Concrete Yield and Relative Yield (ASTM C138)

Whether a load delivered the yards ordered, from the batch weights and the measured fresh unit weight.

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Example

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Details, formula, and sources

yield = total batch mass / unit weight, relative yield = yield / design volume, and actual cement content = cement batched / yield. A 3,993 lb batch at 148 lb/ft^3 makes 26.98 ft^3 (0.999 yd^3) -- a full yard, 564 lb/yd^3 cement. A relative yield below 1.0 is a SHORT load (denser than designed, more cement per yard); above 1.0 is over-yield (lighter or high-air, cement diluted, strength at risk). The unit weight must be measured per ASTM C138, not estimated. Checks volume and cement content, not air or strength. A QC check; the mix design and measurement govern.

yield_ft3 = total_batch_mass_lb / measured_unit_weight_lb_ft3; yield_yd3 = yield_ft3 / 27; relative_yield = yield_yd3 / design_volume_yd3; cement_content_lb_yd3 = cement_mass_lb / yield_yd3.

ASTM C138 / AASHTO T121 (Density (Unit Weight), Yield, and Air Content of Concrete); ACI 211.1, by name; the mix design, the C138 measurement, and the mix producer govern.

The yield = mass / density mass balance is first-principles; the batch weights come from the ticket and the unit weight from the C138 measurement.

Estimate. AHJ and licensed professional govern.

Field names used by the API: total_batch_mass_lb, measured_unit_weight_lb_ft3, design_volume_yd3, cement_mass_lb, yield_yd3, relative_yield, cement_content_lb_yd3

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