In the construction industry, masonry is unavoidable in the process of any building construction. It is a process used in the construction of the walls, columns, lintels, arches, beams, etc. of a building. The core of a wall is faced with masonry such as brick or ashlar. Stones are abundant in nature. Proper usage of such stones can provide an economical material for the construction of various parts of the building. Based on the thickness of joints, continuity of courses and finish of the face, stone masonry can be classified into different types. This masonry is divided into two types which further get divided based on several aspects. Rubble masonry and Ashlar masonry are the two types of stone masonry. This Rubble and ashlar masonry is divided into several types. One such type of rubble masonry is square rubble masonry. This article gives a detailed brief on square rubble masonry and its advantages in the construction industry.
What is Square Rubble Masonry?
This type of stone masonry consists of stones whose corners are shaped into squares by the methods of hammering or chiselling the stone. The stones need not be of the same size. The different sizes of stones can be fitted in equal courses if coursed every third or fourth stone. The usage of this type is often used in hilly regions. Because these are the places where good quality and cheap stones are available. This factor results in it being the least expensive type compared to the other masonry. The stones used in this type are taken straight from the quarry. The square appearance of stones classifies this type of square rubble masonry. In every construction that uses square rubble masonry, the front side has a hammer-dressed finish.
Application of Square Rubble Masonry
Foundations: This masonry is used for constructing strong and durable foundations in soil conditions that require solid, long-lasting construction. This could even be used in retaining walls to hold back soil or water. This is achieved with better interlocking and stability that comes from the irregularity of stones.
Boundary walls and Fences: The availability of local materials and their cost-effectiveness make them highly preferable for the construction of boundary walls or fences. The appearance of a traditional rustic look along with the providence of strength and durability is another factor for preferring square rubble masonry.
Bridges and Culverts: In rural or historical settings, square rubble masonry provides the necessary structural support. It becomes highly advantageous for smaller bridges or culverts where there is no need for precision stone cutting or when using locally available materials.
Retaining Structures for Landscaping: The traditional rustic appearance and the randomness provide structures with a sense of natural beauty. This makes them preferable for building low retaining walls, garden features, or decorative stonework.
Agricultural Structures: Square rubble masonry can also be used for agricultural buildings like barns, silos, and storage tanks. This type is preferred in rural areas where the locally sourced stone is abundant. They can even be used to create durable structures.
Construction Process of Square Rubble Masonry
Site selection and choosing appropriate stones for the masonry are the key initial steps. One should look for abundant local stones that can be shaped to interlock well with each other. Mortar is prepared and the first course or layer is prepared with the use of the largest and most level stones. Then the prepared mortar is applied to create a strong bond between layers. Even though these masonries are not uniform, we must ensure the bond between them is as tight as possible. Subsequent layers are built enhancing the stability of the wall with the interlocking pattern. As the height of the wall increases with the addition of every layer, frequent verification with a level and plumb bob is required. This measurement ensures that the structure is both straight and stable. If it is a retaining wall, then backfilling and compaction should be done. Finally, the smoothening of walls with mortar improves the aesthetic and durability of the masonry.
Advantages of Square Rubble Masonry
- This type of masonry improves the fire resistance of the building. This results in increased fire protection.
- They provide resistance against rotting, pests, weather, and natural disasters.
- Depending on the material used, they provide an attractive rustic or elegant look.
- They provide high durability and are resistant to compressive weight loads.
- The usage of these masonry units increases the thermal mass of buildings.
- They provide longer lifespans as this masonry is extremely strong and can last for centuries.
- Usage of local materials in the construction of the masonry can contribute to sustainability.
Disadvantages of Square Rubble Masonry
- The construction process is a bit complicated as it involves heavy stones. Transporting massive stones before using them is not easy.
- There is a high possibility of developing cracks if any settling of the foundation occurs.
- The process of setting masonry cannot be done in rainy or freezing conditions.
- The need for precision stone cutting demands skilled labour for proper fitting and mortar application.
- Their irregular appearance does not match the sleek or uniform look that some modern constructions prefer.
- It consumes a considerable amount of time.
Cost and Maintenance of Square Rubble Masonry
The two major cost-contributing factors in the construction of square rubble masonry are stone and mortar. In addition, labour costs, tools and equipment, and transportation costs are added. As a ballpark value, the construction of a simple square rubble masonry wall could cost around 4000 rupees to 8000 rupees. In terms of maintenance, regular checks on cracks and settling, mortar deterioration, erosion and weathering, and structural integrity can increase the endurance of the structure.
Conclusion
A square rubble masonry is a form of building that has been in practice for many centuries and combines elements of strength, toughness, and beauty. It’s also a masonry technique that’s cost-effective and environmentally friendly as it uses stones sourced from the vicinity. Even though it is labour-intensive, involves skilled workers and is expensive to prepare, the merits of such a masonry technique outweigh its weaknesses. Apart from the ability to provide construction works that can withstand the test of time for the next hundreds of years, it is a significant resource in the construction industry. In the future, as we look out to build efficient and pleasing structures, it will be vital to learn and adopt traditional techniques like square rubble masonry.