# A Review of the Influence of Steel Furnace Slag Type on the Properties of Cementitious Composites
## 2 Concrete and Mortar with SFS Aggregates  
As the SFS quality and composition can vary based on the steelmaking process, it can perhaps be expected that the properties of mortars and concrete containing SFS aggregates would be variable as well. Table 2 is a summary of the literature, highlighting the effect on a given property for specific SFS aggregates used as a partial to full replacement of the virgin fine and/or coarse aggregates in mortar and concrete. The majority of studies have concerned the use of EAF or BOF slag aggregates, with few studies considering LMF or AOD slag aggregates and no studies using OHF slag aggregates. The majority of studies have focused on mechanical properties, such as strength and elastic modulus, and few studies have considered the effect of SFS aggregates on durability properties.  
It is clear from Table 2 that there are variable trends for a given SFS type. For instance, 51 studies were identified to have considered the compressive strength of cementitious composites when using EAF slag aggregates, of which 37 studies (72%) showed an increase in strength, 4 studies (8%) showed a decrease in strength, and 10 studies (20%) showed no change in strength when compared with a control. Similarly, for compressive strength with BOF slag aggregates, of 27 studies, the distribution was 52%, 30%, and 18% for increase, decrease, and no change, respectively. Therefore, for a given stockpile of EAF or BOF slag aggregates, what is the probability that the SFS aggregate will increase the compressive strength relative to a control? For quality assurance concerns, this is an important consideration since it is impractical to perform all mechanical and durability tests on all stockpiles of all SFS aggregates. However, it should be noted that Table 2 does not attempt to factor in other effects on concrete properties, such as water-to-cementitious ratio, cement content, age, curing conditions, use of SCMs, SFS replacement amount, coarse vs. fine aggregate replacements, gradation effects, control mixture, virgin aggregate type, and so forth. Therefore, the conclusions drawn from Table 2 should remain fairly general.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Component** & **BOF Slag** & **EAF Slag** & **Secondary Steelmaking Slag** & **AOD Slag** \\ \hline CaO & 45 to 54 & 25 to 35 & 30 to 52 & 48 to 68 \\ SiO\({}_{2}\) & 11 to 18 & 8 to 18 & 8 to 23 & 20 to 40 \\ Al\({}_{2}\)O\({}_{3}\) & 1 to 5 & 3 to 10 & 3 to 20 & 1 to 2.5 \\ MgO & 1 to 6 & 2 to 9 & 6 to 12 & 4 to 6 \\ Total Fe & 14 to 22 & 20 to 30 & 0.5 to 12 & 0.4 to 2 \\ Total Mn & 1 to 5 & 2 to 8 & 0.5 to 3 & 0.6 to 1.0 (MnO) \\ Total Cr & 0.1 to 0.3 & 0.5 to 2.2 & \textless{}0.1 to 0.5 & 0.1 to 5 (Cr\({}_{2}\)O\({}_{3}\)) \\ \hline \hline \end{tabular}
\end{table}
Table 1: Typical SFS composition ranges (in wt.%) [21].  
Table 3 details the use of SFS aggregates in geopolymer and alkali-activated concretes. Significantly fewer studies have been performed on SFS aggregates in geopolymer and alkali-activated concretes (Table 3) than portland cement composites (Table 2), although the trends more clearly suggest a positive effect on strength; for compressive strength, of 25 studies identified, 20 studies (80%) indicated that SFS aggregates can increase strength.