Use of strontium isotopes to determine the origin of cement in concretes -Case examples from New Zealand

Combined chemical and strontium isotopic analysis has shown that New Zealan d cements carry geochemical fingerprints from their raw materials, which ca n be used to identify them in concrete. This could prove to have a more gen eral application in tracing the origin of cement and identifying the causes of failure in concrete structures. The fingerprinting of cement in concret e is complicated by aggregate leaching, but this can be minimised by using slightly alkaline or neutral EDTA as the solvent in preference to weak mine ral acids such as HNO3. Although fingerprinting of most New Zealand cements is possible, based on the relative concentrations of Ca, Sr, and Mn, stron tium isotopes can add crucial information in certain cases, particularly wh ere limestones of contrasting geological ages have been used as raw materia ls. (C) 2000 Elsevier Science Ltd. All rights reserved.