The Use of Steel Slag in Manufacturing of Portland cement

Abstract

The main objective of this research is to determine the effectiveness of local Electric Arc Furnace Slag (EAFS) as a replacement material in cement mortar and to determine the degree of its pozzolanicity. The properties of steel slag blended cement have been studied at chemical and physical laboratories of Nile cement Industry in accordance with the international standards (ASTM and BS). Chemical analysis shows that locally produced steel slag contains a high amount of iron due to a purification process in steel manufacturing compared with the standard (ACI 233). In studying the performance of concretes, two concrete mixes have been prepared for class C-50 with cement blended with steel slag in separate mixes with 5% replacement. Different test results together with the literature review were used to analyze the effects of using steel slag in cement and concrete production. Compressive strength test of mortar samples at 2, 7 and 28 days with different percentages of electric arc furnace slag (0%, 5%, 10%, 15%, and 20%) had been conducted The investigation of this thesis has revealed that compressive strengths of cement pastes from 5% steel slag blended Portland cement is comparable with the control one, that is 100% ordinary Portland cement. For 10, 15 and 20% replacement ranges, through the reduction in compressive strength is observed, blended types of cement at these percents satisfy the standard compressive strength limits for high early strength of class of 42.5 MPa as per the EN 197-1 standard. According to the test results, it was found that the degree of pozzolanicity is 95.8 % during 28 days which point out to a good quality electric arc furnace slag and a promising pozzolanic supplementary material in concrete. Observation on the test results also indicated that the effects of blending steel slag on the properties of cement such as consistency, setting times, insoluble residue, and soundness remain within the acceptable ranges of many standards. The investigation also indicated that the replacement of cement steel slag at 5% range, in concrete production, results in comparable compressive strength as of concrete specimens without steel slag with slight slump reduction. Finally, the study proved that using the local steel slag as a pozzolanic material is very efficient in the cement industry.