613 Low Strength Mortar Backfill

1. Specification:

Item 613.02, 603 C&MS

Item 499, 703.05 C&MS


2. Sampling and/or Inspection Requirements:

Fine aggregate gradation should conform to Item 703.05.

Make one or more 1 cubic yard (1 cubic meter) trial batches at different water contents to ensure a flowable material. The mixture is too dry if cracks develop in the mixture as it flows into place. Type 1 mixtures may require a substitution of fly ash in 50 pound (30 kg) increments for sand in increments of approximately 60 pounds (36 kg) to ensure the mixture is bleeding freely. Large adjustments should be considered an Alternative Mix in accordance with section 613.05.

The Contractor may submit an alternative to the proportions found in Section 613.03. The mix design and test data from an independent laboratory should be submitted for approval 30 days before the intended usage.

Ensure that the final mix has the required strength, fills the voids of the intended space and sets up within the time specified for the mix type. Mixture must be discharged within 2.5 hours after adding water. Placement of other fill material over low strength mortar backfill may commence as soon as the surface water is gone.

3. Method of Tests:

ASTM D4832