Irradiation for Amorphization for the Production of Complementary Cements

Studies at various global Institutes established that, due to impact of radiation, crystalline a-quartz of aggregates in concrete transforms into amorphous state, leading to volume expansion and deterioration of concrete. Some of these Institutes are:

• University of California, Los Angels, USA. 2016
• Oak Ridge National Laboratory, Tennessee, USA. 2018.
• The University of Tokyo, Japan, 2024

To simulate the phenomenon, Metachert, a form of quartz with 92% purity of silica, was subjected for irradiation in the JEEP II reactor at the Norway’s Institute for Energy Technology (IEF), the heavy water reactor, at a temperature monitored at around 53.3 oC. But it took about 2 years due to limitations of reactor. The resultant product was studied under Raman Spectroscopy and X-Ray Diffraction (XRD) whereby the changes from crystalline to amorphous state were reconfirmed.

The studies of irradiation, established to prove the adverse impact on set-concrete of nuclear reactors, have been availed by the INSWAREB-Scientists, Dr. Bhanumathidas and N Kalidas, to tap its positive contribution in advanced concrete technology. This is the Innovative dimension of the subject.

Crystalline products are non-reactive, with exceptions; hence cannot be blended with cement. Amorphous products are reactive with lime or ‘lime leached out of cement’. Ordinary Portland Cement (OPC) does release over 25% surplus lime upon hydration (akin to surplus sugar to human body) effecting the durability of concrete. This lime needs to be engaged with amorphous products such as Complementary Cement Materials (CCMs), for mitigating its deleterious impact as well enhancing the strength, micro-structure and overall durability of concrete.

During their studies over last 35 years for enhancing the durability of concrete, the Scientists have established that amorphous products such as silica fume, metakaolin, fly ash etc. do perform as CCMs. Petronas Towers, Malaysia; Akashi Kaikyo Bridge, Japan; Three Gorges Dam, China; Euro Tunnel, UK-France, are some of the reference structures, having used CCMs in their structural concrete.