"As a compacted sand bed under the foundation"

Recently I wrote an article about Do I need a cushion of sand under the foundation. Continuing the theme of talk about the methods with which seals encountered in practice, their pros and cons. And that is why I consider dangerous seal a thick layer of sand.

plugging

The most primitive method of sealing - hand tampers. When they are used too many variables that affect the force of impact. If you want to compact the backfill a trench or a sand bed at the garden path - please. But to achieve uniform compaction over the entire area will not work. Therefore, in preparation for foundation I had never been used.

To seal the sand cushion under the responsibility of the construction took plate compactors. In theory they can be uniformly compacted layer of 10 to 50 centimeters and more. For this it is necessary to count the number of penetrations, depending on the soil type and its characteristics, the impact force required compaction factor, etc. The squatter no one does. But that turns out in practice to tell a little lower.

spilling

If you shed the sand with water, in fact, it can be sealed. This is one of the methods listed in Sec. 2.69 SNiP 2.02.01-83. However, the same SNiPY (n. 2.32) it is said that you can not avoid becoming soaked soil foundation. What to do?

Alluvium and sand seal pillows water really do. To do this, transfer the sand in suspension with water (three times or more greater than the amount of sand). Then, depending on the soil characteristics give reclaimed layer lie for 2-5 years. Wait no one wants, and throws sand bed every second.

I will not argue if shedding water loose sand, it becomes denser. But this water is influenced by the performance of the rest of the soil? Someone lucky and someone is not very ...

wedging rubble

Effective and underrated way of tamping the surface layers of soil. It looks simple: the surface covered with a uniform layer of gravel coarse fractions (50-70), then vibratory plates for several penetrations vtrambovyvayut rubble in the sand. The sharp edges of gravel propped sand base and make it denser.

Not to be confused with the wedging gravel preparation for concrete structures.

What happens in practice

Without determining the coefficient of compacting of soil compaction always get "the mark". On layers of 30-40 cm is not so noticeable. Yes, and go the extra time the rammer is not so difficult.

When it comes to replacing the weak soil layer the sand bag 40 cm (allowed n. 2.69 b SNIP 2.02.01-83) it is important to monitor the compaction factor. Be sure to layer-compacting. If nedouplotnenie goes on each layer in the amount they give serious drawdown - there are holes.

Especially clearly visible error when compacting massive sand pillows under the foundation slab. After heavy rains on a perfectly flat surface "sinks" nedouplotnennyh sand in places. Be careful.

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