Abstract:
The aim of this work was to study the effect of alkali metal oxides, (Na2O and K2O) on some properties of Portland Sudanese cements. The physical properties investigated were compressive strength at (2, 7 and 28 days), initial and final setting time, soundness and expansion. Three brands of cements (El Salam, Atbara and Berber) were analyzed by flame photometry to evaluate their alkali levels. It was found that Berber sample had the lowest alkali content (0.7%). Additive values of 2%, 4% and 6% alkalis (as sodium hydroxide solution), were performed to check the effect of increased alkalinity on strength, setting and soundness. The expansion test was performed on the three samples of cement with 5% alkali addition .Alkali addition reduced both, the compressive and flexural strength properties of Berber cement. Initial and final setting time, were more reduced, and soundness followed the same pattern. In contrast to Berber cement Atbara and Al salam, recorded greater expansion than the permitted maximum percentage of 0.6%. The high alkali content detected in the final product caused many difficulties and affected adversely its properties. Serious attempts to decrease alkali contents in Sudanese cement, hence, become necessary
