Preparing Your Site for a Ready-Mix Pour — The Complete Checklist

The ready-mix truck doesn’t care if you’re ready. It shows up at the scheduled time, the drum is turning, and you’ve got roughly 90 minutes before that concrete starts setting up. Every minute you spend scrambling on site — moving materials, repositioning forms, clearing access — is a minute of workability you’re burning.

The difference between a clean pour and a disaster is almost always what happened the day before the truck arrived. Here’s the full site prep checklist we give to contractors ordering ready-mix from our three GTA locations.

48 Hours Before the Pour

Confirm Your Order Details

Call your ready-mix supplier and confirm:

Volume. Double-check your cubic metre calculation. The formula is simple — length × width × depth in metres — but the number of contractors who under-order is staggering. Always add 5–10% for waste, over-excavation, and uneven subgrade. On a 20 m³ pour, that’s 1–2 extra cubic metres. Cheaper than a short-load callback.
Mix design. Confirm the MPA (megapascal) strength, slump, aggregate size, and any admixtures. For standard residential slabs in Ontario, 25 MPa with a 100mm slump and 20mm aggregate is typical. For structural foundations, you’re likely looking at 30–35 MPa. Don’t guess — check the engineer’s spec.
Delivery time. Schedule the first truck for when your crew is ready, not when the plant opens. If your finishers start at 7 AM and the pour site needs 30 minutes of final prep, don’t book the truck for 7. Book it for 7:30.
Number of trucks. For large pours, you’ll need multiple trucks staged so one arrives as the previous one finishes. Your supplier should help coordinate the spacing. In GTA traffic, allow extra buffer — a truck coming from Mississauga to a Brampton site during morning rush could take 40 minutes for a 15-minute drive.

Check the Weather

Ontario weather is unpredictable, but concrete doesn’t care about your schedule. Check the forecast for:

Rain. Light drizzle after the pour is manageable with tarps. Heavy rain during the pour is a disaster — it dilutes the surface water-cement ratio and destroys your finish. If Environment Canada is calling for heavy rain, reschedule. The cost of rescheduling is always less than the cost of a ruined pour.
Temperature. Below 5°C, concrete sets dramatically slower and is vulnerable to frost damage. Above 30°C, it sets too fast and can crack from rapid moisture loss. Both extremes require admixtures and special procedures. If you’re pouring in November or July in the GTA, talk to your supplier about cold-weather or hot-weather mix adjustments.
Wind. Strong winds accelerate surface evaporation, causing plastic shrinkage cracking — especially on slabs. If wind is forecast above 25 km/h, have windbreaks or evaporation retarder on site.

24 Hours Before the Pour

Subgrade and Base

This is where most pour failures start — not with the concrete, but with what’s under it.

Compact the subgrade. Use a plate compactor or roller to achieve uniform density. Soft spots in the subgrade will cause differential settlement and slab cracking later. On clay soils common across the GTA — particularly in Brampton and north Mississauga — compaction is critical because clay expands and contracts with moisture.
Granular base. For slabs on grade, a 100–150mm layer of compacted granular A or B is standard in Ontario. This provides drainage and a uniform bearing surface. Spread it evenly and compact in lifts if the layer is thick.
Grade to elevation. Check your subgrade elevation against the design. If the subgrade is 25mm too high, your slab is 25mm too thin — and that’s a structural problem. Use string lines or a laser level to verify.
Moisture. Dampen the subgrade the evening before the pour. Dry subgrade sucks water out of the concrete too fast, weakening the bottom of the slab. But don’t flood it — standing water is just as bad. You want damp, not wet.

Formwork

Walk every linear metre of your forms the day before. Check:

Alignment. Are the forms straight and at the correct elevation? Sight down the top edge. A bowed form will give you a bowed slab edge.
Bracing. Every form stake should be secure. The lateral pressure from wet concrete is significant — a 150mm slab exerts roughly 3.6 kN/m² of hydrostatic pressure. If your stakes are loose or spaced too far apart, the forms will blow out during the pour, and cleaning up a blowout mid-pour is a nightmare.
Joints. Are your expansion joints and control joints in the right locations? For slabs, control joints should be spaced at a maximum of 24–30 times the slab thickness. A 125mm slab gets joints every 3–3.75 metres. Mark them now, not while the truck is waiting.
Form oil or release agent. Apply it to all forms. This does two things: prevents the concrete from bonding to the forms, and makes stripping easier without damaging the slab edge. Don’t use motor oil — it stains the concrete. Use a proper form release agent.

Reinforcement

Rebar placement. Rebar should be tied at every intersection and supported on chairs at the correct cover depth. In Ontario, minimum concrete cover for exterior slabs is 40mm. For foundations, it’s typically 75mm against earth. Check the structural drawings — don’t assume.
Chair spacing. Rebar chairs (or bolsters) should be spaced every 600–900mm to prevent the rebar from sagging to the bottom of the form. If the rebar is sitting on the subgrade when the concrete arrives, it’s doing nothing structural. It needs to be in the tension zone of the slab — typically the bottom third for slabs on grade.
Mesh placement. If you’re using welded wire mesh instead of rebar, the same rules apply — it needs to be on chairs, not on the ground. Some crews place mesh and then pull it up during the pour with hooks. This works on small pours but is unreliable on large slabs. Chair it properly.
Inspection. If the municipality or engineer requires a rebar inspection before the pour, schedule it for the afternoon before pour day. Don’t gamble on getting a same-morning inspection — if the inspector is delayed, your truck is waiting on the clock.

Morning of the Pour

Access

Truck access route. A loaded concrete truck weighs 30,000–40,000 kg. That’s heavier than anything else on your site. Ensure the access route can support it — no soft ground, no underground utilities at risk of collapse, no overhead wires in the way of the chute or boom.
Chute reach. A standard truck chute extends about 3–4 metres from the back of the truck. If your pour area is farther than that, you need either a concrete pump, a concrete buggy, or a way to get the truck closer. Figure this out before the truck arrives, not after.
Turnaround space. The truck needs to get in and out. If it’s a tight residential site in Mississauga or a narrow lot in Pickering, measure the access. A standard mixer truck is about 10 metres long and needs room to manoeuvre. If access is tight, tell your supplier in advance — they may send a smaller truck.

Tools and Materials on Site

Before the first truck arrives, have the following ready and within reach:

Vibrator — to consolidate the concrete and remove air pockets, especially around rebar and in forms
Screed (straight edge or power screed) — to strike off the concrete to the correct elevation
Bull float or mag float — for initial smoothing after screeding
Hand floats and trowels — for finishing edges and doing final surface work
Edging tools — for radiused edges along forms
Concrete rake — for spreading mud in the forms before screeding
Water hose — to clean tools, dampen subgrade, and wash down the truck chute after the pour
Wheelbarrow or concrete buggy — for moving concrete to areas the chute can’t reach
Curing compound or plastic sheeting — to apply after finishing to retain moisture
Rubber boots — your crew will be standing in wet concrete. Regular work boots won’t cut it.

Crew Briefing

Walk your crew through the pour before the truck arrives:

Who is on the chute? This person directs the driver and controls where the concrete goes.
Who is screeding? They follow directly behind the placement.
Who is floating? They follow the screed.
Who is handling the vibrator? Critical for walls and foundations. Less critical for slabs, but still needed.
What’s the pour sequence? Start from the far end and work toward the truck access point. Don’t box yourself in.

A five-minute huddle before the truck arrives prevents confusion during the pour when communication is hard over the noise.

During the Pour

Truck Arrival

Check the delivery ticket against your order. Verify the mix design, volume, and slump. If something doesn’t match, call your supplier immediately — before the concrete goes in the forms.
Ask the driver for a slump reading. If you ordered 100mm slump and it’s coming out at 60mm, the concrete will be too stiff to work. If it’s 150mm, it’s too wet and will be weaker. Don’t accept a load that’s out of spec.
Never add water to the truck without talking to your supplier. Adding water on site increases slump but reduces strength. If the mix is too stiff, the plant should adjust the next load — not dump water into the drum.

Placement

Pour in continuous sections. Don’t leave a section half-done while the truck repositions — cold joints (where hardened concrete meets fresh concrete) are weak points.
Consolidate with the vibrator as you go, especially against forms and around reinforcement. Under-vibration leaves voids. Over-vibration causes segregation (the aggregate sinks, the paste rises). Three to five seconds per insertion point is usually right.
Screed to elevation immediately after placement. Don’t let concrete sit unscreeded — it starts stiffening and becomes harder to work.

After the Pour

Curing

This is where most slabs fail. Concrete doesn’t just “dry” — it cures through a chemical reaction that requires moisture. If the surface dries out too fast, you get:

Plastic shrinkage cracks (within the first few hours)
Weak surface layer (dusting and scaling later)
Reduced overall strength

Apply curing compound immediately after finishing, or cover with plastic sheeting weighted down at the edges. In the GTA, summer pours are especially vulnerable — 30°C with wind can dry the surface in minutes.

Cure for a minimum of 7 days. Don’t let anyone drive on a residential slab for at least 7 days — 28 days for full strength.

Cleanup

Wash all tools immediately. Concrete on a trowel is easy to clean fresh — impossible once it sets.
Wash the truck chute area. The driver will want a wash-down spot. Designate one away from storm drains — concrete washout is alkaline and regulated in Ontario.
Strip forms after 24–48 hours for slabs (longer for walls and foundations, depending on temperature).

Common Mistakes on GTA Job Sites

Under-ordering. We see this constantly. A contractor calculates 10 m³ and orders exactly 10 m³. The subgrade had a dip, the forms were slightly wider than planned, and now they’re 1.5 m³ short with a partially poured slab. Always add 5–10%.
No access planning. A 40-tonne truck can’t drive across your freshly graded lawn. Figure out access before the truck is idling at the curb.
Skipping the slump check. Five seconds with a slump cone can catch a bad load before it’s in your forms.
Forgetting about cure. The pour is done, the crew leaves, the surface dries out in the afternoon sun. Three days later, you’ve got surface cracks. Curing isn’t optional.
Pouring in the wrong weather. Ontario spring weather is deceptive — a sunny morning can turn into a rainy afternoon. Check the hourly forecast, not just the daily summary.

Get Your Ready-Mix from 2AZ Group

We deliver ready-mix across the GTA from our three locations:

Mississauga HQ — 3330 Ridgeway Dr, Unit 7, Mississauga, ON L5L 5Z9
Brampton Yard — 2084 Steeles Ave E, Unit 1, Brampton, ON L6T 4Z9
Pickering Depot — 1020 Brock Rd, Unit 5, Pickering, ON L1W 3M1

Call 647-926-2597 or email [email protected] to place your order. We’ll help you calculate volume, choose the right mix design, and schedule delivery so the truck arrives when you’re ready — not before.