Pore solution was pressed out of hardened pastes consisting of different cements and clinker/gypsum-mixtures prepared with the addition of nitrite-containing corrosion inhibitors. The binding of nitrite was studied by comparing the nitrite concentration in the mixing water with that in the pore solution in both the presence and absence of chloride. The sulphate content of clinker/gypsum-mixtures hardly affected binding of nitrite which indicates that nitrite ions are not bound chemically by C3A. The results indicate that a major controlling mechanism is the adsorption of nitrite and chloride ions on the surface of hydration products. However, there is a clear competition between adsorption of nitrite and chloride on cement and, as a result, at higher chloride concentrations there is more free nitrite to inhibit steel corrosion.

  • INTRODUCTION

  • EXPERIMENTAL

  • RESULTS AND DISCUSSION

  • INFLUENCE OF THE NITRITE SALT COUNTER-ION

  • COMPARISON OF CHLORIDE AND NITRITE BINDING WITH SODIUM SALTS

  • SUMMARY AND CONCLUSIONS

  • ACKNOWLEDGEMENTS

  • REFERENCES

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