Every concrete job starts with one decision before a single barrow is filled: where the concrete actually gets mixed. You can have it batched at a plant and delivered ready to pour, or you can mix it yourself on site from cement, aggregate and water. That single choice shapes the strength you end up with, the money you spend, and how much of your day disappears into the work. Ready mix concrete and site mix concrete both have their place, and the right one depends on the size of your pour, the standard you need to hit, and the time you have. Understanding how the two compare is the difference between a slab that lasts for decades and one that fails long before it should.
What is Ready Mix Concrete?
Ready mix concrete is batched at a plant to a set grade, then delivered to your site in a mixer lorry ready to pour. The proportions of cement, aggregate and water are measured by weight under controlled conditions, so every load meets the specified strength. Pro-Mix Concrete supplies it delivered ready-mixed or batched fresh on site by volumetric truck, made to the exact grade your job needs.
- Batched to a precise grade from C10 to C40
- Consistent strength from one load to the next
- Made to BS 8500 and BS EN 206
- Delivered to site, ready to pour on arrival
- Suited to medium and large pours
What is Site Mix Concrete?
Site mix concrete is mixed by hand or in a small drum mixer at the job site itself, using bags of cement and loose or bagged aggregate. You control the process from start to finish, which suits small repairs and jobs a plant delivery would overshoot. The trade-off is that consistency depends entirely on how carefully each batch is measured and mixed.
- Mixed on site from separate materials
- Proportions judged by the person mixing
- Strength varies from batch to batch
- Best for small pours and quick repairs
- No minimum load or delivery to arrange
Key Differences Between Ready Mix and Site Mix Concrete
Both methods produce concrete, yet they part ways across almost every part of the job, from strength and cost to safety and site space. Here is each difference in detail.
Strength and Quality Consistency
Ready mix holds its strength because a plant measures every material by weight to a set grade. The concrete you order is the concrete you get, one load to the next, with no drift across a large pour. That reliability is why structural work is specified as ready mix in the first place.
Site mix depends on hand measurement and a small mixer, which introduces variation with every batch. One barrow may land close to the mark while the next runs weak, and the person mixing rarely knows which is which.
Bottom line: for reliable, specified strength, ready mix leads clearly.
Accuracy of the Mix Proportions
Strength lives or dies by how tightly the proportions are held, especially the water-cement ratio. Each method controls that ratio very differently:
- At the plant: cement, aggregate, and water are weighed to the mix design and held to the same figures for every batch.
- On site: materials are gauged by shovel and bucket, and it is easy to add extra water for a mix that spreads more easily.
That extra splash of water quietly weakens the concrete, which is why hand-gauged proportions rarely match a batched load.
Quality Control and Standards Compliance
Ready mix arrives with a paper trail. Each delivery carries a batching ticket stating the grade, the mix and its conformity to BS 8500 and BS EN 206, and a designed mix can be checked with test cubes at 28 days. For structural work signed off by building control, that documentation is often the proof the concrete met its specification.
Site mix carries no such record. Nobody can state afterwards what strength the concrete mix reached, because nothing was weighed or tested. For a non-structural repair that hardly matters, while for a foundation it can matter a great deal.
Worth Knowing:
A batching ticket is your evidence the mix met its grade. Hand-mixed concrete leaves you with nothing to show an inspector.
Speed and Labour on Site
The mixing method decides how much of the working day goes into labour rather than pouring. The contrast sharpens as the volume grows:
- Ready mix arrives mixed, and your crew pours straight from the lorry
- Site mix turns batching into hours of measuring, loading and mixing
- A small repair barely notices the difference
- A driveway or foundation feels every extra barrow
The larger the pour, the more time ready mix hands back to you.
Handling Large Pours Without Cold Joints
Volume is where the two methods separate most sharply. A single delivery brings several cubic metres of concrete ready to place in one continuous pour, which keeps the whole slab working as one piece.
Hand-mixing a large pour batch by batch creates a hidden risk. Each batch can begin setting before the next is ready, and that leaves cold joints where two batches met but never fully bonded. The Concrete Society notes that a cold joint forms when fresh concrete is placed against a layer that has already stiffened, leaving a weakened plane through the pour. For a foundation or a sizeable slab, those joints undermine the very strength the pour depends on.
Cost for the Size of the Job
Site mix looks cheaper on a small job, because you buy only a few bags and skip any delivery. That maths flips as the volume climbs. Buying, hauling and mixing bag after bag becomes slower and dearer than a single batched load, and the break-even point sits around the volume where hand mixing stops being practical.
Take a driveway needing two cubic metres. Mixing that by hand means dozens of bags and most of a day, while a delivered load pours in a fraction of the time at a comparable material cost.
If your job sits near that line, send us the dimensions of the pour, and we will tell you whether a delivered load works out cheaper than bagging it, and which grade to use.
Site Space Materials and Equipment
Site mixing needs room and kit before any concrete gets made. Ready mix needs little more than access for the lorry. This is what each method asks of your site:
| Requirement | Ready Mix | Site Mix |
| Mixer | Not needed | Drum mixer or mixing board |
| Material storage | None | Space for cement and aggregate |
| Keeping cement dry | Not your concern | Essential, or it spoils |
| Site access | Room for the delivery lorry | Space to mix and stockpile |
| Water supply | Not needed on site | Needed for every batch |
Ordering Accuracy and Waste
Matching the amount of concrete to the job is far easier when it is batched to order. Ready mix is supplied to the volume you need, which limits both leftover material and the shortfall of running out mid-pour. Site mixing leaves you estimating bags, and a wrong guess cuts one of two ways:
- Over-order, and unused bags or mixed concrete go to waste
- Under-order, and the job stops for a second trip to the merchant
For anything beyond a small patch, ordering the exact volume beats guessing at it.
Health and Safety on Site
DIY site mixing puts the physical work and the hazards on you. Wet cement is corrosive, and the HSE warns it can cause serious burns, ulcers and dermatitis when it stays in contact with skin. Mixing by hand means gloves, covered arms and clean-up every time, plus the manual-handling strain of lifting 25kg cement bags and shovelling aggregate through a large pour.
Taking delivery removes most of that. The concrete arrives mixed, and your crew places it rather than spending the day lifting bags and breathing cement dust.
Handle Cement Safely:
Wet cement burns skin on contact. Anyone mixing by hand needs waterproof gloves and covered arms throughout.
Placement and Access Options
Ready mix reaches places a barrow struggles to. A load can be pumped through a line or boom pump to a back garden, a basement, or an upper floor, which keeps a difficult pour moving. Site mixing relies on barrowing every load by hand from the mixing spot to the formwork, which limits how far and how high the concrete can practically go.
Suitability by Project Type
The safest way to choose is to match the method to what the concrete has to carry.
Small Jobs That Suit Site Mix
Fence-post footings, a single paving slab and minor repairs all suit site mixing. The volume is tiny, the strength demand is modest, and a delivery would be more than the task warrants.
Structural Jobs That Need Ready Mix
Foundations, driveways, structural slabs and any pour to a specified grade call for ready mix, where consistent strength is not optional. For work that has to meet a grade, let us batch it for you, delivered ready-mixed or mixed fresh on site by volumetric truck, so the strength is certain before the concrete ever reaches the formwork.
Ready Mix vs Site Mix at a Glance
| Factor | Ready Mix | Site Mix |
| Strength consistency | Uniform, batched to grade | Varies batch to batch |
| Mix accuracy | Weighed at the plant | Gauged by hand |
| Standards and proof | BS 8500 ticket, testable | No record |
| Speed on site | Pour on arrival | Hours of mixing |
| Large pours | Continuous, no cold joints | Cold-joint risk |
| Cost sweet spot | Medium and large jobs | Small jobs only |
| Site space needed | Lorry access | Mixer, storage, water |
| Waste | Batched to volume | Over or under-ordering |
| Safety | Handled for you | Cement and lifting risk |
| Access | Can be pumped | Barrowed by hand |
Which One Wins?
For most jobs beyond a small repair, ready mix concrete is the clear winner. It delivers consistent, specified strength, cuts the labour and time of mixing by hand, matches the volume to your pour with far less waste, and comes with the documentation structural work needs.
Site mix keeps its place for the smallest tasks, a post footing or a minor patch, where the strength demand is low, and a delivery would be overkill. The deciding questions stay simple: how much concrete you need, and whether the pour has to meet a set grade. Once the volume climbs or the strength matters, ready mix is the better choice on every measure that counts.
Final Thoughts
Ready mix and site mix are not rivals so much as tools for different sizes of job. A handful of bags and a drum mixer will see you through a small repair, while anything structural or sizeable belongs in a batched, delivered load made to the right grade. Getting that call right protects both your budget and the finished result.
Pro-Mix Concrete supplies concrete across London and the surrounding areas, delivered ready-mixed or batched fresh on site by volumetric truck, every load made to the grade your project needs. Work out how much you need with our free online concrete calculator, then call the Pro-Mix Concrete team on 0800 772 3808, and we will get the right mix to your site.
- Dennis Broderick is the founder and owner of Pro-Mix Concrete Company, a trusted name in ready-mix concrete solutions across the UK. With over 20 years of hands-on experience in the construction and concrete industry, Dennis brings unmatched expertise, practical insights, and a commitment to quality on every project - from residential driveways to large-scale commercial developments.
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