Pumping Suggestions

Design Engineer

  1. Mixes that are regularly used in a market area will be the most economical. Consult the lightweight aggregate suppliers for detailed mix design information and material capabilities (i.e., unit weight, strength, etc.).
  2. Specify 4 to 7 percent air entrainment for pumpability, workability, finishability, and durability.
  3. Specify the maximum size aggregate rather than specifying individual sizes.
  4. Allow a higher slump into the pump to accommodate the possible slump loss.
  5. Have the testing lab run design curves based on the maximum specified slump and air per ACI 301.
  6. Specify a pre-pump meeting with the following present: engineer, architect, project manager, contractor, ready-mix supplier, lightweight aggregate supplier, testing agency, admixture supplier, and pumping subcontractor.
  7. On large jobs, these same people that atttended the pre-pump meeting should be present at the first concrete pump placement.
  8. Specify where concrete should be tested, preferably at the end of the discharge line as per ACI 304.2R.
  9. Realize that absorbed water does not affect water/cementations materials ratio, as defined in ASTM C125.

General Contractor

  1. Keep everyone communicating; this is a team effort!
  2. Use an experienced pumping subcontractor.
  3. Make arrangements for two ready-mix trucks to unload simultaneously.
  4. Designate a laborer to help the testing lab inspector.
  5. Provide a washout area for ready-mix trucks.
  6. Make use of the ready-mix truck radio when placement delays occur.
  7. Specify to the ready-mix supplier the number of yards needed per hour, not how many truckloads.
  8. Check that the pump line has been properly lubricated before placing the concrete.

Pumping Contractor

  1. Know the required unit weight of the concrete being pumped.
  2. Order concrete to coincide with actual pumping time, not when the pump arrives at the job site.
  3. Maintain continuous placement.
  4. Operator should know the maximum slump allowed.
  5. Clean steel pump lines with a 5″ minimum diameter should be used; minimize the use of rubber hose at the end of pump lines and avoid reducers if possible.
  6. Keep the same pump and operator throughout the duration of the job.
  7. Use a pump whose piston size is as close as possible to the line size to maintain the best performance and minimize slump loss.
  8. It is necessary to properly lubricate the pump line before placing the concrete.

Ready Mix Producers

  1. The lightweight aggregate must be prewetted prior to batching using procedures recommended by the lightweight aggregate supplier.
  2. Check with the lightweight aggregate supplier for a recommended concrete mix design and field correction procedures for pumped concrete.
  3. The aggregate moisture content and/or unit weight should be checked at regular intervals through the day’s placement. This is necessary for concrete yield control.
  4. Make drivers aware of admixtures being used for slump control.
  5. Maintain a minimum of 3″ slump before the addition of high-range water reducing admixture.

Testing Labs

  1. The field inspector shall be ACI Field Technician Grade 1 (or equivalent), per ASTM C94.
  2. Make sure the inspector has properly calibrated tools including a rolla-meter for volumetric air tests and a proper strike-off plate for unit weight determination.
  3. On large jobs use the same inspector for all concrete placements.
  4. The inspector should know fresh unit weight limitations (min & max).
  5. Place test cylinders immediately upon casting in a curing box protected from vibration per ASTM C31.