PSI - Issue 70

Janani P.K. et al. / Procedia Structural Integrity 70 (2025) 525–532

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measurements according to PET- SiO₂ addition levels. The control mix achieved a slump value of 50 mm but the 4g PET- SiO₂ mix recorded a slump of 49.5 mm showing a minimal effect on workability. The PET - SiO₂ mix containing 5g reached 50.5 mm of slump followed by the mix with 6g PET- SiO₂ at 51 mm. PET - SiO₂ acts as a fine filler to cause negligible concrete consistency alterations which helps keep workability within standard operating ranges. 3.2 Mechanical Properties The compressive strength evaluation of PET- SiO₂ -modified geopolymer concrete occurred at 3 days, 7 days, and 28 days while split tensile and flexural strength measurements took place at 28 days. Results showed that the best strength came from 4g PET- SiO₂ w hile it led to increased compressive properties during all observation periods. Strength reduction occurred because of agglomeration effects when the PET- SiO₂ dosage surpassed the optimal amount which affected the concrete matrix structural integrity.

Fig. 4. Strength vs. PET- SiO₂ Content Trend (Strength variations across different PET- SiO₂ dosages)

3.3 Durability and Permeability Results Durability assessments which included water absorption assessments in addition to sorptivity tests and rapid chloride penetration (RCPT) and acid resistance tests measured the prolonged durability of PET- SiO₂ -modified concrete, Table 1. The analysis revealed substantial decreases in permeability as well as water infiltration, which leads to better protection against harsh surrounding conditions.

Table 1. Durability and Permeability Test Results Test

PET- SiO₂ Dosage

Result

Water Absorption (%)

0g

1.6

4g

0.8

Sorptivity (mm/s⁰·⁵)

0g

0.034

4g

0.029

RCPT (Coulombs)

0g

2990.16