When we talk about lightweight concrete, we’re referring to a special type of concrete that’s not as heavy as the regular stuff. It’s made by mixing in lightweight things like shale, clay, or slate, which makes it less dense. The weight of this concrete is usually between 1440 to 1840 kilograms per cubic meter.
The key idea behind making lightweight concrete is to add air to it. There are a few ways to do this:
Using Cellular Porous Aggregates: Instead of regular aggregates, we can use special ones that have holes in them. This is called concrete with light aggregate.
Adding Air or Gas Bubbles: We can fill the concrete with tiny air bubbles. This is known as aerated concrete.
Skipping the Sand: In some cases, we don’t use sand during the concrete-making process. This is called concrete with no fines.
Reduced Density: This concrete can be really light, ranging from 300 to 1200 kg/m3. The lighter type is great for insulation, and the heavier one is good for building things. For instance, lightweight concrete is perfect for precast roofing and floor units. These are easier to handle and transport.
High Strength: Even though it’s light, this concrete is strong. The more dense it is, the stronger it becomes. It has about 15-20% of the strength when pulled, compared to when squeezed. So, a lightweight concrete roof or floor is much lighter than a regular one.
Durability: This type of concrete doesn’t corrode steel as much because it’s a bit alkaline. But we need to take special care of the steel used in it.
Thermal Insulation: It’s a great insulator—much better than bricks or regular concrete. A thin wall of this stuff can do the same job as a much thicker wall of bricks.
Fire Resistance: This concrete is good at resisting fire because it doesn’t let heat pass through easily.
Soundproofing: It’s not as good at blocking sound as regular concrete.
Shrinkage: Lightweight concrete doesn’t shrink much.
Repairability: It’s easy to work with—cutting, drilling, nailing, or sawing is a breeze.
Speed of Construction: Using prefabricated units makes building faster.
Economy: It’s cost-effective because it needs less steel. Using it in construction can save around 15-20%.
Quality Control: Since these units are made in factories, the quality is usually better.
Lightweight Aggregate Concrete: This type uses lightweight materials, either natural or man-made, in its production. Natural ones include pumice and scoria, while man-made ones are altered rocks like shale or perlite.
Natural Lightweight Aggregates: Pumice, Diatomite, Scrofula, Cinders from volcanoes, Rice Husk.
Artificial Lightweight Aggregates: Artificial Cinders, Foamed Slag, Expanded shales and slates, Bloated Clay, Thermocol beads.
No-Fines Concrete: This type skips using fine particles, only using cement, coarse aggregates, and water. Using larger coarse materials makes it lighter.
Aerated Concrete: This is made by adding air or gas to a mix of cement and crushed filler. It forms a cellular structure when it sets.
