concrete specifications

Ensure the Highest Level of Control Over Concrete Quality

Ready mix concrete producers with Verifi can provide unprecedented control over concrete quality. Here’s how concrete specifications can help the entire project team collaborate to achieve consistent quality concrete.

Metered Water in Transit

Some concrete specifications prohibit water from being added to the truck, except on the jobsite. These provisions were written before tools such as Verifi were available, and were intended to allow an inspector or other qualified person at the jobsite to manage all water additions. This process is labor-intensive and may not detect all additions of water.

ASTM C94, the specification for ready mixed concrete, was updated to allow the addition of water in transit on trucks equipped with Verifi. This provides the highest level of control available of concrete water content.

SUGGESTED SPECIFICATION TEXT
“Water additions during transportation shall be made in accordance with ASTM C94/C94M.”

Admixture by Verifi

Verifi can add superplasticizer to maintain slump while ensuring consistent water, strength, setting, and air. Water additions are acceptable as long as they are accounted for in the mix design.  When adding admixture with Verifi, ready mix concrete producers can deliver an even higher level of concrete quality.

Verifi for Concrete Quality Control and Quality Assurance (QC/QA)

Testing on site is manual, time consuming, and subject to sampling and testing errors. Verifi enables producers to measure every load and provide this data to inspectors and engineers. While some manual testing is still needed, Verifi can help bring a higher level of quality control and assurance.

Minimum Cement Content

Verifi helps concrete producers reduce variability and increase concrete strength. However, minimum specified cement contents prevent producers from improving their mix designs. Consider reducing minimum cementitious content for producers who can show consistent quality concrete with Verifi.

Slump Requirements

Concrete slump is not an indicator of water content because nearly every factor affects slump. Admixtures can be used to deliver concrete at any slump the contractor desires. Consider not specifying maximum concrete slump as a means to control water in a mix design. Also, we recommend not to use slump at the jobsite to control water in a mix design.   For example, a concrete mix with a long haul time on a hot day may exceed the maximum water content but have less than the target slump. Instead, rely on Verifi to control water content.

The Verifi Advantage for Specifiers

  1. Measurements of every load.
  2. All water additions controlled automatically.
  3. Consistent quality concrete.

Resources for Specifiers

Sample Specifications

Verifi for Contractors and Engineers

ASTM Change: Water in Transit

Data Access

Ready mix producers can provide inspectors and engineers access to Verifi data.  Inspectors on site can view data on the in-cab display. Contact the concrete supplier for access after the pour.

Calibration

Verifi calibrates in accordance with ASTM C94.

Water: ASTM C94 requires +/- 3%, confirmed upon request every 6 months, for in-transit addition.

Admixture: ASTM C94 requires +/- 3% of total amount required, or dose for 100 lb of cement, whichever is greater.

Slump: No ASTM requirement because slump is for the convenience of the concrete supplier and contractor. Verifi calibrates upon installation and confirms each time slump is measured.