Abstract The cement industry is a major contributor to global warming due to substantial CO₂ emissions, particularly during clinker production, the intermediate step in manufacturing Ordinary Portland Cement (OPC). While blended cements incorporating supplementary cementitious materials (SCMs) such as ground granulated blast-furnace slag powder (GGBS, SP) and limestone powder (LSP) have been used to reduce emissions, it remains difficult to directly compare the impact of reduced OPC content on both compressive strength and CO2 reduction. This study proposes a new index, carbon intensity per unit compressive strength (CIt.MPa), which integrates the CO2 emission factor of cement with the 28-day mortar compressive strength. To validate the concept, blended cements composed of OPC, SP, and LSP were produced and tested. Results show that while the CO2 emission factor decreased linearly with increasing SCM content, compressive strength was partially recovered due to the latent hydraulic reactivity of SP. The CIt.MPa index effectively differentiated cements with similar strength but lower carbon emissions, demonstrating its practical potential for concrete users in selecting eco-friendly cement. This approach provides a quantitative tool for balancing mechanical performance and sustainability, contributing to the development of greener concrete.
Systems of building construction. Including fireproof construction, concrete construction
Abstract This study proposes an innovative and practical retrofitting method for reinforced concrete (RC) roof T-joints with substandard structural details. Retrofitting was performed by assembling steel plates with threaded rods on the roof T-joints, which have typically only been applied to exterior-roof beam–column joints (BCJs). The aim of the retrofitting method was to fully utilize the capability of the column to dissipate seismic energy while limiting the shear demand in the joint panel zone. Four roof T-joint sub-assemblage specimens were constructed and tested using a reverse cyclic loading test. One control specimen and three retrofitted specimens were used with variations in the initial prestressing force, epoxy adhesive, and haunch availability. The effects of the retrofitting variants on the test results, such as the crack patterns, failure mode, and hysteresis behavior, were analyzed. A significant increase in the maximum lateral strength by an average of approximately 138% was observed after applying the proposed retrofitting method. Moreover, when the haunch was removed, the specimen retrofitted with a high initial prestressing force dissipated the most cyclic energy, which was at least seven times that of the control specimen. This considerable seismic performance was achieved when the column was designed with appropriate deformability to develop flexural strength without being hindered by joint shear failure or the short-column effect. Thus, this study makes a notable contribution to the development of seismic retrofitting technology, particularly for BCJs at the roof levels of RC buildings.
Systems of building construction. Including fireproof construction, concrete construction
Taofiq O. Mohammed, Aman Ul Haq, Mohammad Zunaied Bin Harun
et al.
This review study promotes the sustainability of civil infrastructure by advancing the materials science of alternative cementitious materials. Supported by extensive global research and industrial trials, geopolymer cement has emerged as a promising approach to reducing the ecological impact of ordinary Portland cement (OPC) due to its superior engineering properties and eco-friendly benefits from industrial waste utilization. Geopolymers are inorganic polymers formed by the polymerization of aluminosilicate precursors, such as fly ash (FA), slag, and metakaolin, in the presence of alkaline activating solutions. This work integrates findings across multiple domains, including precursor chemistry, microstructural evolution, mechanical and durability performance, and sustainability metrics like carbon footprint and energy consumption. A key contribution of this review is the comparative evaluation of FA-based and slag-based GPC systems against OPC concrete, emphasizing the factors influencing their mechanical and durability properties, while also distinguishing differences in environmental impact, microstructural development, and overall performance. The findings highlight that slag-based systems generally exhibit lower environmental impacts, especially in energy demand and emissions, while regional differences in precursor availability constrain how widely the LCA and economic results can be applied. Building on previous reviews that have considered these topics, this study jointly examines technical performance and sustainability indicators and identifies regional variations that influence feasibility. The synthesis provides a balanced, evidence-based assessment of the potential and limitations of GPC as a lower-carbon alternative to OPC, supporting efforts to reduce the climate impact of future concrete construction.
Nguyen Minh Quang, N. Minh, Nguyen Vo Chau Ngan
et al.
ABSTRACT Low-lying deltas worldwide are extremely vulnerable to sea-level rise. As the risks of climate-induced flooding become increasingly clear, the thirst for infrastructure-driven adaptation increases. This highlights a patent need to understand the impacts of engineering adaptation solutions, especially those targeting built structures such as dykes and sluices, on farmers from a bottom-up, farmer-centred perspective. The study addresses this call by examining cases where dyke policies, while successful in some dimensions, have undermined small-scale farmer livelihoods in Ca Mau – Vietnam’s southernmost rural province. It identifies areas in need of attention and adds empirical data related to this group of farmers. This emphasis, therefore, contributes inputs towards mitigating unexpected impacts of dyke building or other concrete-intensive adaptation solutions which can be found in many disaster-prone countries. A mixed methodology combining qualitative and quantitative data sources, including Wilcoxon signed-rank tests and case examples, was applied. The findings show a distorted livelihood capitals pentagon of the surveyed small-scale farmers after the construction of dykes and sluices in the province, exacerbating small-scale farmers’ climate vulnerabilities. Dyke policies were found to facilitate and exacerbate the impacts of climate change and liberal capitalist expansion in rural areas. The paper, thus, marks a contribution to understanding as to how the wider environment, i.e. adaptation policies and power relations, structure and influence farmers’ livelihoods by broadening or hampering their access to livelihood capitals and their adaptation options. Our results suggest that environmental sustainability and cross-farmer class equity should be mainstreamed in policy implementation and post-implementation plans. Key policy insights National pro-infrastructure adaptation policies that neglect the complexity and integrated nature of local ecology and farmer livelihoods likely result in maladaptation; As livelihood assets vary among farmers, different farmer groups experience the impact of dyke systems differently and disproportionately; Climate-adaptive infrastructure development inadvertently facilitates liberal capitalist expansion and exacerbates power inequalities whereby small-scale poor farmers are not able to cope with the rich, capitalist farmer class and market actors in a rural economy; National policy-makers may need to incorporate and mainstream sustainable livelihood perspectives and local voices in national adaptation policy-making and assessment.
Mohammed Ibrahim, Ashraf A. Bahraq, Babatunde Abiodun Salami
et al.
Abstract The impact of pore structure and its connectivity in ground volcanic pumice (GVP) and nano-silica (nSi)-based AAB on the chloride diffusion leading to corrosion of reinforcing steel for a period of up to 2.5 years was investigated in this study. 1H proton NMR relaxometry was employed as an innovative method to examine the pore structure and connectivity in alkali-activated concrete (AAC), in conjunction with the assessment of bulk chloride diffusion. Alkali-activated GVP with marginal quantities of nSi outperformed similar grade conventional OPC concrete when exposed to bulk diffusion in accordance with ASTM C1556. There was nearly 80–90% reduction in chloride diffusivity in 5.0% and 7.5% nSi mixes and 60% increase in compressive strength. The contour maps showed that nSi incorporation greater than or equal to 5.0% significantly lowered porosity, enabled poor pore connectivity and minimized chloride diffusion, resulting in enhanced protection against chloride-induced corrosion of steel rebar in the AAC. It was revealed that the remarkable resistance of nSi-modified GVP-AAC to the aggressive environment was attributed to the better polymerization and physical influence enhanced the binder structure. The environmental assessment results showed that GVP-based alkali-activated mixes reduced CO2 emissions by 53% to 60% compared to the OPC-based mix, demonstrating their strong potential for lowering the carbon footprint of concrete.
Systems of building construction. Including fireproof construction, concrete construction
Seung-Jun Kwon, Kwang-Mo Lim, Kyong-Chul Kim
et al.
Abstract This study analyzed the chloride ingress repair costs for RC girders by considering cold joints and external force conditions. The diffusion behavior of chloride ions, which varies with the stress conditions, was quantified. A two-span RC continuous girder was assumed to evaluate the magnitude of stress in each section under cracking load, and these results were comprehensively considered along with the quantification of chloride ion diffusion behavior. Then, the change in chloride ion diffusion behavior owing to external forces on the RC girders was analyzed to evaluate the service life under chloride ingress. At the locations with cold joints, the service life decreased by up to 33.9% owing to the higher baseline diffusion coefficient in the cold joint areas than that in sound concrete and significant increase in the diffusion coefficient with increased stress. Furthermore, this study analyzed the chloride ingress repair costs required to achieve the target service life of the RC structure with consideration of the external forces and cold joints using deterministic and probabilistic analyses methods. Probabilistic analysis offers the advantage of deriving the repair frequency and cost results in the form of continuous functions. Considering the four main points of the structure under analysis, the maintenance costs were evaluated at 2777.6 $/m2 in the deterministic analysis and 2337.6$/m2 in the probabilistic analysis. A repair cost analysis flowchart that integrates various repair processes can facilitate the analysis of repair processes that have a dominant influence on the overall maintenance cost estimation of RC girders.
Systems of building construction. Including fireproof construction, concrete construction
Abstract This study investigates the pozzolanic reactivity of ferronickel slag (FNS), the fourth most discharged smelting by-product in China. Cumulative heat of hydration (R3) tests were conducted on FNS with varying fineness levels (111.27 to 4.5 μm) to compare its performance with conventional supplementary cementitious materials (SCMs). The R3 results ranged from 34 to 132 J/g, increasing with finer particle size. Notably, the coarsest FNS showed reactivity similar to quartz filler (34 J/g), while the finest sample exhibited a 3.9-fold increase, though still only half that of fly ash (222 J/g). Similar trends were observed in bound water content and portlandite consumption. Calcium silicate hydrate (C–S–H) was the sole reaction product detected, indicating a pozzolanic reaction. Finer FNS particles enhanced the initial dissolution of Si and Mg, with dissolved silicon playing a key role in C–S–H formation. Despite magnesium being a major component of FNS, its dissolution remained limited (< 2.1 mg/L). A mortar strength test further validated the limited reactivity of FNS, showing a modest reduction in strength when 25% FNS was incorporated. These findings highlight that while grinding improves FNS reactivity, it remains less effective than conventional SCMs, suggesting the need for additional activation methods to enhance its performance.
Systems of building construction. Including fireproof construction, concrete construction
Channel knowledge map (CKM) has emerged as a crucial technology for next-generation communication, enabling the construction of high-fidelity mappings between spatial environments and channel parameters via electromagnetic information analysis. Traditional CKM construction methods like ray tracing are computationally intensive. Recent studies utilizing neural networks (NNs) have achieved efficient CKM generation with reduced computational complexity and real-time processing capabilities. Nevertheless, existing research predominantly focuses on single-antenna systems, failing to address the beamforming requirements inherent to MIMO configurations. Given that appropriate precoding vector selection in MIMO systems can substantially enhance user communication rates, this paper presents a TransUNet-based framework for constructing CKM, which effectively incorporates discrete Fourier transform (DFT) precoding vectors. The proposed architecture combines a UNet backbone for multiscale feature extraction with a Transformer module to capture global dependencies among encoded linear vectors. Experimental results demonstrate that the proposed method outperforms state-of-the-art (SOTA) deep learning (DL) approaches, yielding a 17\% improvement in RMSE compared to RadioWNet. The code is publicly accessible at https://github.com/github-whh/TransUNet.
Johannes Huemer, Markus Murschitz, Matthias Schörghuber
et al.
Efficient material logistics play a critical role in controlling costs and schedules in the construction industry. However, manual material handling remains prone to inefficiencies, delays, and safety risks. Autonomous forklifts offer a promising solution to streamline on-site logistics, reducing reliance on human operators and mitigating labor shortages. This paper presents the development and evaluation of ADAPT (Autonomous Dynamic All-terrain Pallet Transporter), a fully autonomous off-road forklift designed for construction environments. Unlike structured warehouse settings, construction sites pose significant challenges, including dynamic obstacles, unstructured terrain, and varying weather conditions. To address these challenges, our system integrates AI-driven perception techniques with traditional approaches for decision making, planning, and control, enabling reliable operation in complex environments. We validate the system through extensive real-world testing, comparing its continuous performance against an experienced human operator across various weather conditions. Our findings demonstrate that autonomous outdoor forklifts can operate near human-level performance, offering a viable path toward safer and more efficient construction logistics.
Ramadan M. Albtti, Mohamed A. Benhalem, Salim S. Khoujah
Ordinary Portland cement is one of the most widely used construction materials in building and concrete projects, and assessing its quality is a key factor in ensuring that the produced concrete conforms to standard specifications. This research aims to study the quality of ordinary Portland cement produced in several Libyan factories (Zliten, Al-Burj, Al-Fataih, Al-Hawari, and Labda) through a series of physical, mechanical, and chemical tests. These tests included fineness, standard consistency, initial and final setting times, compressive strength (tested using standard mortar cubes after 3, 7, and 28 days), and the main chemical composition of the cement. The results showed that most of the factories (Zliten, Al-Burj, Al-Fataih, and Al-Hawari) conform to Libyan, European, and American specifications. However, the cement from the Labda factory showed deficiencies in early and final compressive strength, making it more akin to low-heat cement. The study concluded with recommendations for improving quality in Libyan cement factories, including optimizing the proportions of mineral components and developing quality control systems.
Abstract Existing concrete creep coefficient prediction models have the limitation of not considering the structural characteristics of CFT. For this reason, these models tend to overestimate the creep deformation of CFT. Therefore, in order to overcome the limitations of existing CFT creep experiments, this study proposes a creep-experiment method involving the use of CFT that passively changes the load applied to a single concrete specimen by calculating the stress redistribution between the concrete and a steel tube in CFT based on a step-by-step method. Furthermore, by actually applying the proposed experimental method, a creep experiment of CFT lasting for approximately 163 days was performed and a superficial creep coefficient model of CFT was proposed based on long-term strain data from the experiment. In order to verify the proposed superficial creep coefficient model, it was compared with two design criteria (CEB-FIP and ACI) based on the experimental results of this study and references. As a result, compared to the existing design criteria, the value predicted by the proposed superficial creep coefficient model showed good agreement with the experimental results of this study and the references, proving that the proposed creep-experiment method of CFT and superficial creep coefficient model are reasonable.
Systems of building construction. Including fireproof construction, concrete construction
Abstract The structural performance of derailment containment provision (DCP) was investigated using a grid steel frame. The DCP which was installed within the gauge of a track was capable of resisting the impact loading in the case of derailed wheels. It was also possible to control the excessive lateral movement of the derailed train. In this study, the structural performance of DCP with a post-installed anchor to a railway concrete sleeper was evaluated. For this purpose, a total of nine specimens were manufactured and static tests were conducted to investigate the structural performance. Furthermore, the shear resistance of the connecting anchor was also evaluated using grid steel frame specimens. The initial test indicated that the developed DCP for railway using grid steel frames had sufficient load-carrying capacity and performance equivalent to about 150% of the design load. The developed DCP also demonstrated sufficient load-carrying capacity up to about 140% of the designed load in combination tests that simulated conceivable boundary conditions. As analytical results, the overall DCP behavior for the specimen railway that utilized grid steel frames was appropriately tracked, and detailed information was presented.
Systems of building construction. Including fireproof construction, concrete construction
Alexander Gladwin Alex, Prakash Arul Jose, Maria Rajesh Antony
et al.
Abstract This research aims to investigate the fresh and mechanical properties of concrete with diatomaceous earth (DE) and polypropylene fiber (PPF). The cement was partially replaced by DE in the concentration ranging from 5 to 20% by weight; whereas, PPF was incorporated in concrete mix as in range of 0.05–0.20% by cement weight. Totally, 25 different mix proportions were developed and their fresh properties were examined using slump, density and compacting factor tests. Besides, mechanical properties were evaluated by. Using compressive, split tensile, and flexural strength analysis at the ages of 7th, 14th and 28th days. Furthermore, concrete durability properties were evaluated using water penetration, chloride permeability as well as sorptivity tests, which have been performed at the age of 28th day. The result exhibits that the incorporation of D.E slightly affects the slump value meanwhile PPF decreases the fresh values. Furthermore, the combination of DE and PPF in concrete significantly enhances the mechanical properties compared to the control mix. The mix proportion of 15% DE and 0.15% of PPF exhibited a noticeable influence on mechanical properties as well as durability properties compare to control concrete.
Systems of building construction. Including fireproof construction, concrete construction
Alexey V. Golkin, Valery G. Shamonin, Stanislav A. Zuev
et al.
There was considered the possibility of solving the problem of emergency exits (EE) optimal location in elliptical corridors with the maximum distance of EEs from each other, minimizing the mixing of human flows (and, accordingly, panic) during evacuation in case of fire or other emergencies. There was examined the location of EE on both sides of the corridor, with at least one EE at the end of the corridor leading to a staircase or safe area. A sequence of steps was proposed to implement the task – to find the optimal configuration of a given number of EEs on both sides of the corridor.
Systems of building construction. Including fireproof construction, concrete construction
Abstract This study investigated the effect of rubber content on the mechanical characteristics of ultra-high-performance rubberised concrete (UHPRuC). The results revealed a distinctive non-linear decrease in the dry density of UHPRuC as the rubber content increased. Notably, lower rubber content led to a columnar failure mode, while higher content (≥ 20%) exhibited a mixed failure mode with vertical cracking and diagonal fracture. Importantly, the compressive strength showed minimal reduction compared to conventional concrete, presenting a remarkable 50% mitigation of strength reduction compared to previous studies. Utilising reference concrete with robust bond strength proved highly effective in preserving strength in rubberized concrete. Despite its effectiveness in mitigating compressive strength reduction, UHPC could not effectively offset flexural strength loss, which ranged from 1.5 to 3 times that of compressive strength loss. The addition of rubber aggregate in UHPC reduced the peak flexural strength, residual strength, and flexural toughness at a similar rate, while significantly increasing the vibration decaying rate. Incorporating 40% rubber in UHPRuC reduced the eCO2 up to 37%. Our findings emphasise the importance of reference concrete with good bond strength and shows that the addition of rubber aggregate in UHPC leads to reductions in strength but increases the energy-dissipating capacity.
Systems of building construction. Including fireproof construction, concrete construction