Ultra-lightweight concrete, which is also known as super lightweight concrete or infra-lightweight concrete, is a state-of-the-art concrete in terms of density and insulation properties and classifies as concrete with a dry density lesser than 800 Kg/m3. This density is the minimum limit for lightweight concrete according to the definition in standard EN 206-1.
Ultra-lightweight concrete is produced by carefully proportioning and mixing cementitious materials, lightweight aggregates, admixtures, and water. It is characterized by low to moderate compressive strength and low thermal conductivity, which makes it suitable for thermal insulation applications.
The ultra-lightweight concrete is considered an alternative to conventional multilayer facades due to its robustness, durability, energy-saving properties, and ease of construction.
- Cementitious materials like high-strength cement, blast furnace cement, limestone powder, nano-silica, alkali-activated materials (geopolymer), ground granulated blast furnace slag, powder coal fly ash, silica fume, micro silica, etc.
- Lightweight aggregates such as expanded glass, expanded clay, and foamed glass
- Admixtures like air-entraining admixture, shrinkage-reducing admixture, and polymer latex
- Other materials like polypropylene fiber, short polymer fibers, and glass fiber-reinforced polymer mesh
- Low to moderate compressive strength ranges from 1.5 to 15 MPa
- Low thermal conductivity
- The density of ultra-lightweight aggregate is less than 800 Kg/m3
Considerations for Production of Ultra-Lightweight Concrete
- Smaller sizes of lightweight aggregate result in higher compressive strength. However, a balance between large and small aggregates should be considered when low thermal conductivity is required.
- Proper grading of aggregate plays a critical role in producing ultra-lightweight aggregate.
- The best cementitious material for developing ultra-lightweight concrete is blast furnace cement because it results in moderate strength, lower thermal conductivity, and lower heat of hydration.
- Increasing cement content does not lead to proportional strength improvement due to the strength limit of lightweight aggregate. High cement content releases greater heat of hydration, initiating cracks.
- Limestone powder is the best option to replace cement and produce moderate compressive strength concrete and low thermal conductivity.
- Micro-silica and nano-silica increase the cohesion of the concrete mixture and significantly reduce bleeding and segregation.
- Rust of reinforcement in ultra-lightweight concrete should be considered due to its high porosity.
- Ultra-lightweight concrete can be used to construct panels suitable for surrounding walls and interior partitions.
- It is suitable for the construction of the façades of houses.
- Easy transportation.
- Speedy installation leads to reduced time and cost of execution. So, the time spent with construction equipment and manpower to execute the construction activities will be reduced.
- Decreased construction cost due to the reduction in dead load, steel bar, and concrete utilization.
- Sound Insulation due to its high porosity.
Ultra-lightweight concrete, which is also known as super lightweight concrete or infra lightweight concrete, is a state of art concrete in terms of density and insulation properties and classifies concrete with a dry density smaller than 800 Kg/m^3.
1. Cementitious materials like high-strength cement, blast furnace cement, silica fume, micro silica, etc.
2. Lightweight aggregates such as expanded glass, expanded clay, and foamed glass
3. Admixtures like air-entraining admixture, shrinkage reducing admixture
4. Other materials like polypropylene fiber and glass fiber reinforced polymer mesh
1. Low to moderate compressive strength ranges from 1.5 to 15 MPa.
2. Low thermal conductivity
3. The density of ultra-lightweight aggregate is less than 800 Kg/m3
1. Easy transportation.
2. Speedy installation led to reduced time and cost of execution. So, the time spent with construction equipment and manpower to execute the construction activities will be reduced.
3. Reduce construction cost due to dead load reduction, reducing steel bar and concrete utilization.
4. Insulate sounds properly because of its high porosity.
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