Technobius

Hyper-pressing technologies and properties of construction products: a review

Tue, 29 Sep 2026 00:00:00 +0500

High-pressure forming is increasingly recognized as a promising method for producing low-energy masonry units from natural minerals and secondary raw materials. This review consolidates current knowledge on compressed earth blocks, cementitious high-pressure bricks, alkali-activated products, and ultra-high-pressure waste-derived bricks. Emphasis is placed on raw material selection, mixture preparation, forming moisture, compaction pressure, curing conditions, structure formation mechanisms, and resulting engineering properties. The literature indicates that pressure-induced particle rearrangement and pore reduction must be integrated with hydration, pozzolanic reactions, alkali activation, or carbonation to achieve stable long-term performance. Increasing pressure typically enhances density, strength, and water resistance up to an effective densification threshold, beyond which further pressure may yield limited benefits or induce microcracking and elastic recovery. Industrial, mining, construction, and agricultural wastes can substitute for significant proportions of natural raw materials; however, their use necessitates careful control of particle grading, chemical variability, soluble salts, and potentially hazardous components. The environmental advantages of avoiding firing may be offset by high Portland cement content, extended transport distances, and energy-intensive waste pretreatment. This review highlights insufficient standardization of terminology, specimen geometry, compaction procedures, curing regimes, and durability assessment as major obstacles to comparison. Future research should focus on long-term exposure testing, full-scale production, environmental safety, life-cycle assessment, and the development of low-carbon binder systems.

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

Fri, 14 Aug 2026 00:00:00 +0500

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

Assel Ospanova, Evgeniya Tkach; Tolebi Myrzaliyev — Sat, 22 Aug 2026 00:00:00 +0500

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.

Effect of curd whey on the shrinkage and water absorption of fired clay building ceramics

Fri, 25 Sep 2026 00:00:00 +0500

This study examines the effect of curd whey, introduced as part of the mixing liquid, on the shrinkage and water absorption of fired clay building ceramics. The ceramic body was prepared from a 50:50 mixture of low-firing clays from the Ivanovo and 24^th Party Congress deposits (Akmola Region, Kazakhstan). Curd whey replaced 15% and 20% of the mixing liquid by volume, with a whey-free composition used as the reference. Specimens were shaped by plastic forming and fired at 850, 900, 950, 1000, 1050, and 1100 °C. Firing shrinkage, total shrinkage, and water absorption were determined on five specimens for each combination of composition and firing temperature; no values were recorded for seven combinations, which are identified in the text. The addition of 15% whey reduced firing shrinkage at every firing temperature at which it was measured: at 1050 °C, firing shrinkage was 0.9 ± 0.08% for the composition containing 15% whey against 1.6 ± 0.08% for the reference. Water absorption of the 15% whey composition remained higher than that of the reference at every firing temperature at which both were tested, reaching 7.9 ± 0.25% against 5.2 ± 0.20% at 1100 °C, whereas the 20% whey composition exceeded the reference at 950–1050 °C but not at 850 and 900 °C. These trends are consistent with the formation of additional porosity through decomposition of the organic constituents of the whey during firing; porosity, density, and microstructure were not measured directly in the present work, so this interpretation is presented as a proposed explanation. The results show that liquid curd whey can be used as part of the forming liquid to modify the shrinkage behavior of clay ceramics and provide a basis for the mechanical and microstructural characterization needed to establish practical performance.

Indoor extension of an inverse acoustic SPL model: a direct-reverberant field correction for multi-pattern construction noise

Shyngys Zharassov, Alisher Imanov — Sun, 27 Sep 2026 00:00:00 +0500

Construction-noise propagation models are typically formulated and validated outdoors, under free-field (FF) conditions, and for a single temporal noise pattern (most often impulsive pile-driving noise). Neither assumption holds for construction and renovation work carried out inside occupied buildings, where reflected sound energy accumulates in the enclosed volume and the operating equipment may be steady, fluctuating, intermittent, or impulsive. This study extends a previously validated outdoor inverse acoustic sound pressure level (SPL) model, based on FF spherical spreading, to indoor conditions by superposing a direct and a reverberant sound field, and tests the extended model against four canonical construction-noise temporal patterns (constant, fluctuating, intermittent, impulsive) reproduced from real recordings and measured simultaneously at five synchronized receiver positions (0.1–6 m) in an enclosed conference hall. The FF model, applied unmodified indoors, showed systematic near-field under-prediction and far-field over-prediction (mean absolute error, MAE, 3.7–6.4 dB), the signature of an unmodelled reverberant field. The direct–reverberant model removed this systematic bias and reduced in-sample MAE by 63–70% and out-of-sample (leave-one-receiver-out) MAE by 56–66%. The fitted effective room constant was physically consistent and source-independent for temporally continuous sources (implied mean absorption coefficient ᾱ ≈ 0.28–0.30, plausible for the hall's construction), but not for the sparse-duty-cycle intermittent source, for which the reverberant field evidently had insufficient time to establish. Counter-intuitively, recovering distance from SPL alone was less accurate with the better-fitting reverberant model than with the FF baseline, because the fitted critical distances (0.57–1.90 m) place most of the measured range in the reverberant-dominated, distance-invariant zone. The results indicate that indoor construction-noise assessment requires an explicit reverberant-field correction, that this correction depends on the source's temporal duty cycle, and that improved level-reconstruction accuracy does not, by itself, imply improved acoustic localization accuracy indoors.