Masonry is a crucial part of every construction process. A structure can be constructed out of bricks, stones, or other such materials. Rubble stone masonry is one kind of stone masonry that is frequently utilised to make walls in contemporary architecture. It can be categorised according to finishing, course continuity, and joint thickness. Stones are an affordable building material since they are widely accessible and prized for their strength and durability. The different kinds, characteristics, and elements of rubble stone masonry will be thoroughly covered in this article.
What is Rubble Stone Masonry?
In rubble masonry, rough and undressed (sometimes even just broken and not cut stones) stones are utilised to erect walls or other similar structures. This design has been a preferred option since ancient times since it gives the structure strength and durability. Some of our old civilisations used this technique to build defensive structures, proving its reliability. The length of the rubble stones, the mortar’s composition, and the mortar’s quality in filling in the spaces between the stones all affect how strong a rubble stone masonry structure is.
Components of Rubble Stone Masonry
Rubble stone masonry comprises stone and mortar.
- Stone
The stones used in masonry must be solid, hard, and free of sand holes, cavities, and other flaws. The availability of the stone and the significance of the structure determine which stone is used in a building project. Stones, including granite, marble, laterite, sandstone, and limestone, are frequently used in masonry.
- Mortar
Mortar binds masonry together and is made from sand, water, and cement or lime, creating a uniform mixture. Key factors for choosing mortar type include:
- Required strength
- Stone colour
- Expected structural loads
Types of Rubble Stone Masonry
The major classifications of rubble stone masonry are as follows:
- Coursed rubble masonry
In this construction style, the height of each stone in a layer or course is maintained to be consistent. The stones are not of the same size, whereas the course is also not of the same height. However, the outcome of the structure is uniform.
Application: This can be widely used in public buildings, residential properties, abutments, and piers of standard bridges.
- Uncoursed rubble masonry
This is the roughest and least expensive type of stone masonry. The stones are available in various sizes and shapes. The undressed stones are directly taken from the nearby quarry. In this type of construction, we find there is no consistent course. Smaller stones are used to fill in the spaces between the larger stones once the larger stones have been positioned. The following describes two common forms of uncoursed rubble masonry used in construction:
- Random Uncoursed Rubble Masonry
A masonry hammer is used to adjust the weal corners and edges of the course rubbles. And so, larger stones are added to strengthen the structure.
- Square Uncoursed Rubble Masonry
In this type of construction, the shape of the rubble stones is square. Hammers are used to dress the front side of the masonry and larger quoins are found at every corner of the course. Chips are not used for bedding.
- Dry rubble masonry
This masonry work is done without using mortar. The small spaces between the larger stones are filled by small stones only. There is no binding composition used between them.
- Polygonal masonry
Polygonal masonry is characterised by the use of stones shaped into irregular polygons. To avoid vertical facework, the stones are placed to create a polygonal shape for each layer to add natural strength to the structure. The vertical facework may weaken the masonry.
- Flint masonry
In places where flint is abundant, flint crushing is utilised. Unevenly shaped bits of silica are called flint stones, and they are extremely hard but fragile. Their lengths vary from 15 to 30 cm, and their edges are between 8 and 15 cm thick.
Properties of Rubble Stone Masonry
| S.no | Properties | Rubble Stone Masonry |
| 1. | Strength | High Strength |
| 2. | Durability | Excellent |
| 3. | Fire Resistance | Low |
| 4. | Handling | Requires lifting devices |
| 5. | Method of Construction | Quarrying, dressing |
| 6. | Cost | High |
| 7. | Use | Pier, Dam, Residential |
Construction Process of Rubble Stone Masonry
Rubble stones need to be tough, long-lasting, and hard enough to meet the required criteria for strength. Before being used, stones should be wet, roughly dressed, and uniformly sized and coloured. Make sure the stone fits snugly to prevent hollow areas in the wall. If at all possible, use step joints to protect masonry work from cracking; otherwise, try to maintain its level. To improve stability, insert through stones at regular intervals.
Avoid lengthy vertical lines in the face by positioning stones to break joints. Use headers, or through stones, every one to one and a half metres. If necessary, add artificial headers, such as RCC. Avoid seams that are too smooth, and make sure the mortar bonding is strong (approximately 20 mm thick). Keep the column faces and masonry 12 mm apart and maintain perfect vertical alignment. Use a wooden mallet and space expansion joints every 15 metres.
Application of Rubble Stone Masonry
- Ordinary buildings that require low height can be constructed using this type of masonry work.
- Residential buildings, boundary walls, godowns, etc. can use these for their strength and stability.
- While constructing public buildings, hospitals, schools, and modern residential buildings, this type of masonry can be used.
- In hilly areas, good-quality stones are naturally available, and this type of masonry is commonly used.
Advantages of Rubble Stone Masonry
This masonry has the following benefits:
- Enhanced fire safety, which makes it perfect for hearths.
- High resilience to weather, natural catastrophes, pests, and decay.
- Depending on the materials utilised, an attractive appearance might range from rustic to exquisite.
- Robust resilience and the capacity to support large compressive pressures.
- Greater thermal mass, which contributes to energy efficiency.
- Greater durability in comparison to alternative materials.
Disadvantages of Rubble Stone Masonry
The disadvantages of rubble stone masonry are as follows:
- Heavy stones make transportation difficult.
- Cracks can form if the foundation settles.
- Not suitable for rainy or freezing conditions.
- Construction is time-consuming.
Conclusion
To put it briefly, rubble masonry is a dependable construction style that blends conventional methods with contemporary uses. Rubble masonry may create sturdy and appealing structures if it is constructed properly. Rubble masonry can use naturally available materials to increase the aesthetic appeal of the construction. Due to its strength and durability, modern architects often integrate this method into new construction.
FAQ’s
The stones used in this kind of masonry are either loosely dressed or partially covered. The thickness of these structures varies. The quality of the mortar used, the use of long-through stones, and the appropriate filling of mortar between the stone joints and voids all affect how strong the rubble masonry is.