Properties and Applications of Ultra-lightweight Concrete and its differences from Traditional Concrete
Lightweight concrete with a dry density of less than 800 kg/m3, called ultra-lightweight concrete or super lightweight concrete, is a state of the art concrete in terms of density and insulation properties.
By carefully proportioning and mixing Cementitious materials, lightweight aggregates, admixtures, and water, ultra lightweight concrete is produced. Low thermal conductivity and low compressive strength make it suitable for thermal insulation applications.
Features of Ultra-lightweight Concrete
Low to moderate compressive strength, as well as low thermal conductivity, defines ultra light concrete. Ultra lightweight aggregates have a density below 800 kilograms per cubic meter.
The density of lightweight concrete must not exceed this value. In addition to its robustness, durability, and energy saving properties, ultra lightweight concrete facades are easy to construct.
Materials of Ultra-lightweight Concrete
This type of construction process requires water. Materials such as Cementitious materials are briefly mentioned below:
1. High strength cement.
2. Blast furnace cement.
3. Limestone powder.
4. Nano silica.
5. Alkali activated materials.
6. Ground granulated blast furnace slag.
7. Powder coal fly ash.
8. Silica fume and micro silica.
Foamed glass, expanded clay, and expanded glass aggregates are lightweight aggregates. They incorporate air entraining admixtures, shrinkage reducing admixtures, and polymer latexes in the composition.
Polypropylene fibers are also used, as are short polymer fibers and glass fiber reinforced polymer meshes.
Key Guidelines for Ultra Lightweight Concrete Preparation
1. Lightweight aggregates with smaller sizes have a higher compressive strength.
2. Low thermal conductivity is required for a proper balance between large and small aggregates should be considered.
3. For ultra lightweight aggregate production, proper grading is critical.
4. Due to its moderate strength, lower thermal conductivity, and lower hydration temperature, blast furnace cement produces ultra-lightweight concrete.
5. Because lightweight aggregate has limited strength, increasing cement content does not lead to various proportional strength improvements. Cracks are more likely to develop in cement with high cement content.
6. A high compressive strength concrete with low thermal conductivity can be produced with limestone powder instead of cement.
7. Concrete mixtures with micro silica and nano silica are more cohesive & reduce bleeding and segregation significantly.
8. As a result of its high porosity, ultra lightweight concrete is prone to corrosion of reinforcement.
Difference between Ultra Lightweight Concrete & Traditional Concrete
The water content of ultra lightweight concrete is much lower than that of traditional concrete. Because porous aggregates increase the time required for cement to dry, aggregates are presoaked in water before being added.
As an alternative to normal concrete, lightweight concrete is a cost effective option, especially since its strength is not compromised. Due to ultra lightweight concrete’s porosity, it is also thermally conductive, which makes it suitable for heat resistant projects.
Due to the presence of denser aggregates in their natural state, traditional concrete can weigh between 140 and 150 pounds per square foot. The result is that many people believe normal concrete to be cheaper than ultra lightweight concrete.
In contrast, traditional concrete projects require additional framing and cladding, along with steel reinforcements ultimately increasing their cost. Therefore, ultra lightweight weight concrete remains a highly cost effective construction material, especially when applied to large projects.
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Benefits of Ultra-lightweight Concrete
Large construction production benefits from easy transportation. Reduced execution time and cost result from speedy installation. In other words, construction activities will be completed in less time with less equipment and labor. As a result of reduced dead load, steel bar, and concrete utilization, construction costs were reduced. As a result of its high porosity, it provides sound insulation.
Uses of Ultra-lightweight Concrete
In addition to being used for surrounding walls and interior partitions, lightweight concrete panels can also be used for exterior walls. The material is suitable for building house especially flat & other multi complex.