Comprehensive evaluation of sustainable Self-Compacting concrete (SCC) with High-Density Polyvinyl Chloride (HDPVC) recycled pipes as partial coarse aggregate replacement

• This study explored the suitability of using recycled HDPVC from scrap pipes as a sustainable alternative to the natural coarse aggregate in SCC. • Fly ash was incorporated as an additional cementitious component to improve the overall performance of the SCC mixtures. • The study explored the influence of incorporating HDPVC on the fresh and hardened characteristics of SCC. • Durability aspects, including exposure to elevated temperatures and chemical attacks, were investigated. • Non-destructive testing techniques were employed to evaluate the internal condition of the SCC. This study explored the potential of recycled High-Density Polyvinyl Chloride (HDPVC) from scrap pipes as an environmentally friendly substitute for natural coarse aggregate in self-compacting concrete (SCC). incorporating fly ash as a supplementary cementitious material. The influence of varying HDPVC replacement levels (5 %, 10 %, 15 %, 20 %, and 25 %) by volume of natural coarse aggregate on the fresh, hardened, and durability characteristics of SCC was examined. The experimental results indicated satisfactory in passing ability, flowability, and segregation resistance for mixtures containing up to 25 % HDPVC. Optimal strength enhancement was observed at 10 % HDPVC replacement, resulting in a 20 %, 16 %, and 17 % improvement in compressive, splitting tensile, and flexural strength, respectively, at 28 days of curing relative to the reference mixture. Conversely, a subsequent decline in strength at higher levels occurred until it nearly equaled that of the control mixture. Furthermore, strong correlations of 0.9704 and 0.9117 were noted in comparison with the compressive strength with Schmidt rebound number and ultrasonic pulse velocity (UPV), respectively. SCC with HDPVC particles demonstrated superior resistance to sulfuric acid attack while maintaining adequate resistance to salt attack compared to reference mixture. However, significant weight and compressive strength losses were recorded at elevated temperature (450 °C), limiting the material’s application in such conditions. Based on the comprehensive evaluation of fresh, hardened, and durability properties, the SCC mixture with 10 % HDPVC replacement is advisable for general construction applications where enhanced mechanical performance and improved acid resistance are beneficial, excluding high-temperature environments due to observed material degradation.