The pit and foundation

By Admin | Building
29 May 2016

Errors in laying the foundation

If the site to house the foundation is below the water table, they should be lower.And if you do not pay attention to it, in the future may have a serious problem - the soil becomes loose and loses its load-bearing capacity.

strip foundation Brute mistake will be laying the concrete foundation for the ribbon of water flooded the area.In such cases, incompetent "builders" for the foundation used almost dehydrated concrete mix, hoping for the water that is in the trenches.

such a foundation will not be able to bear the load of the whole building for several reasons:

  • sole foundation is uneven due to a mixture of soil and concrete.This mixing gives the ground roughness and the concrete becomes loose, with a mixture of earth and large pores;
  • After removing excess water from the trench to the fresh concrete is washed out cement from it.As a result, resistance to the concrete load decreases;It makes no sense to lay
  • dry concrete mixture into the ground water, hoping all this stir in
    the trench.Because in the end, a mixture similar to concrete, which exfoliate due to mechanical impact and its carrying capacity is reduced, and can not be taken into account.

Open dewatering

Once dug a foundation pit, it should be dry.The easiest way - pumping out the water pump from the trench or excavation.Most often it is used where there is a rising phenomenon or suffusion leaching of mineral soil particles.Rising suffusion - ground failure penetrating into the pit to the water, resulting in lost soil resistance required for the construction of the foundation.

drains If you are not familiar way to open dewatering, your actions can lead to serious errors.To avoid this, during excavation or trench in the final place drains, so that the level of groundwater was 20-40 cm below the pouring of the foundation.Otherwise, the ground will be difficult to remove.Drains - a special device that limits of the aquifer water is taken.They are: horizontal, vertical, and versatile - that cross the aquifer completely, reaching water pressure.

When the pit does not have a strong bottom, soil change and is similar to sand, quicksand, it is difficult to prepare for this site a working platform for laying the foundation.Continue works only after burying drain and change the level of reception and precast wells.Continue to excavate should be in the direction of the flow of direct antithesis of groundwater, as detainee flow will erode the soil.

dewatering continues until, until the first signs of suffusion, and if you do not stop pumping water the soil will not suitable for the installation of foundations.

first signs of rising suffusion - the appearance of jets of water that remove particles of soil and deposited them at the exits as the lava erupting from a volcano, the flux is constantly increasing.There is a slump, which it is impossible to predict in advance.These symptoms indicate that the ditch is not ready, and its load-bearing capacity of uncertainty.In this case, cease pumping water and vice versa, we are beginning to raise its level until the phenomenon disappeared suffusion.You then need to find a more reliable way of dewatering or to see a specialist.

ditch to the groundwater level was always the same, it is constantly pumped, preventing to fill the whole pit.If this is not done, unexpected flooding break built structure, for example, the water pressure breaks down multi-layered trough-waterproofing excavation.

start of construction, do not let the above errors.If you spend an open dewatering, try instead to use visual control pumps with automatic control.

To avoid errors

Before you begin construction, you need to get the full information on the ground: the exact data about the level of groundwater, and their volume.In no case do not neglect this information.Located in the ground water, without a runoff, have a different pressure on the structure.

For example, 1 square.m floor basement, which is immersed in the 1 m in ground water, the force from the bottom up to 1 ton.To counter this pressure is laid concrete slab thickness of about 0.46 m. ​​

It so happens that the groundwater level is not properly defined and the choice of the type of waterproofing used insulation from moisture.Later, under pressure from groundwater waterproofing is destroyed, the floor rises and the water floods the basement.Further along the walls penetrates the living quarters, where they form efflorescence and mold on the walls.

foundation To prevent this, remove the water, take a four-standpipe waterproofing.Fill the "reinforced concrete trough" so that the pressure on groundwater was transferred walls.It is expensive and time consuming method.

In addition to determining the level of water you need to know, and their composition.Among the most aggressive elements, which may be in the ground water is the content of sulfate.Sulfates can completely destroy your concrete foundation.This salt destroys the concrete, making it loose, the formation of crystals.The process of destruction of concrete is determined by the appearance on the surface of white plaster plaque, and then soundly bonded after the frost.

to protect the foundation of the destruction of the 350 used Portland cement, slag and less persistent.Due to the presence of moisture on the structural elements of the structure appear white spots - efflorescence is potassium or sodium salts.

Foundation - the foundation of the house and before laying the need to weigh everything, learn to consult with professionals, for home repair - troublesome and costly.And if you still do not just groundwater - invite a specialist.