The large production of cement is resulting in a high-carbon footprint, which is essential to minimize for sustainable concrete construction. Moreover, the large quantity of recycled coarse aggregate (RCA) from the demolition of old concrete structures is creating problems for landfill and disposal. The primary goal of this study is to investigate the seismic efficiency of innovative fiber-reinforced polymer (FRP)-recycled aggregate geopolymer concrete (RAGC) steel-tubed columns (FGSTCs) with an internal steel tube (STT), an external glass-FRP tube (GLT), and RAGC located between the two-tubed components to develop a serviceable structural element. To study their seismic functioning under axial load and lateral repeated load, five FGSTC specimens were manufactured and analyzed under quasi-static loads. The influence of three variables on the performance of FGSTC specimens, consisting of STT reinforcing ratio, compression ratio, and recycled coarse aggregate (RCA) replacement ratio, was investigated in this investigation. The produced specimens’ ductility, hysteretic loops, strain distribution, skeleton curves, stiffness functioning, energy capacity dissipation, damaging functioning, and strength loss were all assessed and discussed. The results of this investigation revealed that percentage substitution of RCA had a minor impact on the seismic functioning of FGSTCs; however, the compression-load ratio depicted a substantial impact. The energy loss of the FGSTCs was 24.5% higher than that of their natural aggregate equivalents. FGSTCs may have a 16.9% lower cumulative failure rate than their natural aggregate counterparts.

Using recycled concrete aggregates from construction and demolition wastes on structural concrete is a sustainable solution to reduce the consumption of natural resources and the detrimental effects of concrete production on the environment. This paper has collected much data from the literature to study fresh, mechanical properties and durability of concrete made of treated/untreated recycled aggregate (RA). Furthermore, the flexural and shear behavior of recycled aggregate concrete (RAC) beams was studied. This study discussed the distinctions and similarities between reinforced RAC beams and reinforced natural aggregate concrete (NAC) beams. The results of this review’s analysis clearly show that reinforced RAC beams with different RAC ratios perform structurally on par with or slightly worse than reinforced NAC beams, demonstrating the viability of RAC for structural applications. Emphasis is placed on carefully choosing and adjusting material models for recycled aggregate concrete. Ultimately, guidelines for future inquiries in this field are delineated and deliberated upon. The review will be advantageous for academics and professionals who aim to acquire a comprehensive comprehension of the behavior of RAC beams. It addresses several practical concerns connected to the numerical modeling of these components, which have not been adequately covered in existing literature.

In this study, the effect of micro-carbon fiber on the properties of concrete incorporating recycled coarse aggregate at three different levels, i.e., 0%, 50%, and 100% by volume replacement of natural coarse aggregate, was studied. Carbon fiber was incorporated at a dosage of 0.5% by volume fraction. The effect of silica fume or micro-silica on the efficacy of fiber reinforcement was also investigated. Studied parameters include important mechanical properties, such as compressive strength, splitting tensile strength, and flexural strength, and physical/quality parameters such as water absorption capacity and ultrasonic pulse velocity. The results showed that the mechanical and durability performance deteriorates with the increasing percentage of recycled coarse aggregate. Carbon fiber can significantly improve the tensile properties of recycled aggregate concrete. The combination of carbon fiber and silica fume proved to be highly useful in addressing both mechanical and durability concerns simultaneously. Concrete made with 50% recycled coarse aggregate, 8% silica fume, and 0.5% carbon fiber yielded 20% greater tensile and flexural strength compared to the control mix. Likewise, concrete containing 100% recycled coarse aggregate with silica fume and carbon fiber yielded higher tensile strength compared to the control mix. Silica fume ameliorated the bonding between fibers and matrix and improved the overall efficacy of fiber reinforcement.

Background: The designing of the reinforced concrete building for the reduction of the seismic load has significantly gained popularity. Most of the buildings in Saudi Arabia are designed for the gravity load, based on its seismicity level. Objective: The study evaluates the effects of the earthquake load on the RC school building located in Saudi Arabia. Method: An equivalent static analysis technique used to apply the seismic analysis and design method according to Saudi Building Code SBC301 (2007). This design code is used to redesign the chosen school building. The SAP 2000 structural analysis software was used to analyses and study the structure behaviour due to the seismic load. Results: The results of the study provide that the RC school building design in Saudi Arabia is inadequate, and unsafe for the earth quakes. Conclusion: One of the important conclusions in this study is that the designer of the school building in Saudi Arabia should take into consideration the earthquake loads. It also emphasizes on the development of the adequate framework for the implementation of the safe designing of the buildings inclusive of earthquake safety measures.