Accurate determination of mixing and compaction temperatures is essential for producing durable asphalt pavements while minimizing energy consumption and binder aging. Conventional temperature selection is based on asphalt binder viscosity, which does not adequately represent the workability of modern asphalt mixtures containing polymer modifiers or alternative mineral fillers. This study proposes a torque-based criterion as a performance-oriented alternative for estimating the required production temperatures of conventional and polymer-modified asphalt mixtures. A high-capacity laboratory workability device was developed to measure the mixing torque of 15 kg asphalt mixtures at temperatures ranging from 120 to 160 °C. The experimental program included surface, binder, and base mixtures incorporating hydrated lime, limestone, and cement fillers, as well as asphalt modified with 4% styrene-butadiene-styrene (SBS) and 5% polyvinyl chloride (PVC). Based on the experimental results, torque criteria were established for conventional hot mix asphalt, and regression models were developed to estimate the production temperatures of polymer-modified mixtures. The proposed torque-based approach predicted mixing temperatures of 163–192 °C and compaction temperatures of 147–176 °C for SBS-modified asphalt, while the corresponding ranges for PVC-modified asphalt were 131–170 °C and 110–149 °C, respectively. The lower PVC compaction prediction of 110 °C represents an extrapolated model value outside the experimentally investigated temperature range and requires experimental verification before practical application. Compared with the conventional viscosity-based method, the torque criterion reduced the required mixing and compaction temperatures by 13–57 °C (6–30%) and 17–65 °C (9–37%), respectively. Validation using a Superpave gyratory compactor demonstrated nearly identical volumetric properties for the two methods, with %Gmm at Ndesign of 95.90% and 95.88%, and air voids of 4.10% and 4.12%, despite approximately 40 °C lower processing temperatures using the torque-based method. These findings indicate that torque-based workability can provide a practical basis for estimating asphalt production temperatures, while its potential for reducing energy demand, limiting binder aging, and supporting more sustainable pavement construction requires further validation.
This study evaluates basalt fiber-reinforced rubberized concrete for building envelopes in Jordan’s hot, dry climate. Two mixes with 6% rubber and 0.5% basalt fibers (M1) or 0.8% basalt fibers (M2) were compared with a reference. Rubber reduced density by 1.0–2.2% but increased absorption by 9.7–24.7% and porosity by 8.7–22.1%. Fibers improved tensile strength by 14–26% and flexural strength by 23–35%, promoting ductile failure. Thermal conductivity decreased by 13.0% (M1) and 4.3% (M2); CTE increased by 10.8% (M1) and 2.0% (M2). M1 achieved the lowest annual energy consumption (0.15–0.28% reduction, with >95% simulation robustness). While material-level thermal improvements are confirmed, they do not translate proportionally into building-scale savings because insulation layers dominate the overall thermal resistance. Tensile enhancements exceeded additive predictions; however, this interpretation is limited by the absence of rubber-only and fiber-only control mixtures and direct microstructural evidence. Therefore, synergy is presented solely as a hypothesis requiring verification through a full factorial experimental design and microstructural investigation. Both materials suit non-load-bearing Jordanian envelopes, with mass-based replacement enabling direct technology transfer. The materials represent a potentially more sustainable option for envelope applications, though long-term durability validation and comprehensive lifecycle assessment are urgently needed. The findings are strongly connected with Jordanian conditions, and direct generalization to other regions is limited and should be stated explicitly.
Stress corrosion cracking (SCC) of prestressing steel threatens prestressed concrete structures with sudden, brittle failure and minimal visible warning. While mechanical stress, localized corrosion, and hydrogen uptake are recognized drivers, the mechanisms connecting sulfide exposure in cementitious materials to hydrogen uptake and crack initiation at the steel–concrete interface remain poorly understood. This review synthesizes the coupled electrochemical, mechanical, metallurgical, and environmental processes governing SCC, with particular emphasis on the interactions of sulfide species with chloride ingress, carbonation, pitting, and hydrogen-assisted cracking under sustained tensile stress. Evidence indicates that sulfides weaken passive-film protectiveness and facilitate hydrogen entry, while localized corrosion and acidification create favorable conditions for crack initiation and propagation. Because SCC susceptibility emerges from the combined effects of environmental exposure, steel microstructure, and mechanical loading, isolated environmental parameters cannot adequately predict risk. Accelerated laboratory tests offer comparative insight but have limited representativeness of the complex conditions of prestressed concrete. A critical gap persists: no quantitative relationship has yet been established between cement sulfide content, sulfide availability at the steel surface, hydrogen uptake, and actual SCC susceptibility. Bridging this gap requires service-representative experiments on stressed prestressing steel embedded in mortar or concrete to develop reliable durability criteria and move beyond precautionary regulatory limits.
Despite the shift toward cleaner energy, coal-fired power plants remain a significant source of global energy, generating excess fly ash that accumulates in large stockpiles—often persisting for decades even after the plants are decommissioned. The study investigated the physicochemical properties and suitability of fly ash recovered from seven ash dams for use in cement-based applications. The recovered ash was beneficiated by drying, breaking agglomerates, and sieving to meet specifications for use as a cementitious material. Subsequently, analyses were conducted for particle size, pH, density, loss on ignition, scanning electron microscopy, oxide composition, X-ray diffraction, thermogravimetry, Fourier transform infrared spectroscopy, and the compressive strength of mortar samples. The results indicate that the samples are Class F fly ashes, containing amorphous aluminosilicates, with a comparable physical, chemical, and mineralogical composition, and that they meet specifications for use in cement-based materials. This remains true despite a slight increase in sulphur-bearing phases in the Kusile ash associated with the plant’s desulfurization technology. Furthermore, the compressive strength results show that, compared with the reference Portland cement mortar, fly-ash-blended mortars exhibit higher strength gain at later ages, indicating good pozzolanic reactivity, though the degree of strength gain depends on each ash’s fineness, amorphous content, and mineralogy.
In most African countries, supplementary cementitious materials (SCMs), such as silica fume, slag, and fly ash, are scarce, creating a need for alternative low-clinker cement that utilises locally abundant resources. Given the limited availability of SCMs, the development of Limestone Calcined Clay Cement (LC3) has emerged as an attractive solution. LC3 is a blended binder composed of ground limestone, calcined kaolinite clay, and ordinary Portland cement clinker. This research assessed the mechanical and durability properties of LC3 binders formulated using raw materials obtained from selected deposits in Tanzania. Two samples of clay from the Pugu deposit were selected: Pugu hard clay (PH) and Pugu soft clay (PS). Limestone and gypsum were sourced from Dar es Salaam. LC3 mixes containing 58% CEM I/42.5N were produced and used to make concrete with a water/binder ratio of 0.4. Two control mixes were made, a mix with 100% Portland cement CEM I/42.5 N and a mix with 100% Portland pozzolana CEM II/P-B 42.5 N. In addition, four concrete mixes were designed for the study: LC3-PH, LC3-PS, CEM I + PH (CC-PH), and CEM I + PS (CC-PS). The mechanical properties evaluated included compressive strength, splitting tensile strength, and flexural strength, whilst durability performance was assessed through sulfuric acid resistance, water sorptivity, and absorption. The results demonstrated the superiority of LC3 concrete compared to CEM I and CEM II concretes. For instance, the LC3-PS mix achieved a 90-day compressive strength of 63 ± 2.1 MPa, compared with 62 ± 1.8 MPa for CEM I. Similarly, water absorption was 1.35% and 1.1% for CEM I and LC3 concretes, respectively. Under sulfuric acid exposure, LC3 concrete exhibited the lowest mass loss (1.6%) and strength loss (17.9%) compared with 2.4% and 23% for CEM I and 2.1% and 21% for CEM II, respectively. The enhanced performance of LC3 concrete was attributed to its denser and more refined microstructure, which reduced pore connectivity and improved resistance to the ingress of aggressive agents.
In this study, a polymer-modified fast-hardening and early-strength cement-based repair material was proposed, using the polymer cellulose ether (HPMC), polymer dispersible polymer powder (VAE) and silica fume. The optimal mixing ratio of the three polymers was designed by an orthogonal test by combinational evaluation of the fresh performance and mechanical properties, complemented by the observation of the changes in the macroscopic properties by XRD and SEM analysis. The results showed that the content of HPMC has a more significant effect on fluidity, consistency and water retention than other factors, and the content of silica fume has a more significant effect on setting time. The content of HPMC is the most important factor affecting the compressive strength and flexural strength. The content of HPMC and VAE has a more significant effect on the interfacial bonding performance, the 1-day interfacial bond strength was significantly higher than that without polymer. According to the SEM results, it was observed that, the porous structure of Ca(OH)2 induced by VAE, and the polymer film formed by HPMC covering the hydration product, the two polymers work together to significantly improve the interfacial bond strength of cement mortar. The optimal mixing ratio of the two interface bonding methods is the same, so the optimal mixing ratio of three factors is obtained: 0.2% of cellulose ether, 0.6% of redispersible polymer powder, and 10% of silica fume strong and fluid repair material.
In designing tall buildings, the primary concern is ensuring an effective lateral load-resisting system in addition to the gravity load system, since it largely governs the overall design. This study investigates the influence of X-cable bracing on the structural weight of tall steel frame buildings subjected to service and wind loading. Three numerical case studies, 10-story, 20-story, and 30-story planar steel frames, were modeled and analyzed using SAP2000, then optimized using Differential Evolution (DE) and Enhanced Colliding Bodies Optimization (ECBO) algorithms. These designs were evaluated under both service and wind load conditions, considering strength and drift constraints. The results indicate that the inclusion of wind loads in addition to service loads leads to a higher total structural weight than considering service loads alone, while cable bracing effectively reduces the overall mass by up to 6%, 38%, and 20% for the 10-story, 20-story, and 30-story frames, respectively, compared to unbraced structures, by improving the internal force distribution among structural components. Strength demands, reflected by the interaction ratio, governed all design cases, while lateral displacement was always less than the maximum limit according to AISC and ASCE requirements. Overall, the results highlight the potential of cable bracing systems to deliver efficient tall building designs; however, further studies are needed to generalize these findings to a broader range of building configurations.
Zinc processing generates large volumes of tailings enriched with potentially toxic elements such as zinc, lead, arsenic, and antimony, creating environmental challenges. Conventional disposal in tailings dams is associated with land occupation, contamination risks, and geotechnical concerns, reinforcing the need for more sustainable management strategies. This study presents a bibliometric and semi-systematic review of alkali-activated binders for the stabilization and solidification of zinc mine tailings, based on nine studies published between 2019 and 2026. The results indicate that this is a recent and expanding research field, with a marked concentration of studies in China. Current research mainly focuses on the links between microstructure, heavy metal immobilization, and mechanical performance. Alkali-activated systems, commonly based on blast furnace slag, fly ash, and coal gangue, can produce dense matrices with compressive strengths of up to 100.77 MPa and high immobilization efficiency. Their performance is largely governed by the type of reaction products formed, particularly calcium silicate hydrate, calcium aluminosilicate hydrate, and sodium aluminosilicate hydrate gels, which control microstructural development and stabilization mechanisms such as encapsulation, structural incorporation, and secondary phase formation. Overall, the reviewed studies suggest that alkali-activated binders have potential as alternative binders to Portland cement for the management and valorization of zinc mine tailings.
Currently, saponite is widely applied in various industries. However, at present this mineral usage conditions are related to a polymineral system with saponite content level of up to 60-65%. Thus, saponite-containing material (SCM) extracted from a recycled water suspension at kimberlite ores enrichment is one of by-products of mining. But to achieve the necessary properties in terms of designed products (including ceramic products), preliminary physico-chemical treatment of SCM is almost always required. Natural saponite contains a significant amount of bound water, which removal at elevated temperatures leads to the mineral basal interlayer compression, the material shrinkage and the microcracks formation. Based on it, the work purpose was to evaluate prospects of using the intercalation with electrolyte solutions as a method of saponite-containing material modification, to minimize fire shrinkage.
The formation of blisters in reactive resin coatings on concrete is a widely known phenomenon that is also a subject of debate in the literature. In particular, blisters forming after curing of the coating can lead to extensive damage. This study was focused on the investigation of blistering between the concrete substrate and the resin coating. The hypothesis is that the cementitious material and the overlying reactive resin coating form a system that leads to damage under certain boundary conditions regarding material composition, as well as moisture and mass transport. Systematic investigations were carried out in an extensive testing program with various substrate mortars that differ in cement type, water-cement ratio, and aggregate. As coating systems, two different EP primers were used with a transparent EP topcoat. The long-term testing was conducted on potential blistering of composite test specimens stored under various (practically relevant) conditions prior and after the coating. It was found that a higher moisture content of the substrate reduces blistering of the EP coating system. EP systems containing benzyl alcohol do not automatically tend to blister. Furthermore, condensation in the substrate provides sufficient amounts of water to cause blistering and ASR can contribute to blister formation.
Ways to increase the industrial housing construction plants competitiveness is shown on the base of the practical examples of professional composite building matrices application. For this purpose the measures taken for expenses and prime costs reduction, in use of the building matrices are described. Economic effects calculations of the building matrices in the facade slabs molding reasonable application are presented using specific practical examples. Substitution of purchased plug-in elements in the enclosing structures production to own manufacture in a factory by the specialized matrices application is a practical way to reduce expenses. In this part, real calculations and practical economic results are also provided. A practical way to achieve a leading position in the industry is given, in times of crisis, taking into account limited demand. This way is to use the large-format architectural elements on facade slabs which molding industrially directly with slab using composite matrices.
Industrial construction development and magnification involves increasing labor productivity on the construction site, reducing building construction time and their cost on account of fully assembled construction technologies usage. It is known that in the 1950s and 1960s, the massive fully assembled buildings construction assumed a number of limitations, such as the uniformity of architectural solutions, small apartment areas, low performance, etc. Currently special attention is paid not only to production indicators, but also to comfortable people living conditions. Comparative analysis of the traditional technologies for the fully assembled construction and one of the modern modular buildings construction methods according to architectural, structural, technical and economic indicators is presented. On the base of results obtained a generalized gradation of characteristics of the buildings erected with various technologies for fully assembled construction was compiled. According to it, in comparison with traditional methods of fully assembled construction it is possible to reduce the construction time by 3–6 months, the cost of construction and installation work by 10–15% and increase the facility under construction operational characteristics.
This study investigates the effect of mass-based replacement of natural coarse aggregate with electric arc furnace (EAF) slag on the performance of ordinary Portland cement (OPC) concrete. Replacement levels of 0%, 30%, 50%, and 100% were examined, with particular attention to the volumetric changes induced by the higher density of EAF slag, which leads to an increase in paste volume. Fresh, mechanical, durability-related, and microstructural properties were evaluated. Results show a continuous reduction in workability with increasing slag content, despite the increase in paste volume, indicating the dominant influence of aggregate morphology on rheological behavior. Mechanical performance exhibited a non-linear response. Within the tested series, the 50% replacement mixture showed the highest mean compressive and splitting tensile strengths; however, the compressive strength difference relative to the control mixture remained small and within typical experimental scatter. In contrast, water absorption decreased progressively, reflecting improved matrix densification. However, this densification did not translate into enhanced mechanical performance, highlighting a decoupling between durability-related indicators and strength. A screening-level CO2 assessment further showed that reductions in aggregate-related emissions were offset by increased cement content associated with mass-based replacement. The results emphasize the importance of considering volumetric effects when interpreting the behavior and sustainability of slag-based concrete. Note: all strength comparisons are based on mean values from three-specimen sets without formal statistical testing and should be regarded as exploratory observations.
In this study, the characteristics of concretes made from mixed recycled aggregate—the cheapest and most common secondary raw material in construction and demolition waste—were determined. For this study, besides experimental concretes using mixed recycled aggregate, reference compositions were developed using river gravel, recycled concrete aggregate, and recycled masonry aggregate. The workability of concrete mixtures was measured as class S1, which is acceptable for use with slipform concrete pavers, and was achieved by varying the water/cement ratio, considering the different water adsorptions of the concrete fillers. The following mechanical characteristics of the concretes were defined on the 3rd and 28th days: density, compressive strength, flexural strength, water absorption, and frost resistance. The test results showed sufficiently high indicators of strength and durability for the recycled aggregate concretes. Moreover, the strength of the concrete developed from mixed recycled aggregate was comparable with that of the reference concretes. Considering the low strength requirements for the construction of the lower layers of rigid pavements, it was established that such an application of recycled aggregate concrete, including that derived from mixed recycled aggregate, could be permitted.
A problem of quality control and assessment at precast concrete plants is relevant, since the quality management effectiveness is quite poor because of following: lack of qualified employees and regulations for nonconforming products management (corrective actions), etc. The paper considers organization of the quality control system based on a graphical interface for reinforced concrete products. A special feature of the system is traceability of all technological chain stages from launching into production to shipment to a buyer in the 1C system: 1C: Production Management in real time and high-quality items production process management. The elaborated quality control system makes it possible identification of an employee committed nonconformity, the nonconformity type/amount, its dynamics over time, etc., as well as efficient working hours usage.
Precast concrete production technologies history from bench technology to pallet circulation line is considered: comparison of solutions, analysis of strengths and weaknesses, impact of digital transformation, development forecast and key requirements for plants wanting to move to a new efficiency level. The redevelopments of the reinforced concrete products full production cycle on a pallet circulation line are given: pallet cleaning; application of separation compound; tooling and magnetic sides installation; reinforcement; concrete laying and molding; vibration compaction; heat treatment; demoulding.
This study experimentally investigates the structural behavior of hexagonal- and square-shaped composite specimens subjected to vertical compression, vertical tension, and diagonal tension loading. The specimens were fabricated using four- and six-layer alkali-resistant (AR) glass textile reinforcements embedded in a modified cementitious mortar via pull, pour, and roll manufacturing techniques. The mechanical performance of polyvinyl alcohol (PVA) fiber-reinforced composite connectors and steel clamp-type elements was also evaluated at the joints of hexagonal specimens under vertical tension and lateral shear loading. The results show that increasing the number of textile layers significantly enhances structural performance. A 50% increase in textile layers improved load-carrying capacity by up to 56% in compression, 104% in tension, and 216% in diagonal tension. Corresponding increases of approximately 20-42% in ductility and up to 266% in energy dissipation capacity were observed. No failure occurred in the connecting elements, confirming their adequate stiffness, strength, and ductility. In addition, validated three-dimensional finite element models were developed to simulate the response of the hexagonal specimens. Overall, the proposed system demonstrates strong potential for applications such as infill walls, cladding, and sandwich panels due to its favorable strength, ductility, and energy absorption capacity.
The integration of advanced additive manufacturing technologies, particularly 3D printing (3DP), also known as Additive Construction (AC), could influence a shift in the construction industry towards improved efficiency and automation. This research evaluated the effect on hardened properties of two different concrete mixes for use in 3DP based on the presence or absence of alkaline-resistant (AR) glass fibers. Furthermore, three different curing methods were evaluated: air-curing, plastic-covered curing, and spray-curing. Concrete beams were printed for flexural testing, and cores were taken from other depositions to evaluate compressive strength and split-tensile strength. An analysis of the size and location of cracks on the beams after curing was performed for the different mixes and curing methods. For beams without fibers, plastic-covered curing produced the highest flexural modulus values, and air-curing produced the lowest flexural modulus values. Plastic-cured beams with fibers had higher flexural modulus values than the air-cured beams with fibers. However, the spray-cured beams with fibers produced somewhat anomalous results, with one flexural modulus value being larger than those of the plastic-cured beams, and the other flexural modulus value being less than those of the air-cured beams. All 28-day compressive strengths and split-tensile strengths across mixes and curing conditions fell within a small band ranging between similar to 19.3-22.1 MPa and similar to 1.7-2.0 MPa (similar to 2800-3200 psi, and 240-290 psi), respectively. There was a large amount of scatter in some of the tests. It appears that neither the presence of the AR-glass fibers, nor the type of curing had a large influence on compressive strength or split-tensile strength. Results showed that the addition of fibers and the use of the plastic during curing significantly reduced the occurrence, the width, and the depth of cracks as a result resulting from the curing process. Plastic-curing was the most effective curing method for minimizing the occurrence of cracks. Any cracks that formed during plastic-curing were extremely fine and had little or no effect on mechanical properties.
The article describes the creation and improvement prehistory of the flexible technology for reinforced concrete structures in limp and stress state production. The technology includes concrete delivery to a molding site, vibration and heating to obtain sturdy products. For its implementation universal stands of CJSC Recon is used. Examples of implemented architectural solutions in different regions of the Russian Federation are given. The equipment can be used not only for specific series of houses. The main production additional equipment with automated cassette units and cassette conveyor lines or hollow flooring lines provides a flexible technology for cost-effective production. Additionally, it is possible to arrange the production of prestressed groove-ridge slabs with poststress for year-round industrial construction of temporary and permanent roads, airfields and railway lines.
The abrupt failure of shear-deficient RC beams may lead to harmful consequences under dynamic loading. The use of Carbon Fiber Reinforced Polymers (CFRP) aims to convert this brittle fracture into a ductile one. However, the complexity of the multiple damage mechanisms makes it difficult to assess their condition using conventional testing methods. In this study, the damage evolution of a shear-critical reference beam and its CFRP-strengthened counterpart was monitored using the acoustic emission (AE) technique. After correcting attenuated AE amplitudes, damage analysis was performed using the Shannon entropy approach based on true source amplitudes. The entropy analysis performed with these corrected data clearly revealed the shear failure in the reference beam through abrupt drops in entropy, indicating damage homogenization. In contrast, the entropy remaining high and dynamically varying over a much longer deflection range in the CFRP-strengthened beam demonstrated that CFRP distributes damage over a wider region and that different damage mechanisms, such as debonding and fiber breakage, in addition to concrete cracking, were simultaneously active.
