Lightweight concrete is a mixture of lightweight and coarse aggregates. Lightweight aggregates such as slate, clay, shale, shale, volcanic pumice, ash or perlite are used to reduce density.
Lightweight concrete is a special type of concrete manufactured for specific purposes. It is not used as often as regular concrete.
Difference Between Lightweight Concrete and Normal Concrete
The differences in the properties of normal concrete and lightweight concrete are as follows.
- The characteristic resistance depends on the standard under consideration. It is usually in the lower range.
- The content is also lower compared to normal concrete and is in the range of 1100 kg/m 3 – 1920 kg/m 3 .
- Use aggregates other than regular concrete.
- Aggregates absorb more water and therefore need to be soaked before use.
- Low thermal conductivity
- High heat resistance
Application of lightweight aggregates
- Construction of an additional floor on top of an existing building as it reduces the weight of the structure
- Use in new buildings
- Used for the construction of bridges, bridge decks, pillars, prefabricated elements, etc.
- Imposing buildings
- Used for insulation of water pipes, roofs, walls, etc. due to its low thermal conductivity and high resistance.
Types of lightweight concrete
- Lightweight concrete
As explained above, the production of concrete using low-density aggregates such as shale, clay, shale, volcanic pumice, ash or perlite falls into this category.
The main feature is the replacement of normal aggregate with this type of aggregate to achieve a reduction in concrete density.
- Aerated concrete, cellular concrete, molded concrete or aerated concrete
These types of concrete are made by introducing voids into the concrete to reduce the weight of the concrete. Air-entrained concrete does not fall into this category.
- No thin concrete
Thin concrete is not produced for special purposes but is lightweight concrete.
Fine concrete does not contain fine aggregates. However, the strength of concrete can be adjusted as needed by controlling the concrete mix.
The article about no thin concrete More information about the purpose of projection and its technical parameters can be studied.
Properties of lightweight concrete
Durability of lightweight concrete
- There is a better bond between the lightweight aggregate and the cement paste. Therefore, it has good homogeneous properties. So there is less chance of concrete cracking due to shrinkage, creep, thermal deformation or stress.
- Lightweight concrete has greater fire resistance.
Water resistance
- During construction it absorbs more water. Therefore, we soak the aggregate before making concrete. However, these types of concrete have better waterproofing properties compared to normal concrete.
- Increasing the proportion of lightweight aggregates in concrete leads to an increase in water permeability.
- At greater depths, water can penetrate the concrete.
Chloride attack
- Several studies have shown that the penetration of chloride ions into lightweight concrete is similar and even lower compared to normal concrete.
- Furthermore, no significant corrosion of the reinforcement was found compared to normal concrete.
Carbonation
- This type of concrete has greater permeability to gases due to its greater porosity.
- The crowning glory of concrete is the penetration of carbon dioxide into the concrete.
- Due to greater porosity, carbon dioxide penetrates concrete more easily compared to normal concrete. Therefore, concrete has a greater depth of carbonation compared to normal concrete.
- Furthermore, the higher moisture content of lightweight concrete due to the higher porosity of the concrete leads to increased carbonation of the concrete.
Advantages of lightweight concrete
- Easy to transport
- Low thermal conductivity
- High heat resistance
- It has good workability
- Unlikely to collapse, although slight
- Due to the higher water content, drying takes longer, but the properties are not significantly affected.
- Can be used as an alternative material
- Due to the lower weight of the structure, the dimensions of the structural elements and the foundation can be reduced.
- Construction is comparatively economical due to weight reduction of the structure
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