Email Address is required Invalid Email Address
In today’s market, it is imperative to be knowledgeable and have an edge over the competition. ACI members have it…they are engaged, informed, and stay up to date by taking advantage of benefits that ACI membership provides them.
Read more about membership
Learn More
Become an ACI Member
Founded in 1904 and headquartered in Farmington Hills, Michigan, USA, the American Concrete Institute is a leading authority and resource worldwide for the development, dissemination, and adoption of its consensus-based standards, technical resources, educational programs, and proven expertise for individuals and organizations involved in concrete design, construction, and materials, who share a commitment to pursuing the best use of concrete.
Staff Directory
ACI World Headquarters 38800 Country Club Dr. Farmington Hills, MI 48331-3439 USA Phone: 1.248.848.3800 Fax: 1.248.848.3701
ACI Middle East Regional Office Second Floor, Office #207 The Offices 2 Building, One Central Dubai World Trade Center Complex Dubai, UAE Phone: +971.4.516.3208 & 3209
ACI Resource Center Southern California Midwest Mid Atlantic
Feedback via Email Phone: 1.248.848.3800
ACI Global Home Middle East Region Portal Western Europe Region Portal
Home > Tools > Frequently Asked Questions
Q. We need to repair a 1962 vintage, elevated, interior parking deck which was designed as a cast-in-place pan/joist system. Joist webs are 5" wide and 10" deep at 25" O.C. The slab is 2½" thick reinforced with welded wire fabric. About 20% of the joists have a horizontal crack at the joist/slab interface as if the joist is separating from the slab. Do you have any ideas, or can you point me in the proper direction, to determine the cause of such cracking? A. To properly determine the causes of the cracks, preliminary evaluation and assessment of the existing structure is required. There are several questions that need to be answered before the causes of the cracks can be determined. Here are some of the questions that an engineer needs to investigate: - To what standard was the slab built to (age, building code)? - Are the original construction documents available? - Has the slab been subjected to heavy loads during its service life? - Where any repairs done to the slab system? ACI has published the first repair code in the industry, ACI CODE-562, Assessment, Repair, and Rehabilitation of Existing Concrete Structures. This standard provides direction and means to professional engineers to evaluate and assess existing concrete structures. This standard will provide consistency to the repair industry and owners’ will appreciate the value that the new standard will provide in terms of what to expect when the structure is repaired and the life expectancy of the repaired structure. ACI has also published, “Guide to the Code for Assessment, Repair, and Rehabilitation of Existing Concrete Structures”. It is a guide that helps engineers better understand how to apply the new standard, presents more in-depth information, and provides real life examples of repair and rehabilitation of structures. One of the examples included in this guide is the repair of precast concrete joist systems. References: ACI CODE-562-21; MNL-3(20); ACI 318 Historical ACI Building Code Requirements (1908-2005) Topics in Concrete: 318 Building Code; Cracking in Concrete; Repair of Concrete
Q. We need to repair a 1962 vintage, elevated, interior parking deck which was designed as a cast-in-place pan/joist system. Joist webs are 5" wide and 10" deep at 25" O.C. The slab is 2½" thick reinforced with welded wire fabric. About 20% of the joists have a horizontal crack at the joist/slab interface as if the joist is separating from the slab. Do you have any ideas, or can you point me in the proper direction, to determine the cause of such cracking?
A. To properly determine the causes of the cracks, preliminary evaluation and assessment of the existing structure is required. There are several questions that need to be answered before the causes of the cracks can be determined. Here are some of the questions that an engineer needs to investigate:
- To what standard was the slab built to (age, building code)?
- Are the original construction documents available?
- Has the slab been subjected to heavy loads during its service life?
- Where any repairs done to the slab system?
ACI has published the first repair code in the industry, ACI CODE-562, Assessment, Repair, and Rehabilitation of Existing Concrete Structures. This standard provides direction and means to professional engineers to evaluate and assess existing concrete structures. This standard will provide consistency to the repair industry and owners’ will appreciate the value that the new standard will provide in terms of what to expect when the structure is repaired and the life expectancy of the repaired structure.
ACI has also published, “Guide to the Code for Assessment, Repair, and Rehabilitation of Existing Concrete Structures”. It is a guide that helps engineers better understand how to apply the new standard, presents more in-depth information, and provides real life examples of repair and rehabilitation of structures. One of the examples included in this guide is the repair of precast concrete joist systems.
References: ACI CODE-562-21; MNL-3(20); ACI 318 Historical ACI Building Code Requirements (1908-2005)
Topics in Concrete: 318 Building Code; Cracking in Concrete; Repair of Concrete
Search other resources on the ACI website for answers to technical questions