Constructionindustry being 2nd most carbon emitting industry in the world,requires massive rework in its model regarding the building material usage and techniques.
There is a robust body of authorswriting explicitly within the construction field who call for a change inconstruction material which catalyst the building process. This has invoked thereplacement of red clay brick and cement with alternative material which isless carbon emitting material. This has led to formation of Autoclaved AeratedConcrete back in 1924 but its acceptance in the construction industry came verylate. A detailed literature review has been conducted in accordance with researchobjective.
The literature review suggested that there are serious benefits of acceptingAAC over clay brick and RC blocks and it also possess the feasibility inmanufacturing the AAC blocks as the market has started accepting it big time.Furthermore, based on it questionnaire will be formed along withsemi-structured interview will be conducted to understand the impact of AAC onproject success. At present, construction works,such as high-rise constructions of commercial and residential houses, in manycountries are growing at very fast rate. Concrete has largely been used asvital construction material for maximum of building because of its exceptionalmechanical properties, low cost and availability. However, structure andfoundation of buildings tend to turn out to be larger due to an increase intheir scale, steering to much more time feeding and cost. Meanwhile, both theeconomic and energy crisis has fuelled the awareness of energy conservation,resulting in a drastic increase in studies on construction material whichincorporates energy conservation.
Whereas, red bricks are one of the mostprominent construction material used for construction and the carbon dioxideemissions in the brick manufacturing process has been certified as a relevantfactor to global warming. Therefore, it becomes necessary to focus more onpursuing environmental solutions for greener environment. (Rathi, n.d.)Subsequently walls being importantpart of any structure as they are the ones which distinguishes the structurefrom the environment; providing insulation, privacy etc. and the brickwork iswhat makes the wall and one very important for us now is AAC blocks which weare comparing with regular Burnt Clay Bricks. The feasibility of AAC block mustbe determined to make it an ideal replacement for the red clay brick along withidentifying the right materials that has to be added while making it, sincenumerous substance are available to make it feasible, but question remainswhich suites the best for the application in construction.
Therefore, the basis of thisdissertation is to identify whether the AAC blocks are the ideal replacementfor the red clay bricks and RC blocks and to understand the feasibility ofmanufacturing the AAC blocks in which getting the right mixture of substance isvital as different substance react differently in different climatic condition,since walls being the one which always remains in direct contact with weather,it becomes the topic of importance while considering the manufacturing mixturefor AAC blocks.Itis widely acknowledged that the need of an hour is to reduce carbon footprintsand move towards the sustainable world where carbon emission is as minimalisticas possible. To do so, the construction industry must reframe their methodologyas the operation of building accounts for atleast 40% of total energyconsumption of the country which is equivalent to 13% of global CO2 emission (Yangand Lee, 2014). To overcome this, cement and concrete must be reduced but alsothe material used in the building must provide thermal insulation which reducesthe use of energy to maintain the temperature.Inline with the study’s first research objective this review will look at thebroad body of literature surrounding the concepts of Autoclaved AeratedConcrete blocks as it has become the attractive construction material in themarket which has picked up the pace for utilization inplace of clay bricks andvarious other reinforced concrete blocks since the properties like lightweight, high strength, good durability, heat preservation, sound insulation,fire proofing, impervious, good anchoring has lead them to come in limelightand made it an ideal choice of replacement for traditional masonry with claybricks which lacked in this field when compared to AAC blocks (Yang and Lee, 2014).Tostart with the research, the manufacturing of AAC block must be reviewed, asthe red clay brick manufacturing process emitted the maximum CO2 gas.
Manufacturingprocess explained by Jain and Shah(2014), consist of aluminium (0.15%) in place of aggregate along withPortland cement, silica, fly ash and water. The burning temperature plays animportant part in baking the AAC block as the composite material which areadded in place of aggregate to make it more sustainable reacts differently atvaried temperature and if overly baked reduces the block’s compressive strengthdue to excess hydrogen gas formation. In the process of making AAC blocks, hydrogengas generation method helps the initiation of chemical reaction betweenmaterials at varied temperature and form hydrogen atom which makes the blockporous and decrease the density of the block substantially which when comparedto clay brick or the reinforced concrete (RC) block is almost 1/3rd to them.
Theright balance must be struck with the density, since compressive strength anddensity are inversely proportional. Due to the porosity, blocks have highthermal performance, hence the substantiality of blocks and the viability forthe use in condition of acoustic insulation is ideal, however, based on thefire resistance properties of block, they can have multiple application in theinfrastructure sector and can be easily used as the replacement for the claybricks or reinforced concrete (RC) blocks. During the comparison of AAC blockwith clay brick, the result obtained by author clearly suggested AAC block havean upper hand in the field of productivity as the size of block is almost the 8times the clay brick which speed up the masonry work and eventually saves theconstruction cost. However, the manufacturing process explained by Dhote andSingh (2016), consist of fly ash as the major ingredient along with cement,silica, aluminium and water. Fly ash being the waste generated from powergenerating factory and used as major material for AAC blocks helps reducing thecarbon footprint and makes the manufacturing process cheaper compared to otherbricks available in market.
Fly ash cements on heating make the block firmenough to carry the load same as the clay brick although the density is almostthe 1/3rd the clay brick. Author also supports the thought ofproduct viability that arises from the fact that there is a huge existingmarket for conventional clay bricks which neither offers huge technicaladvantages obtained from AAC, nor is the manufacturing environment friendlycompared to AAC production.