Technobius

Fine-grained self-compacting concrete with polyfunctional additive and enhanced performance properties

2025-10-28T17:37:02+05:00

The results of experimental studies aimed at improving the strength characteristics of cement stone and fine-grained self-compacting concrete through the use of polyfunctional modifying additives based on nano-silicon dioxide (nano-SiO₂) and micro-dispersed mineral components are presented. It was established that the introduction of 0.03% nano-SiO₂ by weight of cement increases the compressive strength of cement stone by up to 32%, which is associated with the intensification of clinker mineral hydration processes, the formation of an additional amount of low-base calcium hydrosilicates, and an increase in the number of crystallization centers in the early stages of hardening. The effectiveness of the combined use of nano-SiO₂ with microsilica and micro-calcite, which are similar in composition to cement but differ in structure and functional activity, has been experimentally confirmed. The use of two-component systems made it possible to increase the flexural strength of cement stone by up to 29% compared to the reference samples. The greatest effect was achieved by adding a polyfunctional three-component additive, including nano-SiO₂, microsilica, and micro-calcite, to the composition of fine-grained self-compacting concrete. The use of this system increased the compressive strength of concrete by 44% (to class B60) and the flexural strength by up to 12.5 MPa (an increase of 53.7% relative to the reference composition). It was additionally established that the complex of additives contributes to the acceleration of self-organization processes in the early stages of hardening by increasing the density of crystallization centers and a more uniform distribution of hydration products in the cement matrix volume.

Vibro-pressed concrete for wall blocks based on lightweight expanded clay aggregate obtained with the addition of oil sludge

2025-12-16T10:56:25+05:00

This study develops lightweight expanded clay aggregate (LECA) from local low-expanding loams using an oil-sludge-based fuel-containing additive and evaluates its use in vibro-pressed lightweight aggregate concrete (LWAC) wall blocks. LECA was produced by granulation and firing, then characterized by bulk density, water absorption, and compressive strength. LWAC blocks were manufactured via a semi-dry vibro-pressing route and tested for density, compressive strength, thermal conductivity, and freeze-thaw resistance. The LECA incorporating oil sludge showed a strength increase from 1.38 MPa to 2.8-3.1 MPa with a moderate density rise (316 to 350-400 kg/m³) while maintaining ~25.8% water absorption. Blocks achieved 800-950 kg/m³ density and 10-12 MPa compressive strength, with 0.75-0.8 W/(m·K) thermal conductivity and 50-75 freeze-thaw cycles. XRD pattern fitting indicated silicate- and spinel-type crystalline phases, though some matches require verification. Overall, the raw material and processing route enable structural wall units with improved thermal performance. The future work should prioritize moisture-related durability under higher saturation.

Low thermal conductivity silica ceramics based on diatomite modified with loam

2025-12-25T19:03:21+05:00

This study investigates diatomite-based silica ceramics designed for low thermal conductivity, using diatomite from the Utesai deposit (Aktobe region, Kazakhstan) and loam from the Romanovskoye deposit (West Kazakhstan region, Kazakhstan) as a modifying additive. The raw diatomite is characterized by high porosity and low thermal conductivity, while the ground fraction shows favorable technological behavior for ceramic processing, including low drying sensitivity. Calcination at 950 °C increases density and thermal conductivity, indicating partial densification. Silica-ceramic specimens were produced by plastic and semi-dry molding and fired at 950 °C, both from pure diatomite and from a diatomite-loam composition. The results show that 10% loam addition improves the fired structure: density and strength increase, whereas water absorption and total shrinkage decrease, with only minor changes in thermal conductivity. The combined trends demonstrate the feasibility of producing lightweight silica ceramics with improved integrity while maintaining heat-insulating performance.

Utilization of waste glass, ceramic scraps, and slag in manufacturing ceramic building materials

2025-12-28T17:11:28+05:00

This study examines the potential for reducing the consumption of natural clay raw materials while simultaneously recycling various types of waste in the production of clay ceramic materials. Crushed ceramics, thermal power plant slag, and cullet were used as technogenic components. The compositions were prepared using clay with varying waste content (5-20% by weight relative to clay) and the addition of an alkaline additive, NaOH (10% of the clay weight). After forming cylindrical samples, they were dried and fired at temperatures up to 1000 °C for 1 hour. The chemical composition of the raw materials was studied using XRF/EDS, and the microstructure was studied using SEM. Density, water absorption, linear shrinkage, and compressive strength were determined. The combined introduction of waste has a synergistic effect on the sintering processes and structure formation. Glass cullet acts as a fluxing agent and promotes compaction of the body, ceramic waste acts as an inert filler, reducing the risk of deformation, and slag introduces reactive aluminosilicate components that influence phase formation. An optimal waste content range has been demonstrated: moderate dosages improve performance without compromising processability. The best results were obtained with a composition of 10% glass cullet, 10% ceramic waste, and 5% slag (at 10% NaOH): compressive strength was 16 MPa, water absorption was approximately 7%, and density was approximately 1.32 g/cm³. The results confirm the potential of integrated waste recycling for producing ceramic materials at lower firing temperatures.

A field-validated finite element framework for predicting transient temperature fields in multilayer pavements

2025-12-29T10:18:48+05:00

Extreme continental climates in Kazakhstan impose large diurnal and seasonal thermal gradients in pavements, accelerating temperature-related distress. This study develops and validates a two-dimensional finite element model for predicting non-stationary temperature fields in multilayer pavement–subgrade systems from geographic location and climatic inputs. The transient heat-conduction problem with a surface thermal-balance boundary condition was implemented in MATLAB (PDE Toolbox). Validation used hourly temperatures from embedded sensors on the Kyzylorda-Shymkent (at km 2057) and Oskemen-Zyryanovsk (at km 0+075) highways during 1-31 July 2014. Predictions reproduced the attenuation of temperature amplitude with depth and closely matched measurements: coefficients of variation were <0.25 and correlations approached 1.0 at 2.1 m. Root mean square errors ranged from 0.44-7.49 °C and 0.26-5.65 °C for the two sites. The approach supports climate-resilient pavement design using readily available air-temperature data.

Optimizing sodium sulfonate dosage in non-autoclaved aerated concrete: effects on pore stability, strength, and abrasion resistance

2025-12-31T22:56:13+05:00

This study evaluates sodium sulfonate as a structuring surfactant for non-autoclaved aerated concrete to stabilize pore formation and improve performance. A laboratory dosage series (0-0.25% by cement mass, water-to-cement ratio 0.45) and a pilot D700 production verification (GB1-GB4) were performed. At 28 days, the reference mixture reached 1.5-2.0 MPa, while 0.10-0.15% sodium sulfonate increased strength to 2.3-2.7 MPa; higher dosages reduced strength and impaired pore stability. In the pilot series, average density ranged from 610 to 740 kg/m³ and compressive strength from 2.0 to 2.5 MPa, with GB3 showing the best strength-to-density balance (SQC 0.034). Abrasion improved from 0.84 to 0.71 g/cm². The additive improved plasticity and pore uniformity. Overall, 0.10-0.15% is recommended for practical production with minimal process complexity.