Despite the fact that concrete is very important building material, many constructors try to save as much as possible on it. But not many understand that this is not the best approach. We have to realise that foundation is called “foundation” because it is the most important part of the construction and bears the whole load of the building hence the whole stability of the building depends on it. It is good to take few facts into consideration before choosing the type of your concreting.
Choose a concrete mixing plant that is in convenient distance from your site. Under the most favourable circumstances the ready mix concrete should be poured into foundation at site in 45 minutes from its mixing at the plant. By adding chemical admixtures you are able to prolong the time limit of its setting.
You can find the exact time limit in the delivery note from your supplier. This limit is accounted from adding water and dry cement into the concrete mixer. If you do not have the plant in convenient distance, there is also a possibility to hire a supplier that has a fleet of volumetric mixing vehicles which are ready to mix your concrete on site depending on your concrete demands and volume you need.
Be cautious if the supplier tries to convince you that they add the same dry cement as any other mixing plant but they are more effective when mixing the concrete. The quality of your concrete depends mostly on the quality of the aggregate the supplier uses.
Many suppliers try to make maximum saving on aggregate and therefore you are able to spot fragments of dirt (e.g. pieces of wood or construction waste) in your mix. They do this in order to sell you concrete for “better” prices.
In this article we write about two “types” of concrete – concrete mixed in a mixing plant is called “ready mixed concrete” and concrete mixed on your site is “onsite mixed concrete”. The supplier is able to adjust the qualities of the mix to your highest expectations thanks to the presence of a volumetric mixing truck.
This is ready to mix your concrete on site and in your presence. You can control the volume of concrete they mix according to your demands.
If the weather forecast says there are going to be temperature swings, heavy rain or wind, you should rather reconsider to move the date of your concreting to more suitable time.
The best temperature for concreting is between 10 – 25°C. There should not be direct sunlight shine on your site and it should not be very windy as well. If you are forced to do the concreting despite the unpleasant weather mind this:
* Protect the surface of your concrete against negative temperature by covering it with thermal insulating mats (they hold your concrete´s temperature). Avoid concreting when the outside temperature drops below 0°C – curing will be interrupted and you may face the spalling of your concrete
* When the temperature is high you also need to protect your concrete against too fast hydration. You can do this by ponding or spraying the concrete surface
Check the measurements, location and tightness of the formwork joints before the beginning of concreting and check also the accuracy of position and the distribution of the reinforcement (if you use reinforced mat slabs).
You need to inspect the placement of insulation that is going to be covered by the concrete. When checking the mat slabs bear in mind that there should be minimal cover between joined slabs.