How to Order Ready-Mix Concrete
A good order is a short list of facts: how many yards, what strength, where the truck goes and when. This checklist covers what the plant will ask and what to prepare before the truck arrives.
Before you call: know your quantity
Calculate the volume, add waste and round up. For a 24 × 24 ft slab 5 in thick, the net volume is 8.89 yd³ and the order with 10% waste is 9.78 yd³. Tell the plant the volume and also what you are pouring, so that the dispatcher can suggest a mix. If you are unsure, use the slab calculator and have the Show the math panel ready to read out.
The details the plant will ask for
| Item | What to say | Notes |
|---|---|---|
| Quantity | Cubic yards, with waste | Ask for the minimum load and the step size |
| Strength | 28-day compressive strength in psi | See the PSI guide |
| Slump | The consistency you want, in inches | About 4 in is common for slabs |
| Air entrainment | Yes or no, and percentage | Needed for freeze-thaw exposure |
| Aggregate size | Maximum stone size | Often 3/4 in; smaller for pumping thin sections |
| Admixtures | Water reducer, accelerator, retarder, fiber | Ask which are included |
| Location and access | Address, gate width, surface, slope | Tell them about overhead wires and soft ground |
| Pump | Whether a pump is needed | Pumps are booked separately |
| Delivery time | Date and start time | Plan for the trucks’ spacing |
| Payment and fees | Delivery, short load, standby, washout | Get them in writing |
Strength, slump and air
Strength is the compressive strength at 28 days, in pounds per square inch. Residential flatwork is typically ordered somewhere between 3,000 and 4,500 psi depending on exposure. Where concrete is exposed to freezing and thawing, air entrainment is normally specified, and the plant will quote a mix designed for it. The guide on concrete PSI explains the common values.
Slump is a measure of how stiff or fluid the fresh concrete is. A slump of about 4 in is a common slab target. A higher slump is easier to place but results from added water or a chemical water reducer. Do not ask the driver to add water on site without understanding the effect, because every added gallon lowers the strength and durability. If you need an easier mix, ask the plant for a water reducer.
Access and site readiness
- Gate and path: a mixer truck is wide and heavy. Check clearance for the width, height and weight.
- Surface: trucks can damage driveways, septic covers and soft lawns. Lay plywood or ask about a pump.
- Slope: a steep drive can be a problem for a loaded truck.
- Chute reach: the chute reaches only a short distance, and everything beyond needs barrows or a pump.
- Space to turn around and to wash the chute.
- Overhead lines and low branches.
Timing and the clock
Ready-mix is perishable. Standard practice under ASTM C94 is to complete discharge within about 90 minutes of batching, or before the drum reaches 300 revolutions, whichever comes first. Plants usually allow a set time on site per yard, often a few minutes per cubic yard, and charge standby time beyond it. That is why all forms, base, reinforcement, tools and helpers should be ready before the first truck arrives. On hot days the available time is shorter, and in cold weather the concrete sets more slowly.
Do not order for the earliest slot if you cannot be ready. A confirmed time with a half-hour margin is more useful than a hurried morning pour.
Fees to ask about
- Delivery or fuel charge.
- Short-load fee for small orders, typically for under about 7 yd³.
- Standby or overtime charge after the allowed unloading time.
- Washout fee, which covers disposal of the leftover in the drum.
- Pump booking, hourly rate and hose length.
- Extra yardage price for a small overage.
- Weather surcharges for cold mixes.
- Taxes.
Placing the concrete
Have at least two people for a small pour and more for a larger one. Use a screed board to strike off the surface, a bull float to flatten it and a hand float and edger once the bleed water has gone. Do not work the bleed water back into the surface. Cut or tool control joints on time, and start curing as soon as the finish is set. The slab pouring guide and the curing guide cover these steps.
Leftover concrete
If you have ordered the amount you need plus a small allowance, the truck may have some concrete left. Have a plan: a small pad, stepping stones, or a prepared spot for a washout. Pouring leftover concrete on the ground or into a storm drain is usually not allowed. The plant will tell you where to put the washout, or the driver may return with it.
After the pour
- Keep the surface moist or covered with curing compound.
- Protect it from foot traffic, animals and rain for at least the first day.
- Cut joints within the recommended time.
- Keep vehicles off until the concrete has gained enough strength, usually about seven days for a car.
- Seal later, if the plan calls for it, after the concrete has cured.
Questions to ask the plant
- What is your minimum load, and the charge below it?
- How long do I have to unload before standby charges start?
- What mix do you recommend for exterior flatwork here?
- Is air entrainment included, and at what percentage?
- Can the truck wait if my crew is not ready?
- What happens if the order is cancelled or weather delays it?
- Do you offer fibers or a water-reducing admixture?
- Where should the washout be done?
A sample call
A typical order sounds like this: “I need 3 cubic yards of 4,000 psi air-entrained concrete with a 4 inch slump and three-quarter inch stone, for a patio slab, delivered Saturday morning at 8. The truck can back to within 20 feet of the forms on a paved driveway. What are your delivery and short-load charges, and how long do I have to unload?” Writing the details down beforehand makes the call shorter and avoids confusion on the day. Confirm the order by email or text so that the quantity, the mix and the price are in writing.
Frequently asked questions
What do I tell the concrete plant?
The quantity, the strength you need, the slump, whether you need air entrainment, the address and access, the delivery time, and whether a pump is needed.
How long do I have to unload a concrete truck?
The plant sets an allowed time, often a few minutes per yard, and charges standby time beyond it. ASTM C94 limits total time before discharge to about 90 minutes.
Can I add water to the truck?
Only if the plant allows it and you understand that it lowers strength and durability. Ask for a water reducer instead.
What is a short load?
An order below the plant’s minimum for free delivery, which carries an extra fee.
How much extra concrete should I order?
Five to ten percent over the calculated volume, and round up to the plant’s step size.
Do I need a pump?
If the truck can’t get within chute reach of the forms, or the pour is over a structure, yes. Book it in advance.
Sources
Estimate only. Results depend on the numbers you enter, ground conditions and your supplier. For structural work consult a licensed engineer and follow local codes. Brand names such as Quikrete and Sakrete are used only to cite published product data. This site is not affiliated with any brand.