Table of Contents
Column and pile designs are at first sight very similar. At least, in elevated part. However, properties and technologies of their construction differ. The column base first of all is designed to reduce material consumption and base bid, is used only on soil with normal bearing capacity. Pile, allows to build houses on problem sites with weak top layer of soil. Let’s tell about features of construction of the column and pile bases the hands.
The column base without grillage
The most economic view of the bases, is minimum on material consumption, is simple in production. Represents separate columns and it is applied at construction of buildings which do not need continuous tape support. These are easy houses in which structure the bearing lower bar (framework structures of all types) and constructions which walls consist of horizontal large-size elements (all types of wooden fellings) is provided.
As well as for tape, the lower mark of the column base it is possible to arrange below normative frost depth. Or it can be shallow-depth. The first option is reliable, the basis of columns will not be exposed to forces of frosty rebound. The second at the correct device is not less strong, but costs considerably cheaper and is applied more often. In midland of Russia the bottom of columns of the soil 40-60 cm lower than level is enough to arrange. However, if soil has signs of heeliness (contains clay), under each column it needs to be chosen up to the full frost depth with stock down in 20 cm and to replace with mix of clean coarse sand with crushed stone or gravel. Sandy adding should be stamped well, it is abundant the passage water, it is important.
The step of columns determines their section and massiveness of the building. The house is heavier, the more often there has to be step and columns are more powerful. To have columns is closer, than 1.5 meters are to each other irrational, the material consumption is high. On the maximum length of restrictions, except already mentioned is not present, but you should not exceed size in 3 meters. For the average frame house the step of columns will make 2 meters. Section of columns directly depends on the applied material and production techniques of works.
Columns of circular section
The construction of columns of the base with use as fixed timbering of ready pipes is least labor-consuming and takes not enough time. The best option — metal pipes, but costs metal very much today. Though, sometimes on scrap metal dealers and in the construction organizations it is very cheap possible to buy scraps. Are strong, but too are expensive, asbestos-cement pipes. The column base for the easy house which is filled in in asbestos-cement cover can even be not reinforced. The choice of possible diameters of both types of pipes is very big.
At the limited budget it is possible to use as timbering plastic sewage pipes, gray or black, domestic. Polymeric pipes with a diameter of 110 mm cost little absolutely, on such columns it is possible to put small giving or farm building. Also application of pipes with a diameter of 150, 200 and partly 250 mm is justified from the economic point of view. At further increase in the sizes the price of pipes increases considerably and it is more reasonable to fill in square columns in wood form. It is worth looking in advance among suppliers of those who implement the rejected products. Small defects, cracks and chips do not influence durability of products in any way, and reduce cost significantly.
There is one more option if not free, then very cheap. It is possible to contract roll from two-three of layers of roofing material and to use it instead of pipe, having established in hole. It is more difficult to fill in concrete in ruberoid “straw”, of course, than in rigid pipe. It is necessary to fill it with mix layer-by-layer, at the same time falling asleep for the same level of bosom in the earth that bituminized cardboard has not torn. Diameter of columns in “soft” timbering has to be not less than 20 cm, but it is better to be reinsured and make more, 25 cm.
Columns of square section
It is possible to cast columns and in removable timbering. As a rule, it is the wooden boards made in the place. There is also qualitative and very convenient industrial metal timbering intended for production of columns. Unfortunately, it is expensive: purchase in property is unjustified, and rent can be favorable only on condition of high speed of construction. Section of concrete poles cannot be less, than 20х20 cm on condition of good consolidation of concrete and normal quality of mix. Besides, just in case, under residential building it is better to put columns section not less, than 25х25 cm. By the way, not to bother with quality classes, solution is enough to mix in proportion cement/sand/crushed stone or gravel in classical proportion 1/3/5. Cement has to be not overdue, brand 500 or at least 400, without lime content (these data always are on packaging). Concrete in the course of filling should be condensed with immersion vibrator or at least wooden stick. Then columns should be moistened and covered from above with film or roofing material that from concrete moisture did not evaporate. The timbering can be removed not earlier than in three weeks after filling.
It is possible to build the column base and of butobeton in timbering. But, as it is impossible to proarmirovat it normally and durability of such laying less, the section of columns owes too big. At least 50х50 cm.
Theoretically, it is possible to build columns of the base and brick, section from 38х38 cm, these are one and a half bricks. Practically to find suitable qualitative well flame brick at reasonable prices today it is unreal.
After installation of walls of the house intervals between columns close sheet material, flat asbestos-cement sheets are more convenient and stronger other.
All columns, except filled in in metal in asbestos-cement (for easy buildings) pipes, need to be reinforced. Quite often just thrust several steel rods into concrete, without having connected them among themselves in any way. It in root is wrong. The competent decision — to build full-fledged prefabricated reinforcement cage. On height of column place rectangle four rods (for round columns it is possible three), connect with each other by “transversely” with step 40 cm. It is more preferable to fix framework by lashing wire, than to use welding. For the main armature use armature of AIII of corrugated profile with a diameter of 10-12 mm. For cross elements it is possible to take wire from 8 mm.
The easiest and fast way to make holes for columns in not stony soil — to use petroldrill. In all rolling offices of construction tools such tool is, rent costs it little money. For one change without problems it is possible to make dredging under all design. If there is no such opportunity, it is necessary to use hand tool. Preferable option — special drill TISE which allows to do the wells of variable section extending below. At the worst the normal garden drill will go.
Under the columns cast in removable timbering, trenches should be dug the big size and manually.
Basic part of column
Correctly executed reinforced concrete column will sustain quite heavy load, but soil at small area bearing can sink. The house is heavier, the columns have to have big area of basic part. The more area of “heel”, the better. If the trench is torn off shovel, it can be made more widely and at first to expose timbering and to cast support, then column. Generally, the heels size is done twice more, and height — about two thirds of section. If the size of 30х30 cm, then support about 60х60 cm, and height of its about 20 cm has column. Under the columns of circular section which are filled in in pipes drill openings bigger, than column, the size. Exception — “cunning” drill TISE by means of which it is possible to do superficial wells of variable profile. At first in hole fill in couple of buckets of concrete, it will be support. Later establish fixed timbering (pipe, roofing material) and lower in it prefabricated reinforcement cage.
The column base with grillage
Grillage — the bearing reinforced concrete beam connecting columns from above. The base with grillage (tape and column) is applied to construction of stone buildings which heavy walls need to be opirat on all length. Columns build on the same technologies, as for easy houses with only that difference that their section more, and step more often. The grillage can be monolithic or is executed from the factory elements established on columns. The prefabricated reinforcement cage of columns for the base with monolithic grillage has to be located above column mark on 10-15 cm, it will be connected with horizontal framework of grillage. The grillage is surely reinforced, diameter of the horizontal bearing rods has to be not less than 12 mm, cross communications put through 40 cm. The more the step of columns and loading from walls, the more powerfully has to be framework. Grillage width — not less than the section of columns and two thirds of width of overlying wall. Symmetry axes of wall and grillage have to match. Height of grillage should be done not less its width, for the heavy house (brick walls, steel concrete overlappings) — is one and a half times more.
The grillage should not lean on soil at all or to be buried in it even if soil not puchinisty. In the winter the soil which is inevitably rising under the influence of forces of frosty rebound has to have possibility of free vertical movement. Otherwise the grillage, especially assembly, can tear off from columns, the base is inevitably deformed. On sandy soil the distance from the surface of soil to the lower part of grillage has to be not less than 5 cm, on heaving 10-15 cm. It is possible to provide this gap in two ways. In the first case horizontal part of timbering, “bottom”, expose on weight. It is difficult. The second method is simpler. To the level of design mark of bottom of grillage fill, condense and level sand. Roll strip of roofing material or bituminous and polymeric analog on charge. Isolation interferes with effluence from mix of water and cement, improves conditions of hardening and can be used as waterproofing. Then establish timbering, only vertical side elements. Reinforce and fill in. Within three weeks concrete needs to be humidified and protected from drying, covering with film. After this term the timbering is removed and sandy adding is deleted.
The gap can be filled with soft material, for example, to insert into slot heater cover for pipes. Or at all to fill with nothing. The slot from the street and the house is closed sheet material, flat asbestos-cement sheets perfectly approach. After the outside blind area and internal charge is executed, it is only possible to guess existence of air gap.
Piles differ from columns in the principle of supports and length of vertical elements. The column bases build on soil with normal bearing capacity, pile — to weak. Often top layers of peaty, oozy or dust sandy soils have the small thickness, several meters. Problem of piles — “to puncture” weak soil and to reach the bearing layer, having provided reliable supports of the building. Before making the decision on construction of the pile base, it is necessary to conduct research: trial drilling to make sure of technical capability “to reach” the bearing soil. If thickness of weak layers is too big, it is worth paying attention to plate structure of the base.
The most reliable and effective technology — swamping in soil of factory concrete piles by means of special machines. Allows to overcome layers of earth in tens of meters and to build very heavy buildings. Unfortunately, drive piles cost very much and in private construction are used extremely seldom. The drilling technology is similar to the device of columns: as boring installation or hand drill with lengthening nozzles choose soil, will not reach the bearing layers yet. Further use metal or asbestos-cement pipes, filling them with concrete. Concrete in asbestos pipes is reinforced. As we see, the pile base, unlike column, it is not always possible to make independently and without attraction of the equipment.
Recently there is popular technology of screw piles. Though, quite often it is applied also at construction on strong soil. In this case apply piles well, they perform function of columns. But, anyway, “drill” (the lower part of pile) has to be placed lower than frost depth. The screw pile represents metal pipe with edge and bladed drill on the end. It is just twisted in soil, having only planned hole in the earth. Thus, earthwork operations is minimized. Three persons can twist pile in soil without stones easily: two, using as loma levers, the pile body inserted into openings, twists it to the earth, the third controls vertical position of occurrence. It is desirable to connect after mounting of screw support them among themselves. It can be done, having welded from the inside on pipes armature or having built grillage. The screw base is used only at construction of easy buildings, manages rather cheap, is built quickly. It is not necessary to have the shed, to store materials and tools, to knead water mortars.
Under heavy buildings the pile base is carried out with steel concrete grillage. The principles of the device same, as on columns. On screw piles the grillage is done metal, having welded on pipes channel or corner from two parties.
In conclusion we will tell that the column and pile bases are suitable not only for construction of houses and farm buildings. This economic and rigid base for porches, terraces, platforms, fences and other constructions.
Waterproofing and warming
The pile and column bases as well as other types, if necessary it is possible to waterproof or warm. From moisture apply standard ways to isolation: plastering or pasting by bituminous and polymeric materials, cement structures. It is necessary to tell that it is not always possible to achieve 100% of waterproofing. Completely it is possible to isolate column only on condition of its casting in removable timbering.
For warming use the materials which are not absorbing moisture: polystyrene foam, including extruded. As the grillage if it in general is, does not go to soil, often warm part of the base above the ground and blind area.