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What is Ultra Lightweight Concrete?
Ultra lightweight concrete is a very low density concrete. The other name of ultra lightweight concrete is super lightweight concrete. It is a state-of-the-art concrete in terms of bulk density and thermal insulation properties and is considered to have a dry density of less than 800kg/m3. This apparent density is the minimum limit for lightweight concrete.
Ultra-lightweight concrete is made by thoroughly mixing cement-based materials, lightweight aggregates, admixtures and water. It has low to medium compressive strength and low thermal conductivity making it suitable for insulation applications. Due to its strength, durability, energy-saving properties and ease of construction, ultra-lightweight concrete is considered as an alternative to traditional laminated facades.
Ultra Lightweight Concrete Mix
Different types of raw materials such as high-strength cement, blast-furnace cement, limestone powder, nanosilica, alkali activator, blast-furnace slag pulverization, pulverized coal fly ash, silica fume, and microsilica are used to make light weight concrete.
Lightweight aggregates such as foam glass, expanded clay and foam glass are used in the design mix. Additives such as air entrainment additives, shrinkage reducing additives, polymer latexes
Other materials such as polypropylene fiber, short polymer fiber and glass fiber reinforced polymer mesh. Water is used to mix all the raw materials.
Properties of Ultra Lightweight Concrete
Due to low density its compressive strength is very low. It can not be used to pour structurul members such as beam and column. It posses low to medium compressive strength in the range of 1.5-15 MPa. Its thermal conductivity is low.
Density of ultralight aggregate is less than 800kg/m3.
Design Consideration
- The smaller the size of the lightweight aggregate, the higher the compressive strength. However, if low thermal conductivity is required, a balance between large and small aggregates must be considered.
- Proper grading of aggregates plays an important role in the production of ultralight aggregates.
- The best cementitious material for developing ultralight concrete is blast furnace cement. This is due to its moderate strength, low thermal conductivity and low heat of hydration.
- Increasing cement content does not lead to a proportional improvement in strength due to the strength limit of lightweight aggregates. A high cement content increases the heat of hydration and causes cracking.
- Limestone powder is the best choice for replacing cement and creating concrete with moderate compressive strength and low thermal conductivity.
- Microsilica and nanosilica increase the cohesion of concrete mixtures and significantly reduce bleeding and segregation.
- Due to the high porosity, a reinforcing grid of ultralight concrete should be considered.
Uses
Ultralight concrete can be used to build slabs suitable for perimeter walls and interior partitions. Suitable for building facades of houses.
Pros
- Easy transport.
- Quick installation saves time and execution effort. This reduces the time spent on construction equipment and personnel to carry out construction activities.
- Reduced construction costs by reducing the weight, iron bars, and amount of concrete used.
- It has excellent sound insulation due to its high porosity.
Drawbacks
Ultra lightweight concrete can not be used for structurul members. This type of concret can not be used to bear high amount of load.
Faq
What are the Uses of Ultra Lightweight Concrete?
Ultra lightweight concrete is used to make non-load bearing walls, panels and facades.