Assessment of thermal stability of external enclosing structures and justification of an effective structural solution

2026-08-14T20:28:45+05:00

This paper presents a study of the thermal stability of traditional external enclosing structures in hot climates, taking into account exposure to intense solar radiation. The objects of analysis are a wet facade and a mounted ventilated facade with an air space, widely used in the construction practice of the Republic of Kazakhstan. Calculations were performed for the climatic conditions of Shymkent city using a normative methodology to determine the amplitude of temperature fluctuations on the internal surface of the enclosure. It was found that, when exposed to extreme outdoor temperatures and solar radiation, the actual amplitude of temperature fluctuations exceeds the standard values, which leads to a decrease in thermal stability and an increase in heat gain into the premises. It is shown that the temperature of the external surface of the enclosures can reach 65-72°C, which significantly degrades the performance characteristics of traditional structures. Based on the conducted analysis, the use of the developed adaptive design of the external enclosure with an air space, ensuring increased energy efficiency and thermal stability, is justified. The simulation results showed that in winter, the internal surface temperature increases by 1.5-2.3°C, reducing heat loss by 12-18%. In summer, the external cladding temperature decreases by 3-5 °C, reducing heat gain by 8-14%. The results confirm the effectiveness of the proposed structural solution and can be used in the design of energy-efficient buildings in hot climates.

Effect of polypropylene fiber length on the mechanical properties, frost resistance, and microstructure of silica fume-modified self-compacting concrete

2026-08-22T16:49:52+05:00

This study investigates the influence of polypropylene fiber length (6–20 mm) on the mechanical properties, frost resistance, density, and microstructure of silica fume-modified self-compacting concrete (SCC). Microstructural analysis by scanning electron microscopy (SEM) was performed on the fiber-free reference mixture and the optimum fiber lengths of 12- and 15-mm. Polypropylene fibers affected the durability and strength performance of SCC: mixtures with 12 mm and 15 mm fibers performed best overall, reaching the highest 28-day compressive strengths (55.3 and 54.9 MPa), average density up to 2412 kg/m³, and frost resistance up to F350. Water absorption decreased from 4.8% in the fiber-free reference mixture to 4.1-4.2% in these mixtures. SEM observations indicated a relatively dense cement matrix with fewer visible pores and apparent fiber–matrix contact in the 12 mm and 15 mm mixtures. Because all mixtures contained the same silica fume dosage, its individual effect could not be experimentally isolated; based on the literature, its pozzolanic and microfiller effects may have contributed to the observed matrix morphology, while differences among mixtures were primarily associated with fiber presence and length. Overall, 12 mm and 15 mm fibers provided the best combination of mechanical and durability-related properties among the lengths tested.

Technobius

Assessment of thermal stability of external enclosing structures and justification of an effective structural solution

Effect of polypropylene fiber length on the mechanical properties, frost resistance, and microstructure of silica fume-modified self-compacting concrete