When pouring a monolithic foundation of the house, the required volumes of concrete often exceed several cubic meters. Large construction companies solve this problem with the help of heavy special equipment - a mixer and a concrete pump, with their help the solution is mixed and fed into the formwork. However, such equipment is not always affordable for private developers, in addition, in small areas there may be no access roads for heavy equipment. A concrete mixer will partially solve the problem, but the volume of the solution prepared in one load is limited at the same time. At builders thus there is a question: whether it is possible to fill in the foundation in parts? Will this affect the operational properties and strength of the foundation?
Is it possible to fill the foundation with parts of
Concrete maturation stages
Concrete is a mixture of cement and fillers - sand, gravel, expanded clay - with water. To improve the fluidity of the solution, increase the frost resistance and give it special properties during mixing, various additives and plasticizers are also added to the concrete.
Liquid solution after the preparation is poured into a mold, called formwork, after which the concrete begins irreversible processes:
- Grasping of concrete. During this stage, the liquid concrete solution passes into a solid state due to the interaction of the cement and water components. However, the bonds between the components are still very fragile, and under the action of the load they can collapse, and there is no re-setting of the solution.
This phase lasts depending on the air temperature from 3 hours to 1 day. The lower the temperature, the longer the concrete sets. At the initial stage of setting, it remains liquid without any changes in the structure. If during this period of time add a new batch of concrete to the formwork. There will be no destruction of the cement bonds. For a temperature of 20 ° C, the "liquid" stage lasts about 2 hours, at zero temperature it lasts about 6-8 hours.
It is possible to extend the time before the setting starts by permanently mixing the concrete, but this will worsen its characteristics, so you should not abuse this method.
- Hardening of concrete. This phase continues for quite some time, due to the gradual hydration of concrete components, the foundation has been gaining strength for many years. The first 28 days is a mandatory period of exposure of concrete to the set of strength, corresponding to its brand. Hardening occurs fairly quickly in the first day, then its speed slows down.
- In the first hours after setting, the hardness of concrete is still low, and adding the next batch of concrete can lead to microcracks due to increased load. After three days of hardening, as a rule, these loads do not exert such influence on the first layers of concrete.
Based on the characteristics of maturation of concrete, you can say: you can fill the foundation with parts. In doing so, it is necessary to observe certain rules:
- With consecutive mixing of batches of concrete, the time between filling them into the formwork should not exceed 2 hours in warm weather and 4 hours in the off-season. The seams are not formed, the strength of the foundation does not change.
- If you need to make a long break in work, it should be at least 2-3 days. After a break, the surface of the foundation, on which a fresh portion of concrete will be filled, must be cleaned of dust, moisture, and cleaned with a metal brush. The seam will have good grip.
- When pouring the foundation with parts, all reinforcement recommendations must be observed.
How to reinforce the corner at the base of the
Layered or blocks?(fill in parts)
Another question that worries developers is how to properly distribute portions of concrete? There are three types of seam arrangement:
- Horizontal;
- Vertically;
- Angled.
SNiP on this account gives specific instructions: the seam between the sections of the monolithic foundation must be directed perpendicular to the axis. That is, for columns and piles is suitable only layered pouring of concrete with the formation of horizontal seams.
For tape monolithic foundation joints can be located both vertically and horizontally. To maintain the strength of the foundation, a qualitative reinforcement must be directed perpendicular to the joints of the monolithic blocks. If the seams are made vertically, the longitudinal reinforcement must necessarily firmly bind the corners of the building. When layered horizontal filling, the installation of vertical reinforcement is mandatory. In practice, the strip foundation is usually poured in layers, since additional formwork is required to fill individual vertical blocks.
The process of foundation pouring with parts of
When pouring a band foundation with layers, it is necessary to take into account one feature: if the formwork is erected only in the aboveground part of the foundation, and the underground part is poured into the excavated trench, the joints of the rows are made according to the level of the ground. Before pouring the plinth, it is necessary to wait for the hardening of concrete in the underground part for several days, otherwise the mass of concrete poured into the formwork, by its weight, can destroy insufficiently hardened cement-hydrated bonds. In the concrete there will be microcracks, it will become more hygroscopic and eventually start to break down.
Pouring the band foundation
When pouring a plate foundation, the seams are placed either horizontally or vertically in a direction perpendicular to the short side of the plate. This arrangement of seams will reduce the probability of a fault with a non-uniform load and ground punching.
Filling technology for monotonous foundation
Plasticizers
The addition of additives and plasticizers improves the flowability of concrete, so that the vibration of the concrete can be eliminated from the priming process. This will reduce the impact of a new portion of the solution on the already filled layers.
The mixing of the solution is carried out after a preliminary calculation. When adding plasticizers, you must strictly follow the manufacturer's recommendations in terms of dosage, as non-observance of proportions can lead to the opposite result.
Concrete mixing process
