Making It Light By AAC Blocks

Autoclaved aerated concrete (AAC) is a lightweight, precast, foam concrete building material suitable for producing concrete masonry unit (CMU) like blocks. Composed of quartz sand, calcined gypsum, lime, cement, water and aluminum powder, AAC products are cured under heat and pressure in an autoclave. Invented in the mid-1920s, AAC simultaneously provides structure, insulation, and fire- and mold-resistance. Forms include blocks, wall panels, floor and roof panels, cladding (façade) panels and lintels.

AAC products may be used for both interior and exterior construction, and may be painted or coated with a stucco or plaster compound to guard against the elements, or covered with siding materials such as veneer brick or vinyl siding. In addition to their quick and easy installation, ACC materials can be routed, sanded, or cut to size on site using standard power tools with carbon steel cutters.

AAC is a highly thermally insulating concrete-based material used for both interior and exterior construction. Besides AAC's insulating capability, one of its advantages is quick and easy installation, because the material can be routed, sanded, or cut to size on site using standard power tools with carbon steel cutters.[citation needed]

AAC is well suited for high-rise buildings and those with high temperature variations. Due to its lower density, high-rise buildings constructed using AAC require less steel and concrete for structural members. The mortar needed for laying of AAC blocks is reduced due to the lower number of joints. Similarly, the material required for rendering is also lower due to the dimensional accuracy of AAC. The increased thermal efficiency of AAC makes it suitable for use in areas with extreme temperatures, as it eliminates the need for separate materials for construction and insulation, leading to faster construction and cost savings.

Even though regular cement mortar can be used, most of the buildings erected with AAC materials use thin bed mortar in thicknesses around ⅛ inch, depending on the national building codes. AAC materials can be coated with a stucco or plaster compound to guard against the elements, or covered with siding materials such as brick or vinyl.

Advantages

• Improved thermal efficiency reduces the heating and cooling load in buildings.
• Porous structure gives superior fire resistance.
• Workability allows accurate cutting, which minimizes the generation of solid waste during use.
• Resource efficiency gives it lower environmental impact in all phases of its life cycle, from the processing of raw materials to the disposal of waste.
• Lightweight saves cost and energy in transportation, labour expenses, and increases chances of survival during seismic activity.
• Larger size blocks leads to faster masonry work.
• Reduces project cost.
• Environmentally friendly: It produces at least 30% less solid waste than traditional concrete. There is a decrease of 50% of greenhouse gas emissions.
• Fire resistant: As with regular concrete, AAC is fire resistant.
• Great ventilation: This material is very airy and allows diffusion of water. This reduces the humidity inside the building. AAC will absorb moisture and release humidity. This helps to prevent condensation and other problems that are related to mildew.
• Non-toxic: There are no toxic gases or other toxic substances in autoclaved aerated concrete. It neither attracts rodents or other pests nor can it be damaged by such.
• Accuracy: The panels and blocks made of autoclaved aerated concrete are produced to the exact sizes needed before leaving the factory. There is less need for on-site trimming. Since the blocks and panels fit so well together, there is less use of finishing materials such as mortar.
• Long lasting: The life of this material is extended because it is not affected by harsh climates or extreme weather changes. It will not degrade under normal climate changes.

Disadvantages

• AAC has been produced for more than 70 years, however, some disadvantages were found when it was introduced in the UK (where cavity wall with clay brick two-skin construction has been the norm).
• Installation during rainy weather: AAC is known to crack after installation, which can be avoided by reducing the strength of the mortar and ensuring the blocks are dry during and after installation.
• Brittle nature: they need to be handled more carefully than clay bricks to avoid breakage.
• Attachments: the brittle nature of the blocks requires longer, thinner screws when fitting cabinets and wall hangings and wood-suitable drill bits or hammering in. Special, large diameter wall plugs (anchors) are available at a higher cost than common wall plugs.
• Insulation requirements in newer building codes of northern European countries would require very thick walls when using AAC alone. Thus many builders choose to use traditional building methods installing an extra layer of insulation around the entire building.

References:-

Wikipedia