Studies with Inorganic & Organic Additives for Cr(VI) reduction in Cement

Portland cements tend to contain impurities of soluble Cr (VI), the Chromium content being contributed from the Cement Raw materials and fuel or from the Cement Mineral additives such as fly ash, granulated slag, etc.

            The soluble Cr (VI) being formed in the process of clinkerisation or contributed from the cement additions. A potentially serious condition can occur when cement containing Cr (VI) comes into contact with the skin. Construction workers are likely to be at risk. European countries have the regulations from COSHH (Control of substance hazardous to health) for Cr (VI) in cement according to which the acceptable levels are up to 2ppm.

            At the authors labs a substantial amount of investigative work has been carried out to study the effect of additions of different inorganic and organic reductants on the reduction of the water soluble Cr (VI) in cements.

            Inorganic as well as organic additives were studied to evaluate their effectiveness for Cr (VI) reduction in the cement samples. The additives were incorporated in cements during grinding process .The Difference in Cr (VI) with and without the additions  for the particular additive was analysed and monitored  using UV-Visible spectrophotometer by 1,5 -diphenyl carbazide method at 540nm.  The reduction in soluble Cr (VI) in cement due to the use of additive was reconfirmed using an UV-Visible spectrophotometer at 372nm and 274nm. Total chromium was analyzed on inductively coupled plasma optical emission spectrometer (ICP-OES).

            The paper discusses a comparative study of the efficacy of various additives for reduction of soluble Cr (VI) in different Cements. This would be a step forward towards evolving alternatives for meeting the environmental norms of soluble Cr (VI) in Cements of the future.  The Paper was presented and published at 11th NCB Int Seminar

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