Reversible thermochromic polymers have emerged as compelling candidates in recent years, captivating attention for their application in heat detection systems. This comprehensive review navigates through the multifaceted landscape, intricately exploring both the virtues and hurdles inherent in their integration within these systems. Their innate capacity to change colour in response to temperature fluctuations renders reversible thermochromic nanocomposites promising assets for heat detection technologies. However, despite their inherent potential, certain barriers hinder their widespread adoption. Factors such as a restricted colour spectrum, reliance on external triggers, and cost considerations have restrained their pervasive use. For instance, these polymer-based materials exhibit utility in the domain of building insulation, where their colour-changing ability serves as a beacon, flagging areas of heat loss or inadequate insulation, thus alerting building managers and homeowners to potential energy inefficiencies. Nevertheless, the limited range of discernible colours may impede precise temperature differentiation. Additionally, dependency on external stimuli, such as electricity or UV light, can complicate implementation and inflate costs. Realising the full potential of these polymer-based materials in heat detection systems necessitates addressing these challenges head-on. Continuous research endeavours aimed at augmenting colour diversity and diminishing reliance on external stimuli offer promising avenues to enhance their efficacy. Hence, this review aims to delve into the intricate nuances surrounding reversible thermochromic nanocomposites, highlighting their transformative potential in heat detection and sensing. By exploring their mechanisms, properties, and current applications, this manuscript endeavours to shed light on their significance, providing insights crucial for further research and potential applications.

The study has two objectives. First, it experimentally measures the indoor and outdoor temperatures of a building in Peshawar and conducts validation with CFD modeling. Second, it simulates the building with the addition of locally available, natural, and recycled insulator materials on the rooftop to keep the indoor environment within a comfortable temperature range, especially in the winter and summer seasons. To achieve these objectives, experimental temperature data for January and June were recorded and validated, followed by a simulation, using ANSYS-Fluent 16 CFD, of the residential building with the application of waste thermal insulators such as straw bale, sheep wool, and recycled glass materials on the rooftop to reduce the indoor temperature. Experimental temperature measurement showed that the lowest recorded indoor temperature was 15°C on 2 January 2022 and that the highest recorded indoor temperature was 41°C on 11 June. The predicted and validated temperature results were similar, with a slight difference of less than 15%. Recycled glass positively and significantly reduced the indoor temperature in summer by 10.2% and thermal amplitude by 48.3%, with a time lag increase of 100% and an increase in the period of comfort hours of 380%. In winter, the daily average temperature increased by 7.4%, thermal amplitude was reduced by 59.3%, and the time lag increased by 100% in comparison with the baseline case results. The study concludes that recycled glass distribution gives the best improvement compared to straw bale and sheep wool.

Concrete is brittle; hence, it is incredibly likely that concrete buildings may fail in both local and global ways under dynamic and impulsive stresses. An extensive review investigation was carried out to examine reinforced concrete (RC) slab behavior under low-velocity impact loading. Significant past research studies that dealt with experimental and numerical simulations and analytical modeling of the RC slabs under impact loading have been presented in this work. As a result, numerous attempts to define failure behavior and to assess concrete structures’ vulnerability to lateral impact loads have been made in the literature. Based on analytical, numerical, and experimental studies carried out in previous research, this article thoroughly reviewed the current state of the art regarding the responses and failure behaviors of various types of concrete structures and members subjected to low-velocity impact loading. The effects of different structural and load-related factors were examined regarding the impact strength and failure behavior of reinforced concrete slabs reinforced with various types of strengthening procedures and exposed to low-velocity impact loads. The reviews suggested that advanced composite materials, shear reinforcement, and hybrid techniques are promising for effectively strengthening concrete structures.

Blast damage to structural members poses serious risks to both buildings and people, making it important to understand how these elements behave under extreme loads. Columns in reinforced concrete (RC) structures are especially critical, as their sudden failure can trigger progressive collapse, unlike beams or slabs that have more redundancy. This state-of-the-art review brings together the current knowledge of the blast response of RC columns, focusing on their failure patterns, dynamic behavior, and key loading mechanisms. The studies covered include experiments, high-fidelity numerical simulations, emerging machine learning approaches, and analytical models for columns of different shapes (square, rectangular, circular) and strengthening methods, such as fiber reinforcement, steel-concrete composite confinement, and advanced retrofitting. Composite columns are also reviewed to compare their hybrid confinement and energy-absorption advantages over conventional RC members. Over forty specific studies on RC columns were analyzed, comparing the results based on geometry, reinforcement detailing, materials, and blast conditions. Both near-field and contact detonations were examined, along with factors like axial load, standoff distance, and confinement. This review shows that RC columns respond very differently to blasts depending on their shape and reinforcement. Square, rectangular, and circular sections fail in distinct ways. Use of ultra-high-performance concrete, steel fibers, steel-concrete composite, and fiber-reinforced polymer retrofits greatly improves peak and residual load capacity. Ultra-high-performance concrete can retain a significantly higher fraction of axial load (often >70%) after strong blasts, compared to ~40% in conventional high-strength RC under similar conditions. Larger sections, closer stirrups, higher transverse reinforcement, and good confinement reduce spalling, shear failure, and mid-height displacement. Fiber-reinforced polymer and steel-fiber wraps typically improve residual strength by 10–15%, while composite columns with steel cores remain stiff and absorb more energy post-blast. Advanced finite element simulations and machine learning models now predict displacements, damage, and residual capacity more accurately than older methods. However, gaps remain. Current design codes of practice simplify blast loads and often do not account for localized damage, near-field effects, complex boundary conditions, or pre-existing structural weaknesses. Further research is needed on cost-effective, durable, and practical retrofitting strategies using advanced materials. This review stands apart from conventional literature reviews by combining experimental results, numerical analysis, and data-driven insights. It offers a clear, quantitative, and comparative view of RC column behavior under blast loading, identifies key knowledge gaps, and points the way for future design improvements.