What are ground floors? List some of their types?
The floors constructed at plinth level of different buildings are called ground floors. These floors are connected to provide a clean, smooth non-absorbent and durable surface to live at ground levels of buildings.
These floors may be consisting of bricks, stones, concrete, woods, etc. Since a ground floor rests directly on the soil when not accompanied by a basement floor, its base usually consists of the following two layers:
a) 100mm thick layer of coarse sand over consolidated earth or murum filling. of concrete is known as base concrete.
b) 100mm thick layer of lime concrete (1:4:8) or lean cement concrete (1:8:16). This layer Sometimes, rubble filling also known as hardcore consisting of gravel pebbles or dry bricks having 50 to 100mm thickness is provided over the sand over the sand.
The purpose of providing the layer of course sand is to provide rise of moisture due to capillary action and to prevent in dampness through the floor.
The purpose of rubble filling or hard core is to increase the strength of the base of the floor. The object of providing lime or cement concrete layer is to have solid bed or base for floor covering.
The various materials used for floor covering of ground floors are bricks, tiles, concrete, terrazzo, mosaic, etc.
Types of ground floors
Types Ground floors are mainly classified into the following types:
1) Murum or mud floors: The ground floor having its topping consisting of murum or mud is called murum or mud floor. These floors are cheap and easily repairable. But these floors do not provide an impervious structure.
2. Brick floors: The floors having its toppings consisting of bricks are known said brick floor. This floor can be easily constructed and repaired. But this type of floor provides a rough surface. They can easily absorbs moisture from the surrounding areas and may cause dampness in the buildings.
Difference between Ground Floor, Basement Floor and Suspended Floor | Civil Engineering
3. Tile floors: The floor having its topping consisting of tiles is called floor. The tiles used in a tile floor may be of desired quality, shape thickness and colour. Following are the sizes of floor tiles commonly used:
1. 150mm x 150mm x 15mm
2. 200mm x 200mm x 20mm
3. 225mm x 225mm x 22mm
4. Flag stone floors: The floors having its topping consisting of stone slabs are known as flag stone floor. The stone slab to be used to be used in such floors may or may not be of the same size but these slabs should not be more than 0.75m in length and not less than 350mm in width and 38mm in thickness.
5. Types of cement concrete floors: These are of two types
a) Non-monolithic or bonded fish concrete floors: The cement concrete floor having not laid monolithically with the base concrete is known as non-monolithic or bonded fish concrete floor. In this type of concrete floor, topping is laid on the third day of laying the base concrete. Thus, the floor provides a non-monolithic construction. The base
concrete consists of 100mm thick lime concrete (1:4:8) or lean cement concrete (1:8:16) which is laid over 100mm thick clean sand spread over consolidated earth.
a. Monolithic finish concrete floor: The cement concrete floor having its topping consists of 20mm thick cement concrete (1:2:4) laid monolithically with the base concrete is known as monolithic finish concrete floor. In this type of concrete floor, the topping is laid within 45 minutes to 4 hours after placing the concrete.
List out the specifications for different types of floors?
Following are the specifications for all types of floors:
1. Unless otherwise specified, the base course for all floors in contact with the ground shall consist of:
a.100mm of stone layer or stone filling;
b. Anyone of the following layers:
I. 100mm of lime concrete
II. 100mm lean cement concrete (1:8:16)
Ill. Flat single brick or flat brick blocks, having 25mm wide joints filled with cement concrete (1:2:4)
2. The earth filling shall be stopped at such a height as to allow full thickness of sand, base concrete and the correct thickness of surfacing.
3. In areas, where the water table is near the ground level, a suitable treatment shall be provided to prevent the rise of moisture into the floor.
4. A reference level shall be marked all-round on the walls 150mm or so above the floor level with the help of a water level.
5 Base concrete shall be made in a uniform layer of 10cm thick absolutely true parallel to the required surface.
Specifications for conglomerate floors
The specifications for conglomerate floors are as follows:
1. Unless otherwise specified, conglomerate flooring on the ground floor shall consist of a pavement of 25mm, 38mm or 50mm thickness of cement concrete topping laid over 100mm thick layer of base concrete and 100mm of coarse sand.
2. In case of a suspended floor, the conglomerate topping required thickness shall be laid over the base concrete of about 38 to 50mm thickness over the R.C.C slab without any provision of layer of sand.
3. Where the conglomerate topping is equal to or less than 38mm thickness, the coarse aggregate shall be of 10mm nominal size and where it is of more than 38mm thickness, the coarse aggregate shall be of 15mm nominal size.
4. The slump of cement concrete to be used for conglomerate topping shall not exceed 38mm.
5. The cement concrete shall be laid in panels not exceeding 1sq mtr in area and the maximum dimension of each panel shall be 1.5mm.
Specifications for terrazzo floors
The specifications for laying terrazzo are given below:
a. The marble chippings shall be of 3mm gauge or as specified by the engineer-in- charge. The dividing strip shall be of aluminium, brass, copper, zinc, ebonite etc. at least of 20 gauge.
b. The under layer of 32mm thick cement concrete shall be laid in panels as discussed in case of conglomerate floor except that no trowelling of the surface is to be done.
c. The cement and pigment shall be mixed dry with the marble chippings in the ratio of 1 cement and 1¹2 marble chippings. The mixture shall be well turned over adding just enough water to obtain a fairly dry but workable mixture for laying the finishing coat of the terrazzo floor.
d. The terrazzo mixture shall be laid on the under layer in a slightly more than 6mm thickness so that after rubbing down, the finished face is not less than 6mm in thickness.
e. The surface of the top layer shall be temped and brought down to the required levels by using a straight edge.