How many yards does a concrete truck hold?

The standard mixer carries 10 cubic yards; depending on the market and the truck, 8- and 12-yard loads exist. Plan around 10 unless your plant tells you otherwise — and remember weight limits can cap a legal load below the drum’s capacity on some routes.

How far apart should ready-mix trucks be spaced?

The usual spacing is 30–45 minutes, which lands roughly 13–20 yards an hour on your site. But the real answer is: at your placement rate. A chute-fed crew and a boom pump are different animals — match the rotation to how fast you can actually place and finish, and call dispatch to speed up or slow down as soon as you can see the drift, not after trucks are stacked at the curb.

What is a short-load fee?

A surcharge for orders below the plant’s economical load — commonly applied under 4 yards, often in the $50–100 range, and it varies by market. It’s why running one yard short mid-pour is expensive twice: you pay the fee, and the pour waits on the truck.

How much extra concrete should you order?

Round up — modestly on flatwork, firmly on structural pours. The waste on an extra half-yard is real but small; running short on a wall or a slab that can’t wait invites a cold joint, an emergency short load, and forty-five minutes of a full crew standing still. Order the last truck as an "on will-call" load if the plant offers it, and confirm your take-off against the formwork before you call.

How long can concrete stay in the truck?

The working rule from ASTM C94 is discharge within 90 minutes or 300 drum revolutions from batching, whichever comes first — adjustable by agreement and with admixtures, and practically shorter on a hot day. The spacing you order is what protects that clock: a truck that waits an hour in line spends its working time idling.

Ordering Ready-Mix: Truck Loads, Spacing & the Clock

The order you phone into the plant is not a shopping list — it’s the pour plan, stated in trucks and minutes. Dispatch will execute exactly the rate you asked for, whether or not it matches what your crew can place, and every mismatch shows up on your site as either a line of trucks burning their clock at the curb or a crew standing on finished edges waiting for mud. Here’s the math worth getting right before you dial.

The units the plant thinks in

A standard mixer holds 10 cubic yards — some markets run 8s, a few run 12s, and road weight limits can cap a legal load below drum capacity. Under a full load you’re into short-load territory: plants commonly add a fee below about 4 yards, often in the $50–100 range, because a two-yard delivery costs them the same truck and driver as a ten. The ordering consequences are simple: think in full trucks where you can, put the odd yardage on the last load, and ask for that last truck on will-call so you can size it against what the forms actually took.

And round up — modestly on flatwork, firmly on anything structural. The half-yard you send back costs a disposal line on the invoice. The half-yard you’re missing costs a short-load fee, a forty-five-minute wait with a full crew standing, and — if the placed concrete takes its initial set while you wait — a cold joint in a wall that will outlive everyone on the pour.

Spacing: the order rate is the pour plan

Trucks spaced the usual 30–45 minutes apart deliver 13–20 yards an hour. That’s the number to hold up against your placement rate — a chute-fed flatwork crew and a boom pump running 70–90 yards an hour need completely different rotations. Order faster than you can place and the queue at the curb spends its 90-minute clock idling; order slower than the pump and the placement stalls between loads, which is how a cold joint happens with everyone doing their job. Two habits keep the rotation honest: time the first truck to when the crew and pump are actually ready to take it — not to when people are scheduled to arrive — and call dispatch to stretch or tighten the spacing the moment you can see the drift. Plants adjust rotation all day; they just can’t un-batch the truck that already left.

The clock on every load

Every drum is on the ASTM C94 clock from the moment water hits cement: discharge within 90 minutes or 300 revolutions, whichever comes first. It’s adjustable by agreement, retarders stretch it, and a 95°F afternoon shrinks the practical window no matter what the ticket says. The full story — and what the deadline means for cold joints — is in the 90-minute-window guide; the ordering takeaway is one line: the spacing you ask for is the mechanism that protects the clock.

What to have ready when you call dispatch

Yards, rounded with intent, with the last load flexible or on will-call
Mix and PSI per the spec — plus admixtures: a non-chloride accelerator for cold-weather pours, retarder for hot ones, and say if it’s a pump mix
Slump the spec allows
First-truck time and spacing — your placement rate, stated in minutes between trucks
Site contact and phone — the person at the pour, not the office
Access and washout — where trucks stage, turn, and rinse

When the pour moves, dispatch is call number one

Every number above lives on a schedule somewhere. The failure mode isn’t getting them wrong — it’s a pour that moves after you’ve ordered, and a plant that never hears. A gate time slips, weather flips overnight, and the rotation you carefully built starts rolling toward a site that isn’t pouring; the group text reliably reaches the crew and reliably misses the dispatcher. That’s the coordination gap the Place & Finish pour board exists to close: the plant and its order number ride on the pour card, and when the pour is confirmed, moved, or canceled, one click notifies the plant, the pump, the GC, and the crew — old date and new. The truck math is yours; making sure everyone’s doing the same math is what the board is for.

Order like the schedule depends on it

Because it does: the rotation you phone in is the skeleton of the pour day. Get the loads, the spacing, and the clock right — then keep every vendor on the same version of the plan when it moves. Planning Ops is built for concrete subs, veteran-owned, with a 14-day free trial and your whole crew riding free as viewers. Put the Plant on the Pour Card →

Ordering ready mix: the truck math, the spacing, and the clock