# Siderurgical Aggregate Cement-Treated Bases and Concrete Using Foundry Sand
## 2 Materials and Methods
### Siderurgical Aggregates  
In an initial stage, a sieve analysis was made by standard EN-933-2 (Figure 1). Because the material came without grading separation, a representative sample of the SA was taken to determine how much of the material was bigger than 31.5 mm aggregate size. Sizes bigger than 130 mm were observed (Figure 2). It was determined that 35% of the total weight of the SA was bigger than 31.5 mm aggregate size, which allowed 65% of the SA for use. The 0/31.5 mm fraction was separated in three different aggregate fractions to manufacture the SAC: 0/4, 4/8 and 8/31.5 mm, respectively. For the CTB, the 0/31.5 mm fraction was used. The grading curves are shown in Figure 3.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**SiO\({}_{2}\)** & **CaO** & **Al\({}_{2}\)O\({}_{3}\)** & **Cr\({}_{2}\)O\({}_{3}\)** & **Fe\({}_{2}\)O\({}_{3}\)** & **SO\({}_{3}\)** & **K\({}_{2}\)O** & **TiO\({}_{2}\)** & **P\({}_{2}\)O\({}_{5}\)** & **Others** \\ \hline
83.90 & 7.83 & 2.87 & 1.67 & 1.40 & 0.72 & 0.53 & 0.13 & 0.06 & \textless{}0.05 \\ \hline \hline \end{tabular}
\end{table}
Table 1: X-ray fluorescence (XRF) chemical composition analysis of FS (%wt.).  
Figure 1: Foundry sand (FS) and siderurgical aggregate (SA) grading curve.  
Table 2 shows the XRF chemical analysis of the SA. The main composition of the SA is Fe\({}_{2}\)O\({}_{3}\) and CaO. A study over several years has been carried out comparing the chemical compositions of EAFS. The composition is more less homogeneous in this plant with higher chromium and manganese traces found compared to those from other studies [52]. In any case, the products used in the manufacture of CTB are encapsulated in a cementitious matrix and, therefore, the degree of danger is significantly reduced.  
Characterization of the physical, mechanical and durability properties of SA was made using European standards (EN-1097-6) for calculating density, porosity and absorption., flakiness index (FI) EN-933-3, Los Angeles wear test (LA) EN-1097-2, sand equivalent (SE) EN-933-8, freezing thawing (F-T) EN-1367-1, humidity-dryness loss (H-D) EN-146510 and crushing value (CVA) EN-83112:1989. The results are shown in Table 3. Density results were similar to values reported, whereas porosity and absorption were higher than in other studies [30; 53; 54; 55].  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline
**Fe\({}_{2}\)O\({}_{3}\)** & **CaO** & **SiO\({}_{2}\)** & **MgO** & **MnO** & **Al\({}_{2}\)O\({}_{3}\)** & **Cr\({}_{2}\)O\({}_{3}\)** & **SO\({}_{3}\)** & **TiO\({}_{2}\)** & **P\({}_{2}\)O\({}_{5}\)** & **BaO** & **V\({}_{2}\)O\({}_{2}\)** & **Na\({}_{2}\)O** & **Others** \\ \hline
37.27 & 31.00 & 9.78 & 5.61 & 5.12 & 4.24 & 4.04 & 0.36 & 0.36 & 0.25 & 0.06 & 0.03 & 0.01 & \textless{}0.01 \\ \hline \hline \end{tabular}
\end{table}
Table 2: XRF chemical composition of SA (% wt.).  
Figure 3: SA aggregate fraction grading curves.  
Figure 2: Untreated siderurgical aggregates.  
Freezing-thawing loss of mass was similar to that in other works [37; 38] and Los Angeles wear test showed that the SA in this study had a higher value than others SA [56; 57; 58]. These result could be due to the fact that the SAs had more pores than conventional siderurgical aggregates.