WATER ABSORPTION TEST ON ROOFING TILES

To determine the percentage of water absorption of roofing tiles

APPARATUS

A sensitive balance

SPECIMEN

Two tiles shall be used for this test from the sample selected.

PROCEDURE

(I) Dry the tiles selected in an oven at a temperature of 105 ° TO 110 °C till they attain constant weight and then cool and weigh ().

(ii)When cool, immerse the dry specimen completely in clean water at 27±2°C for 24 hours.

Remove each specimen, wipe off the surface water carefully with a damp cloth and weigh the specimen nearest to a gram () within 3 minutes after removing the specimen from the tank.

CALCULATION

Percentage of water absorption

Where =wt. of the specimen after 24 hours immersion in clean water

= wt. of the dry specimen.

RESULT

Water absorption of the given roofing tiles= ………………..%

Types of Tiles used in Building Construction and their Applications

Tiles in building construction are thin plates or elements used to cover surfaces like roofs, floors, and walls. Types of tiles and their applications are discussed.

Tiles in present scenario are a primary element in bringing building interior as well as exterior finishing and beauty. They are mainly made up of clay material or any form of inorganic raw material.

Nowadays tiles are also manufactured from recycled materials, making the element eco-friendlier. The shape of the tiles is obtained by the different processes like extrusion or pressing at room temperature or any other method.

After the shaping, they are allowed to dry. These dried elements are subjected to fire. This stage of firing is to ensure that they gain the required properties, that they are meant to acquire when they are in the market and in the building application.

Different types of tiles used in building construction are available in glazed or unglazed form. They are incombustible in its nature. Tiles are unaffected under the light.

Types of Tiles based on Application

There is a different type of tiles used in building construction which are unique to the type of surface where it must be applied.

Following are the types of tiles based on surface of application:

• Roofing tiles,
• Flooring tiles,
• Wall tiles, and
• Partition tiles.

The roofing tiles are earthenware that is baked products. Its manufacture is similar to that of brick.

The wall tiles as well as the floor tiles, are employed in the interior as well as the exterior of the building. This is mainly employed based on the requirement of decoration or aesthetics. These belong to the class of ceramics and are called as white wares.

Tiles that are used on walls and floor are available in both glazed and in the unglazed forms. Mostly the wall tiles are glazed by a thin layer of glazing when it is available in the market.

Floor tiles are too designed to bring the beauty of flooring and movement. But it is subjected to higher load, pressure and other undesirable material action. So, these tiles are made more durable, abrasion resistant, water impervious and easy clean form.

Floor tiles along with the mentioned properties should also provide good aesthetics. The degree of burning is the parameter that differentiates the wall and the floor tiles.

When compared to floor tiles, the wall tiles burned at a lower temperature. After this, it is glazed and re-fired at a lower temperature.

Type of Tiles based on Materials and Manufacture

Based on material and manufacture, following are the types of tiles used in building construction:

• Ceramic tiles or non-porcelain tiles, and
• Porcelain tiles.

Ceramic Tiles

Ceramic tiles are used for the interior floors, swimming pools, exterior floors, walls and for special installation both in interior and exterior cases.

Most types of tiles come under the category of ceramic tiles. They are made from a mixture of clay and other materials. They are fired in a kiln.

Following are the various types of unglazed and glazed forms of ceramic tiles:

1. Earthenware tiles
2. Terracotta and faience
3. Fully vitrified tiles
4. Glazed tiles
5. Stoneware Tile

The earthenware tiles are made of clay while the stoneware tiles have a large quantity of silica that is present in the form of sand, crushed stoneware etc. Silica in the stoneware tiles are added to prevent the shrinkage when the fixing process is carried out.

Terracotta tiles are manufactured by the use of high-grade fired clay. When the firing is done twice unlike the case of terracotta tiles, we obtain the faience. Faience initially is subjected to fire, that is initially terracotta. After glazing the terracotta tiles, it is again fired. This will finally give Faience.

The Faience is available in large variety of color change. This would help for improving the terracotta works.

Fig.: Terracotta Tiles

Fig.: Faience Tiles

Glazed and Vitrified Ceramic Tiles

Glazed and vitrified tiles ceramic are developed presently. The glazed tiles were only used for walls, at initial stages. Glazed ceramic tiles are mainly manufactured by two processes.

• Step 1: With the help of special white clay that is fired at a temperature of 1200 degree Celsius, the body of the tiles are made. These final elements are called biscuits.
• Step 2: The biscuits are accompanied by glazing and decorations if any, and are fired in the oven.

The glazes in ceramic tiles can be of two types:

• Earthenware glazes, and
• Colored enamels.

The colored enamels are also of different types.

• Bright or glossy surface
• Eggshell, vellum finishes
• Matt finishes

For different types of floor and different abrasion due to traffic, the glazing techniques can be improved.

Vitrified ceramic tiles are tiles that are made from clay materials plus other finely ground materials. These are subjected to a higher temperature firing. Fully vitrified tiles are those tiles whose whole thickness are also vitrified.

Vitrified ceramic tiles have higher abrasion resistance and can be employed in the areas of heavy traffic. These tiles are said to hard as granite. These are polished with the help of carbide or diamond abrasive tools.

When compared to vitrified tiles, the glazed tiles are not long lasting.

Porcelain Tiles

The manufacture, absorbing capacity and the breaking strength of porcelain tiles differ from the ceramic tiles. The porcelain tiles are also made from clay. But compared with the ceramic tiles, they make use of heavy or denser clay.

Porcelain tiles during manufacture are subjected to heavy temperature for a longer time. This baking is carried out until all the water present in the element is evaporated. This unique method of manufacture makes these tiles harder and denser compared to ceramic tiles.

This is the reason why porcelain tile is regarded as a superior product when factors of durability, design, color and value factors are considered.

Porcelain tiles are highly impervious to water. It has a water absorption rate lesser than 0.5%.

The cost of porcelain tiles is higher when compared to the ceramic tiles. The porcelain tiles gain more application in surface areas that have high traffic. These tiles are a type of vitrified tiles. It is sometimes referred to as porcelain vitrified tiles.

The porcelain tiles demand special cement for their installation. These tiles are harder and denser compared to ceramic tiles. So, when these tiles are used for wall surfaces, the cement that has high adhesive property are used.

The porcelain tiles that are polished are also available in the market. After firing of the tiles, they can be polished. This would bring a shine in the tile, without any glazing.

Types of RCC Columns and its Construction Methods

There are various types of RCC Column based on its shape, length and forces. Function and construction methods are discussed here for these types of column.

Column is a vertical member which takes complete load of the beam, slabs and the entire structure and the floor and other area of the building is adjusted as per the requirement of the client or owner.

The size of the columns, quantity of cement sand and aggregate to be mixed, the number of steel bars to be placed, spacing between the stirrups is all mentioned in the structural drawing which is designed by structural designer as per the actual load on the column and considering the factor of safety.

A column is a vertical member which effectively takes load by compression. Basically column is a compression member as load acts along its longitudinal axis. Bending moment may occur due to wind earthquake or accidental loads.

Column transfers the load of the structure of slabs beams above to below, and finally load is transferred to the soil. Position of the columns should be so that there are no tensile stresses developed at the cross section of the columns. Columns location should be such that it hides in the walls partially or fully.

Types of RCC Column and its Functions and Construction Methods

Types of RCC Column

Types of RCC Column based on Shapes

• Circular for exposed outside for good architecture view
• Square or rectangular traditional for any structure

Types of RCC Column based on length 

• Short column – if L/B<=12
• Long column – if L/B > 12

Where L is the height of the column, B is width

Generally, floor height is approximately 3 m or 10 feet, L/B ratio will be less than 12, so in maximum cases short column is placed. In case where height of floor is more than 3 m or 10 feet, we need to check L/B ratio so result may be long or short column. Generally, on long column there are more forces generated so should be designed carefully.

Types of RCC Column based on moments

• Biaxial column: Designed for axial load and moment in 2 directions
• Uniaxial columns: Designed for axial load and moment in 1 direction

Generally, in a building corner most columns are biaxial columns and side column is uniaxial column and internal columns can be any of these.

Construction Methods of RCC Columns

Construction of RCC columns involve following four steps:

• Column layouts
• Column reinforcement work
• Column formwork
• Pouring of concrete

Layout of Columns

Column layouts are done by laying rope in the grid lines and mark the location of columns

Column Reinforcement

Column reinforcement works needs following checklist on site:

• Check the numbers and diameter of vertical bars
• Spacing between vertical bars
• Check Development length which depends on diameter of bar
• Lapping in alternate bars should come at same height.
• Lapping should not come inside beam or slab.
• Lapping should be at l/3 or 2l/3 of column as per structural notes
• Spacing between stirrups is as per the drawing
• Hook should be bend properly at right angles.
• Check the stirrups corner. Vertical bar should come at right angle edge of stirrup properly bound with binding wire.

Column Reinforcement and Layout

Column Formwork

Columns carry the load of structure and hence they are critical. It is important to align them for verticality so that load is transmitted properly. The column shuttering should be strong enough to take the pressure of fresh concrete and remain in position during concreting.

Some Guidelines on column shuttering

• To hold the concrete shuttering firmly in place and for proper alignment a concrete pad called starter is cast before fixing the shuttering. The thickness is about 45 mm to 60 mm and dimensions are precisely the same as the dimensions of proposed column. The starter should be cured for a day or 2 so that it is hard enough to fix the shuttering around it.
• Column box or shuttering for columns is made of plywood sheets or steel sheets fabricated with adequate stiffeners.
• A thin films of oil or grease should be applied to inner surface of the shuttering to enable easy removal of the column after the concrete hardens.
• Shuttering should be properly aligned to its verticality and diagonals to be checked to ensure accuracy in dimensions.
• Formwork has to be thoroughly supported with props size before pouring the concrete so that it does not moves horizontally or vertically during concreting.
• The gaps near the shuttered joints should be sealed with plaster or a piece of wood to prevent any leakage of slurry.
• Appropriate space is to be provided in the inner face of the shutter and reinforcement by fixing cover blocks of about 40mm.
• It is preferable to remove shutters after 24 hrs. of casting and if they need to be removed earlier, it should not be removed within sixteen hours.
• The removal of shutters has to be done gently without jerks so that edges of columns are not damaged.
• Care should be taken regarding fixing and supports of column shuttering to prevent it from movement during concreting.
• Diagonals of the shuttering to be checked to ensure dimensional accuracy.

Concreting of RCC Column

Concreting of an RCC column can be done

• Manually
• With the help of machine or pump

Manual Concreting of RCC Column

Concreting of RCC Column using Pump

Following points to be followed during and after concreting:

• For less quantity machine mix concrete is done and for larger quantity ready mix concrete (RMC) is ordered.
• Approval of placing concrete whether by pump or manually has to be taken from client.
• Concrete should be poured up to slab bottom; the remaining column gets concreted during pouring of slab & beam.
• Mechanical vibrator to be compulsorily used in the column but excess vibration can cause segregation. Each layer should be thoroughly compacted.
• Target slump to be 160 mm.
• Height of pouring concrete should not exceed 1.5 m.
• Construction joint should be avoided in the column.
• Proper cover as per structural drawings to be maintained.
• Temperature should be below 30 degree while pouring concrete.
• After the pouring of concrete and vibrating it with the help of a vibrator the horizontality and verticality of column to be checked