Uses of pointing in construction and its varieties
Pointing is a process of finished mortar joint of a wall or similar structure, usually formed from cement mortar or lime mortar that is used to protect the joints from atmospheric agents and also to improve the appearance.
During the pointing process, brick masonry and stone masonry mortar joints are strengthened and repaired. It is recommended to remove the old mortar joints that have cracked and disintegrated by hand or power tool and replace them with new mortar, preferably of the same composition.
Due to the difficulty of detecting defective points, and there may also be adjacent joints that need repairing, pointing is usually done in an entire wall or entire structure. In the deepest layers, it reaches a depth of 10 mm to 20 mm.
In construction, there are various types of pointing, including
- flush point,
- weathered point,
- keyed point,
- V-grooved point,
- beaded point,
- struck point,
- recess point,
- tuck point.
Motive of Pointing
Due to the reason of placing the mortar joints in the right position not only protects them from atmospheric influence but also enhances the appearance of the wall by displaying their pattern, thickness, colours, and texture.
Some of the uses of pointing work are as follows:
- Sealing the voids and spaces can prevent water from getting into joints and causing them to decay.
- A well-done and aesthetically pleasing pointing job reduces regular maintenance.
- At the joints of brick/stone masonry, it gives a strong and reliable bond finishing.
- Even in low precipitation regions, it has application in various places.
Mortar Used For the process of Pointing
Lime Mortar
For pointing work, lime mortar is prepared by mixing fat lime with fine sand in equal parts and then grinding the mixture thoroughly in a mortar mill.The most commonly used ratio in lime mortar for pointing work is 1:3 or 1:2
Lime Mortar is generally used in the pointing work of:
- New structures and buildings while using traditional methods.
- In old buildings.
Cement Mortar
Suitable proportions of cement, sand, and water are mixed to prepare cement mortar. Pointing work is generally done with cement mortar in a ratio of 1:3. To avoid early setting of the mortar, it should be used within 30 minutes of being prepared.
Pointing can be done on both new and old buildings.
Surkhi Mortar
It consists of lime and surkhi mixed with water in the right proportions. Pointing usually involves the use of Surkhi mortar of ratio 1:2. Surkhi Mortar is used for the pointing of old structures and buildings.
Varieties of Pointing
Flush Pointing
The mortar is filled and pressed into a mortar joint during flush pointing. A smooth finish is then achieved by finishing the bricks or stones flush with their edges. Lastly, a trowel and straight edge are used to neatly finish the edges.
A trowel or piece of rough cloth may also be used to wipe over the polished pointing.
- There is nothing appealing about it.
- It is durable because it prevents dust, water, and sand from accumulating.
- In building construction, it is one of the most common types of pointing.
Weathered pointing
A weathered point is accomplished by pressing mortar into a joint, and pressing the tops of horizontal joints by about 3-6 millimetres with the pointing tool while the mortar is still fresh. They are sloped from the tip of the joint to the bottom of the joint.
The weathering resistance of this type of joint is adequate, as implied by its name. This type of joint does require an exceptionally large amount of water.
Keyed Pointing
These keyed types of pointing are formed by trowel pressing mortar into joints and finishing it properly with the face of the masonry surface. After that, small-diameter steel squares (6 mm in diameter) are pressed lengthwise into the joint. An arc groove will be formed into a mortar joint. Also, the vertical joints will be formed in the same way.
Keyed mortar is first pressed into the joints then.
- Tools or small steel bars are used to form a semi-circular curve type notch.
- There is nothing better than the appearance of these types of pointing.
- The most common application of keyed pointings is for vertical wall joints, particularly those that are superior.
To get more details, watch the following video tutorial.
Video Source: Civil Study
V-Grooved Pointing (V Pointing)
In many ways, V pointing resembles keyed pointing. In order to create a joint, the mortar has to be filled and pressed.
A V shape tool is used to create the V-shaped groove in the joint. The name is derived because the shape of the pointing resembles the letter V.
This pointing is generally used in ashlar and rubble masonry work.
Beaded Pointing
In Beaded Pointing a steel tool with a concave shape is used to form concave grooves in a joint using the mortar pressed into a masonry joint shape.
The beaded pointing gives the mortar joint an excellent appearance, but it is prone to damage.
In spite of its good appearance, it is an unstable material that easily wears out and is susceptible to damage.
Merits of Pointing
- Some amount of weather resistance is provided by it for bricks and stones masonry.
- Pointing work can be used to reduce the entry of water through voids or spaces between brick/stone masonry.
- By insulating the cavities with repointing work, a wall's thermal properties can be maintained.
- Joints are prevented from cracking and shrinking.
- Using repointing work to insulate the cavities of walls will maintain their thermal properties.
- The cement mortar needed for this method is less.
- In addition, it reduces the chance of the brick wall being further damaged.
Demerits of Pointing
- Joint fillings are the only applications where it is reliable.
- In the wrong hands, it does not produce a smooth and plain aesthetic appearance.
- Brick/stone masonry may have defects even after pointing.
- The process of pointing can not be done in areas with heavy rainfall.
- Stonework with cracks may appear spider web-like if pointing is not sat properly.
- There can be difficulties painting brick masonry pointing and stone masonry pointing.
