In order to highlight the benefits of irradiated CCM, the proponents of the project, Dr N Bhanumathidas and N Kalidas have arrived to certain postulations which caused to raise the eyebrows in the cement concrete fraternity. In this context, the scientists felt the need to provide the scientific rationale behind the postulations pending the studies on irradiated CCM which are yet to be produced upon getting suitable nuclear reactor.
Postulations made by the Scientists:
- higher grade strength, to ~63-83 MPa.
- Multiplying the cement production by 2-3 times without adding up to clinker production.
- Producing high-grade blended cements with low grade clinker.
For the production of PPC, cement plants avail composite fly ash (to have volumes) whose reactivity doesn’t cross 15%, but still, the resultant cement is yielding to 43 Gr. Then where is doubt in looking for higher grade strengths to over 63 to 83 MPa when fly ash with ~60% reactivity is added!
The scientists have already practiced concrete formulations in some of the live structures wherein 1/3rd OPC and 2/3rd fly ash were blended (achieving 3 times as blended cement) for concrete achieving 40-60 MPa strength. The fly ash used in such occasions was having reactivity of 20-30%.
For manufacturing irradiated-amorphous fly ash, it is aimed to avail fly ash from 1st field (of ESP) that contains reactivity of 3-5%, having balance of the portion as crystalline matter; containing majorly a-quartz at over 55-60% and balance being mullite together with other minor constituents. Thus, upon irradiation, the reactivity increases from 3-5% to over 55-60%. The mullite remains as passive filler, if doesn’t get reactivity, which would be known upon irradiation.
While OPC is multiplied to blend by 3-times and already put to practice with fly ash of 20-30% reactivity, where is doubt in achieving the same with 55-60% reactivity!
Before understanding the subject of enhancing the grade strength of blended cement with irradiated CCM, it is necessary to know the background about the manoeuvring of mineralogy-composition of OPC with reference to two principal mineralogies, C2S and C3S. Their ratio was ~2:1 in low grade cements (23-33 Gr) which was changed to ~1:2 to enhance the grade strength to 43-53 MPa. The focus of this change is to provide ‘high heat of hydration’ associated with C3S (against C2S) that facilitates rapidity of hydration chemistry in the urge for high early strengths.
This means the portion of lime is enhanced unmindful of the fact that lime is always surplus in OPC, leaching out to its major portion during hydration process. To elaborate further, out of C3S, it is basically SiO2 that gets into strength-rendering mineralogy. When such SiO2 is provided in amorphous state to participate in early hydration chemistry, the dependence on heat becomes redundant but the grade strength of such cement is bound to increase. This is proved in the case of FaL-G in lime route with LT fly ash, which doesn’t have heat of hydration but develops high early strengths due to rapid hydration chemistry of amorphous phases with lime. Such strengths are higher than those of FaL-G with HT fly ash in cement route, despite the presence of heat of hydration.
All the above postulations are going to be confirmed first, upon producing irradiated CCM in trial production, before proceeding to set up commercial plants.