The word masonry is derived from the word “Mason”. Masonry walls are the upright construction having much length and height than breadth; build by joining and stacking of masonry units which can be easily held on hand, with the binding material.
Depending upon masonry units whether they are stone, bricks, tiles, blocks, or concrete blocks they can be distinguished into different types.
So, the Stone masonry wall is a type of wall in which the units of masonry are used as stone. Depending upon the types of mortar and arrangements of stones they are further can be categorized into a different class.
Stone masonry is one of the very old ancient techniques to perform construction work. Thus most of the ancient and historical monuments are made of stone masonry works.
For the stone masonry wall, the stones are needed to be quarried and crushed from rock sources, so that they can be made masonry units, i.e. easily held in hand and can be made easily lifted during construction by a mason.
Moreover, for proper arrangement of such stone over the wall and smooth & good appearance of the wall faces they have further proceeded for dressing operation.
Stonemasonry wall is generally used to build retaining walls, barriers, river training works, gravity dams, etc. because of its high self-weight and easy & economical method of construction.
However, they are also used for structural purposes, for building houses in very rural areas in the traditional way. And sometimes to preserve and restore the historical, traditional, and aesthetic values of the monuments, they are used for rehabilitation and reconstruction works.
In the rural area and hilly area where there is abundant availability of rock and are not developed; stone masonry walls are popularly adopted to build one or two stored buildings.
Types of stone masonry wall
A) On the basis of the stone and its arrangement
1) Random rubble stone masonry retaining wall
In such masonry walls, stones are randomly laid during construction with no or very little dressing of the stone. There is no definite course of layers of stone, thus they are also known as Un-coursed rubble mass.
The dressing is minimum in such walls, thus no proper shape arrangement is required for such walls and gives a rough finishing appearance. Due to this reason, they can be categorized as low-cost construction works.
They can be abundantly found used for the Retaining walls, River training works where appearance has no any importance.
However, when there is the abundant use of nearly square-shaped stones, they are simply known as Square un-coursed rubble stone walls, such walls have definite shape and appearance but the courses are not of uniform height stones.
2) Coursed Rubble masonry
Here, stones are laid very uniformly as well as in dressed manner. Each course has a nearly equal height of stones (15 cm – 30 cm). The same height of each course might not be achievable, at such conditions any course shouldn’t vary bigger in size in comparison to the course below it (allowance for varying height is 2 -4 cm).
This wall has relatively good dressing and is so compactly arranged rubble stone masonry. So they are used for general construction and high strength. So can be used for structural units and foundations.
If the stoned used are nearly squared shaped or dressed, and each stone has nearly the same height and arranged uniformly over a single course, then they are simply known as Square Coursed Rubble masonry wall.
3) Ashlar masonry
In such masonry wall, the stones are well dressed (sometimes even polished and chamfered) brought on accurate shapes. They are very useful for decorative purposes and increase the aesthetic beauty of the structure.
Stones are dressed by different cutting tools like a chisel, hammer, mechanical cutter exactly as to the shape of bricks. They are further divided into different types according to the dressing operation of the stones.
- Ashlar Fine tooled: Wall face with very smooth polished texture face
- Ashlar rough tooled: Wall face with rough-looking on touch
- Ashlar rock-faced: Naturally roughed-looking undressed stone face are aligning to the exposing face of the wall.
- Ashlar chamfered: Blocks are chamfered at edges of the wall facing planes. Chamfered is 45° up to 20mm- 25mm.
4) Polygonal masonry wall
These walls have polygonal-shaped dressed stones. Thus they give a polygonal arrangement appearance.
There is no distinct separation of courses of stone. These walls have very good bonding and joints, as there is complete negligence of the vertical joint with interlocking structure. These kinds of walls are also favorable to build the arch structure.
5) Laterite Stone masonry
These are the special type of wall in which stone named Laterite is used and arranged in a very compact manner. These stones are abundantly found near the iron sources and are thus red in appearance.
The rocks are freshly quarried, dressed, and used for the construction of the walls so that, after long exposer to the environment they gain high strength and hardness.
B) On the basis of mortar used
- Cement mortar stone masonry wall
- Mud mortar stone masonry wall
- Lime mortar stone masonry wall
Dry stone masonry wall: In such masonry wall there is no use of any mortar or binding material. The stones are just laid and stack one over another. Used generally for temporary barriers.
Advantages of Stone masonry wall
- Stonemasonry walls have very high self-weight. And thus very advantageous to build the structure like gravity dam, the foundation of the building, etc.
- Stone has very less water absorption about 1.5% only|(20 times lesser than brick). So, these wall causes less dampness to the wall surface.
- The stone masonry walls are more durable in damper places as it doesn’t absorb water much and weather easily. Thus it is advantageous to use for high groundwater table area, underground foundation.
- They are completely fire resistant
- They increased the aesthetic beauty along with natural appearance, and are very suitable for old moments and temples.
- They are a cheap method of construction for areas with abundant stone and rocks.
Disadvantages of stone masonry wall
- Dressing of stone consumes a lot of time and labor. So not useful for massive and fast construction works.
- Thickness is generally kept more than needed from structural design consideration. Thus they consume more space and have less space efficiency.
- Only suitable for the 2 – 3 stored building
- Cannot be used for the partition wall and panel wall
- No toothing can be allowed on such walls. So all walls are needed to be built at the same time.
- Rock or stone should be hard, sound, and free from weathering, cracks, and holes.
The construction process for masonry wall can be explained as below:
- Selection of rock or stone: Rock from where the stone for the masonry work is obtained or quarried should be hard, and free from weathering, cracks, cavities, and injurious veins. The stone should be such that it shouldn’t absorb water more than 5%.
- Crushing and dressing of the stone: Stone is then crushed into the required size and the dressing operation is done according to the required amount of accuracy and finishing needed (or types of stone masonry).
If the wall is a general retaining rubble wall, simple dressing by means of the hammer is performed. If the wall is needed for the smooth ashlar wall then, they might even need to be cut with a mechanical cutter.
The minimum size of crush stone is generally 10 cm -15 cm
- Stones are well wetted in water before subjected to use(laying).
- Laying of stones: The stones are then laid by skilled Mason, along with suitable mortar spread. The work is carried by a skilled mason along with the use of plum bob to attain verticality and help of thread to keep desire alignment (and slope in case of retaining walls)
During laying stone few things must be taken in consideration. They are:
- The dress face of the stone should always be aligned in the exposing part of the wall
- The larger stones are kept at the faces and the smaller at the heart of the wall
- Through stones are the bigger stone relatively of equal width as that of the wall (up to 600mm of the wall) are needed to be laid at the plinth, sill, lintel, and roof levels as much as possible. There should be at least one through stone (also called bond stone) for every 0.5 m2 area facing the surface plane of the wall.
- Stone is needed to align in the natural bed plane of stone and is needed to be embedded solidly in mortar by hammering with a mallet or hammer.
- Stone chips (small fragments of crushed rocks) are needed to be filled in the heart (middle) of the wall to avoid a thick mortar joint. But they should be spread in the void after laying a stone in the heart.
- The uniform layer of mortar of definite thickness should be laid over each layer
- The wall must be made only up to a height of one meter at a single time of construction
- All the connected walls are needed to be built uniformly at the same level by laying stone uniformly all over the same time. There should not be the formation of toothing in stone masonry. If one part of the wall is needed to be left and then later to be filled, then the adjacent joining stone walls should be racked at 45° angle.
- During the laying of the stone, like in brick masonry, the vertical joints must be break by suitable selection and fitting adjacent stones.
- The joints are then, completely filled with the mortar. Facet joints are needed to be maintained around 20mm thickness.
- The top of the masonry wall is usually sealed with a stone. But in lack of such stones, there is a general adaptation of laying the concrete of a certain thickness.
I hope this article on “Stone Masonry Wall” remains helpful for you.
Happy Learning – Civil Concept
Civil Engineer – Rajan Shrestha