hydration and engineering properties of mechanically-activated composite cement from processed steel slag and limestone

The present research work aims to evaluate the feasibility of processing and utilizing steel slag in binaryand ternary cement blends with limestone. the physical and microstructural properties of binary and ternaryblended cements produced by inter-grinding mixtures of ordinary portland cement clinker, processed steel slag, andlimestone in a laboratory ball mill with replacement levels varying from 0 wt.% to 30 wt.% were studied. the effectsof processed steel slag and limestone incorporation on the density of dry cement mixes and water consistency, settingtime, and volume stability of fresh and hardened cement pastes were investigated. also, density, water absorption,total open pore volume (%), and compressive strength of cement mortars were measured. the mix with 15 wt.%limestone and 15 wt.% processed steel slag was selected as a typical ternary cement mix for complementary studiesincluding x-ray diffractometry, thermal gravimetry, fourier-transform infrared spectroscopy, and scanning electronmicroscopy analyses. the results show that removal of relatively high metallic content of steel slag increases itsgrindability for mechanical activation and improves its hydraulic properties effectively and makes it suitable forbeing recycled in the cement industry. the results show that mechanical activation of the cement mixes enhancesthe poor hydraulic activity of the processed steel slag and compensates for the strength loss to some extent. thephysical and chemical properties of all studied blended cement mixes comply with astm standard specifications,except the compressive strength of the cement mixes at 28-days containing 20 wt.% or higher amounts of limestoneground to the relatively low blaine specific surface area of about 3000 cm^2/g. all cement mixtures in all blainespecificsurface areas had less compressive strength than plain cement.