ASCC position statement #12 responsibility for buying concrete

Concrete Construction, June, 2004

Concrete contractors are typically responsible for providing a concrete structure that meets the specifications. To do this, they must match the needed concrete mixture proportions and properties with appropriate finishing equipment, tools, methods, and personnel. By using their experience with different concretes for different applications, they provide the owner with a concrete structure that meets or exceeds specification requirements, even in adverse cold and hot-weather environments and with challenging time schedules.

Concrete contractors traditionally purchased concrete from the ready-mixed concrete producer. Now, however, more and more construction managers (CM) and general contractors (GC) are purchasing the concrete. The usual reason for this practice is economics. Some CMs and GCs believe that by purchasing the concrete they can reduce the project cost for the owner. The CMs or GCs also can benefit when they mark up the concrete cost. The markup will vary depending on the local market and how much coordination is required to interact, communicate, and make mixture adjustments throughout the concrete placement schedule.

Concrete is not a commodity material. Concrete contractors use their expertise and judgment to evaluate proposed mixtures. This evaluation is especially important for mixtures to be used for floors that require hard-trowel finishes. When the CM or GC purchases concrete, it eliminates a critical review and evaluation procedure that is inherent when the concrete contractor purchases the mixture. When concrete has been selected solely on the basis of compressive strength and price, a contractor's means and methods can't always compensate for mixtures with poor placeability and finishability.

Concrete contractors can be solely responsible for meeting the project specifications only when they purchase the concrete. If another party purchases the concrete, there is a joint responsibility for uniformity of surface appearance and texture, flatness, occurrence of cracking, and other specification requirements.

ASCC contractors want the responsibility for conformance with project specifications and for owner satisfaction. This responsibility includes input--before and during construction--that helps the concrete producer develop a delivery schedule and supply concrete with mixture proportions that satisfy requirements for both placing and finishing and hardened concrete properties. ASCC concrete contractors will accept this responsibility only if they purchase the concrete. ASCC concrete contractors will also cooperate with CMs or GCs who purchase concrete when there is a willingness to share responsibility for meeting project specifications.

If you have any questions, contact your ASCC concrete contractor or the ASCC Technical Hotline at 800-331-0668. To learn more about the American Society of Concrete Contractors, contact them at 314-962-0210, at www.ascconline.org, or circle 38 on the reader service card.

ASCC Position Statements

Here are the position statements we've published so far and those still to come:

#1-Hard Trowel Finish on Air-Entrained Concrete (March 2003, p. 66)

#2-Location of Rolled Welded-Wire Fabric (June, p. 50)

#3-Coatings That Affect Bond to Reinforcement (September, p. 52)

#4-Trowel Marks on Concrete Floors (August, p. 44)

#5-Specifications for Crack Repair (October, p. 46)

#6-Division 3 versus Division 9 Floor Flatness Tolerances (November, p. 55)

#7-Birdbaths on Concrete Slabs (December, p. 48)

#8-Bugholes in Formed Concrete (January 2004, p. 60)

#9-Slab Thickness Tolerances (February, p. 104)

#10-Moisture-Sensitive Floor Coverings on Concrete Slabs (March, p. 58)

#11-Appearance Requirements for Concrete Slabs (April, p. 24)

#12-Responsibility for Buying Concrete (June, this page)

Other position statements are still being finalized.