FLY ASH AGGREGATES FOR PRODUCTION OF LIGHTWEIGHT CONCRETES

CIVIL ENGINEERING

Fly ash aggregates produce lightweight concretes (LWCs) with adequate mechanical strengths. It is necessary to confirm whether LWCs also offer protection to the steel reinforcement. Test data indicate that LWCs with ‘sintered fly ash aggregates’ provide adequate protection to steel, especially when fly ash is added as ‘partial cement replacement’ in concretes. Fly ash is converted into coarse aggregates by ‘pelletising’ followed by ‘sintering’ actions. Powdery granules of FA can be agglomerated minerologically by sintering and then used as CA. These sintered fly ash aggregates (SFAAs) are highly porous and hence, concretes made from them aggregates would be also lightweight in nature. These lightweight concretes (LWCs) would absorb comparatively more water than the conventional 'normal weight concretes' (NWCs). It is necessary to examine whether LWACs have reduced resistance to steel embedded in concrete. This aspect is discussed in this paper and the test data shows that by appropriate design of binder matrix, it is possible to achieve satisfactorily corrosion resistance behaviour in concretes containing SFAAs as coarse aggregates.

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