PRODUCTION OF REINFORCED CONCRETE MEMBERS BY SPRAYED CONCRETE CONTAINING WASTE PLASTICS

Abstract

Wet-mix shotcrete is commonly utilized as a placement method in tunneling and ground support. In terms of productivity gains, using a set accelerating admixture offers significant benefits. Little is known about effects of Waste Plastic Fiber (WPF) in wet-mix shotcrete mixtures. Shotcrete concrete containing WPF is used in fabrication of structural members which is innovative in this work. To be able to produce shotcrete concrete, a shotcrete machine was manufactured and modified to be able to shoot the specific shotcrete concrete that incorporates with WPF. Extensive research was done in this project to generate wet-mix shotcrete combinations using locally sourced waste materials like beverage bottles. The qualities of WPF shotcrete concrete (SC) were investigated in terms of fresh, hardened, mechanical, and bending behavior. Five SC formulations (0.25, 0.5, 0.75, 1.0, and 1.25) percent WPF content, as well as the control shotcrete (SC0.00), were used in this study. In addition, the flexural behavior of SC beams manufactured from the produced shotcrete incorporated with the same waste materials was studied. The initial component of the experiment was measuring the fresh properties of SC (750, 780, 790, 880, 750, and 690) seconds for slump flow, (0, 0.5, 1, 1, 1, and 1) seconds for T500, and (15.1, 13.4, 11.2, 9.6, 9.1, and 8.3) seconds for sieve segregation, for (0.00, 0.25, 0.5, 0.75, 1.0, and 1.25) % respectively, to see how different amounts of WPF affected SC. The harder properties of SC mixes, including as dry density were (2364, 2368, 2377, 2373, 2358, and 2355) kg/m3, water absorption (0.67, 1.08, 1.48, 1.68, 1.75, and 1.85) %, voids content (0.80, 1.27, 1.87, 1.95, 2.19, and 2.62) %, III and ultrasonic pulse velocity tests (4.46, 4.38, 4.37, 4.29, 4.26, 4.14) km/sec. for (0.00, 0.25, 0.5, 0.75, 1.0, and 1.25) % respectively, were covered in the second section. The mechanical properties of SC mixes, such as compressive strength (40.2, 36.0, 31.3, 30.3, 25.3, and 24.4) Mpa, splitting tensile strength 3.2, 3.4, 3.8, 3.9, 4.1, and 4.4) Mpa, and modulus of elasticity (21.45, 19.86, 17.39, 16.51, 15.93, and 15.12) Gpa, were discussed in the third section for (0.00, 0.25, 0.5, 0.75, 1.0, and 1.25) % respectively. The results showed that addition of WPF improves the splitting tensile strength of SC. The final part of the experiment was examining the structural performance of reinforced concrete beams with various WPF (12.8, 13.8, 13.3, 12.8, 13.3, and 14.84) mm as ultimate deflection for (0.00, 0.25, 0.5, 0.75, 1.0, and 1.25) % respectively. The results showed similar flexural behavior in term of formation of crack patterns and width in addition to ductility index (2.03, 2.29, 2.02, 1.94, 2.16, and 1.99), and stiffness (5.50, 4.59, 4.48, 5.01, 4.81, 1.31) for (0.00, 0.25, 0.5, 0.75, 1.0, and 1.25) % respectively, of all SC beams. SC beams showed lower post-cracking flexural resistance. Ultimate deflection of SC beams decreased with the increasing amount of WPF till 0.75%. Finally, the study showed that the SC produced with waste materials increase the density of the shotcrete mixes when WPF reach 0.5%. The analysis of mechanical properties of SC specimens revealed that there was not much improvement except splitting tensile strength. While SC with 0.75% WPF replacement provides the best flexural performance in term of ultimate deflection, ductility, and stiffness. Waste materials such as WPF should be limited in shotcrete because of their low values of hardened properties