Sand is the most widely used material for constructing buildings, bridges, and roadways. Mostly, aggregates are used to achieve strength and load-bearing capacity. However, due to the scarcity and high cost of natural river sand and other aggregates, alternative sand types are being used.
One such type is moram sand, a type of laterite sand. It is used for various purposes in the field of construction, alongside other construction materials. In this article, we will learn about the properties of regional moram sand and its applications.
For clarity and consistency, this article uses ‘Moram‘ to refer to the sand type, acknowledging regional spellings such as Moorum, Murum, or Moram.
What is Moram Sand?
Moram is a locally available sand which is formed through breakdown of rocks. It is available in the regions of tropical and subtropical areas. These areas are subjected to heavy rainfall and high temperatures. Due to this process, rocks are weathered down and lead to the accumulation of sand.
Moram doesn’t contain humus because organic matter is rapidly decomposed and carried away by rain. This sand contains an accumulation of iron oxide and aluminium. The silica content is also leached away. The presence of iron gives it a dark red and brown appearance.
Moram sand has low compressive strength and is porous in nature. It is used as subgrade material in the construction of buildings, roadways, and filling plinth areas for its low-cost factor.
Composition
Moram sand is made of
- Sand and gravel particles (60-70%)
- Silt (20-30%)
- Clay (10-20%)
The appearance and gradation of particles vary from region to region. This variation is based on weather conditions and the parent rock from which it is formed.
As already discussed, Moram sand is rich in iron oxides and aluminium. The Moram sand looks reddish-brown in colour due to its iron content. Moreover, the iron and aluminium content cause degradation to plant growth and cause acidity in the sand.
Properties of Moram Sand
In India, Moram sand is abundant in the states of Tamil Nadu, Odisha, Kerala and other regions of the Northeast. Moram sand properties vary based on the weather conditions in these regions. There are some geotechnical properties to understand the quality of Moram sand which are discussed below.
Specific Gravity
Specific Gravity of sand helps understand how it behaves under different moisture levels. It is an important aspect to understand whether sand has the load-bearing capacity. Moram sand has a specific gravity of 2.6-2.7. It means it is heavy in nature. It can provide stability to a moderate level if it is compacted well.
Liquid Limit
Usually, sand tends to absorb and hold water. It influences the workability and strength of sand. To find out this, the liquid limit of a sand is calculated. For instance, Moram sand has a 41-42 % liquid limit which is high. It means it changes shape under different moisture levels. It easily changes from plastic level to liquid level.
As Moram sand has a high liquid limit, it is prone to settlement and deformation. Think of a wet clay, when we add water, we can mould into any shape. But if we add more water, the plasticity of clay changes to liquid. Though it is moldable into any shape, it is unstable.
That’s why Moram sand is stabilised before use for construction purposes. So, the strength and volume of Moram sand are not balanced when it is exposed to high water content.
Plastic Limit
Plastic limit is essential to understand sand stability and settlement behaviour. It determines the moisture content at which sand starts to crack when remoulded. The plastic limit of Moram sand is 19-20%.
This indicates that it will start to crack when a certain stress or force is applied. Hence, Moram sand exhibits moderate workability and strength.
Plasticity Index
Plasticity refers to a sand’s ability to resist cracking or breaking while undergoing deformation. The plasticity index is calculated by subtracting the plastic limit value from the liquid limit value.
High plasticity index indicates soil’s vulnerability to settlement and deformation. It means the soil is mostly of clay or colloidal nature.
Moram sand’s plasticity index value ranges from 22-23%, indicating slightly high plasticity. As a result, Moram sand has deformation and settlement issues.
Optimum Moisture Content and Maximum Dry Density
The ability of sand to be compacted is crucial for understanding its load-bearing capacity and stability. At optimum moisture content (OMC), sand can be compacted to achieve maximum dry density.
Compaction is usually done through pressing, tamping, or vibrating sand to densify it. If the water content is below this level, it is difficult to attain Maximum Dry Density. In simpler terms, sand cannot be properly compacted and densified, leading to settlement issues.
Unconfined Compressive Strength
The compressive strength of sand enables it to support structural loads under pressure. Unconfined compressive strength of sand is found when pressure is applied vertically and not horizontally. It shows how it withstands pressures at constant vertical force.
Moram sand has an unconfined compressive strength of 180-185 KPa. It shows that moram sand has low to moderate compressive strength.
California Bearing Ratio
California Bearing Ratio (CBR) is calculated to find the strength of sand. It shows whether sand has the stability to support loads. To find out this, a piston is inserted into the sand to a certain millimetre level. It is compared to the penetration done on hard stone or rock.
If the penetration is comparatively stiffer, the sand has a stronger subgrade level. moram sand has a CBR of 9.6-9.8% which is low. It means moram sand is suitable for low-rise buildings, roadways, and filling purposes.
| Property | Values |
| Specific Gravity | 2.6-2.7 |
| Liquid Limit | 41-42 % |
| Plastic Limit | 19-20 % |
| Plasticity Index | 22-23 % |
| Maximum Dry Density | 1.6-1.7 gm/cm3 |
| Optimum Moisture Content | 13-16 % |
| Unconfined Compressive Strength | 180-185 KPa |
| California Bearing Ratio (soaked) | 9.6-9.8 % |
Stabilisation of moram Sand
For construction, we need cost-effective as well as high-quality sand. moram sand, although readily available and cost-effective, has limitations for projects due to its reduced stability, porosity, and settlement issues.
Despite these challenges, moram sand is widely used in road construction in India. However, for road construction, stability and compressive strength are crucial. To address this, moram sand is stabilised using various materials.
Simply put, sand stabilisation enhances sand properties, converting it into a stronger construction material.
In studies, it was found that adding a mixture of coconut fibre and sawdust increases the strength and compaction of moram sand. A 2% mixture was added along with 50% water to the sand sample. After 2 days, the moram sand showed increased strength.
In another study, Terrazyme, a natural compound found in fruits and vegetables, was used as a stabiliser. Terrazyme acted as a protective layer in the moram sand, preventing water infiltration.
As a result, moram sand showed reduced permeability and water absorption and increased compaction. So, stabilising moram sand in this way makes it an ideal sand for road construction and pavements.
Uses of moram Sand
moram sand is utilised for various purposes due to its availability and properties.
Road Construction
In India, moram sand is majorly used in road construction because it is easy to compact. It is the primary base of roads and it supports the other base materials also.
The long network of roadways is made possible through using this cost- effective sand. It helps in promoting the economics of India by reducing cost.
Plinth Filling
We have seen the construction of homes where a type of red sand is heaped over in the plinth areas. This is moram sand, characterised by its larger particles and higher density, which effectively fills gaps.
It serves as a sub-grade sand, providing a stable base for the structure. Other aggregates are often mixed with moram sand to further enhance its stability.
Once the moram sand is poured into the plinth regions, water is poured over it. After the moram sand has soaked well in the water, the layer of sand is compacted well using vibrators. The Plinth Filling process reduces water permeability and increases the strength of the sand.
Backfilling
moram sand is ideal for backfilling purposes, as it reduces voids and provides a proper base. In some homes, sand is used to level empty or uneven spaces.
moram sand can be used to level up areas where sand has been eroded or removed. Specifically, moram sand can be effectively utilised in slope areas, such as car parking slopes and entrance ramps of homes, to create a stable and even surface.
Landscaping
moram sand is useful for landscaping purposes. Its porous nature and good drainage make it ideal for gardens, parks, and playgrounds. It prevents waterlogging, reducing the risk of sand erosion. moram sand’s stability also supports slope areas and prevents landslides.
Limitations of moram Sand
- moram sand cannot support heavy structures and is not ideal for building structures. The reason is its loose structure and unbalanced volume at different moisture contents.
- moram sand is acidic in nature and has a low water retention capacity, making it not ideal for high-fertility crops.
- As it is porous in nature, the process of compaction is quite difficult.
- Additionally, moram sand can generate dust and spread it to surroundings, causing pollution.
Conclusion
To conclude, moram sand has its own unique properties along with some limitations. Despite this, it can be used for specific purposes. Moreover, they are environmentally friendly and don’t cause harm like manufactured sands. By following proper standards, moram sand can be effectively used for construction and agricultural purposes.
FAQs
Yes, moram sand is a type of laterite sand with a high amount of iron oxide and aluminium.
Moram sand is used as:
Filling material
Base material in roadways
For cultivation of specific crops (like tea, coffee, and rubber)
Moram sand is found in tropical and subtropical regions which have heavy rainfall and high temperatures.