2.2 Ready-Mixed Concrete Delivery, ASTM C94 Standards & Batch Ticket Verification
Key Takeaways
The delivery ticket identifies the batch and records required delivery and adjustment information. Actual ingredient quantities may require additional records.
The 2017 editions of ASTM C94 separate the 90-minute completion-of-discharge default from the applicable revolution limit for starting discharge.
Beginning with ASTM C94/C94M-21, the discharge deadline is established for the order and recorded on the ticket.
Check measured water additions against the total water allowance. Remix at least 30 revolutions at mixing speed after the permitted adjustment and then take the acceptance sample.
For aggregate moisture and absorption percentages expressed on an oven-dry basis, wet aggregate mass uses total moisture and mixing water uses only moisture above absorption.
2.2 Ready-Mixed Concrete Delivery, Batch Tickets & Water Adjustments
Identify the approved mixture and the edition of ASTM C94/C94M governing the delivery. ICC's 47C catalog lists C94/C94M-07 through -17a as exam reference options. Projects may use another edition. Check the approved documents and purchase requirements before interpreting the truck clock, drum counter or adjustment record.
Ticket and batch records
Match the plant, ticket and truck identification, job, date, quantity, mixture designation and time loaded or of first mixing to the delivery being observed. Look for water requested by the purchaser or designated representative, the amount and initials, and the applicable adjustment and revolution information. Section 14 distinguishes required delivery information from additional certification data supplied when requested under the job requirements. The mixture designation identifies the accepted proportions. Obtain the batch record or certification detail when actual quantities, constituent types or measured adjustments matter.
Link acceptance test reports to the delivery ticket and the actual placement location. When one delivery serves two areas, record the represented work rather than just the truck number. A water allowance on the ticket helps track the load, but an unexplained tank withdrawal or undocumented previous addition prevents the remaining allowance from being verified by subtraction alone.
Measuring materials and correcting moisture
ASTM C94/C94M-17a Section 9 bases several batching tolerances on the type of scale or the fraction of scale capacity used. Check the applicable case.
| Measurement | Selected checks under Section 9 |
|---|---|
| Cementitious materials | Weigh hydraulic cement first where cumulatively weighed with SCMs. Above 30% of full scale capacity, check hydraulic cement and cumulative quantities at each applicable intermediate weighing to ±1% of required mass. For smaller loads in the stated range, the provision specifies no underbatch and up to 4% over. |
| Aggregate, individual weighing | ±2% of required mass, with ±0.3% of scale capacity when the required amount is below 15% of capacity. |
| Aggregate, cumulative weighing | ±1% of required mass at each successive weighing at or above 30% of scale capacity, and ±0.3% of capacity below 30%. |
| Water | Plant batch water is measured to ±1% of the designed mixing-water quantity. Total mixing water has a separate ±3% accuracy requirement. Compare the actual water to the applicable mixture and project limits. |
| Chemical admixtures | Powder by mass and liquid by mass or volume. Check the allowable batching deviation in Section 9.4 against the quantity required. |
For a batch requiring 1300 lb oven-dry sand, measured total moisture of 5% and absorption of 1%, the plant weighs lb of moist sand. Free moisture is lb. Of the 65 lb of total water on and in the sand, 13 lb is absorption. Subtract the 52 lb from otherwise required metered mixing water and account separately for other water inputs.
Delivery time and drum speed
In ASTM C94/C94M-17 and -17a, the time provision concerns completion of discharge. The 90-minute default starts when mixing water is introduced to cement and aggregates or when cement is introduced to aggregates, as applicable. The purchaser can specify a shorter limit for conditions that promote rapid stiffening. The edition also permits the purchaser to waive the time limit if the concrete can be placed after the limit at its existing slump or slump flow without adding water. Check project restrictions and who may act for the purchaser.
The revolution provision in these editions concerns start of discharge. Section 6.1.9 addresses the applicable order or manufacturer limit. A 300-revolution default appears in earlier editions such as C94/C94M-09. It does not apply as a fixed universal limit under -17 and -17a. An order can specify 300 as its actual limit.
Beginning with ASTM C94/C94M-21, the purchaser specifies the time from the applicable start of mixing to completion of discharge. If the purchaser gives no limit, the producer establishes and communicates it before delivery. The established limit is recorded on the delivery ticket. A specified 90-minute deadline can still apply.
For truck-mixed concrete, ASTM C94 Section 12.5 uses 70 to 100 revolutions at the equipment manufacturer's designated mixing speed under the prescribed mixing procedure. Agitating speed serves transport after mixing. Confirm the speed designation on the equipment rather than assuming a universal rpm for all trucks.
Worked timing example. A C94/C94M-17a job has no approved shorter period or waiver. The applicable mixing time starts at 08:15. The 90-minute completion deadline is 09:45. Starting discharge at 09:50 is already 95 minutes after the start. A reading of 185 revolutions within the stated revolution allowance cannot satisfy the separate discharge time requirement. Record both quantities, notify the contractor and follow the project disposition process. Model IBC Section 1704.2.4 requires escalation to the building official and responsible design professional if a discrepancy remains uncorrected before completion of the phase.
Water adjustment and acceptance sampling
- Confirm that an adjustment is permitted and that the purchaser or designated representative has authorized the requested addition as required. Identify the concrete's status from the preliminary slump or slump-flow check and the approved mix. The preliminary sample permitted under C94 is separate from the C172 acceptance sample.
- Compare the measured addition with the water remaining under the approved mixture after all applicable water sources and prior adjustments. The retained water allowance for the truck is a load quantity. Convert units on a consistent basis before comparing with a per-yard design limit.
- Make the permitted adjustment before discharge for placement. After the adjustment, turn the drum at least 30 revolutions at the manufacturer's mixing speed, within applicable delivery limits. Record the actual addition on the ticket.
- Take a representative acceptance sample after final adjustments and remixing. Confirm the results against the applicable project limits and report discrepancies.
For an eight-yard load at a maximum of 32 gallons per yard, the load limit is 256 gallons. If verified total mixing water before adjustment is 240 gallons, 16 gallons remain available. A permitted 12-gallon addition uses 12 of those 16 and gives 252 gallons total, or 31.5 gallons per yard. The 4 gallons left on the water calculation do not establish that any further addition is permitted. Use the applicable procedure and record actual quantities.
A project incorporates ASTM C94/C94M-17a with the 90-minute default and no purchaser waiver. The applicable mixing start is 08:15. At 09:50, the contractor starts discharging with 185 revolutions, within the separate order limit. What should the inspector document?
Both limits are met because the counter is under 300
Both limits are met if slump is within range
A contractor liability waiver resolves the timing
The completion deadline has already passed and the discrepancy must be reported
An eight-yard load has a 32 gal/yd³ maximum and verified mixing water of 240 gallons. The preliminary slump is below its allowed range. The designated purchaser representative authorizes 12 gallons before placement and delivery limits allow the adjustment. What follows?
Record the addition, turn at least 30 revolutions at mixing speed and obtain an acceptance sample afterward
Turn the drum 10 revolutions at agitating speed
Add a Type A admixture to offset the additional water
Place immediately because the added water is under the allowance
The required oven-dry sand mass is 13,000 lb. Total moisture is 6% and absorption is 1%, both on an oven-dry basis. What are the moist batch mass and free water contribution?
13,130 lb and 130 lb
13,780 lb and 650 lb
13,650 lb and 780 lb
14,040 lb and 520 lb
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