Ready Mix Delivery and Truck Coordination

Purpose

A pour fails as a supply problem before it fails as a concrete problem. Order to a quantity instead of a placement rate and the third truck waits while the second one's edge goes cold, and the shop owns a cold joint it never drew. Let a driver open a hose at the gate and the slab is not the mix that was sold, with nothing on the ticket to show it. Take a load that batched 80 minutes ago because rejecting it feels expensive and the evidence arrives two winters later as a scaled surface. This procedure exists so a crew leader can reject a load with the ticket in hand, and so the shop can prove later what arrived and who authorized every gallon.

Scope

Covers ordering, scheduling, site access, ticket verification, fresh-concrete acceptance at the chute, on-site water control, discharge continuity and washout, from the order call to the driver's release.

It does not cover mix design, which belongs to the supplier and the engineer; cylinder sampling and strength acceptance, owned by the cylinder sampling SOP; or the subgrade, forms and steel that must already be released before a truck is called. Weather limits route to the hot and cold weather pour standards, which set the temperature ceilings this procedure enforces at the chute.

Roles and responsibilities

Procedure

1. Order to a placement rate, then convert to trucks. Compute neat volume from the drawing, add the waste allowance your own history supports for that form type, and divide by the rate the crew places with the equipment booked. Acceptance: an order sheet carrying neat volume, allowance, total ordered, cubic yards per hour and the truck interval in minutes, all five written. Wrong looks like an order in yards with no interval, which dispatch fills by sending everything at once; stop rule, do not release the order until the interval is on it and the crew leader has agreed the rate. Hazard: none here, it is arithmetic and a phone call.

2. Confirm ticket contents with the plant the day before. Name the mix identifier, specified strength, nominal slump, air content where the work sees freezing, aggregate size and any admixture, and confirm the plant prints batch time and batched water on every ticket. Acceptance: written confirmation of each, and the first ticket matching it. Wrong looks like ordering by strength alone, so an interior mix with no entrained air arrives for an exterior slab that spalls its first winter; stop rule, no truck is called until the identifier is confirmed in writing. Hazard: none here, it is an office task.

3. Spot the truck before it moves, not while it moves. Walk the approach, mark the discharge position, identify soft ground, buried utilities and any overhead line, and assign one spotter with a signal agreed with the driver. Acceptance: a marked position, an approach the loaded truck will not rut, one named spotter. Wrong looks like a driver backing on a mirror while three people wave; stop rule, the truck stops the moment either loses sight of the other. Hazard: a loaded mixer backing with an obstructed rear view is the killer here, and 29 CFR 1926.601(b)(4) requires either a reverse signal alarm audible above the noise or an observer signalling that it is safe to back, so the spotter stands out of the path and never behind the truck; a raised chute or boom near an overhead line is treated as energized and kept outside the utility's stated approach distance, settled now rather than by a driver reaching for a lever.

4. Read the ticket at the chute before concrete moves. Check mix identifier against step 2, batch time against the clock, yards on the load, water batched, water withheld, and any water added before arrival. Acceptance: identifier matches, and discharge will complete inside the ASTM C94 limit of 90 minutes from introduction of the mixing water to the cement, or 300 drum revolutions, whichever comes first, unless the specification approves otherwise. Wrong looks like a ticket pocketed unread, which is how a load batched 70 minutes out discharges at 105; stop rule, a load outside the limit or on the wrong mix is rejected before the chute swings. Hazard: this puts a person beside a turning drum and a swinging chute, so stand outside the chute arc, get the driver's eyes before stepping in, and keep hands off the chute pins while the drum turns.

5. Test the first load, and retest when anything changes. Sample per ASTM C172 from the middle of discharge, run slump per C143, air per C231 for normal weight concrete, temperature per C1064. Acceptance: slump inside the specified value and the ASTM C94 tolerance the specification carries, air inside the specified range, temperature inside the ceiling or floor the weather standards set. Wrong looks like eyeballing the load off the back of the truck, which reads over-watered as workable; stop rule, C94 allows a retest from another portion of the same sample and a second failure fails the load. Hazard: fresh concrete is caustic to skin and eyes, so waterproof gloves, sleeves and sealed eye protection go on before sampling and any contact is flushed at once per the wet concrete contact SOP.

6. Route every gallon added on site through one person. Only the crew leader authorizes water, and only where measured slump is below the specified value. Acceptance: ASTM C94 permits one site addition to bring slump up to the specified value provided the maximum specified water-cementitious ratio and maximum slump are not exceeded, requires at least 30 revolutions at mixing speed afterward, and requires the amount recorded on the ticket, so acceptance is a signed ticket line plus a re-run slump. Wrong looks like a hose opened because the crew wanted an easier load, buying workability with strength nobody wrote down; stop rule, an undocumented addition fails the load. Hazard: the drum turns at mixing speed for this, so everyone stands clear of the discharge arc and nobody reaches into the hopper.

7. Keep the front alive, and joint deliberately when it will not be. Track the interval against the placement rate and watch the leading edge. Acceptance: new concrete lands against an edge still plastic enough to respond to a vibrator or to the screed. Wrong looks like pushing a load into an edge that has set, producing a cold joint disguised as a monolithic slab that cracks along itself in the first season; stop rule, when the gap will not close, stop at the nearest planned joint line and form a construction joint with the load transfer the drawing calls for. Hazard: this is where crews hurry, so buggy runs stay clear of the screed crew, internal vibrators are lifted by the hose and never the cord, and every powered tool is on a GFCI protected circuit.

8. Wash out to a contained point, then release the driver. Direct washout to a lined pit or purpose-built container away from any inlet, ditch or waterway, agreed before the first truck. Acceptance: all wash water and solids inside the containment with freeboard left, nothing running to a storm inlet, ticket copies retained. Wrong looks like a chute rinsed at the curb; stop rule, if containment is full or absent the truck leaves with its chute unwashed. Hazard: washout slurry is strongly alkaline, commonly pH 12 to 13 for cement in water, and burns skin and eyes exactly as fresh concrete does, so the operator stands upwind of the spray in face and eye protection and waterproof gloves; the discharge itself is prohibited under the EPA construction general permit, or your state's equivalent where the state is the permitting authority.

The record this produces

One delivery log per pour, plus the original tickets. Fields: job and pour identifier, neat volume, allowance and total ordered, planned rate and interval, then per load the ticket number, mix identifier, batch time, arrival, discharge complete, yards, slump, air, temperature, any authorized water with its signed ticket line, and accept or reject with the reason.

It sits on the job record beside the pre-pour checklist. The PM reads it the day a customer reports cracking, and a load over the discharge limit or retempered without a signature shows up in one column. The estimator reads it across a season: a shop rejecting a load every fourth pour has a plant problem, not bad luck.

One pass, with a step that failed

A 46 ft by 20 ft driveway at 5 in. Step 1: neat volume is 920 sq ft at 0.4167 ft, or 383.3 cu ft, which is 14.2 cu yd. With the shop's allowance for edge forms the order went out at 15 cu yd, split 8 and 7, against a confirmed rate of about 12 cu yd per hour off the chute with two buggies, giving a 35 minute interval. Step 3 marked the discharge point at the top of the drive and put one man on the street as spotter.

Truck 1 arrived 07:05, batched 07:41 on the ticket, identifier matching. Step 5 read 5.0 in slump, 6.1 percent air, 74 F, all inside. Placement ran clean.

Truck 2 failed step 6. The ticket showed 8 gallons added at the plant gate, unsigned, with no re-run slump, and measured slump came back 6.5 in against the 5 in ordered. The crew leader ran the C94 retest from another portion of the same sample, got 6.5 in again, and rejected the load. That is the stop rule performing as written, and the argument with dispatch happened at 07:50 over two written numbers rather than in March with a customer pointing at a surface.

Rejecting mid-pour is why step 7 exists. Truck 1 carried 8.0 cu yd and the crew had placed to roughly 25 ft up the drive. The joint layout put transverse lines at 11.5, 23 and 34.5 ft with one longitudinal line at 10 ft, giving eight panels of 11.5 by 10 ft, 115 sq ft each. The nearest full line behind the leading edge was 23 ft, which is 460 sq ft, or 7.10 cu yd. The crew pulled back to that line, formed a construction joint there with the dowels the drawing called for, and put the leftover 0.9 cu yd into two pier holes already dug on the job. The replacement load arrived 09:20 and the remaining 460 sq ft took the same 7.10 cu yd, so the day used 14.2 cu yd against the 14.2 computed.

Placing that second load instead of rejecting it produces a driveway that looks identical at handover. What it produces later is a slab whose second half carries more water than the half beside it, and the customer finds the boundary as a line where one side scales and the other does not.

When the site does not match the order

The load is short: check ticket yards against the batch weights before accepting, because a short load found at the chute is a phone call and one found at the end of the pour is a cold joint. Someone tells you to take a late or wrong load: the answer is the batch time and the mix identifier, in writing, and the shop does not place material it will warrant against a specification it cannot meet. Access is blocked on arrival: hold the truck at the street with the drum turning and solve access against the discharge clock, because minutes spent arguing come out of the 90.

References

• ASTM C94/C94M, specification for ready-mixed concrete, for the 90 minute or 300 revolution discharge limit, the site water addition provision and the retest rule on slump and air.
• ASTM C172/C172M for sampling fresh concrete, C143/C143M for slump, C231/C231M for air content by the pressure method, C1064/C1064M for temperature.
• 29 CFR 1926.601(b)(4), motor vehicles, reverse signal alarm or observer where the rear view is obstructed.
• EPA construction general permit, or your state's permit where the state is the permitting authority, prohibiting discharge of concrete washout water.
• See related: the pre-pour checklist and subgrade verification SOP, the hot and cold weather pour standards, and the wet concrete skin contact SOP.