{"id":6111,"date":"2026-06-26T08:01:59","date_gmt":"2026-06-26T08:01:59","guid":{"rendered":"https:\/\/taiguo-steamboiler.com\/blog\/aac-block-specifications\/"},"modified":"2026-06-26T08:01:59","modified_gmt":"2026-06-26T08:01:59","slug":"aac-block-specifications","status":"publish","type":"post","link":"https:\/\/taiguo-steamboiler.com\/es\/blog\/aac-block-specifications\/","title":{"rendered":"Bloques AAC: especificaci\u00f3n completa, tama\u00f1o, grado y referencia de precio"},"content":{"rendered":"
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Updated June 2026 \u00b7 Reviewed by the Taiguo Boiler technical team<\/p>\n

An aac block (autoclaved aerated concrete) is a lightweight, precast walling block made from fly ash or sand, cement, lime and gypsum, expanded with aluminium powder and then steam-cured under pressure in an autoclave<\/strong>. It weighs roughly one-third of a clay brick, yet a single block can replace eight or nine of them. This reference pulls the real numbers – sizes, density grades, compressive strength, thermal and fire performance, weight, and 2026 India pricing – from the Indian Standard itself rather than the shorthand most buyer guides repeat.<\/p>\n

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In one line:<\/strong> AAC blocks are graded by compressive strength (IS 2185 Part 3 Grade 1 and Grade 2), sold by density (commonly 551\u2013650 kg\/m\u00b3) in 600\u00d7200 mm faces from 75 to 300 mm thick, and priced in India around \u20b945\u2013110 per piece (about \u20b93,200\u20133,500 per cubic metre) as of mid-2026.<\/p>\n<\/div>\n

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Quick Specs, AAC Block at a Glance<\/h3>\n\n\n\n\n\n\n\n\n\n\n\n
Full form<\/td>\nAutoclaved Aerated Concrete<\/td>\n<\/tr>\n
Standard (India)<\/td>\nIS 2185 (Part 3)<\/a><\/td>\n<\/tr>\n
Face size<\/td>\n600 \u00d7 200 mm (also 400\/500 lengths)<\/td>\n<\/tr>\n
Thickness<\/td>\n75, 100, 125, 150, 200, 225, 230, 300 mm<\/td>\n<\/tr>\n
Dry density<\/td>\n451\u2013650 kg\/m\u00b3 (commercial default 551\u2013650)<\/td>\n<\/tr>\n
Compressive strength<\/td>\n3\u20135 N\/mm\u00b2 (Grade 1 \u22654, Grade 2 \u22653 at 551\u2013650 band)<\/td>\n<\/tr>\n
Thermal conductivity<\/td>\n0.21\u20130.24 W\/m\u00b7K<\/td>\n<\/tr>\n
Fire resistance<\/td>\nNon-combustible; up to ~4 h for a 100 mm wall<\/td>\n<\/tr>\n
Cure<\/td>\nAutoclave, ~180\u2013200\u00b0C high-pressure steam<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Ranges compiled from IS 2185 (Part 3)<\/a> and peer-reviewed AAC studies; commercial values vary by brand and density. See sections below for sourcing.<\/p>\n<\/div>\n

What Is an AAC Block? Composition & the Autoclaving Process<\/h2>\n
\"What<\/figure>\n

An AAC block is a precast block of aerated concrete whose strength comes from a high-pressure steam cure rather than ordinary air drying. The mix is simple: a siliceous base (fly ash in most Indian plants, or quartz sand), plus Portland cement, lime and a little gypsum. The reactive ingredient is aluminium powder – about 0.05-0.08% by weight. When it meets the alkaline lime-cement slurry it releases hydrogen gas, which foams the mix into millions of tiny pores. That porous structure is why AAC is so light.<\/p>\n

The cure is the part buyers rarely see – and the part that actually set the grade. After the slurry rise and is wire-cut into blocks, the green cake is moved into an autoclave: a large pressure vessel that holds saturated steam. In commercial AAC production the blocks are cured for the better part of a day under high-pressure saturated steam – commonly around 180-200C and roughly 10-12 bar, depending on the plant. IS 2185 (Part 3) governs the autoclaved-block class in India. Under that heat and pressure the lime, silica and water react to form tobermorite<\/em>, a stable calcium-silicate-hydrate crystal. Tobermorite is what gives autoclaved blocks their dimensional stability and strength – and it’s the reason a non-autoclaved foam block such as cellular lightweight concrete (CLC)<\/a> cures slower and lands at a lower strength for the same density.<\/p>\n

\n\ud83d\udcd0 Engineering Note<\/strong><\/p>\n

The cure window isn’t cosmetic. Too short a soak or an uneven pressure ramp under-develops the tobermorite, and the block leaves the line lighter but weaker than its density rating imply. This is why production-grade AAC needs a properly sized AAC block autoclave built to a pressure-vessel code, not an improvised steam chamber.<\/p>\n<\/div>\n

In short, AAC is a lightweight concrete<\/a> where engineered air replaces aggregate. Every buying decision – weight, insulation, strength, fire rating – comes back to how much air is in the block and how thoroughly it was autoclaved. The lightweight nature of AAC – also called autoclaved cellular concrete, or simply autoclaved concrete – comes from this air structure, giving it a far lighter weight than dense masonry; the cellular structure of AAC is what defines its performance.<\/p>\n

AAC Block Sizes, Dimensions & Weight (Standard Sizes Chart)<\/h2>\n
\"AAC<\/figure>\n

AAC blocks are supplied with a standard 600\u00d7200 mm face; the thickness (width) is chosen to suit the wall application. IS 2185 (Part 3) cites nominal lengths of 400, 500 and 600 mm; heights of 200, 250 and 300 mm; and widths of 100, 150, 200 and 250 mm. Two points matter for site installation: the actual<\/strong> manufactured size is the nominal minus 10 mm (the standard assumes a mortar joint), and a tolerance of \u00b15 mm on length and \u00b13 mm on height and width is permissible. Commercial plants also add a 75 mm partition thickness below the IS range. Block weight scales directly with density, a relationship quantified in experimental AAC testing<\/a>. For architects and builders, the workhorse unit is the 200 mm block on a 600 mm x 200 mm face.<\/p>\n

\n\n\n\n\n\n\n\n\n\n
Standard AAC block sizes, weight and brick-equivalence (600\u00d7200 mm face, 551\u2013650 kg\/m\u00b3 density).<\/caption>\n
Thickness<\/th>\nCommon name<\/th>\nApprox. weight \/ block<\/th>\nTypical use<\/th>\n<\/tr>\n<\/thead>\n
75 mm<\/td>\n3 inch<\/td>\n~5\u20136 kg<\/td>\nLight partitions<\/td>\n<\/tr>\n
100 mm<\/td>\n4 inch<\/td>\n~7\u20138 kg<\/td>\nInternal partition walls<\/td>\n<\/tr>\n
150 mm<\/td>\n6 inch<\/td>\n~10\u201312 kg<\/td>\nInternal & light external walls<\/td>\n<\/tr>\n
200 mm<\/td>\n8 inch<\/td>\n~13\u201315 kg<\/td>\nExternal & structural infill<\/td>\n<\/tr>\n
230\u2013250 mm<\/td>\n9\u201310 inch<\/td>\n~16\u201318 kg<\/td>\nExternal \/ load-bearing infill<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Typical weights for 551-650 kg\/m\u00b3 blocks are as shown (weights scale with density and moisture). Dimensions per IS 2185 (Part 3); weights from manufacturer technical data.<\/p>\n<\/div>\n

How Many Bricks Equal 1 AAC Block?<\/h3>\n

For example, an 8-inch (600\u00d7200\u00d7200 mm) block holds a volume of about 0.024 m\u00b3. An average Indian clay brick (190\u00d790\u00d790 mm) is about 0.0015 m\u00b3. By volume, one AAC block replaces roughly 15-16 bricks; but because bricks need thick mortar beds, the practical wall-coverage equivalence quoted across the industry is about 8-9 bricks (some quotes range as high as 12). Either way it means fewer units, less mortar and quicker construction. [Worked example – copy the method with your own block and brick dimensions.]<\/span><\/p>\n

AAC Block Density Grades & Compressive Strength Classes<\/h2>\n
\"AAC<\/figure>\n

This is perhaps the one fact most widely confused when buying AAC. Most books, papers and even official technical documents simply refer to \u201c Grade 1 equals density 551-650 kg\/m \u201d. Although this is a convenient shorthand used by some manufacturers when sourcing blocks for procurement purposes, it conflates two completely separate parameters. In IS 2185 (Part 3) the density band and the Grade describe different physical properties: the density band describes the relative density (weight, dead-load and insulating qualities), while the Grade describes the minimum compressive strength (structural capacity). These are two dimensions the market often simplifies into one label, making it worth while to seek both on a test certificate. Peer-reviewed testing<\/a> confirms compressive strength rises with density across the bands.<\/p>\n

The 5 Band Density-Grade Ladder<\/h3>\n
\n\n\n\n\n\n\n\n
The AAC Density-Grade Ladder \u2014 how IS 2185 (Part 3) pairs density band with Grade 1\/Grade 2 compressive strength.<\/caption>\n
Dry density band<\/th>\nGrade 1 strength<\/th>\nGrade 2 strength<\/th>\nWhere it fits<\/th>\n<\/tr>\n<\/thead>\n
451\u2013550 kg\/m\u00b3<\/td>\n\u22652.0 N\/mm\u00b2<\/td>\n\u22651.5 N\/mm\u00b2<\/td>\nInsulation-led partitions<\/td>\n<\/tr>\n
551\u2013650 kg\/m\u00b3 (default)<\/strong><\/td>\n\u22654.0 N\/mm\u00b2<\/td>\n\u22653.0 N\/mm\u00b2<\/td>\nMost external & infill walls<\/td>\n<\/tr>\n
Higher bands<\/td>\nHigher<\/td>\nHigher<\/td>\nHeavier-duty \/ load-bearing systems<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Source: IS 2185 (Part 3), Table 1. The minimum allowable code strength is 1.5 N\/mm\u00b2. Shown are the commonly quoted minimum strengths (based on manufacturer test certificates).<\/p>\n<\/div>\n

What this means on the ground: if a supplier states “551-650 density, Grade 1”, they mean a block in the standard commercial weight band (551-650 kg\/m\u00b3) that also meets the 4.0 N\/mm\u00b2 minimum strength of Grade 1. If a supplier only gives a density figure (e.g. 600 kg\/m\u00b3), ask to see the grade on the test certificate too – because two blocks both at 600 kg\/m\u00b3 density can still legitimately be Grade 1 (4.0 N\/mm\u00b2) or Grade 2 (3.0 N\/mm\u00b2).<\/p>\n

What Is the Grade of AAC Blocks?<\/h3>\n

is the compressive-strength class determined in accordance with IS 2185 (Part 3): Grade 1 is higher-strength grade and Grade 2 is standard grade, where each are determined per density band. For typical infill in residential\/commercial construction in India, a 4.0 N\/mm 551-650 kg\/m 3 Grade 1 block is the typical specification. The autoclave cure previously mentioned is what permanently sets the strength into the whole batch and it\u2019s this part of the spec, more than anything else about the production, that will differentiate the supplier\u2019s actual process from their marketing pitch.<\/p>\n

Thermal, Acoustic, Fire & Water Performance<\/h2>\n
\"Thermal,<\/figure>\n

The inherent reason why AAC has performance figures that justify the expense is because of it being air filled. The figure is the spectacular thermal insulation. According to one peer-reviewed article indexed by the US National Library of Medicine<\/a> there’s a relationship from an AAC conductivity of 0.10-0.70 W\/mK for AAC with a density of between 400-1700 kg\/m, while the blocks in common use in India of 551-650 kg\/m often fall in the region of 0.21-0.24 W\/mK in the supplier\u2019s datasheets.<\/p>\n

Fired clay brick measures around 0.8-1.0 W\/m\u00b7K, so an AAC wall conducts roughly four to six times less heat for an equal wall thickness. These thermal insulation properties, together with the block’s fire safety as a non-combustible material, are why AAC is specified in code-driven construction.<\/p>\n

\n\n\n\n\n\n\n\n\n
AAC block technical properties with units and the standard or study behind each.<\/caption>\n
Property<\/th>\nTypical value<\/th>\nBasis<\/th>\n<\/tr>\n<\/thead>\n
Thermal conductivity<\/td>\n0.21\u20130.24 W\/m\u00b7K<\/td>\nCommonly reported; 0.10\u20130.70 across density (peer-reviewed study)<\/td>\n<\/tr>\n
Fire resistance<\/td>\n~4 h (100 mm wall), non-combustible<\/td>\nManufacturer test data <\/td>\n<\/tr>\n
Sound reduction<\/td>\n~43 STC (100 mm) to ~45 (200 mm)<\/td>\nManufacturer test data <\/td>\n<\/tr>\n
Water absorption<\/td>\ncommonly cited \u226410% by mass<\/td>\nAttributed to IS via trade sources <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

A peer-reviewed study on the NIH PMC database<\/a> adds an important caveat: AAC only delivers its rated insulation in the air-dry state, and both moisture content and workmanship accuracy materially change real-wall performance. That’s the bridge to AAC’s one honest weak point.<\/p>\n

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\n\u2714 Strengths<\/strong><\/p>\n