PSI - Issue 70

Maahira M. et al. / Procedia Structural Integrity 70 (2025) 642–649

644

1.1. Materials The Primary materials which were used for making the artificial aggregates were GGBS (Ground Granulated Blast Furnace Slag), Copper slag of 90 micron, and binding materials such as sodium hydroxide pellets and sodium silicate were used. All these materials were purchased from Astra chemicals.

Table 1. Composition of Copper Slag.

Component

Percentage (%)

SiO 2

35 to 45 30 to 40 8 to 16 5 to 15

Fe

CaO

Al₂O₃ MgO

1 to 6 1 to 5

S

Cu

less than 1

Table 2. Composition of GGBS.

Component

Percentage (%)

SiO 2 CaO

35 to 45 35 to 45 10 to 15 5 to 15

Al₂O₃ MgO

2. Methodology 2.1. Manufacturing process of aggregates

These artificial aggregates were prepared using pelletization process, an effective method for agglomeration that transforms finer particles into large solid particles. The pelletizer had a featured handle with plate to avoid the aggregate agglomeration in one place (Fig.1). The rotation of the pelletizer facilitated the aggregate formation. The speed, time and angle of pelletizer influence the formation of aggregates faster. Speed and longer duration resulted in larger particle size due to agglomeration. Hence to optimize the aggregate formation the pelletizer is set at an angle of 45 degree at 60 rpm for 1 hour Ground Granulated blast furnace (GGBS) and copper lag were combined in a ratio of 80: 20 with alkaline solution at a ratio of 1: 2.5. The dry mixture was pelletized, and the alkaline solution was slowly added. As the pelletizer rotated, pellets formed, and the aggregates were collected and cured at room temperature. Initial testing revealed that the physical and mechanical properties of the aggregates did not meet the required standards (IS 3838). Consequently, a second trial involved oven-curing the aggregates, which improved their

properties (Fig.2). 2.2. Mix proportion Ash

: 2kg

Ash ratio: GGBS

: 80%, Copper slag: 20%

L/A ratio

: 0.4

Na 2 SiO 3 /NaOH : 2.5:1 Molecular weight of NaOH : 40 8M of NaOH

: 8×40:320 : 10 x 40 = 400 : 12 x 40 = 480

10M of NaOH 12M of NaOH Mix for 8M: