However,the manufacturing process explained by Dhote and Singh (2016), consist of flyash as the major ingredient along with cement, silica, aluminium and water. Flyash being the waste generated from power generating factory and used as majormaterial for AAC blocks helps reducing the carbon footprint and makes themanufacturing process cheaper compared to other bricks available in market.
Flyash cements on heating make the block firm enough to carry the load same as theclay brick although the density is almost the 1/3rd the clay brick. Authoralso supports the thought of product viability that arises from the fact thatthere is a huge existing market for conventional clay bricks which neitheroffers huge technical advantages obtained from AAC, nor is the manufacturing environmentfriendly compared to AAC production. Withaim to identify a sustainable and affordable alternative material to replacethe conventional bricks for the primary building applications, Habib, Begum andHafiza (2015), explained potentialityand formation techniques of aerated concrete blocks which become thealternative sustainable option for developer which could lower down theconstruction cost beside the reduction of carbon footprints. The AACmanufacturing process include the aluminium powder in varied percentage whichis mixed with cement, silica, lime and water. From the experiment conducted,the author supported the usage of 0.
15% aluminium in the mixtures which alignwith the views of Jain and Shah (2014).As this gave the best possible results when compressive strength and density areconsidered since high aluminium decreases the compressive strength. Otherreasons for choosing AAC block over clay brick and RC blocks is, they are lightweight, provides insulation against the fire and are mould resistance. Air Permeabilityand porosity in AAC blocks which is caused due to hydrogen gas generation hasled to acoustical properties and lends the upper hand over clay bricks. Becauseof closed cellular structure of the material, the water absorption is lower.This is much better than the water absorption of conventional clay bricks,hence gives advantage as blocks forms the major part of the walls of thebuilding henceforth water absorption must be least in this scenario.Rathiand Khandve (2016), supports the viability of using AAC blocks in residentialand commercial buildings by specifying the amount of cost saved on every aspectof construction as the AAC blocks are smooth and almost eight times bigger thanthe red bricks and are lighter than the normal red clay bricks.
The larger sizeof AAC blocks leads to faster masonry works and reduces the cost of theproject. Autoclaved Aerated Concrete (AAC) is a certified green buildingmaterial, which is porous, nontoxic, reusable, renewable and recyclable henceare ideal for using it for commercial, industrial and residential construction.From the various test performed in the laboratory, supposedly AAC blocks hadthe better performance in size, weight, density, workability, water absorption,moisture content, curing behaviours, mortar requirement, quantity requirement,plaster requirement, time require for construction, finishing alternatives,structural behaviour, strength and stability, etc when compared with red claybrick or the RC blocks. As these blocks are lightweight compared to red claybrick hence the dead load of wall on the beam is reduce which helps to reducethe cost of construction by maximum of 20% (Shaikh et al.
, 2017)Usingthe AAC blocks reduces the use of cement mortar that is laid between thebricks. This led to reduction in the requirement of materials like cement andsand upto 55% and eventually benefits the pocket of the developer. Shaikh et al.
(2017) argues with stats against the use of clay bricks and proving a point touse AAC blocks which helps the environment by saving the top red soil of motherearth that is used in clay brick making and reducing the carbon footprint byusing the waste material from coal factory and waste glass tensile in the AAC blockwhich not only benefit the properties of the block but also increase theefficiency of the construction. AAC blocks being less dense and utilizing morespace on wall compared to bricks, the productivity increases apart from whichit has better insulation (30% more) and sealing from the environment. Bringingin the thermal insulation for the building which is very hard for clay brickconstructed structure as they require material to be applied on the outer wall.This can be avoided if AAC blocks are used as they possess high porosity withenclosed pores which makes it a lightweight concrete and is suitable for providinghigh thermal insulation. Also, the compacted pores aids to reduce thepermeability of water (Andolsun, Tavukçuoglu, Salt?k, n.d.
).Yardimet al. (2012), presents the effectiveness of AAC precast slab compared toprecast reinforced concrete slab by conducting an experiment of load testing inboth direction i.e. horizontally and vertically. In the test, the ferrocement isplaced in the mould of mesh which takes up the tensile load on the slab whereasthe AAC block placed in between the ferrocement mesh takes up the compressiveload while bending. The reduction of weight was visible compared to RC slabi.e.
by 33%, whereas the load carrying capacity remained the same. Henceforth authorconcluded that the dead load on the walls and beams of building is reducedwhich eventually helps to reduce the structural load on foundation and resultsin cost saving scenario. The building gradually becomes lighter which makes itprone to earthquake since lighter building can sustain the earthquake shakingas less force of inertia is applicable at the centre of the building. Indeed,their high deformability allied to their light weight reduces the inertiaforces of these vertical elements and, in addition it gave AAC anon-combustibility and fire-resisting nature (earthquakes are commonlyassociated with fires); therefore, blocks can be an alternative to reinforcedconcrete frame structures. (Costa et al.,2008)