of this investment was targeted on infrastructure repair, and practices, materials and approved approaches are rapidly entering the commercial building marketplace.
Now, code officials’ awareness of standardized concrete repair techniques is about to change. Responding to owner’s concerns, ACI has developed the Concrete Repair Code. This document is expected to soon be recognized at part of the International Building Code. When that happens, local jurisdictions will be referencing this document’s mandatory requirements for common concrete repairs.
Knowing that this increased emphasis of standardizing concrete repair procedures will affect contractors. owners, and engineers, supporting ACI committees are updating their reference documents covering concrete repair.
At the 2014 ACI Convention recently, committee members provided some key comments on the newly updated 546R-14: Concrete Repair Guide. Last updated about a decade ago, this document has doubled in size and reorganized to make it an important contractor reference.
ACI 546-14 provides guidance on the selection and application of materials and methods for the repair, protection, and strengthening of concrete structures. The committee has provided an up-to-date overview of materials and methods for a particular concrete repair application. And for those who really want the details, the Guide contains current references that can lead to in-depth information on the selected materials or methods.
There are four key chapters for contractors. Chapter 1 was rewritten to redefine the relationship between contractor, owner, and engineer. This was an important change as the information now provides a consistent approach that will help bid document be consistent with the new Concrete Repair Code.
Industry research on failed concrete repairs has determined one common causes of premature failure is poor surface prep. To address this common mistake, ACI 546-14’s Chapter 3 presents the most current recommended procedures for surface prep. The chapter includes guidance on how to avoid the common mistakes observed for the past 20 years.
There are at least three important revisions in surface prep procedures. The document emphasizes deeper repair excavations to enable the use of large aggregates, awareness of how repair geometry can affect durability, and preference of sand blasting of rebar and host surfaces to wire brushing.
The new information in chapter 4 — Repair Materials — may be of most interest to mason contractors. With so many innovations, this portion of guide exploded from 10 to 50 pages. The subject matter was expanded to include the basic information contractors need to know when selecting repair material. Information was reviewed so that it is consistent with information found in the ACI 546.3R Material Section Guide.
Materials explained in this section are described in two categories:concrete replacement and overlays and those materials used in crack repair. The Guide describes 9 common repair materials used for crack repair. Descriptions are provided for the use and applications for: epoxy resin, urethane resin, polyurethane chemical grout, polyurethane sealant, silicone sealant, methacrylate, polymer grout, polymer cement grout, and cement grout. The chapter also describes bonding materials, scrub coats, coatings on reinforcement, reinforcement, admixtures, and other new products.
Finally, Chapter 5 updates contractors on the most common types of repair techniques as related to materials selected for the project. The chapter provides information on three common repair techniques, including:
Crack repair techniques — epoxy injection, gravity feed, chemical and cement grouting, sealants, and strip sealing.
Concrete repair replacement techniques, commonly used on deteriorated or damaged concrete element — horizontal repair, form and pour, form and pump, hand applied, dry packed, shotcrete, low pressure spraying, preplaced aggregate, and bonding repair.
Reinforcement repair techniques — rebar replacement, rebar coupling, supplemental, reinforcing coating post tension tendon repair.
To order these document, visit ACI's Bookstore, and for more information check out this 1-hour webinar cosponsored by ACI and ICRI. Lawrence F. Kahn (past Chair of ACI Committee 562, Evaluation, Repair, and Rehabilitation of Concrete Buildings) and Keith Kesner (Chair of ACI Committee 562) present an overview of the development and organization of the new ACI 562 concrete repair code.
(Please note that continuing education credit is not currently available for watching this recording. An ACI Online CEU course based on this webinar is being developed to address this situation.)