It is more convenient and easier to order a ready -made solution for the foundation, but this is not always possible for economic and other reasons. An independent knead of the concrete mixture and the device of a tape or column foundation are more often practiced.
The reliability, durability and strength of the base depends on the correctly prepared concrete solution and the components of the mixture, which depend on the type of foundation, the composition of the soil and the design of the base of the house.
The composition of the concrete mixture for the foundation
It is clear that the composition of any concrete mixture cement and sand. Their proportions and brand cement are important. Crushed stone of the middle fraction is used as a filler for light concrete.
With the development of industry, a large number of additives to concrete have been developed, which regulate the time of hardening the mixture, increase its ductility and resistance to low and high temperatures.
Concrete mixtures are classified primarily by the consistency of the working solution:
For foundations designed for high loads, hard concrete solutions are used, 1800 kg/m3 density. Such a solution is very thick, resembles wet soil. It is difficult to pour it by gravity. Be sure to compact the mixture flooded into the formwork after pouring, since the solution freezes very quickly;
liquid solution is characterized by lower strength, since it contains a lot of water. But such a consistency is convenient for pouring formwork without voids at a fast pace, which significantly reduces the timing of construction work. It is important to consider that liquid solutions completely dry and hard over 24 to 30 days.
If you plan to build a two -story building of heavy materials (stone, brick), it is better to stop on a hard solution, although this is more expensive and longer in time. But a hard solution guarantees the stability of the foundation with high loads.
Concrete brand – characteristics and features
What are the characteristics of the most popular and affordable brands of concrete for foundations:
M50 is the cheapest cement that does not differ in strength. Can be used to arrange the foundations of light structures (arbors, verandas). The composition of the mixture is part of the cement 400, six parts of crushed stone of the middle fraction and four parts of the sand;
M100 – three parts of sand and five parts of crushed stone are needed for part of the cement. The most popular, rather durable solution. It is important to monitor the density. Usually, a kilogram of cement is sufficiently 0.5 – 0.7 liters of water.
In order for the solution to acquire optimal plasticity, it is recommended to use crushed stone fractions of 20 – 40 mm, not smaller and not larger. Masters advise taking crushed stone of several factions. In this case, thoroughly filling the formwork without voids and caverns is guaranteed.
What sand is needed for a concrete mixture
It is preferable to choose pure dry sand, without impurities of clay and extraneous inclusions, from 1.2 to 3.5 mm. Check the cleanliness and the presence of impurities is simply. It is necessary to dilute the sand with water and shake, if the water is not muddy, then the material is clean, without impurities.
When defending a solution of water with sand, you can also notice the suspension of clay and other particles.
Which cement is better for the foundation
On sale you can find the following cement brands:
Portland cement is the most inexpensive and popular material;
slag portland cement – hards slowly, but has high moisture resistant and frost -resistant characteristics. It is used in regions with winter temperatures below -20 and for high humidity soils;
Quickly hardening concrete mixtures – grasps very quickly, so it is necessary to prepare the formwork in advance and pour the mixture continuously. Reduces the deadlines for filling the foundation to two weeks.
For simple strip or column foundations, a standard Portland cement can be used. Digital marking of cement indicates the limit of the strength of the material. For the foundation, brand 400 is recommended. Additional strength and frost resistance can provide additives to concrete.
Address to concrete for the foundation
It is necessary to choose additives to concrete based on the features of the soil and the temperature characteristics of the region. Also sometimes you need to accelerate the process, then additives will be needed to accelerate the hardening of the mixture.
plasticizers – component of additives liggonfunding salt;
anti -control additives – prevent the freezing of water in concrete, the main component is calcium nitrate;
waterproofing additives – polymers. Reduce the porosity of concrete, but reduce the thermal insulation properties of the foundation.
Adding bastard lime (20 percent of the weight of cement), washing powder (150 grams per 50 kg of cement), PVA glue (200 grams per bucket of solution) also improve the plasticity of the mixture.
