PSI - Issue 11

Stefanie A. Campos et al. / Procedia Structural Integrity 11 (2018) 145–152 Stefanie A. Campos et al./ Structural Integrity Procedia 00 (2018) 000–000

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Table 1. Physical and mechanical properties for steel slag and natural fine aggregate. Determination Fine Aggregate Slag Los Angeles Abrasion (%) - 22.80 Fineness modulus 2.50 2.50 Maximum characteristic dimension (mm) 2.36 2.36 Apparent specific gravity (g/cm³) 2.62 3.40 Specific gravity (g/cm³) 2.63 3.68 Absorption (%) 0.20 2.25 Percentage of materials less than 0,075 mm (%) 1.70 1.70

Fig. 1. Grading curves for natural and steel slag sand used in this work.

The sand and slag used were analyzed under a microscope to determine the shape of their grains. To better analyze the shape of the slag grains, the AIMS equipment was used, which makes it possible to obtain grain shape and angularity through digital image processing (Bessa et al., 2013). The results obtained with the use of this apparatus are presented in Figure 2. It is noticed that the natural fine aggregate is rounded and sub-rounded, while the slag grains are angular and lamellar and, it is observed that most of the slag particles are in the moderate and high scale, that is, their particles are more elongated and angular, confirming the shape of the grains predicted in the microscopic analysis. For the analysis of the chemical composition of the slag, the x-ray fluorescence (XRF) test was carried out in a sample, allowing the knowledge of the existing oxides contents, as shown in Figure 3a. The mineralogical analysis was performed through an X-ray diffractometry (XRD), allowing the determination of the crystalline and amorphous structures that make up the analyzed residue, which is presented in Figure 3b. In view of the analysis carried out, it was known that the slag is a material with large amount of oxide of iron, also containing oxides of calcium, manganese and silicon. Due to more than 50% of the sample being composed of iron oxides, the slag is expandable in contact with water due to corrosion and consequent iron expansion. Therefore, the scoria expansion was also analyzed, aiming at a better characterization of this material.