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Since the nineteenth century, reinforced concrete was evolved as a crucial material for construction. This popular composite material is broadly used in different building typologies. However, the decaying of steel rebar due to corrosion is identified as a hindrance that can affect the quality of reinforced concrete structures. In reference to this, the glass fiber-reinforced polymer (GFRP) bar is essential because of corrosion-resistant properties. The researchers performed various tests and numerical analysis to know the response of GFRP-reinforced flexural members in shear and bending. Based on studies over the last decade, this study critically analyzes the response of flexural member reinforced using glass fiber-reinforced polymer (FRP) bars. Understanding the behavior of the FRP bar as the alternating reinforcing material will be aided by this review. Since the GFRP bar has high strength and no yield point, the conventional characterizations of ductility may not be applicable to determine whether GFRP-reinforced concrete components are ductile. Hence, a detailed study is needed to understand the behavior of such structures. This paper explores various properties of GFRP-reinforced beams to appreciate the applications of GFRP reinforcement in flexural members.

Geopolymer concrete with time is gaining recognition as a sustainable alternative to Portland cement concrete, offering lower carbon emissions and utilising industrial by-products. While prior research focussed on its mechanical properties for structural purposes, this study explores its potential for paving applications. A unique geopolymer concrete mixture suitable for paving, referred to as paving quality geopolymer concrete (PQGC), was developed by incorporating slag sand (SS) as a substitute for river sand (RS). The investigation primarily assessed fatigue life PQGC mixes. The findings demonstrate that the inclusion of SS in PQGC has no significant impact on its setting times or workability. However, PQGC formulated with 100% SS, w.r.t PQGC containing RS, exhibited enhanced mechanical strength of 7% in compression, 16.7% in flexure and 8.3% in split tensile tests at 28 days of open-air curing. Following a 14-day period of curing, PQGC achieved a compressive strength of 46 MPa, surpassing the minimum requirement of 40 MPa as per IRC:58 2015 for pavement quality concrete (PQC) by 15%. To evaluate fatigue performance, PQGC beam specimens were subjected to repeated loading at stress levels ranging from 0.9 to 0.6. The resulting fatigue data were employed to develop stress-fatigue life (SN) and Weibull two-parameter fatigue failure models. Comparative analysis with fatigue failure models such as Indian Road Congress (IRC) and Darter revealed that PQGC exhibits superior fatigue resistance and longer life expectancy compared to PQGC. In conclusion, this study confirms that PQGC incorporating SS is an efficient and eco-friendly choice for constructing rigid pavements with advantages such as curing without water, enabling early opening of roadways to traffic, and excellent resilience under cyclic loads.

Several countries have started using recycled aggregate as a partial replacement to natural aggregate in concrete. Recycled aggregate contains adhered mortar, which distinguishes it from the natural aggregate. In the present study, natural coarse aggregates were entirely replaced by two kinds of recycled coarse aggregates. The recycled aggregates obtained from the jaw crushing method were named recycled coarse aggregate-1 and the aggregates that were further processed by the ball milling method were named recycled coarse aggregate-2. The performance of control concrete and two kinds of recycled coarse aggregate concretes were studied experimentally with respect to mechanical properties. Results indicate that the processing method to obtain recycled coarse aggregates plays an important role in developing the required mechanical properties. The ball mill processed aggregates performed better than the jaw crushed aggregates in concrete. The performance was also assessed with respect to the microhardness of the interfacial transition zone around the surface of the aggregates. The presence of adhered mortar in recycled aggregate weakens it because of the presence of an old interfacial transition zone that affects the strength of concrete. The interfacial transition zone hardness at the aggregate-mortar interface is 53.94, 34.21, and 44.08 % of bulk concrete for control concrete, recycled coarse aggregate-1 concrete, and recycled coarse aggregate-2 concrete, respectively. The addition of silica fume improved the average microhardness, and the same was reflected in the mechanical properties of both the recycled coarse aggregate concretes. It is recommended to use ball mill processed recycled coarse aggregates as a complete replacement to natural coarse aggregates along with a 5 % addition of silica fume for better performance.

Sulfate attack is one of the severe concerns for concrete's durability in sulfate-rich soil, groundwater, and the marine environment. The ingress of dissolved sodium and (or) magnesium sulfate in concrete leads to the formation of expansive products such as gypsum, ettringite, brucite, and magnesium-silicate-hydrate (M–S–H), causing extensive cracking and disintegration of concrete based on the severity of the attack. The consequence of ingress of magnesium sulfate is more severe than sodium sulfate. The present article aims to assess the long-term behavior of a novel cement composite incorporating 80% class-F fly ash (F-FA) and 20% ordinary Portland cement with varying volume fractions of polypropylene fibers exposed to 5% magnesium sulfate solution for up to two years. The compressive strength, weight, and volume changes of the specimens measure these effects. The mixes with higher volume fractions of PP fibers undergo a 40% reduction in compressive strength, 6.7% weight gain, and 3.5% volume change at two years. The morphological features revealed through SEM images and EDX analysis find the formation of M–S–H, brucite, gypsum, ettringite traces, and unreacted F-FA. The outcomes of this study encourage the utilization of F-FA to a much higher volume to help reduce the carbon footprint and promote sustainability.

In the construction sector, the material supply chain of aggregates is frequently disturbed due to seasonal unavailability, quarrying issues, and environmental norms. The production of artificial aggregates has gained prominence to conserve natural resources and promote green construction practices. The current study encompasses the production of alkali-activated artificial aggregates through cold-bonding pelletization technique using three different raw materials, including fly ash, ground granulated blast furnace slag, and seashell powder in binary and ternary blending combinations. The cold bonding was achieved by alkali activation of binders with the aid of a sodium-based alkaline solution, which acts as an activator and hydrating liquid. The fresh artificial aggregates were subjected to surface treatment using the same alkaline solution to enhance their characteristics. The mechanical properties of artificial aggregates confirmed their potential as a substitute for conventional aggregates by exhibiting crushing and impact values of 18.19–27.53% and 12.06–18.85%, respectively. The microstructural and mineralogical characteristics depicted dense microstructure and compact matrix. The study concludes that artificial aggregates can effectively replace natural coarse aggregate in making structural concrete with many economic, environmental, and technical advantages.

Dynamic response of base isolated multi-storey symmetrical and asymmetrical space frame structures with multiple tuned mass dampers (MTMD), subjected to bi-directional harmonic and Mexico earthquake ground motions are studied. A four-storey space frame structure having six degrees of freedom (three translations along x, y, z-axes and three rotations about these axes) at each node is considered for study. Each tuned mass damper (TMD) is modelled using a two-noded element having two translational degrees of freedom at each node. MTMD with uniformly distributed frequencies are considered for this purpose. The effectiveness of MTMD in suppressing the structural response is determined by comparing the response of corresponding structure without MTMD. It is found that the MTMD can be used effectively to suppress the responses of the symmetrical and asymmetrical base isolated space frame structures. The effect of important parameters on the effectiveness of the MTMD is also studied. The parameters include the fundamental characteristics of the MTMD such as damping, total number of MTMD, tuning frequency ratio and frequency spacing of the dampers. It is shown that these parameters have considerable influence on the effectiveness of the MTMD in reducing the dynamic response of the base isolated structure.

The present study concentrates on the performance evaluation of calcined and uncalcined cashew nut-shell ash (UCCNA and CCNA) with treated total recycled concrete aggregate (TRCA) in self-compacting concrete. The achievement of sustainable self-compacting concrete (SCC) is possible by the implication of four stages, which includes TRCA treatment process, gradation selection process through Bailey aggregate grading technique, by considering TRCA replacement percentage with an increment of 25% and up to 100% and by considering UCCNA or CCNA replacement with an increment of 5% and up to 20%. Hardened and fresh properties of SCC have been performed and analyzed based on the compliance requirements of SCC. In addition finding results through microstructure assessment was in line with the findings of the hardened and fresh properties of SCC. In addition, quality and dynamic instability assessments of SCC were analyzed through ultrasonic pulse velocity and drying shrinkage aspects. Besides CO2, the emission rate and the efficiency rate of SCC, composites were analyzed in detail. Overall findings revealed that CCNA-based SCC mixes performed effectively than UCCNA-based SCC; specifically, incorporation of 75% of TRCA with 15% CCNA was found to be optimal. But with regard to shrinkage performance UCCNA found to be better by imputing less shrinkage compared to CCNA-based SCC mixes. Further with regard to efficiency rate of SCC composites revealed the gain of maximum efficiency of about 0.156 MPa/kg CO2/m3and 0.160 MPa/kg CO2/m3for 15% and 20% CCNA-based SCC mixes.