Taking a new approach to concrete

4. Building officials now have a tool for evaluating rehabilitation design.
Before ACI 562, rehabilitation of existing structures was sometimes held to unrealistic standards. Without a repair-specific code, building inspectors referred to codes intended for new construction, such as ACI 318. This often resulted in unnecessarily extensive or costly repairs. By establishing minimum life safety requirements for rehabilitated structures, the newer ACI code is designed to help preserve existing structures that would otherwise be neglected or demolished.

ACI 562 requires inspection and testing of concrete repairs to meet the minimum inspection requirements of the existing building code or local jurisdiction. The LDP must specify these requirements within construction documents, as well as supplemental inspections and tests appropriate to the project (Chapter 10.1.1).

To facilitate construction observations, the LDP must specify that existing conditions and reinforcement cannot be concealed with construction materials before the work is inspected. However, the code allows the designer to determine (on some projects)
that only representative repair locations need to be inspected.

5. Several resources can help specifiers implement the code.
To help concrete professionals interpret the new code’s requirements, ACI and ICRI have collaborated to create the Guide to the Code Requirements for Evaluation, Repair, and Rehabilitation of Concrete Buildings. (The guide is available in print and digital formats through at www.icri.org and www.concrete.org). The reference expands the users’ knowledge base and provides options for designers to use their professional judgement in determining how to provide better repair solutions.

‘Chapter guides’ summarize each chapter of ACI 562 and provide insights into how each of these chapters of the code applies to different aspects of concrete repair, including:

• basis for compliance;
• evaluation and analysis;
• design of structural repairs;
• durability; and
• construction.

Flowcharts such as the one in Figure 1 illustrate key decision-making points in the process, and call-out boxes—such as “Is a Structural Evaluation Always Required?”—provide additional analysis, commentary, and references not explicitly covered by the code.

The guide uses real-world project examples to show how ACI 562 requirements apply to common repair scenarios, including:

• typical parking garage repairs;
• typical façade repairs;
• repair of historic structure for adaptive reuse;
• strengthening of two-way flat slab; and
• strengthening of double-tee stems for shear.

Project descriptions include photos and design details, as well as references to ACI 562 provisions that correspond to each phase of work, from evaluation through design and construction. Rather than providing a ‘how-to’ manual, these examples illustrate ways in which designers can apply the code to fit unique repair scenarios.

Licensed design professionals, owners, and contractors can learn more about ACI 562 through the institute’s educational sessions where engineers (including this article’s authors) present case studies to explain the repair design provisions and their applicability to quality assurance (QA), structural repairs, and external reinforcing systems. (For example, the ACI Spring Convention takes place in Milwaukee, Wisconsin, April 17−21. Committee E702 will host an educational session, entitled “Applicability and Use of ACI 562 Concrete Repair Code.” Visit www.concrete.org/events/conventions.aspx). Further, members of the ACI Committee 562—many of whom are consulting engineers with experience in the code’s intricacies—are also available to assist with questions on an ongoing basis.

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