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Conforming concrete

Conforming concrete

How to work with a third-party concrete testing company.

By James Handzlik and Jeremy Lake

A big part of maintaining high-quality construction and safe buildings is access to properly formulated concrete that meets ASTM standards. Third-party materials testing companies play a key role in maintaining concrete construction quality and ensuring that the concrete used at the site meets the job-specific requirements set by the professional engineer of record.

This means that anyone responsible for quality control on construction projects must know how to obtain proper results from a materials testing company, while also enabling construction to continue without quality-related delays. The following suggestions on how to accomplish this successfully come from an experienced testing laboratory that is part of a larger multidisciplinary firm offering a range of inspection and engineering-related services.

How do I ensure the third-party testing company is qualified?

Part of the role of a concrete testing service is to make sure that reinforcing steel meets specifications and is adequate to the purpose before the concrete is poured. Photo: courtesy of Encorus Group

One important aspect an owner/builder should investigate when looking for a testing company is professional qualifications, which might include accreditation through American Association of State Highway and Transportation Officials (AASHTO) re:source (formerly known as the AASHTO Materials Reference Laboratory), accreditation by the U.S. Army Corps of Engineers (USACE), and laboratory inspection by the Cement and Concrete Reference Laboratory (CCRL).

Owners, consultants, and contractors should refer to the websites of these organizations and search for third-party testing companies in the geographic area of the project location.

Doing a geographic search is important in part because ASTM C31 requires that transportation time of concrete test specimens shall not exceed four hours. In some parts of the country there may be many qualified laboratories within a four-hour radius, but in other places, the number of qualified firms may be more limited.

It is important to search the websites of accrediting and certifying entities to check if the firms you’re considering carry the necessary, current qualifications. It is also advisable to verify that the technicians used by the testing firm also hold all necessary certifications to provide the required testing in both the field and the laboratory.

Proof that testing was completed by qualified professionals can serve as protection in the case of a legal dispute.

How can I find the materials testing company that’s right for my job?

Civil testing services cover more than concrete testing, with inspectors responsible for tasks such as checking the formwork, reinforcing steel, placement/finishing methods, and curing operations, as well as ensuring that the work meets all specifications and relevant drawings.

  • The complex nature of services to be provided requires the use of an experienced firm with a well-trained staff of professionals. It is essential to select a firm that employs a sufficient number of experienced professionals who:
  • are familiar with construction sites and the tight timelines involved with ready-mixed concrete deliveries;
  • are capable of reading and understanding drawings and able to easily assess whether the concrete formwork is constructed according to the approved plans;
  • are well versed in building codes and other regulatory requirements about rebar, such as spacing of the elements and quality specifications;
  • utilize appropriate and properly calibrated equipment;
  • are able to accurately perform all steps of the sampling process, including the temperature check, slump tests, air content, unit weight, and casting compressive strength test specimens without impeding construction schedules;
  • can be trusted to inform the appropriate personnel promptly if a test result is out of tolerance (for both the onsite and offsite tests) to solve the problem as quickly as possible and minimize or eliminate construction delays; and
  • are able to respond expeditiously to requests for onsite inspection in a manner that meets the construction schedule.

What is my firm’s role in the testing process?

Sample cylinders of concrete undergo simulated natural weather conditions, including high humidity, in the “fog room” of a concrete testing facility. Photo: courtesy of Encorus Group

Note that it is outside the testing company’s scope to make recommendations for actions to be taken if a nonconforming item is found, such as concrete field tests not meeting the project specifications. The contractor is responsible for providing an acceptable solution that is approved by the professional engineer of record to any nonconformance uncovered by the testing firm.

It is also important for the contractor to play its part by informing the testing company within a responsible time frame of construction activities that will require inspection. If the testing company is not given adequate notice before a concrete pour, there may not be time for the firm’s staff to be appropriately dispatched.

Before concrete is poured, the testing company must review drawings, check the forms and rebar, and set up any equipment required before the concrete truck arrives. In cases where the testing company does not have time to perform the necessary inspections, construction may be delayed. By providing adequate notice to the testing company, such delays can be avoided.

Building and maintaining a positive, ongoing relationship with a testing company facilitates effective communication methods, helping to ensure that high-quality construction can be carried out smoothly.

James Handzlik is the director of Civil Materials Testing and Jeremy Lake is the civil laboratory supervisor at Encorus Group (www.encorus.com) in Buffalo, N.Y.