The assortment of ready-made concrete blocks is widely represented in the building materials market. It includes solid blocks for laying foundations and hollow blocks for building walls. This material is an alternative to brick walls and floodplain foundations. The properties of the blocks make it possible to build any object much faster.
Kinds of blocks
In manufacture blocks of different names and sizes are manufactured. In accordance with GOST 13579-78 the main types of blocks are:
• FBS - solid monolithic solid blocks.
• VBW - with cutout for installation of communications and jumpers.
• FBP - hollow blocks with open holes.
The alphanumeric marking of products consists of the designation of the unit name, length, width and height in decimeters and the type of concrete from which it is made( "T" - from concrete M100, "2T" - from concrete grade M200, "P"porous aggregate( expanded clay concrete), "C" - dense silicate).
FBS blocks are used for mounting the basic structure of the founda
In addition to those listed, foundation blocks FL are widely used, the requirements for production are defined in GOST 13580-85.Here, their standard sizes are determined.
Foundation blocks, dimensions according to GOST
In GOST 13579-78, a number of sizes of FBS units have been determined, allowing to design structures with the required bearing capacity:
• In height, there are two main grades - 280 and 580 mm.
• The widths of the blocks are graded in steps of 100 mm from 300 to 600 mm.
• In length, there are integral and additional gradation elements of 880, 1180 and 2380 mm.
In accordance with GOST, the foundation blocks FL have a length of 3 grades - 780;1180 and 2380 mm, have a width of 10 values from 600 to 3200 mm, and they can be 300 or 500 mm in height. These blocks have a specific trapezoidal section widening downward, which is why they are often called foundation pillows. These foundation blocks( slabs) are used mainly in the construction of country houses, other buildings, as well as in the construction of basement floors of buildings and cellars. They often act as a foundation for the ribbon foundations and allow a large footprint of the structure to be obtained.
As a rule, foundation blocks, the sizes of which are determined by GOST, are made of heavy concrete. Their construction must be reinforced.
Foundation blocks 20x20x40
The use of lifting equipment is absolutely essential for the use of FBS and PL units. The foundation blocks with dimensions of 190x190x390 mm do not have this disadvantage. The weight of such products is about 30 kg, which allows using only manual labor.
In the market there are several variants of such blocks from different manufacturers at a price from 35 to 75 rubles.a piece. Foundation blocks 20x20x40 are contained in one cubic meter of masonry in the amount of 62.5 pieces. The cost of the foundation of the blocks can be less than its device in the fill way.
Wall blocks 20x20x40
In addition to foundation blocks, there are variants of a similar size for sand-concrete or sand-cement blocks with voids for building walls and half the width for making partitions. Such a variety makes it possible to seriously compete with brick structures, because in terms of size and volume, one block replaces 7 bricks. As a result, construction is much faster, the masonry is more economical, durable and resistant to external aggressive environments. The appearance of the masonry is not inferior to brickwork and is suitable for painting.
Advantages of erecting block foundation
The erection of foundations from blocks gives such advantages over the way of monolithic foundation pouring: it does not require the obligatory construction of the formwork and allows to start laying the walls of the structure without waiting for the hardening of concrete. As a result, the work is accelerated, and the cost of the structure, based on the foundation blocks, is not much different from the jellied method.
What determines the cost of concrete blocks
The cost of concrete blocks depends on the availability of direct supplies from producers of raw materials, availability and remoteness of warehouses, transport and communications.
Mounting from blocks FBS of the tape foundations contains following stages of works:
• excavation of an excavation( trenches) for the basement;
• breakdown of axes;
• preparation of the substrate;
• achievement of the horizontality of the base;
• installation of foundation blocks;
• planned high-altitude survey of the finished foundation.
Breakdown of axes
When breaking down, move the axles to the base of the prepared foundation trenches. To do this, pull the axial strings and, using plumb lines, transfer the position of their intersection points to the base of the trenches. From the points obtained lay the dimensions that the foundation blocks have, and designate their position with metal rods, so that the pier spaced between them is 2-3 mm from the side faces of the foundation.
If the soil is sandy, then at this stage it is only necessary to level the base by level. With other soils, a cushion of sand 1 m thick is laid. Bulk or loosened soil under the pillow must be removed, falling asleep instead of rubble or sand. Grooves more than 1 dm are to be filled with concrete or butane.
Achieving the horizontality of the
base At this point, stationary inspection viziers are installed at the ends of the sections, the top of which must be higher than the base mark by the value of the running test viz. The control sights are checked on a daily basis by the level of the level. In the intervals between control sights, pegs are jammed into the ground so that the test vizor placed on them is on the horizon in the same plane as the control sights. As a result, the top of the pegs must correspond to the base level. Horizontality of the base is achieved by means of a rule with a level by adding or removing a layer of sand at the base level obtained. Sand base make 2-3 dm more than the size of the foundation.
units First install lighthouse blocks foundation at the corners of the foundation and in the places of its partitions. Installation of lifting equipment is carried out at a sufficient distance from the edges of the excavation to avoid its collapse. Once the beacon blocks have been installed, check the horizontality of their installation, transfer the cord-pier to the height of these blocks and make the installation of intermediate foundation blocks according to the laying scheme. The horizontality of the masonry is checked with the installation of each block, and it is impossible to shift the blocks in the base, it is only possible to lift them and re-install them after correcting the base defects. Slings lifting equipment removed only after the unit has been installed in the correct position. The end part of the FBS blocks has grooves which, after the next series of blocks have been completed, are poured with concrete. Each next row of blocks, except for the lower one, is installed on a concrete cushion from a fresh solution.
The planned high-altitude survey of the
foundation. The erection is completed by carrying out a planned high-altitude surveying with the help of geodetic instruments, marking the axial directions of the walls with risks. As a result of the shooting, an executive diagram is drawn up indicating the actual position of the foundation in terms of height and height.
On the basis of the data given in the article, we hope that you will be able to select the concrete concrete foundation that you need with the help of which you will be able to realize your dreams.