- What is TISE and what is its peculiarity
- The use of TISE and the myth of the basement floors
- Well drilling with an earth plow TISE-F
- Reinforcement and pouring
- Manual pile making – advantages and disadvantages
- Alternative method of filling in PET pipes
This time we will talk about one of the most technologically advanced and easy-to-use types of foundations for buildings with low weight. We will tell you what are the advantages of the TISE foundation over other types, where its use is most relevant, and most importantly – how to do the work yourself.
What is TISE and what is its peculiarity
The TISE foundation is a part of the complex, which makes it possible to create a solid and reliable foundation for the subsequent erection of a building with masonry with small-sized elements up to three floors high. At the same time, the emphasis in the construction of such a foundation is placed on manual labor without the use of mechanization means..
Structurally, the foundation is similar to the pile foundation, but has a shallower depth due to expanders at the base of each pillar. Thanks to the hydrophobic shell of concrete piles, their saturation with moisture is excluded, that is, when heaving, the soil cannot break the concrete – it simply does not freeze to it.
1 – waterproofing; 2 – fittings; 3 – concrete М350
With a diameter of the narrow part of 200 mm, a pillar made of sand concrete of class B25 will provide guaranteed strength under a load of up to 40 tons. This is more than enough, given the pile base area of 0.8 m2, allowing you to reliably support 4-5 tons on a pillar even when building a foundation in weak and wet loam.
The use of TISE and the myth of the basement floors
Of course, the TISE foundation is not a panacea at all, but this technology can rightfully be called the least costly for construction in conditions where nothing can be built without a reinforced foundation. Unfavorable conditions include heaving and water-saturated soils, regions with a freezing depth of more than one and a half meters and areas close to water bodies.
TISE, however, is practically useless on quicksand and in rocky ground. But it is indispensable for the quick construction of small farm buildings and frame-type country houses. Due to their low weight, such buildings do not require high bearing capacity from the foundation..
It is believed that columnar foundations exclude the possibility of building a basement or basement under the house. In the standard view, it may be so, but after all, both columnar foundations and TISE, as their particular variety, are often used to stabilize slab bases and increase the bearing capacity of the basement due to additional support on deeper, and, therefore, denser soil layers.
Both the pillars’ heads and the grillage (slab) are located at the bottom of the common pit below the freezing depth. Such a foundation will be optimal for buildings on monolithic reinforced concrete frames, characterized by significant weight.
Well drilling with an earth plow TISE-F
A pile drill is a product that requires knowledge and understanding of the mechanics of the processes that facilitate excavation to be used properly..
The hole itself can be drilled by almost any, including a motorized drill with a diameter of at least 250 mm. TISE-F has two inclined cutting edges for these tasks, in the lower part of which there is a pair of teeth that loosen the soil. Both cutting edges are located inside a 200 mm high ring storage for fast loose material removal.
Drilling begins with digging along the pits for easier penetration of the drill into the ground. With a slight vertical pressure, the drill is turned clockwise, after 2–3 full turns it is removed and cleaned from the ground. On average, it takes one person 2.5 hours to drill a two-meter well, and about 40 minutes for two..
Expansion sampling is carried out after installation on the plow. Due to the telescopic device of the drill rod, the plow is pressed against its axis while the drill is suspended. When pressure is applied to the handles, the mechanism moves the plate to the side, thus, at a depth, a hemispherical cavity is gradually “gnawed out”.
Well drilling technology TISE: 1 – board formwork; 2 – sand; 3 – reinforcing cage; 4 – concrete
Further preparation of the wells consists in installing a waterproofing liner. For these purposes, roofing material is applicable, although it is recommended to use PET sheets or bitumen impregnated fiberglass if possible. The waterproofing pipes are cut with a knife along a common secant horizontal plane, a square formwork is installed at the tops, knocked down from 120 mm boards.
Reinforcement and pouring
If you arrange the foundation with a high groundwater level, before filling each well into it, you need to lower the submersible slurry pump until the liquid is completely removed. A 20 cm sump under the extension, where water remains accumulates, helps a lot in this..
For the reinforcement of the pile, a case structure of four longitudinal rods of 12 mm reinforcement is used with transverse ligation with clamps every 40–45 cm. In plan, the reinforcing frame has a square section with a side of 180 mm. To fix the reinforcement exactly in the center of the pile, 35 mm distance rings are put on the rods at intervals of a meter.
Filling occurs as follows: a bucket of coarse gravel or road rubble is poured onto the bottom of the well. The reinforcing frame is installed in place: if a concrete grillage is planned over the pillars, the tails of the reinforcement are released above the pile formwork by 30-40 cm.
For pouring concrete of class 20-25 is used. The most suitable from the point of view of compaction of the mass can be called sand concrete or concrete on granite screening with a ratio of cement grade 400 to filler as 1: 3.5.
After pouring the concrete, it must be sealed by pinning, and then the vibrator must be immersed several times into the well. The upper end of the pillar is trimmed with a trowel, protruding reinforcement must be immediately washed from the cement. The piles gain full strength like any concrete – in 28 days, but after 100 hours, the construction of superstructures is possible, and the concrete grillage can be completely cast on the same day with the pillars.
Manual pile making – advantages and disadvantages
The foundations of TISE did not make a revolution – the expansion piles were introduced into the construction site much earlier. And there are a number of circumstances when preference should be given to the standard method of constructing such a foundation without cunning drilling devices..
At the very beginning, we noticed that the tensile strength of the pillar is much higher than the supporting capacity of the soil even with expansion. This difference can be used profitably if you arrange the expansion manually and reinforce it correctly, which will increase the pile installation step to 3-4 meters.
Wells of 100×100 cm are dug under such pillars, the bottom is poured 150 mm with the laying of gratings of 14 mm reinforcement rods in two layers and mortgages for reinforcing the piles. After that, a formwork is built – a square pillar with a clearance inside of 200×200 mm, diverging in a plywood trapezoid 35 cm from the base. So it becomes possible to build an expansion proportional to strength, correctly reinforce and waterproof concrete, arrange a backfill around the pillars with material that is not subject to heaving.
Alternative method of filling in PET pipes
In conclusion, we present a similar version of such a foundation, in which substandard PET or wide HDPE pipes are used. The method is especially good in the presence of minimal mechanization – a gas drill or KBM from local utilities.
A well with a diameter of 400 mm is torn off 50 cm below the freezing depth, 30 cm of concrete is poured onto the bottom over a sand bed. Plastic pipes are inserted into the set, but not frozen concrete, and are leveled at the level, which subsequently play the role of formwork, waterproofing and a casing sleeve that prevents the soil from freezing.
The diameter of the pipes must be at least 200 mm; for light household buildings, it is permissible to use standard 110 mm pipes with a pile spacing of no more than 1.6 meters. The pillars need to be poured with sand concrete, pinned and seated with vibration, and then drive 3-4 rods of 12 mm reinforcement in the entire length of the pile inside, without worrying about the protective layers.