Potential of ladle furnace slag as supplementary cementitious material in concrete

Abstract

This research investigated the suitability of a locally available ladle furnace slag (LFS) as a supplementary cementitious material (SCM) to partially replace cement in concrete. The engineering properties of the LFS blended concrete were evaluated through an extensive experimental program. The SCM was used as (i) raw slag and (ii) sieved (finer than 75 µm) slag to use to produce different strength class concrete, viz., C35 and C40. Mechanical strengths and non-destructive tests were conducted for concrete with 5%, 10%, 15%, 20%, 25%, and 50% LFS replacement by weight of cement for various curing duration. Besides, indirect durability tests such as sorptivity and nitrogen gas permeability tests on LFS blended concretes were performed. Uniaxial compressive strength (UCS) for lower-grade concrete at 5% and 10% LFS levels are always higher relative to the control sample, regardless of the material type and curing period. The ultrasonic pulse velocity (UPV) test on concrete suggests that pulse velocity has a pattern similar to that of the UCS. Nitrogen gas permeability varies by LFS level, temperature, and material fineness. Capillary absorption indicates an evident general trend of increased water absorption with exposure/absorption time and LFS level. These properties for higher-grade concrete are reasonably similar to that of lower-grade concrete, however, the finer material shows better performance in this case.

Keywords

• Cement
• Capillary absorption
• Gas permeability
• Ladle slag
• Strength
• Sustainability