Lightweight Concrete is concrete with a density that is lighter than concrete in general. Lightweight concrete can be referred to as aerated lightweight concrete (ALC) or called (Autoclaved Aerated Concrete / AAC), which has the primary raw material consisting of silica sand, lime, cement, water, plus a developer material which is then treated with water vapour pressure. Unlike ordinary concrete, the weight of lightweight concrete can be adjusted as needed. In general, the weight of lightweight concrete ranges from 600 – 1600 kg/m3. Therefore, the main advantage of lightweight concrete is its weight, so if it is used in high-rise building projects, it will be able to significantly reduce the building’s weight, which in turn impacts foundation calculations.
There are several advantages of lightweight concrete or Autoclaved Aerated Concrete (AAC), namely:
• AAC blocks are easy to shape. So it can be quickly and accurately cut or shaped to meet the demands of building decoration. The tools used are simple, just use carpentry tools. Find out more about light weight concrete selangor.
• Because the size is accurate but easy to shape, it can minimise the remnants of unused building materials.
• AAC can simplify the construction process. To build a building, the products that will be used can be minimised. For example, there is no need for stones or gravel to fill a concrete floor.
• Its light weight reduces transportation costs. Moreover, the AAC factory was built close to its consumers.
• Because it’s light, builders don’t get tired quickly. So fast in the process.
• The special cement is only 3 mm long.
In addition to the advantages, AAC Concrete also has several disadvantages:
• Due to its large size, it will consume a large amount of waste for a moderate size. Therefore, additional expertise is needed for the craftsman who will install it because the impact will result in waste and installation quality.
• The adhesive used must be adjusted to the manufacturer’s requirements, generally instant cement.
• its compressive strength is limited, so using it for (structural) reinforcement is not recommended.
• The price tends to be more expensive than conventional brick. Lightweight concrete is sold in m3 volume, so with a size of 60cmx20cmx10cm / m3, light bricks consist of 83 pieces.
The manufacture of lightweight concrete, in principle, creates air voids in the concrete. There are three ways to make aerated concrete, namely:
• The simplest is to provide aggregate/mixture of lightweight concrete. The aggregate can be pumice, styrofoam, or fly ash that is turned stone.
• Remove fine aggregate (fine aggregate is filtered, for example, dust/fly ash is cleaned).
• Blowing or filling the air in the concrete. This third way is further divided into mechanical and chemical.
The process of chemically making lightweight concrete or Autoclaved Aerated Concrete is now more often used. Before the concrete is aerated and dried by autoclave, this lightweight concrete mixture is made first. The dough consists of quartz sand, cement, lime, gypsum, and aluminium paste (developing agent). To produce 1 m3 of lightweight concrete, only ± 0.5 – 0.6 m3 of material is needed because later, this mixture will expand. In its composition, in general, quartz sand has a reasonably high percentage, around 60%. Adhesives consisting of cement and lime are 30%, and the remaining 10% is a mixture of gypsum and aluminium paste. The cement used types I cement.
