Whether you’re pouring a driveway, a path or a simple base, getting a good result comes down to following the right process in the right order. Here’s what to think about at each stage, from working out how much concrete you need through to curing the finished slab.
## 1. How much concrete do you need?
Before you order, work out the approximate volume required:
**Length (m) × Width (m) × Depth (m) = Volume (m³)**
Make sure every measurement is converted into metres before you multiply — it’s easy to mix up millimetres and metres when working from a depth figure like 100mm. Real sites are rarely perfectly flat or square, so it’s sensible to allow a bit extra — typically 5–10% — to cover variations in level and ground conditions rather than risk running short mid-pour.
## 2. Preparing the ground
However good the concrete, it’s only as strong as what’s underneath it. Mark out and excavate the area to the required depth, leaving enough room for both the sub-base and the concrete itself, and strip out any vegetation, topsoil or unstable ground.
A suitable sub-base material, properly compacted, gives the concrete a firm, level and stable foundation — this layer does a lot of structural work that isn’t visible once the job is finished. Where a damp-proof membrane is needed (for example, on slabs forming part of a building), lay polythene sheeting over the prepared sub-base, overlapping and sealing joints and turning the membrane up at the edges where appropriate.
## 3. Installing the formwork
Formwork holds your slab to the shape, size and level you want. Install timber formwork around the perimeter and secure it firmly — any movement during placing and compaction can throw off the finished job.
Check levels properly once the formwork is in place, and build in a fall at this stage if the area needs one for surface drainage.
## 4. Placing and compacting
Place the concrete evenly, making sure it reaches every edge and corner rather than dumping it in one spot and dragging it around. Excessive movement or rehandling can cause the mix to separate and weaken the finish.
Compact the concrete — typically with a tamping beam worked steadily across the surface — to drive out entrapped air and bring the material to the required level. Top up any low spots and repeat until the surface is consistent, then strike off to the finished level using the formwork as your guide.
## 5. Finishing the surface
The right finish depends on how the area will be used:
– **Tamped finish** – textured and low-slip, a common choice for driveways and paths.
– **Floated finish** – smoother and more level, though more slip-prone when wet.
– **Brushed finish** – fine texture lines for improved grip, similar in purpose to a tamped finish.
Whichever you choose, avoid overworking the surface or adding extra water during finishing — both can weaken the top layer and lead to dusting or crazing later.
## 6. Curing
Curing is what allows the concrete to reach its full strength, and it should begin as soon as practicable after finishing. Covering the concrete with polythene sheeting, secured at the edges, is a simple and effective way to prevent rapid moisture loss. Give the concrete time to develop sufficient strength before trafficking or loading it — loading too early is one of the most common causes of early-life damage.
## A few extra factors worth knowing about
Fibre reinforcement, jointing on larger areas, and the effect of hot, cold or windy weather can all influence how a pour turns out. We’ll be covering each of these in more detail in upcoming posts — keep an eye out for our guides on **expansion joints**, **fibres**, and **concreting in hot and cold weather**.
If you’d like advice tailored to your project, get in touch with the Welton Aggregates team when you place your ready-mix order.
Concrete moves. As it cures and as temperatures change, every slab expands, contracts and shrinks slightly — and if that movement isn’t planned for, it shows up as random, uncontrolled cracking. Joints are how you take that risk out of the equation.
## Two types of joint, two different jobs
**Expansion / isolation joints** separate a concrete slab from adjoining structures or fixed features — a wall, a column, a manhole — so that movement in the slab doesn’t transfer stress into whatever it’s butted up against.
**Control / contraction joints** work differently. Rather than separating the slab from something else, they create a deliberate weakened line within the concrete itself, giving shrinkage cracking a planned place to happen rather than letting it occur wherever the slab happens to be weakest.
## Where joints are typically needed
As a general guide, joints are worth considering:
– In slabs larger than around 6 m²
– Between separate concrete pours
– Where concrete meets walls, columns or other structures
– Around fixed features such as manholes or service penetrations
– Wherever a change in slab shape or dimensions could concentrate stress
For larger or more complex slabs, joint layout isn’t something to work out on the day — it should form part of the structural design from the outset.
## Installing expansion / isolation joints
These are formed before the pour, by installing a suitable compressible joint material along the full length of the required joint. It needs to stay securely in position while the concrete is placed around it, so that it does its job of keeping the slab properly separated from the adjoining structure or feature.
## Installing control / contraction joints
Control joints are usually formed by saw cutting the concrete once it has hardened. A few rules of thumb are worth knowing:
– **Depth** – cuts should be at least a quarter of the slab thickness. On a 100mm slab, that’s a minimum of 25mm.
– **Spacing** – a useful guide is roughly 30 × the slab thickness. On a 100mm slab, that works out at approximately 3m between joints.
– **Timing** – cuts should be made as soon as the concrete has hardened enough to avoid surface damage, generally within 12 hours of finishing. Leave it too long and you risk the slab cracking before the cut is made.
## Getting the layout right
Where possible, aim to divide the slab into roughly square sections — an aspect ratio close to 1:1 is ideal, and it’s worth avoiding anything beyond about 1.5:1. A 5m × 5m section, for example, sits at 1:1; a 2m × 3m section is already at 1.5:1. Where it helps the finished look, joints can also be positioned beneath walls or other features to keep them less visible.
For larger or more complex slabs needing multiple joints, this layout should be worked out by a structural engineer rather than estimated on site.
Getting joint layout right at the design stage is one of the simplest ways to avoid unsightly, uncontrolled cracking later on. If you’d like advice on joint spacing for your project, speak to the Welton Aggregates team when you place your order.
Fibre reinforced concrete isn’t a single product — it’s a way of modifying how ordinary concrete behaves by mixing discrete fibres through it. Depending on the fibre type and dosage used, this can improve crack control, toughness, and how the concrete performs after cracking has occurred.
## Where it’s typically used
Fibre reinforcement suits a wide range of applications, including:
– Concrete requiring enhanced crack control
– Industrial floors and slabs
– Precast concrete elements
– Screeds and toppings
– Sprayed concrete
– Structural slabs and foundations
## What fibres actually add
The benefits depend on the fibre system chosen, but generally include:
– **Crack control** – helping to manage how and where cracking forms
– **Distributed reinforcement** – fibres are spread evenly throughout the mix rather than positioned at fixed points, unlike traditional steel reinforcement
– **Improved toughness** – better ability to absorb energy and resist damage
– **Post-crack performance** – structural fibres can keep contributing to the concrete’s performance even after cracking has begun
## The main fibre types
– **Micro-synthetic fibres** – mainly used to help control plastic shrinkage cracking in the early stages of curing
– **Macro-synthetic fibres** – used where enhanced toughness and post-crack performance are needed
– **Metallic fibres** – used where higher levels of toughness and structural post-crack performance are required
Each type behaves differently, so the right choice comes down to what the concrete needs to do once it’s in place.
## Getting the mix design right
Fibre type and dosage should always follow the specified design and the fibre supplier’s recommendations — this isn’t something to estimate on site. A few other factors matter too: fibre additions can mean an increased fine aggregate content is needed to maintain cohesion and workability, apparent workability can drop as dosage increases, and entrapped air content can rise, which needs to be accounted for when assessing strength.
Where structural fibres are specified, the fibre system and dosage are normally developed and trialled with the fibre supplier to achieve the required performance, with distribution tested to confirm it’s been achieved.
## Batching and placement
Consistent batching and thorough mixing matter more with fibre reinforced concrete than standard mixes, as poor dispersion can lead to balling or clumping. Structural fibres in particular can affect pumping and finishing characteristics at higher dosages, so it’s worth thinking through the placement method as part of the mix development — and being aware that fibres can become visible at the finished surface, which may need managing during finishing.
Fibre reinforcement can be a genuinely useful addition depending on what your slab needs to do, but getting the specification right matters. If you’re considering fibre reinforced concrete for your project, speak to the Welton Aggregates team about the right fibre type and dosage for your application.
Warm weather might seem like the ideal time to pour concrete, but heat actually works against you in several ways. It speeds up moisture loss and cement hydration in fresh concrete, which shortens the working window and raises the risk of defects if the pour isn’t managed with that in mind.
## How hot weather affects fresh concrete
**Consistence** – Concrete can lose workability more quickly in hot conditions. It’s tempting to add water to loosen it back up, but doing so increases the water/cement ratio, which can reduce the concrete’s eventual strength and durability.
**Setting time** – Higher temperatures speed up hydration, which means setting time is reduced. In practice, that’s less time available for placing, compacting and finishing than you’d have on a cooler day.
**Surface finish** – Rapid surface moisture loss can make concrete look ready for finishing before bleeding has actually finished underneath. Finishing too early traps that bleed water beneath the surface, increasing the risk of delamination or flaking later on.
**Plastic shrinkage cracking** – High temperatures, low humidity and air movement all increase surface moisture loss, which raises the risk of plastic shrinkage cracking appearing while the concrete is still fresh.
**Thermal cracking** – Heat generated by hydration can raise the internal temperature of the concrete. When this is followed by cooling — a hot day into a cooler night, for example — the resulting temperature difference can increase the risk of cracking.
## Minimising the effects
**Admixtures** can help manage consistence and setting time in hot weather. Depending on conditions, this might mean adjusting plasticiser dosage where extra retardation is needed, using admixture combinations to improve consistence retention, or using a superplasticiser to reduce water demand and, in turn, the heat generated by hydration. Any change to admixture type or dosage should be properly assessed before use rather than adjusted on the fly.
**Aggregates** can lose moisture significantly in hot, dry conditions, which increases the risk of them absorbing water back out of the mix. Monitoring aggregate moisture and applying corrections is worth doing closely in these conditions — and where moisture drops very low, particularly with absorptive aggregates like limestone, pre-wetting or spraying can help.
**Cement type** matters too. CEM I tends to hydrate faster and generate more early heat, which further eats into the time available for placing and finishing in hot weather. Cement combinations that include additions such as GGBS or PFA can offer a slower rate of hydration and reduced heat development, which may suit hot-weather pours better.
**Planning** is often the simplest lever available. Hot weather increases the risk of concrete setting before the next load is placed, which can result in cold joints. Planning production, delivery and placement to minimise gaps between loads helps avoid this — and where it’s practical, placing concrete during cooler parts of the day, such as early morning or late afternoon, gives you a longer working window. It’s also worth having curing arrangements ready in advance, so the concrete can be protected from rapid moisture loss the moment finishing is complete.
Hot weather doesn’t rule out a good pour — it just means a bit more planning around timing, mix design and curing. If you’re planning a pour during warmer weather, talk to the Welton Aggregates team about mix options and scheduling to help things go smoothly.
Where hot weather causes concrete to dry and set too quickly, cold weather has the opposite problem — it slows hydration and strength development right down. The real risk, though, is frost: if early-age concrete is allowed to freeze, the water within it can freeze and expand, causing damage that can’t be undone.
## Two temperatures to keep an eye on
When concreting in cold weather, it’s worth tracking both the ambient air temperature and the temperature of the concrete itself — they don’t always tell you the same story, and both affect how the pour needs to be managed.
## The strength threshold that matters
As a general guide, concrete needs protecting from freezing until it’s developed a strength of around 2 N/mm². For most mixes, that’s achievable within the first 48 hours, provided the concrete temperature is kept at or above 5°C throughout. Even once that threshold is passed, cold conditions keep slowing strength development, so it’s worth building in extra time before loading the concrete or striking formwork rather than working to a standard schedule.
## Three levels of cold weather, three levels of precaution
**Ambient temperature below 5°C, no frost** – There’s generally no frost risk here, but hydration and strength development will still be slower than usual. Allow extra time before loading or removing formwork, and if faster early-age strength is important for your schedule, it’s worth reviewing the mix specification — including cement content and cement combination — to suit the conditions.
**Slight frost at night** – This is where active protection becomes necessary. Freshly placed concrete needs to be kept above freezing, which means the concrete should be at least 5°C at the point of delivery, with protection in place immediately after placing. Useful precautions include:
– Frost blankets or other insulating covers
– Insulated formwork — timber formwork itself provides some insulation
– Temporary enclosures and heating, where appropriate
– Protecting exposed surfaces as soon as finishing is complete
It’s also worth checking before you place that the sub-base, formwork, reinforcement and any equipment coming into contact with the concrete are free of frost, ice and snow — placing onto a frozen surface undermines all the other precautions.
**Severe frost, day and night** – Persistent severe frost calls for more robust measures to keep the concrete at a suitable temperature throughout placing and protection. If the concrete temperature can’t realistically be held at or above 5°C, or adequate protection genuinely can’t be provided after placement, the sensible option is to delay the pour until conditions improve rather than risk frost damage to a slab you can’t put right afterwards.
Cold weather doesn’t have to stop a pour, but it does call for a bit more planning around timing, mix choice and protection. If you’re weighing up a winter pour, talk to the Welton Aggregates team about mix options suited to the conditions.
Curing and drying get lumped together fairly often, but they’re two distinct stages in a concrete slab’s life — and confusing the two can lead to problems, particularly if a floor finish or coating goes down before the concrete is actually ready for it.
## What’s the difference?
**Curing** is the process of maintaining suitable moisture and temperature conditions so that cement hydration can continue and strength can develop. **Drying**, by contrast, is what happens afterwards — the gradual loss of moisture from hardened concrete as it comes into equilibrium with the surrounding environment. Curing is about giving the concrete what it needs to gain strength; drying is about the concrete losing what it no longer needs. Get the order confused and you risk drying a slab out before it’s actually cured.
## Why curing matters
Cement needs both moisture and suitable temperatures to keep hydrating. If concrete loses moisture too quickly, hydration is restricted and the hardened concrete simply doesn’t perform as well as it should. Effective curing helps to:
– Promote strength development
– Improve durability
– Reduce the risk of surface cracking and dusting
– Improve surface hardness and abrasion resistance
– Reduce rapid moisture loss from the concrete
Curing should start as soon as practicable after placing and finishing, and continue for a period that suits the concrete, the application, and the conditions on site — there’s no single fixed duration that fits every job.
## Common curing methods
**Water curing** keeps the surface continuously moist through spraying, ponding or wet coverings.
**Curing membranes** are a suitable compound applied to the surface to form a film that reduces moisture loss — these should always be applied in line with the manufacturer’s instructions.
**Polythene sheeting** covers the concrete to retain moisture, with sheets overlapped and secured to minimise evaporation.
Whichever method you choose, the goal is the same: stop moisture escaping too soon, so hydration can carry on properly.
## What happens during drying
Once curing is complete, drying is the slower process of excess moisture working its way to the surface and evaporating. Unlike curing, there’s no fixed timeframe after which concrete can be considered fully dry — it depends on factors like concrete thickness, water content and mix design, cement type, ambient temperature, relative humidity, ventilation, and whether one or both surfaces are exposed. Thicker slabs and cool or humid conditions generally mean longer drying times.
## You can’t judge dryness by eye
This is worth taking seriously if a moisture-sensitive finish is going down. Appearance alone is not a reliable guide — concrete can retain significant moisture even when the surface looks completely dry, while dark patches or visible condensation may simply indicate drying is still in progress. Where the moisture condition genuinely matters, proper testing is the only reliable approach:
– **Moisture meters** – useful for comparative or preliminary checks
– **Relative humidity testing** – assesses moisture conditions within or at the surface
– **Plastic sheet test** – taping a roughly 450mm × 450mm sheet of polythene to the surface for at least 16 hours; condensation or darkening suggests moisture is still moving, though this is only an indicative check
Where a moisture-sensitive finish is specified, always follow the specified test method and acceptance criteria rather than relying on a general check.
## Helping concrete dry properly
Once the required curing period is done, drying can be encouraged by providing the right conditions: adequate ventilation and air movement, suitable ambient temperatures, and avoiding unnecessary additional moisture. Give the slab enough time for its thickness and type — trying to rush it rarely ends well. Where faster drying is genuinely needed, specialist dewatering systems using purpose-designed mats and vacuum equipment can be considered.
Getting curing and drying right — in the right order, over the right timescale — protects everything you’ve already invested in the pour. If you’re planning a project with a moisture-sensitive finish on top, speak to the Welton Aggregates team about the right approach for your slab.
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