Fly ash is widely used as a supplementary cementitious material in the production of cement and concrete, and improves durability and strength of the concrete. However, as for all materials of mineral origin fly ash is a source for natural radioactivity; hence, its need for responsible use. The aim of this study is to investigate the radiation impact from fly ash as an additive to concrete compared against concrete without fly ash. For this purpose eight concrete mixtures are experimentally tested, followed by a computation of the radiation dose when used as bulk material in building constructions.
The results demonstrate an increase in the total radiation dose from around 0.8 mSv with no fly ash up to 0.92 mSv when fly ash is used. The increase mostly comes from external radiation, while the radon exhalation factor reduces and sometimes even reduces the radon dose despite the higher radium content. The work has demonstrated that the impact from fly ash on the radiation exposure is limited when applied as a supplementary cementitious material. At the same time fly ash provides real benefits to the quality and durability of the concrete. For this reason exemption strategies for such applications should be developed.