In this work, the experimental and simulation analysis of the performance of geopolymer composites reinforced with steel fiber and polypropylene fiber is investigated. By embedding hooked end steel fiber and polypropylene fiber with various volume fractions of 0%, 0.5%, 1%, 1.5% to the geopolymer concrete mixture, the mechanical behavior was enhanced significantly through experimental results. The compressive strength was improved 26% with 0.5% of polypropylene fiber and 46% with 1% of hooked end steel fiber while the increment of splitting tensile strength was 12% and 28%, respectively. The flexural strength of specimens using two fiber types was also improved when compared with the non-fiber geopolymer concrete. The highest increment obtained with 1.5% of fiber volume content was from 26% to 42%. The compressive performance and flexural performance of fiber-reinforced geopolymer concrete were also better than specimens without fiber, with a higher load carrying capacity, higher stress, higher toughness and smaller strain. Using hooked end steel fiber resulted in better mechanical strength than using polypropylene fiber, and the presence of fibers is an important factor related to the strength improvements. A finite element analysis was modeled by the ANSYS program, and this showed that the load–deflection response and crack patterns also agreed quite well with experimental results.

The use of fluid catalytic cracking (FCC) by-products as aluminosilicate precursors in geopolymer binders has attracted significant interest from researchers in recent years owing to their high alumina and silica contents. Introduced in this study is the use of geopolymer concrete comprising FCC residue combined with fly ash as the requisite source of aluminosilicate. Fly ash was replaced with various FCC residue contents ranging from 0–100% by mass of binder. Results from standard testing methods showed that geopolymer concrete rheological properties such as yield stress and plastic viscosity as well as mechanical properties including compressive strength, flexural strength, and elastic modulus were affected significantly by the FCC residue content. With alkali liquid to geopolymer solid ratios (AL:GS) of 0.4 and 0.5, a reduction in compressive and flexural strength was observed in the case of geopolymer concrete with increasing FCC residue content. On the contrary, geopolymer concrete with increasing FCC residue content exhibited improved strength with an AL:GS ratio of 0.65. Relationships enabling estimation of geopolymer elastic modulus based on compressive strength were investigated. Scanning electron microscope (SEM) images and X-ray diffraction (XRD) patterns revealed that the final product from the geopolymerization process consisting of FCC residue was similar to fly ash-based geopolymer concrete. These observations highlight the potential of FCC residue as an aluminosilicate source for geopolymer products.

This paper presents the results of an experiment study and suggests a theoretical formulation for the bond behavior of reinforced fly ash-based geopolymer concrete. Three grades (20 MPa, 30 MPa and 40 MPa) of a geopolymer concrete along with three reinforcement diameters (12, 16, and 20 mm) were selected for experimental work. The bond behavior of the reinforced geopolymer concrete is determined using pullout test, finite element analysis (FEA), and theoretical work. The test data indicated that the bond strength of reinforced fly ash-based geopolymer concrete increases about 1.97 to 2.56 times with the increase of compressive strength from 20.33 MPa to 41.12 MPa. For grade 30 MPa and 40 MPa specimens, the concrete cover to diameter ratio (c/d_b) increased up to 4.19 resulted in the increase of bond strength. Then, the bond strength decreases with the increase of the c/d_b ratio from 4.19 to 5.75, while grade 20 MPa specimens is vice versa. The bond-slip relations between the reinforcement and geopolymer concrete determined from FEA is in good agreement with experimental results. The coefficient of variation (CoV) is only 0.01. However, this behavior is quite different from the data calculated by the fib model.

A fixed ratio amount, i.e., L-arginine (LA) and trisodium phosphate dodecahydrate (TSP) at 2:0.25, is considered as a hybrid inhibitor. This research aims to extensively investigate the impact of utilizing the hybrid corrosion inhibitor on the corrosion resistance properties in accelerated condition, mechanical characteristics, and predictive estimation of the lifespan of reinforced concrete (RC) structures. Various experiments, such as setting time, slump, air content, porosity, compressive strength, and chloride diffusion coefficient, were conducted to elucidate the influence of the hybrid corrosion inhibitor on the mechanical properties of the concrete matrix. Meanwhile, linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) in 10 wt. % NaCl under wet–dry cycles are utilized to assess the corrosion resistance property, corrosion initiation time, and kinetics of the passive film formation on the steel rebar. Alternatively, both deterministic and probabilistic-based predictions of service life by Life 365 software are utilized to demonstrate the efficacy of the hybrid corrosion inhibitor in protecting the steel rebar in RC structures. All the results confirm that the HI-4 mix (LA:TSP = 3.56:0.44) exhibits excellence in preventing the corrosion and extending the service life of RC structures, due to the adsorption of inhibitor molecules and formation of P-Zwitterions-(Cl)-Fe, Zwitterions-(Cl)-Fe, and FePO₄ complexes onto the steel rebar surface. However, HI-3 shows the optimal mechanical and electrochemical properties for RC structures.