Improving Stress-Strain Behavior of Waste Aggregate Concrete Using Affordable Glass Fiber Reinforced Polymer (GFRP) Composites

Abstract

Several studies have highlighted the potential of crushed brick aggregates in non-structural concrete. This is because crushed brick aggregates offer substandard mechanical properties in comparison to natural stone aggregates. Synthetic Fiber Reinforced Polymer (FRP) sheets have been known to overcome this issue. However, enormous costs associated with synthetic FRPs may limit their use in several low-budget applications. This study recognizes this issue and propose a cost-effective solution in the form of low-cost glass fiber (LC-GFRP) sheets. Two types of brick aggregates (i.e., solid-clay and hollow-clay brick aggregates) were used to fabricate concrete by replacing 50% of natural aggregates. Experimental results of 32 non-circular specimens were reported in this study. To overcome the substandard mechanical properties of recycled brick aggregate concrete (RBAC), specimens were strengthened with 2, 4, and 6 layers of LC-GFRP sheets. Noticeable improvements in ultimate compressive stress and corresponding strain were observed and were found to correlate positively with the number of LC-GFRP sheets. It was found that 4 and 6 layers of LC-GFRP sheets imparted significant axial ductility irrespective of the brick aggregate type and inherent concrete strength. Several existing stress-strain models for confined concrete were considered to predict ultimate confined compressive stress and corresponding strain. Accuracy of existing models was assessed by mean of the ratio of analytical to experimental values and associated standard deviations. For ultimate stress predictions, the lowest mean value of the ratio of analytical to experimental ultimate compressive stress was 1.07 with a standard deviation of 0.10. However, none of the considered models was able to provide good estimates of ultimate strains.

Experimental Study and Theoretical Analysis on the Compression–Shear Multiaxial Mechanical Properties of Recycled Concrete

“…A mathematical regression analysis of the normal and shear stresses in recycled concrete under different RA replacement rates was carried out by applying Equation (11), and the values of parameter d and e were obtained. Specifically, the values of d are basically similar.…”

“…Specifically, the values of d are basically similar. In order to further simplify Equation (11), the value of d was set as its mean value, which is −0.17. Then, the normal stress and shear stress data of recycled concrete was used to perform mathematical regression analysis on Equation (11), to determine the value of e under different RA replacement rates, as shown in Figure 14.…”

“…It was found that, when the fiber content exceeded the threshold level, the diffusion of chloride ions in recycled concrete structures became more obvious as the fiber content was increased and with the decrease of pre-compression stress. In view of the replacement of coarse aggregates with broken brick aggregates having a great effect on the mechanical properties of concrete, Rodsin, K. et al [ 11 ] applied FRP to reinforce a recycled concrete column. The results indicated that, with the increase of FRP layers, the ultimate compressive stress and deformability of the recycled concrete column were significantly improved.…”

Environmental Impact on the Behavior of CFRP Sheet Attached to Concrete

“…Until now, their cost and long-term behavior make their development doubtable. Enormous costs associated with synthetic FRPs may limit their use in several low-budget applications [1,2]. Low-cost and easily available fiber rope-reinforced polymer composites were used to strengthen concrete columns [1].…”

“…Low-cost and easily available fiber rope-reinforced polymer composites were used to strengthen concrete columns [1]. Moreover, low-cost glass fiber sheets were used to upgrade concrete with waste aggregate [2]. Carbon fiber-reinforced polymer (CFRP) has superior mechanical properties and higher tensile strength, stiffness, and durability compared with other fiber-based systems.…”