All About Concrete
Making concrete worktops, and concrete sinks every day means that we are the experts in our choice material – concrete. We thought it’s probably a good idea to share some of this knowledge with our clients, so you can understand a part of the process in the making of your worktops.
What is concrete made from?
In its purest form, concrete is a mixture of paste and aggregates (or rocks). The paste is made from cement and water and is used to coast the surface of the fine aggregates. In using a well-known chemical reaction known as ‘hydration’, this paste then hardens and toughens into a rock-like form that we call concrete.
Why is concrete used for so many things?
Concrete is so valuable to us as it is incredibly malleable when in its pre-hardened state. This allows you to mould it into pretty much any shape you want.
The character of the concrete is decided by the quality of this paste mixture. So, the strength of the paste is decided by the ratio of water to cement. High-quality concrete is produced by lowering the water-to-cement ratio without sacrificing the malleability of the fresh concrete. This allows it to be properly placed, consolidated and cured, creating the concrete shapes we see all around us.
What is the perfect concrete?
The perfectly designed blend will have the workability for the fresh concrete to produce an optimum shape, whilst holding its durability and strength.
The mix for the perfect concrete is approximately 10-15% cement, 60-75% aggregate and only 15-20% water. Entrapped air in many concrete mixes could also take up to another 5-8%.
What water is used for concrete?
Almost any regular water that is clean and has no prominent taste or smell may be used as mixing water for concrete. However, any excessive impurities in the water used for mixing may not just affect setting time negatively, it could also affect the integrity of the concrete.
Impurities in water can even cause efflorescence (migration of a salt to the surface), staining, unsuccessful reinforcement, affect volume, induce instability and also reduced durability.
It’s therefore imperative that high-quality water is used when mixing concrete. We’re very lucky that here in North Wales, we have access to an extremely high level of water quality. The UK water is all around very good, which means that we generally, throughout the country, avoid any negative consequences from bad water in concrete.
How is a concrete aggregate for concrete chosen?
Aggregate, on the other hand, is more important to select ingredients carefully. The reason being is that aggregate makes up over 60% of the total concrete volume. The type and size of aggregates used will depend on the thickness and purpose of the final concrete product.
After the aggregate, cement and water are combined, the mixture will begin to cure (harden). The Portland cement we use is hydraulic cement, which sets and hardens through the hydration process.
Once the concrete is thoroughly and professionally mixed, and in a workable state, it should be placed in forms before the mixture becomes too hard to work with.
If you’d like to know more about the process, simply contact us and we’d be happy to go into more detail. Also, feel free to call us to discuss your concrete design ideas!