The Workability of Concrete – Why is it Important?

One of the most important features of ready-mix concrete is its workability. Here Madmix, a leading concrete company in Cambridgeshire, examine what the term means, how it is achieved, and how we can supply an admixture which meets your needs.

The Definition

‘Workability’ is defined as ‘how easily freshly mixed concrete can be placed, consolidated and finished with minimal loss of homogeneity or consistency’. There are five main factors that affect how workable concrete is:

1. The Ratio of Water to Cement. Broadly speaking, the higher the percentage of water, the more workable the concrete will be, but there could be some trade-offs. Concrete with a higher percentage of water is more prone to shrinkage, cracking, and will lose some of its overall strength over time.
2. The Aggregates. This refers to the size and shape of the stones and sand used in the admixture. As the surface area of aggregates increases, the more cement paste is needed to cover their surface. So, concrete mixes with smaller aggregates will typically be less workable compared to larger sizes.
3. The Admixtures. These can be used not just to improve the strength of the concrete (once set), but also to improve its workability. Examples include plasticisers (that help with consistency), air entrainers (to improve freeze/thaw resistance), and internal curing (which helps reduce any cracking and loss of strength).
4. Temperature. The warmer or hotter the weather, then the more quickly the water in the concrete will evaporate when it is poured or laid down, making it less workable.
5. Time. The longer you leave the concrete, whatever the weather, type of admixture, or size of the pour, it will become less workable it will become (particularly in warmer weather, as outlined above).

Where is Workability Important?

You need your concrete to be workable in a number of scenarios. First and foremost, when the pour is a large one (usually in construction projects), where the extra working time is needed because of the sheer volume of concrete involved.

Secondly, where the concrete needs to be pumped from some distance away (including from a lower height). For example, many multi-storey buildings (such as car parks) and locations that are generally inaccessible to delivery vehicles.

At Madmix, we provide pumpable concrete for both commercial and domestic use in St Ives, St Neots, Ely, Huntingdon, Newmarket and across Cambridgeshire. If your projects needs concrete to be pumped we recommend Boxfast Plant Concrete Pumping Specialists for pump hire.

Workability is also important where effective compaction of concrete isn’t possible. Compaction is the process which expels air from freshly placed concrete and packs the aggregate particles together to increase the concrete’s density.

Where is it Not so Important?

There are some types of projects where you don’t need such a high degree of workability. For example, concrete used in road making is usually very dry and is laid down by power-operated machines. This means it should be level and not require much additional work.

The same can be said for domestic projects such as shed bases and driveways which cover a small area; working with, and smoothing out, the admixture shouldn’t take very long.

Ready Mix Concrete from Madmix, a Concrete Company in Cambridgeshire

At Madmix we supply a range of admixtures, one of which is sure to fit your individual needs.

As well as pumpable concrete, we also supply waterproof concrete (which is ideal for bridges and dams), concrete reinforced with polypropylene fibres (which will give extra strength), and domestic admixtures which are suitable for paths and driveways.

If you’re not sure which type of concrete to choose, give us a call on 01954 212212 and we’ll advise you on the best type for your needs, as well as how long it’s likely to be workable for. You can also contact us by clicking on this link and filling in the online form.