Studies on Portland Slag Cement Made Using Blast-Furnace and Linz-Donawitz Slag

This study aims to investigate the possibility of using Linz-Donawitz (LD) slag as one of the cementitious materials for preparation of composite slag (having 8 and 15% LD slag), which will subse-quently be used for manufacturing portland slag cement (PSC). PSC samples (having overall 4 to 9% LD slag) were prepared using LD slag from two sources in a laboratory ball mill. PSC samples were analyzed for various chemical characteristics and physical properties. Studies were conducted on concrete mixtures prepared at water-cement ratios (w/c) of 0.65 and 0.40. Fresh, hardened, and durability properties of concrete mixtures prepared using PSCs made with composite slag having up to 15% LD slag were found to be comparable to their corresponding control mixtures. Based on results, it was observed that composite slag having LD slag up to 15% of total slag can be used up to 60% for manufacturing PSC along with clinker and gypsum. The 3-, 7-, and 28-day compressive strength of PSC samples containing LD slags in different propor-tions were found to be comparable to control PSC samples and meeting the requirements of IS 455:2015. Even though the free lime content in LD slags was significantly higher (free lime content of 3.03 and 3.48%) in comparison to granulated blast-furnace slag (GBFS), it had almost a negligible effect on the PSC prepared using LD slag and soundness of experimental and control PSC was comparable because the maximum amount of LD slag added in overall PSC was restricted to 9%. The addition of LD slag in different proportions up to 9% in overall PSC does not seem to have any detrimental effect on performance of concrete in terms of sorptivity, carbonation depth, chloride penetration, and diffu-sion, which indicates its suitability for application in reinforced concrete structures.