Science and Engineering

The worldwide awareness toward sustainability motivated the human innovativeness to investigate and apply additional environmental solutions like the use of fiber-reinforced polymer (FRP) as a reinforcement instead of steel in order to lower the greenhouse emissions and energy consumption associated with the excessive structural work. The deterioration of structural members is always expected due to many factors such as corrosion of steel, severe weather and unexpected loads, therefore the use of fiber-reinforced polymers gained popularity due to their advantageous properties such as lightweight, high strength and corrosion resistance. The arising concerns about climate change and depletion of natural resources paved the way to conduct comprehensive studies to assess the environmental impact of FRP during its life service. Life cycle assessment is used to evaluate the environmental impact of a product or a process. This paper seeks to contribute to the existing literature of studies related to the life cycle assessment, mechanical behavior, and the applications of different FRP composites used as a reinforcement in concrete beams. The reported results from literature were compatible with each other where using FRP composites in beams enhance the stiffness and strength and at the same time reduce the environmental impacts compared to traditional building materials like steel, also developing the design and construction codes for reinforced concrete beams by using FRPs will encourage the use of these materials
in constructions.

Unconfined compression tests were performed to determine the benefit of using randomly distributed polypropylene fiber reinforcement mixed with Portland cement on the engineering behavior of sandy soils. Fiber length was 19 mm and the content of fiber was 0%, 0.1%, 0.3%, and 0.5% by the dry weight of soil while the content of cement was 3%, 5%, and 7% by the dry weight of soil. The samples were prepared at optimum water content and cured for 7 and 28 days in a moisture-curing tank. The results show that the addition of fiber reinforcement to the cemented soil results in increasing the unconfined compressive strength and axial strain at failure and it changed the behavior of the cemented soil from brittle behavior to more ductile behavior.

The urbanization process adds to the increase in solid waste generation, increased environmental impacts, and solid waste management failures. Due to the restricted deployment and proper disposal of solid waste, the environmental implications are a concern. There has been an increase in interest in sustainable practices regarding waste management and recycling, which the civil construction sector has substantially absorbed. Plastic waste can be recycled and can be used in many applications. One such application is in concrete, for which the recycled-based plastic aggregates or plastic fibers can be substituted for natural aggregates or steel-reinforced mesh (SRM). Many researchers have investigated the mechanical properties of such concrete; however, the environmental assessments are limited in the literature. This research evaluates and consolidates environmental studies on recycled plastics in concretelike aggregates and fibers. A summary of the applications of recovered plastics is presented. Following that, the works on environmental implications are thoroughly discussed and analyzed. In addition, research gaps and challenges related to environmental assessments are highlighted in this work.

The main purpose of this study is to improve the engineering properties of sandy soil by mixing it with different materials such as cement, bentonite and fiber. The tests were performed at Istanbul Technical University, Geotechnical Laboratories. First, the soil was classified by performing sieve analysis and then its specific gravity and permeability were determined after that standard Proctor compaction test was performed to obtain the optimum water content and maximum dry unit weight for the soil. To evaluate the strength properties of the soil, unconfined compression tests and shear box tests were performed for the prepared samples. For the first stage samples were prepared to be used in unconfined compression test by using mini compaction device by mixing sand with (3%, 5% and 7% cement by weight) and randomly distributed 19 mm fiber with different ratios of (0%, 0.1%, 0.3% and 0.5% by weight) and optimum water content of the sand. The samples preserved in a moisture tank for 7 days or 28 days as curing time. The results for this stage showed that cemented samples with no fiber behaved in brittle way while by adding fiber the behavior changed from brittle to ductile behavior and it showed that the addition of fiber increased the unconfined compressive strength but the improvement percentage was dependent on cement percentage and fiber ratio. For smaller cement percentages like 3% cement, the effect of fiber was higher and more noticeable and it reached 80% improvement for 0.5% fiber content compared to the cemented samples without fiber and 50% improvement for 0.3% fiber while for 7% cement the effect of fiber was less where the percentage of improvement was between (20% to 30%) for (0.3% to 0.5%) fiber compared to the cemented samples without fiber. The unconfined compressive strength for the samples increased after curing the samples for 28 days compared to the 7 days cured samples. At the second stage, samples were prepared for unconfined compression test by using mini compaction device. The way of preparation was by mixing sand with (0%, 3%, 5% and 7% cement by weight) and (0%, 5%, 10% and xxii 15% bentonite by weight) and after sufficient mixing, optimum water content was added to the mixture to ensure maximum dry unit weight. The samples were preserved in a moisture tank for 7 and 28 days curing time. The obtained results from the second stage showed that cemented sand samples and cemented samples mixed with bentonite had a brittle behavior while the sand bentonite samples had a ductile behavior. The results showed that increasing the bentonite content for (0%, 3% and 5%) cement increased the unconfined compressive strength radically while for 7% cement; the addition of bentonite increased the UCS for 7 days in a small percentage and decreased UCS after 28 days. Curing the samples for 28 days increased the unconfined compressive strength compared to the 7 days cured samples. After preforming unconfined compression test, direct shear test was performed to gain a better knowledge about the effect of fiber reinforcement and bentonite on the shear strength and friction angel properties for the sandy soil. First fiber was mixed with sand in different ratios (0% 0.1%, 0.3% and 0.5% by weight), later optimum water content was added to the samples, and after one day, the samples were sheared by using direct shear machine. Adding fiber to the sandy soil increased its shear strength and friction angle for the tested samples. For this second stage (0%, 5%, 10% and 15% by dry weight of sand) bentonite were mixed with sand and later optimum water content was added to the mixture and after one day the samples were molded and sheared by using direct shear machine. The addition of bentonite in general decreased the shear strength of the samples and the friction angle.

The construction sector is well known for its critical environmental impact resulting from the consumed amounts of raw materials and the tremendous emissions of greenhouse gases. Therefore, scientists need to promote and study the environmental implications of using alternative solutions such as fiber-reinforced polymers (FRP) throughout their service life. FRPs have gained increasing popularity in the last few years due to their durability, high corrosion resistance, lightweight, and high strength. Life cycle assessment is considered one of the most important methods to investigate the environmental impacts of the FRP. The aim of this paper is to present an overview of fiber-reinforced polymer composites in concrete structures with an investigation focusing on the environmental and mechanical properties in civil engineering structures. The main focus is set on the properties of fiber-reinforced polymers, their use as a strengthening technique in concrete structural members and their environmental impact using the life cycle assessment method.  The reported results from the literature reveal that utilizing FRP composites in structural members instead of traditional materials improves their strength and stiffness and reduces environmental impacts.

Environmental awareness and the need for sustainable construction inspired researchers and practitioners to explore innovative alternatives that might reduce greenhouse gas emissions and energy use related to excessive structural work. One such alternative is the utilization of Fiber-Reinforced Polymer (FRP) bars as a reinforcement in reinforced concrete members. FRP bars possess favorable characteristics like high tensile strength, lightweight and corrosion resistance compared to steel. This feature makes FRP bars a potential solution for utilizing seawater instead of fresh water in concrete mixtures, especially in areas facing a harsh climate and water shortage like the Arabian Peninsula. This paper aims to assess and evaluate the environmental impacts through life cycle assessment of glass fiber-reinforced polymer bars, carbon fiber reinforced polymer, and steel glass fiber-reinforced polymer bars compared to
steel bars. Moreover, another LCA was conducted comparing steel-reinforced beams made with desalinated fresh water to GFRP/CFRP reinforced beams made with seawater for the concrete mixture. The results indicate that the GFRP bar performed better than the steel bar in 10 out of 14 categories, while the carbon fiber-reinforced polymer bar performed worse than the steel bar in 10 out of 14 categories. The SGFRP bar had a result between the steel and GFRP bar, outperforming the steel bar in 10 categories. Furthermore, the GFRP beam exhibited better environmental performance than the steel beam in 9 out of 14 categories, while the CFRP beam performed better than the steel beam in 8 categories, attributed to the reduction in reinforcement ratio due to the high tensile strength of CFRP and GFRP bars compared to steel bars. Overall, this study sheds light on the possible environmental advantages of using FRP bars in construction and highlights the importance of sustainable construction practices in minimizing environmental impacts.

The advancement of eco-friendly technology in the construction sector has been improving rapidly in the last few years. As a result, multiple building materials were developed, enhanced, and proposed as replacements for some traditional materials. One notable example presents geopolymer as a substitute for ordinary Portland concrete (OPC). The manufacturing process of (OPC) generates CO2 emissions and a high energy demand, both of which contribute to ozone depletion and global warming. The implementation of geopolymer concrete (GPC) technology in the construction sector provides a path to more sustainable growth and a cleaner environment. This is due to geopolymer concrete's ability to reduce environmental pollutants and reduce the construction industry's carbon footprint. This is achieved through its unique composition, which typically involves industrial byproducts like fly ash or slag. These materials, rich in silicon and aluminum, react with alkaline solutions to form a binding gel, bypassing the need for the high-energy clinker production required in OPC. The use of such byproducts not only reduces CO2 emissions but also contributes to waste minimization. Additionally, geopolymer offers extra advantages compared to OPC, including improved mechanical strength, enhanced durability, and good stability in acidic and alkaline settings. Such properties make GPC particularly suitable for a range of construction environments, from industrial applications to infrastructure projects exposed to harsh conditions. This paper comprehensively reviews the different characteristics of geopolymers, which include their composition, compressive strength, durability, and curing methods. Furthermore, the environmental impacts related to the manufacturing of geopolymer materials were evaluated through the life-cycle assessment method. The result demonstrated that geopolymer concrete maintains positive environmental impacts due to the fact that it produces fewer carbon dioxide CO 2 emissions compared to OPC concrete during its manufacturing; however, geopolymer concrete had some minor negative environmental impacts, including abiotic depletion, human toxicity, freshwater ecotoxicity, terrestrial ecotoxicity, and acidi-fication. These are important considerations for ongoing research aimed at further improving the sustainability of geopolymer concrete. Moreover, it was determined that silicate content, curing temperature, and the proportion of alkaline solution to binder are the major factors significantly influencing the compressive strength of geopolymer concrete. The advancement of geopolymer technology represents not just a stride toward more sustainable construction practices but also paves the way for innovative approaches in the field of building materials.

The advancement of eco-friendly technology in the construction sector has been improving rapidly in the last few years. As a result, multiple building materials were developed, enhanced, and proposed as replacements for some traditional materials. One notable example presents geopolymer as a substitute for ordinary Portland concrete (OPC). The manufacturing process of (OPC) generates CO 2 emissions and a high energy demand, both of which contribute to ozone depletion and global warming. The implementation of geopolymer concrete (GPC) technology in the construction sector provides a path to more sustainable growth and a cleaner environment. This is due to geopolymer concrete's ability to reduce environmental pollutants and reduce the construction industry's carbon footprint. This is achieved through its unique composition, which typically involves industrial byproducts like fly ash or slag. These materials, rich in silicon and aluminum, react with alkaline solutions to form a binding gel, bypassing the need for the high-energy clinker production required in OPC. The use of such byproducts not only reduces CO 2 emissions but also contributes to waste minimization. Additionally, geopolymer offers extra advantages compared to OPC, including improved mechanical strength, enhanced durability, and good stability in acidic and alkaline settings. Such properties make GPC particularly suitable for a range of construction environments, from industrial applications to infrastructure projects exposed to harsh conditions. This paper comprehensively reviews the different characteristics of geopolymers, which include their composition, compressive strength, durability, and curing methods. Furthermore, the environmental impacts related to the manufacturing of geopolymer materials were evaluated through the life-cycle assessment method. The result demonstrated that geopolymer concrete maintains positive environmental impacts due to the fact that it produces fewer carbon dioxide CO 2 emissions compared to OPC concrete during its manufacturing; however, geopolymer concrete had some minor negative environmental impacts, including abiotic depletion, human toxicity, freshwater ecotoxicity, terrestrial ecotoxicity, and acidification. These are important considerations for ongoing research aimed at further improving the sustainability of geopolymer concrete. Moreover, it was determined that silicate content, curing temperature, and the proportion of alkaline solution to binder are the major factors significantly influencing the compressive strength of geopolymer concrete. The advancement of geopolymer technology represents not just a stride toward more sustainable construction practices but also paves the way for innovative approaches in the field of building materials.