Effect of high-alumina ladle furnace slag as cement substitution in masonry mortars

• Ladle furnace slag (LFS) is a non-uniform by-product, and can be high-alumina or high-silica slag.
• High-alumina LFS has a better hydraulic reaction in mortars than high-silica LFS.
• Partial substitution of cement by LFS in amounts of 20% by weight has no negative effects.
• LFS-mortar mixes show useful properties for building sector applications.

Ladle furnace (white or basic) slag is a significant by-product of the steelmaking industry; nowadays the manufacturing process yields two types of basic slag that are either low or high in alumina. The present research focuses mainly on the composition of the high-alumina slag and the reactivity of its compounds such as calcium aluminates, free calcium oxide, and free magnesium oxide, when aged at room temperature and at water steam temperature (accelerated aging). Additionally, a characterization was performed of pastes and masonry mortars that incorporate high alumina ladle furnace slag as a supplementary cementing material in partial substitution of Portland cement in amounts of 10% and 20% by weight. Different properties are studied such as porosity distribution, volumetric stability, mechanical strength and durability, mainly referring to wetting-drying aging cycles. The study concludes that high-alumina ladle furnace slag can induce slight hydraulic reactivity and its partial addition has no negative effect on the fundamental properties of cement masonry mortars.