Good day, dear guests!
This article is dedicated to strengthening and restoration of strip foundations common methods used today.
It is important to say that you must first make a comprehensive assessment. Do we need to do to make gain or will be enoughpinpoint the cause of the destruction?
This requires the foundation to conduct a survey and find out what places and what was found crack opening, identify possible causes, etc. It was only after the evaluation - to work. Perhaps it will avoid further damage designs tap moisture from the foundation or insulation.
Before proceeding to the step by step actions should relate to the reasons underlying the decision to strengthen the structure:
- Found subsidence, and thus the angle / angles of the building (In practice, the lion's share of cases - a Soaking base: otmostka broken or defective suction well hidden stormwater - split in winter).
- Planning for the completion of the overlying floors and replacement of wooden ceiling in the RC, etc. (All that will give additional load on the base).
- The complete reconstruction of the house.
- Repairing the foundation for cracks after the frost heaving.
So, first thing in the estimation of access to the structure:
When costly repairs, access to the basement from the inside part will be limited, so all the work is done from the street. The ideal option of course is accessible from all sides, but not always so. There are cases where, and with external parties access is limited due to the close neighboring buildings standing. Thus - Least selected "destructive" option.
Goal: The only function of the foundation is to transfer the load from the house to the base, ie, our mainland soil. Our goal - to evenly distribute the load on the structure, so that the pressure does not exceed the carrying capacity of the soil calculated resistance.
Where to start?
You should begin with soil geology. If it is sandy soil, then tighten nedozvolitelno workflow in the implementation of the work thus required to provide a high rate. If the soil - clay, easier to work with, it allows you to spend some or other work in the longer term.
The calculation of the structural part of the gain
Strip foundation is calculated as a beam on an elastic foundation. If there podmokanie, the beam is involved in the work of the console and it is important to focus on the calculation of the upper zone reinforcement. If frost heaving squeezed angle - the tensile stress of the lower belt is not strong enough, there is strengthened and reinforced lower part of the foundation.
At this stage it is important to clearly understand which part of the foundation we need to strengthen:
- Strengthen the load-bearing capacity - expansion of the foundation sole.
- Reduce the tensile stress in the beam - an additional reinforcement of the lower zone.
- Strengthen the arm portion - the reinforcement of the upper zone.
- All of the above in combination.
Stepwise implementation of works
Work will be carried zahvatki. On every few zahvatok - allocated part of the two men. Practice shows that two persons perform a working day for 2 - 3 zahvatki. The optimum size of zahvatki - 1 m in order to avoid creating additional negative conditions for the foundation and does not weaken the foundation..
First of all, the transfer of the foundation plan onto paper, define the number of zahvatok and quantitative composition of the teams. We plan to paint the daily work with each group zahvatok.
The optimal solution is considered to be the organization of simultaneous work on every fourth segment. Furthermore, compulsory arranged shelter from the rain and made alternate undermine the old foundation. Temporary shelter - a must!
Reinforcement is also produced with the necessary portions of the rods overlap on each other. When reinforcing, carefully maintained protective layer 50-70 mm.
It is important to note that the concrete is poured over an existing foundation about 10 cm., As is required to create pressure in the sole of the old foundation, usually work flow using deep vibrator.
In the production of such works - special preference aluminous cement. This type - self-expanding. (Work hard with him, as the reaction proceeds faster than usual, and grasped a little slower gypsum).
In practice, the ordinary cement to add 15-20% alumina. From the point of view of chemistry - it's not quite right, but in practice - grade strength is lost not by much. By using such a solution - successfully compensated shrinkage of ordinary concrete, and increasing in volume, hardening composition "picks up" the old foundation.
Similarly, the upper basement amplified belt pieces are cut walls according zahvatok plan portions are reinforced and filled with concrete.
As a result, our reinforced foundation takes the form of prefabricated reinforced foundation, where the lower and the upper zones are already quite free to work on stretching.
In conclusion, it should be noted that the cost of strengthening the foundation varies from 60 to 90% of the cost of new construction. The lion's share of funds takes an expensive aluminous cement and hard work of builders.
And of course, all you need to enhance the tape is not always the case. If the calculation of your foundation goes to the point of supporting an increase in the area, do not hesitate to make the point reinforcing projections, sometimes enough to implement its plans.
In fact, this is not the only way. You may be able to redirect the focus from the basement to the ground and produce sealing or grouting base. But more about that in future articles.
Thanks for attention!
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