Current Issue : October-December Volume : 2026 Issue Number : 4 Articles : 5 Articles
This study addresses the environmental challenges of carbon dioxide (CO2) emissions from Portland cement by investigating the valorization of crystalline black slag (CBS) as an eco-sustainable precursor for geopolymer mortars (GPMs). A novel thermal activation process was employed, where CBS was calcined at 800°C and rapidly water-quenched to produce granulated black slag (GBS) with an amorphous structure. The research evaluates the impact of this thermal treatment and the subsequent chemical activation using sodium hydroxide (NaOH) and sodiumsilicate. Furthermore, the effect of substituting GBSwith metakaolin (MK) at various levels (20%, 50%, 80%, and 100%) was analyzed. Characterization of raw materials was performed using X-ray diffraction (XRD), XRF, FTIR, and laser granulometry. Six GPM blends were synthesized: two using 100% GBS with varying precursor/activator (P/A) ratios (1.5 and 2.0) and four incorporating MK at a constant P/A ratio of 1.5. All specimens were cured at 60°C for 24 h. Analytical techniques including thermogravimetric (TGA), differential thermal analysis (DTA), and XRD confirmed the successful structural transformation of CBS into a reactive granulated slag. Mechanical testing showed that compressive strength (CS) and flexural strength (FS) were significantly influenced by the MK content. The optimal performance was achieved with an 80% MK substitution, yielding 27.34MPa in CS and 16.52MPa in FS at 28 days. Microstructural investigations via scanning electron microscopy (SEM)-EDS and XRD revealed that this specific blend promoted a denser matrix and enhanced pore distribution. These findings demonstrate that thermally activated black slag is a viable geopolymer precursor and that its synergy with MK offers a highperformance, sustainable alternative for the construction industry and the development of low-carbon binders....
The influence of Bacillus subtilis (Solution A) and Paenibacillus polymyxa (Solution B) bacteria on the properties of conventional concrete with a design compressive strength of fc = 210 kg/cm2 and on the repair of microcracks and fissures was evaluated. Yura Type IP and Frontera Type IP cements were used, together with aggregates from the Chiguata and La Poderosa quarries (Arequipa, Peru). Two mix design methods were applied: ACI 211 and the fineness modulus of the combined aggregates. For microcrack repair, injections of Solutions A and B were applied, followed by either water curing or curing in the corresponding bacterial solution. For water replacement, both solutions were used at concentrations of 10%, 15%, and 20%. Compressive strengths were measured at 7, 14, 21, and 28 days. The results indicate that bacterial incorporation, together with reductions in the effective water-to-cement ratio associated with bacterial solution replacement, was associated with improvements in compressive strength and microcrack repair through mechanisms consistent with calcium carbonate (CaCO3) precipitation. For the injection group, a maximum strength of 196.09 kg/cm2 was obtained. For the water replacement group, a maximum strength of 335.71 kg/cm2 was reached, representing a 59.9% increase over the standard design. The P. polymyxa solution consistently outperformed B. subtilis across all groups and concentrations evaluated. These findings suggest that bacterial solutions—particularly P. polymyxa—may represent a promising complementary strategy to improve concrete performance and durability under the evaluated experimental conditions....
To improve the performance characteristics of concrete, mineral and chemical additives, fibrous materials, dispersed particles, and nanomaterials are incorporated into its composition. However, the use of construction waste as concrete modifiers remains an understudied yet relevant area of research. This study aims to investigate the effectiveness of modifying concrete with dispersed powders of fraction −0.026+0 mm, obtained by grinding recyclable construction waste, in an amount of 10%–50% of the cement mass. The objectives of this study are to obtain dispersed powders by grinding waste building bricks, to develop optimal compositions, and to study the compressive strength of concrete modified with the obtained dispersed powders. The methodological basis of the experimental studies includes the use of modern methods for determining the physicochemical characteristics and granulometric composition of dispersed concrete modifiers, as well as the structure and mechanical properties of concrete samples. The study revealed that dispersive modification with powders of the above sizes in an amount of 10%–30% improves the concrete samples’ characteristics, including an increase in compressive strength in the range of 27.947–46.112 MPa and elastic modulus of up to 39.23–51.70 GPa across the entire percentage range of dispersed additives. It was proven that the best mechanical properties of concrete can be achieved by adding 20% of dispersed fraction powder to the cement mixture. Within the experimental studies, it has been established that the size, concentration, and chemical composition of dispersed particles significantly affect the mechanical properties of concrete mixtures modified with construction waste powders. The use of concrete mixtures with modifying additives from construction waste will improve the performance characteristics of concrete without increasing its cost, as well as reduce the environmental impact associated with construction waste....
In the intelligent recognition of construction drawings, architectural components significantly vary in size, and small objects are easily overlooked. To address these two challenges, this paper proposes a multi-scale feature fusion method based on channel and spatial attention mechanisms. Specifically, the method constructs a hybrid feature pyramid structure (ArchFuse-Net) to enhance multi-scale feature representation. Subsequently, a small-object perception module is introduced to improve the recall rate of small components. Finally, the bounding box regression loss function and post-processing mechanisms are refined to boost detection accuracy and localization precision. Experimental results demonstrate that the proposed method effectively improves overall detection accuracy across varying sizes and significantly boosts the recall of small objects, providing a robust solution for architectural drawing analysis....
Small-radius curved shield tunnels have gradually become a popular research topic in the field of urban underground space development. This study presents a comprehensive numerical investigation of the construction mechanics of large-diameter shield tunnels in small-radius curved sections based on the Wuhan Lianghu Tunnel project. A three-dimensional finite element model was developed using ABAQUS, featuring dimensions of 160m width × 111m length × 110m depth . The dynamic construction process was accurately simulated through sequential modeling of tunnel advancement, segment assembly, and shield tail grouting using the element birth and death technique. The study investigated the influences of the shield tail clearance, construction load, and grouting parameters on the deformation of the tunnel segments and surrounding soil. The results show that surface displacement evolves into a characteristic “V”-shaped deformation pattern with maximum settlement reaching 16.03 mm. Quantitative analysis revealed that reducing shield tail clearance from 115 to 35mm decreased crown settlement by 46.2%. Furthermore, optimal performance was achieved with hardened grout elastic modulus exceeding 120 MPa, which reduced segment tensile stress by 16.7% compared to the 40 MPa condition. Therefore, the results of this study provide a practical reference for the expanded application of shield tunnel construction technology and parameter design....
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