PSI - Issue 70

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

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2.3.1 Mechanical properties The laboratory applied IS 516-1959 together with ASTM C39 and ASTM C496 and ASTM C78 to run tests of compressive and tensile and flexural strength.The testing standards outline the specimen dimensions and testing methods for evaluating concrete strength. Compressive strength is tested using a 100 mm × 100 mm × 100 mm cube as per IS 516-1959 or ASTM C39 at 3, 7, and 28 days. Split tensile strength is determined using a 100 mm × 200 mm cylinder based on ASTM C496 at 28 days, while flexural strength is measured with a 500 mm × 100 mm × 100 mm beam following ASTM C78 at 28 days to assess the concrete's resistance to bending and tension.

Fig.3. Compressive and Flexural Strength Testing Setup :(a) Compressive Testing Machine for Cube Testing, (b) Universal Testing Machine for Flexural Strength Testing

2.3.2 Durability and permeability analysis Tests on PET- SiO₂ -modified geopolymer concrete evaluated its durability by measuring water absorption combined with sorptivity and rapid chloride penetration testing and acid resistance assessment.The durability of concrete is assessed through various tests: water absorption is measured by the percentage weight increase of a 100 mm cube according to ASTM C642, sorptivity is evaluated by the sorptivity coefficient of a 100 mm cube based on ASTM C1585, and RCPT determines the charge passed through a cylinder following ASTM C1202. Acid resistance is tested on a 100 mm cube per IS 3370-2 by evaluating the percentage weight and strength loss. 2.3.3 Microstructural and spectroscopic analysis The analysis of PET- SiO₂ integration employed SEM, EDX and UV -Vis spectroscopy for assessing microscale features and chemical components as well as stability tests. The testing procedures deliver an entire picture regarding physical effects of PET- SiO₂ on geopolymer concrete which can serve for subsequent investigation. 3. Experimental Investigation The experimental study assesses the strength, durability, and microstructure of PET- SiO₂ -integrated geopolymer concrete. Mechanical tests evaluate compressive, tensile, and flexural performance, while durability tests analyze permeability and acid resistance. SEM-EDX and UV-Vis spectroscopy provide insights into matrix densification and polymer dispersion. The results highlight PET- SiO₂’s role in enhancing strength, reducing permeability, and improving structural feasibility. 3.1 Workability The workability evaluation of PET- SiO₂ -modified geopolymer concrete occurred through the slump test method. All concrete mixtures demonstrated uniform workability characteristics apart from insignificant changes in slump