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RAW MATERIALS AND RECIPE TO PRODUCE NON AUTOCLAVE AERATED CONCRETE (ALC/NAAC)

The mixture for aerated concrete has a simple composition. It is easy to understand and remember. Let's take a closer look at each element.

Main ingredients (Raw Materials)

Water

Water for concrete mixture shall have any suitable drinking water. It is preferable to water from surface sources, unsalted, soft or medium hardness. It is also preferred to provide the required amount of water lukewarm/hot for best results.

Portland Cement

Virtually all of Ordinary Portland Cement (OPC 53 Grade) suitable for the production of aerated lightweight concrete. Cement should be fresh, lumps free. Preferred use of a good standard brand.

Quick lime

Quicklime is produced by heating naturally-occurring limestone rock, which contains calcium carbonate. It is recommended to use fresh quick lime. More purity provides better results.

Fillers

As part of aerated concrete mix, fly ash/fine silica sand or dolomite can be used as filler.

Fly ash/Pond ash - is from thermal power plants (fly ash is silica rich product, which is industrial waste obtained from thermal power plants)
Silica sand - fine-grained, without foreign inclusions like stones, branches, particles larger than 1 mm, without silt and clay (or with a minimum content of such substances).
Dolomite - Dolomite is a common rock-forming mineral. It is a calcium magnesium carbonate (or called Limestone flour in simple language).

Foaming Agent

Small quantity of aluminum powder is used for Foaming of concrete

Additives

Just like other concrete, additives such as activators/accelerators may be used to improve and stabilize the quality of the final product.

Quantity per Cubic Meter for Natural curing type aerated concrete ( ALC )

Water : 200-280 Ltrs
Ordinary portland cement : 180-280 Kg
Quick lime : 15-30 Kg
Fillers (fly ash/fine sand) : 350-550 Kg
Aluminum powder : 400-500 gms
Additives : Quantity depends on raw material properties

Note : Raw material quantity depends on the quality of raw material. it may vary from place to place

Process of production

Measured quantity of water is poured in the mixer.
Measured quantity of fly ash (filler) is added in the mixer.
Desired quantity of cement is mixed with fly ash (filler) slurry.
Measured quantity of lime is added to the mix.
Additives (if required) are poured in the mixer.
Aluminum powder premixed with a small quantity of water is added in the mixer.
After mixing for about 30 seconds, Prepared concrete slurry is poured in lubricated molds.
After filling the mold, the mixer moves towards the next mold for filling (for stationary lines).
After filling the mold, the mold moves towards pre pre-curing area and a new mold moves towards the mixer for the next fill (for conveyor lines).
In filled mold, Concrete slurry rises (just like Bread dough) and volume increases up to desired height in 15-20 Minutes.
After 3-5 Hrs. raised concrete gets its initial strength and mold panels are removed for the cutting process.
Then this concrete “cake” is sliced in required sizes Horizontally and then Vertically with cutting machines.
After cutting the sliced concrete blocks are left overnight for the initial hardening process.
Next day these blocks are removed from the mold base and shifted to a curing area for natural (water) curing.
Curing is done by simply spraying water on a stack of blocks, and keeping it wet for a minimum for seven days.
After curing and drying blocks are ready for shipping

ALC Production Process