Determination of free lime in Sudanese cement Samples

Abstract

Cement free lime value generally indicates quality of raw materials, the completeness of the clinkering reaction and the quality of the burning practices hence the quality of the cement. A high free lime clinker is usually due to in-homogeneity and coarseness of cement raw mix or to improper burning and cooling condition in the kiln. Excess free lime results in undesirable effects such as volume expansion, increased setting time or reduced strength; hence it is critical to measure free lime content to ensure the quality of cement. The aim of this research was to determine the percentage of free lime in different Sudanese cement samples (Berber cement and Atbara cement) by using methods that depend on extraction with ethylene glycol using different methods and also to study the effect of extraction temperature, extraction time and the concentration of hydrochloric acid on the results obtained by extraction with ethylene glycol. The results obtained by all methods showed that the samples containing free lime percentage agreed with accepted values (not more than to 2% max according to ASTM).Also it is found that the percentage of free lime increased withincreasing extraction temperature (50, 70 and 100°C), extraction time (5, 10 and 20 minutes) and hydrochloric acid concentration (0.05, 0.1 and 0.2 M).