Specifying ACI certification builds confidence in concrete flatwork construction

by sadia_badhon | October 28, 2020 1:27 pm

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by John W. Nehasil, FACI, Bryan M. Birdwell, and Jerry A. Holland, FACI

Many of the largest retailers have been specifying, or soon will be specifying, certified individuals on new construction projects. It is worthwhile for owners and specifiers on projects of all types to follow their lead.

Good quality control can result in significant cost and time savings. Therefore, it is in every owner’s interest to promote quality and require contractors who maintain the highest industry standards that are confirmed by certification, such as the ones offered by the American Concrete Institute (ACI).

ACI offers nearly 30 certification programs across three practice areas:

• testing programs focus on performing and reporting the results of concrete field/laboratory tests (i.e. concrete, aggregate, cement, and masonry testing);
• inspection programs detail how to inspect various concrete installations and construction practices (i.e. general concrete construction and transportation-related structure inspection); and
• construction/specialist programs cover a range of concrete construction practices (i.e. concrete quality management, tilt-up concrete construction, and anchor installation).

There are currently more than 100,000 ACI-certified individuals throughout approximately 100 countries. ACI provides online and app-based resources enabling specifiers to quickly verify the status of ACI-certified individuals using simple search functions, including by an individual’s name or certification identification number, or by program area (an option that yields the total number of ACI-certified individuals in an area).

ACI also offers sample language for specifications and contracts[2] (to be used as a guide only). For example language, see “Concrete Floor Finishing.”

CONCRETE FLOOR FINISHING

The following sample specification language is excerpted from “Section 03 3560 – Concrete Floor Finishing:” 1.01 Quality Assurance A. Interior Slab-on-Ground and Slab on Metal Deck Installer: Construction of interior slabs shall be performed by Installer capable of achieving high quality control in finished product as measured in terms of surface flatness and levelness, uniformity in texture, smoothness, and appearance of hard steel troweled surfaces, precision in construction of joints, and minimization of slab shrinkage, plastic cracking, and edge finishing swale. Engage Installer, fully experienced in ways, means, methods and materials of slab-on-ground and suspended slab concrete construction, capable of producing high quality finished product for this project, and as acceptable to Owner’s representative. B. Perform Work in accordance with standards referenced. C. American Concrete Institute (ACI) Certifications: Floor contractor finishing crew shall have a minimum number of concrete finishers with the following current certifications. Certifications will be verified using ACI Cert app. 1. ACI Specialty Commercial-Industrial Flatwork Finisher & Technician: One. 2. ACI Advanced Concrete Flatwork Finisher or Concrete Flatwork Finisher: Three.

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ACI certification: A case study

To give a behind-the-scenes look at how ACI creates its certification programs—and to illustrate how such programs provide value to project owners—concrete flatwork finishing certification serves as an example.

The need for a new certification

Large-scale commercial/industrial buildings often require concrete slabs measuring 9290 m² (100,000 sf) or larger. Conventionally constructed floors in these environments can be problematic. In retail operations, the concrete surface often serves as the finished floor and must be aesthetically pleasing to shoppers. Increasingly, there are also functional needs for very flat floors in retail, big-box spec, and industrial warehouses, as well as logistic and fulfillment centers. These floors must accommodate high-density, tall-rack storage, narrow aisles, robotic equipment, and wire-guided lift trucks operating along pre-defined paths, and extreme loading from heavy installed equipment or warehouse stock.

For the purposes of commercial and industrial floors, floor flatness (FF) measures departures from a theoretically flat plane (i.e. a floor’s bumpiness). Floor levelness (FL) is defined as deviation from a horizontal plane. ACI’s Fmin values represent a separate system from traditional FF and FL. An Fmin number is used to define the lowest acceptable flatness on a superflat floor that has defined traffic patterns (where the vehicle wheels are always in the same wheel path).

ACI COMMITTEE C640 CONCRETE FLATWORK DEFINITIONS

A concrete flatwork associate (formerly concrete flatwork technician) is a person who has demonstrated knowledge (via a written examination) on proper procedures to place, consolidate, finish, edge, joint, cure, and protect concrete flatwork. A concrete flatwork finisher (formerly concrete flatwork tradesman) is a craftsperson who has demonstrated the skills (via a hands-on performance exam) necessary to place, consolidate, finish, edge, joint, cure, and protect concrete flatwork. An advanced concrete flatwork finisher (formerly concrete flatwork finisher and technician) is a craftsman who has demonstrated the knowledge and skills and/or experience necessary to place, consolidate, finish, edge, joint, cure, and protect concrete flatwork. A specialty commercial/industrial concrete flatwork finisher & technician is a person who has demonstrated a basic knowledge of finishing procedures for specialty commercial/industrial concrete flatwork finishing, including high tolerance floor construction, application of surface treatments, and silica fume concrete, and who has demonstrated skill in operating mechanized finishing equipment. A specialty commercial/industrial concrete flatwork technician is a person who has demonstrated a basic knowledge of finishing procedures for specialty commercial/industrial concrete flatwork finishing, including high tolerance floor construction, application of surface treatments, and silica fume concrete, but who lacks sufficient work experience and verified skills needed to qualify as a specialty commercial/industrial concrete flatwork finisher and technician.

If installed floors are low quality, or even if they are built to outdated specifications, not only will they need extensive repairs during their service life, but also cause wear-and-tear on robotic and other industrial equipment. This translates to unnecessary costs and lost time for facilities managers, maintenance staff, and project owners. Further, some of the benefits of flat floors are not immediately tied to construction concerns. For example, when lift trucks and other moving vehicles can travel easily over floors that are not marred by roughness, cracks, or unevenness, they can handle materials faster, leading to greater facility productivity. They can even navigate tighter spaces, allowing for more consolidated storage and reducing the square footage required for a facility’s operation.

These new demands have brought about specialized methods of concrete floor construction that meet far tighter tolerances than traditional slabs. To address the market’s needs, ACI’s certification department and ACI Committee C640, “Craftsmen Certification,” developed a program titled “ACI Specialty Commercial/Industrial Concrete Flatwork Finisher/Technician” to support a higher minimum standard for all commercial/industrial concrete flatwork. The committee brought together representatives from the materials and engineering side of the business as well as representatives from the application side. Its goal in creating the program was for architects and engineers to drive improvement by specifying a minimum number of people on a flatwork crew are ACI-certified.

The Specialty Commercial/Industrial Concrete Flatwork Finisher/Technician certification program was introduced at World of Concrete (WOC) 2008. Since then, ACI Committee C640 has ensured flatwork certification sessions be consistently held at WOC as well as being offered through various supporting organizations. During a typical two-day program, seminars present information on site preparation and placing environment, high-quality concrete flatwork-related materials, preplacement setup, concrete placement and consolidation, application of surface treatments, and finishing various classes of floors, surface tolerance issues, curing, special considerations for silica fume, and more. Special attention is called to commercial and industrial flatness requirements. Seminar content draws heavily from ACI 302.1R, Guide to Concrete Floor and Slab Construction, and the Silica Fume Association’s Silica Fume Manual.

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While finishers make up a significant portion of the WOC seminar audience each year, engineers, concrete material suppliers, concrete construction managers, and other related personnel also attend. Recently, ACI Committee C640 has focused on facilitating certification for individuals who have work experience but were previously hindered in seeking certification due to language barriers or educational challenges not associated with their knowledge and skills in concrete finishing.

Concrete flatwork finishing certification is offered in the following categories:

• concrete flatwork associate, finisher, and advanced finisher;
• decorative concrete flatwork finisher and associate; and
• specialty commercial/industrial flatwork finisher and technician.

Associate, finisher, and advanced finisher designations used within the three ACI finisher programs differ not only in the knowledge required to gain certification, but also in the level of hands-on skill required. The three finisher programs represent types of finished flatwork installation. Concrete flatwork certification focuses on proper procedures and equipment to place, consolidate, finish, edge, joint, cure, and protect concrete flatwork. Decorative concrete flatwork certification focuses on placing, finishing, curing, and protecting decorative concrete flatwork. Specialty commercial/industrial flatwork certification addresses additional areas of concern and has several riders, or add-ons, available. The high tolerance floor construction rider requires an applicant to know how to manipulate fresh concrete to achieve floor tolerances that meet predefined numerical levelness and flatness measurements. The surface treatments rider includes information on items such as applying and embedding aggregate hardeners. The silica fume rider requires applicants to place, finish, control evaporation, and cure silica fume (also called micro-silica) concrete. Those who wish to obtain their ACI certification as a specialty commercial/industrial flatwork finisher and technician must take a written examination and complete a performance examination, constructing an actual superflat slab using a vibratory truss screed and/or riding trowels, straight edges, check rods, channel floats, finish blades, and various hand tools. For full definitions of certification categories, see “ACI Committee C640 Concrete Flatwork Definitions.”

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Adoption of the flatwork certification programs

Soon after the certification’s initial offering, specifiers for big-box stores and other commercial/industrial facilities began to require flatwork crews have at least one ACI-certified commercial/industrial finisher. In the more than 10 years since, requirements for certified personnel have grown significantly. For example, the largest online retailer, who previously required the use of ACI flatwork finishers, has added a requirement for ACI commercial/industrial flatwork finishers on every project. Considering they have more buildings currently under construction than any other private entity—approaching 100 in the United States alone—this represents a great increase in demand for ACI-certified flatwork specialists. In many of these facilities there are thousands of robots, whose efficient operation depends on extremely high-quality concrete floors with respect to flat and level floor tolerances as well as minimal cracking and defects. Shutting a facility down for floor repairs is unacceptable.

Another extremely large retailer has plans to build approximately 60 distribution facilities in the United States. They have stated their intention to specify ACI-certified advanced finisher personnel (in addition to ACI-certified flatwork finishers, who have been required for more than 15 years) for construction of both distribution facilities and stores. Yet another big retailer has specified ACI-certified flatwork finishers for a similar period of time and also expects to soon require advanced flatwork finishers and commercial/industrial finishers.

Many retailers are now building stores with polished concrete surfaces. These floors are aesthetically pleasing, have lower first and maintenance costs, and a lower potential liability for slips and falls. However, retailers have learned that if the floors are not flat enough, the polished surface makes imperfections such as humps and dips very noticeable. Thus, they are specifying higher F-numbers and ACI-certified flatwork finishers and commercial/industrial finishers to ensure the floors meet or exceed the owner’s expectations.

Across all industries, assessment and certification credentials demonstrate competence and skill. Concrete construction work should not be an exception. The construction industry should not only expect quality work, but also specify craftspersons that have proven their knowledge and experience by becoming ACI-certified. Specifying these tradespersons ensures concrete installations reflect the expectations of the owner, requirements of the general contractor, and intent of the specifier.

[6]John W. Nehasil, FACI, is the managing director of certification for the American Concrete Institute (ACI). He has been employed by ACI for more than 40 years, including over 14 years of editorial and publishing experience and 29 years of experience in certification program administration. Nehasil is an ACI Fellow, graduate of the U.S. Chamber of Commerce’s Institute for Organizational Management, and a member of the American Society of Association Executives (ASAE).

[7]Bryan M. Birdwell is a senior floor and paving consultant and a principal with Structural Services Inc. He was an owner of a concrete construction company for many years that had a wide range of projects including commercial and industrial high tolerance slabs-on-ground, suspended slabs, parking lots, and pavements.

[8]Jerry A. Holland, PE, FACI, is vice-president and director of design services for Structural Services Inc.  He has over 50 years of worldwide experience in the design, construction, and troubleshooting of concrete materials, floors, pavements, structures, and geotechnical problems.  Holland is a long-term member of all of the American Concrete Institute (ACI) committees that deal with the design and construction of concrete floors and paving.

Source URL: https://www.constructionspecifier.com/specifying-aci-certification-builds-confidence-in-concrete-flatwork-construction/

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