PSI - Issue 70

S. Rajeshkumar et al. / Procedia Structural Integrity 70 (2025) 287–294

289

RHA

GSA

Fig.1. Physical appearance of GSA and RHA

Table.1. Key properties of RHA and GSA Property RHA

GSA

Physical Properties Color

Greyish white

Light brown

Fineness (Passing 75 µm sieve)

94% 460

92% 525

Bulk Density (kg/m³)

Particle Size Specific Gravity

45 µm

52 µm

2.12

2.36

Chemical Composition (% by weight) Silica (SiO₂)

89.32 1.76 0.87 0.92 1.65 3.10

60.27 13.45 4.10 3.22 7.80 5.31

Alumina (Al₂O₃) Ferric Oxide (Fe₂O₃) Magnesium Oxide (MgO) Calcium Oxide (CaO) Loss on Ignition (LOI)

3. Experimental Methodology The research evaluated M30 grade concrete performance through the use of GSA and RHA as cement substitutes. The concrete blend adhered to IS 10262:2019 standards with a fixed ratio of 1:1.75:2.95 for cement, fine aggregate, and coarse aggregate, accompanied by a water-binder proportion of 0.48 and the Table 2 outlines the mix proportions for each formulation. The experimental procedure included making a control mix which did not use any cement replacement. The other concrete mixes substituted cement with equal proportions of GSA and RHA to achieve a total replacement rate of 25%. The materials followed standard procedures to achieve accurate weighing and mixing. The moulds received fresh concrete followed by compacting before the samples went through water curing after removal from the moulds. The concrete specimens underwent water curing prior to strength and durability assessments.

Table.2. Mix Proportions with Material Quantities (kg/m³) Mix ID Cement RHA GSA M-Sand Coarse Aggregate

Water

CC

380

0

0

700

1180 1180 1180 1180 1180 1180

182 182 182 182 182 182

R5G20 285 R10G15 285 R15G10 285 R20G5 285 R25G0 285

19 38 57 76 95

76 700 57 700 38 700 19 700

0

700

The testing of concrete compressive strength occurred at days 7, 28, and 56 to evaluate its resistance to axial forces. The test for split tensile strength was performed at 7 and 28 days to measure concrete resistance against tensile forces. The 28-day assessment of modulus of elasticity determined concrete stiffness. The water absorption (WA) test