Ready-Mixed Concrete: Accept the Delivery, Not Just the Slump

ASTM C94/C94M-26c covers ready-mixed concrete supplied to the purchaser and allows the purchaser’s stated requirements to govern. Its scope excludes subsequent placement, consolidation, curing and protection. Delivery acceptance therefore has a defined boundary, not a whole-structure guarantee. [1]

OlbrichCo recommends one receiving record that follows each load from the approved mixture to its destination in the structure. The decision is whether that delivery may proceed under the agreed requirements. Keep it separate from later strength acceptance, curing inspection and permission to load the structure. A satisfactory slump result should not close every field on the record.

Before ordering concrete for an Iranian project, bring the designer, contractor, producer and testing agency together. Agree the applicable specification and edition, mixture identifiers, fresh-property limits, sampling locations and frequency, permitted adjustments, retest rules and named acceptance authority. Resolve conflicts between the order, drawings and inspection plan before trucks arrive; do not select the most convenient clause during a dispute.

Make responsibilities visible on a Persian receiving sheet: who checks the ticket, performs tests, authorises an adjustment, holds the load and issues the decision. Give each role an alternate for shift changes. Arrange a direct producer contact and a paper or offline record, so an unavailable portal or mobile connection does not become an informal permission to discharge.

NRMCA’s March 2026 specification guide explains that ASTM C94 removed its default 90-minute limit in favour of a time limit agreed by purchaser and producer. This does not remove a project’s contractual limits or authorise unlimited delivery time. [2]

Our advice is to obtain an approved delivery and discharge basis for the actual mixture, placing method and expected conditions. Ask the producer what supporting trial or production evidence is appropriate. Do not copy a foreign default or relax an existing limit on site. Any proposed revision should pass the project’s technical and contractual review before it is used.

Build the dispatch plan from credible site information: travel-time variability, access restrictions, truck holding space, pump capacity, testing resources and the crew’s placing rate. Consider the forecast and the site’s hot, cold or windy exposure without assuming that every Iranian project has the same climate. Agree who slows dispatch when access or placement stops, and how the next shift receives the revised plan.

Check readiness before calling the first load: authorised formwork and reinforcement inspections, safe access, placing equipment, backup arrangements, testing station and curing resources. Have the engineer define the response to a prolonged interruption, including any construction-joint decision. The receiving team should not be forced to choose between an unreviewed placement and an improvised change to the structure.

The Concrete Society’s UK guidance makes site water addition conditional on measured and recorded quantities, the specified water–cement limit and the reason for low consistency, including excessive delay. It is not a blanket permission to add water or an Iranian rule. [3]

At arrival, reconcile the truck and ticket with the approved mixture, order and intended element. Record the plant, load identifier, quantity, batching and arrival times, and the relevant declared mixture information. Flag missing or contradictory entries for resolution. If the same truck has delivered elsewhere or the remaining quantity is uncertain, obtain a clear account before an adjustment is considered.

Have the producer and responsible engineer define whether any water or admixture adjustment is permitted, by whom, within what remaining allowance and with which mixing and verification sequence. Require a reliable measurement and a cumulative record of authorised additions, including earlier additions in transit. Do not calculate an allowance from a slump reading alone or assume a water-reducer can rescue an unsuitable load.

Record the request, reason, authorisation, material, measured amount, time and subsequent checks. Keep the original readings; a revised result must not erase the adjustment history. If permission, measurement or the remaining allowance cannot be established, hold the decision and contact the authorised reviewer. The driver, pump operator and test technician should not inherit design authority through an undocumented verbal instruction.

ASTM C172/C172M-25 addresses representative sampling of fresh concrete. Its scope generally requires composite samples; the individual test methods supply their own detailed requirements. A convenient scoop is not automatically an acceptance sample. [4]

ACI’s sampling guidance calls for several portions from a batch, protection against moisture loss and minimal handling. It recognises that the specified sampling point may be the mixer discharge or another location, such as the pump outlet. [5]

Use those principles through a project-approved sampling plan, executed by competent technicians with the full applicable methods. Distinguish any preliminary consistency check from the acceptance sample, and identify how authorised adjustment and remixing precede the final sampling sequence. Agree how the required representative sample will be obtained while controlling the disposition of concrete discharged for sampling; do not invent a procedure beside a waiting pump.

Record the actual sampling point and time, load identity, test method, instrument identity and verification status, raw readings, conditions and technician. Where additional checks are required after pumping, label their purpose and location separately. Provide a protected work area and the specified specimen-care arrangements. Never silently substitute an easier sampling location or report a result for concrete whose identity was lost.

Agree explicit statuses: awaiting evidence, accepted for the stated delivery scope, held for review, or rejected under the contract. A hold is not an invitation to keep altering the load until one number passes. Define the specified retest route and the person who interprets conflicting or borderline results before the pour, including what happens if the test itself is invalid.

For a deviation, preserve the ticket, observations, readings and adjustment history. Ask whether the issue is wrong identity, a fresh-property result, an exceeded limit, an unauthorised change or defective testing. Obtain the relevant technical decision while the contractor manages dispatch and placing continuity. Keep commercial allocation of delay or returned concrete separate from the technical permission to place it.

Do not place disputed concrete merely because later strength specimens can be made. If placement has already occurred, map its actual extent immediately and raise the project’s nonconformance process. The responsible engineer should define investigation, interim restrictions and disposition; the receiving team should not retrospectively relabel the load to make the register look complete.

Plan safe truck movement, sampling access, fresh-concrete handling and the destination of rejected material under the site’s approved safety and environmental arrangements. Do not improvise disposal or send personnel into equipment to recover a sample. Include return logistics and authorised communication in the order so the last unresolved action is not left with a driver at the gate.

For one representative pour, reconcile the complete chain: approved mixture revision, delivery ticket, adjustments, sample and specimen identifiers, receiving decision, placed quantity and element location. Record split loads and interruptions explicitly. Link later laboratory reports and nonconformance decisions to that same history, while retaining separate records for placement, curing and any early-age release.

Test the workflow with a paper exercise before production: a wrong mixture code, an incomplete ticket, a low-consistency result and a communications failure. Ask each person to show their next action and authority. These are proposed rehearsal scenarios, not reported OlbrichCo project results. Revise the sheet and contact route where the exercise exposes an ambiguous decision.

During the pilot, track loads with complete identity records, undocumented adjustments, valid tests versus planned tests, holds by cause, decision time and unresolved placement locations. Report counts with denominators. Compare waiting and rejected quantities only alongside compliance and evidence quality; a lower rejection rate obtained by weakening the criterion is not an improvement.

Retain an owner-held, searchable register with Persian instructions and an offline export. Revisit the plan after a mixture, plant, route, placing method or crew change. Applicable Iranian requirements, contracts, site conditions and competent local engineering review control implementation. This note supplies no universal slump, temperature, water allowance or rejection limit; the cover is an editorial metaphor, not a sampling instruction.