The effect of carbonation on the phase composition in salt-contaminated (0.8% Cl- and 1.5% S03) anduduncontaminated OPC and blended cement mortar specimens exposed to elevated temperature is described.udChanges in the phase composition were monitored using X-ray diffraction and differential thermal/udthermogravimetric analyses. Results indicated the transformation of cement hydration products to calcite inudOPC, while calcite and aragonite were detected in the blended cements. The quantity of calcium carbonate in theudcontaminated cements was more than that in the uncontaminated specimens. The enhanced carbonation in theudcontaminated specimens may by attributed to: (i) an increase in the alkalinity of the pore solution; and (ii)udchanges in the morphology of the hardened cement, brought about by the chloride-sulfate contamination.
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