International Journal of Structural Engineering (12 papers in press)

Regular Issues

• Tri-waste geobrick innovation: performance evaluation of earth bricks over laterite, crushed palm seed, and rice husk ash  
  by K. Chithra, M. Bhuvaneshwari 
  Abstract: Climate change, escalating construction demand, and increasing resource scarcity have intensified the need for sustainable and low-cost building materials, particularly in climate-vulnerable regions. Conventional fired clay bricks are energy-intensive, non-renewable, and associated with high greenhouse gas emissions, while offering limited thermal resistance and environmental adaptability. Addressing these limitations, this study proposes a novel tri-waste geo-brick formulated using laterite, crushed palm seed (CPS), and rice husk ash (RHA) as an unfired compressed stabilised earth brick (CSEB). Five mix combinations were developed using Taguchi experimental design and evaluated through ASTM/EN standards, supported by SEM, XRD, FTIR, life-cycle assessment, and cost-benefit analysis. Results indicate that mix 4 and mix 5 achieved optimal performance, with 5.4 MPa compressive strength, 1.21 W/m
  Keywords: compressed stabilised earth brick; CSEB; rice husk ash; RHA; crushed palm seed; CPS; laterite; sustainable building material; thermal conductivity; SEM; XRD; life-cycle assessment; LCA; cost-benefit analysis.
  DOI: 10.1504/IJSTRUCTE.2026.10077245
   
  
• The rheological, mechanical and durability behaviour of high strength Pozzolana lightweight self-compacted concrete mixed and effect exposure to high temperatures and cycles of freezing and thawing  
  by Laith M. Daradkeh, Ahmed Ashetyat, Mu'tasime Abdel-Jaber, Nasim Shatarat 
  Abstract: This study investigates the influence of Pozzolana on the rheological, mechanical, and durability properties of self-compacting concrete (SCC). Cast specimens included 66 cubes and 15 cylinders prepared from six different mix proportions containing varying percentages of Pozzolana. The specimens were tested for compressive strength, water absorption, ultrasonic pulse velocity (UPV), and flexural strength. In addition, durability performance was evaluated under elevated temperatures (25 C, 400 C, and 600 C) and 200 freeze-thaw cycles. The rheological properties of fresh Pozzolana self-compacting lightweight concrete were examined using slump flow and L-box tests. Results indicate that increasing Pozzolana content improves the rheological behaviour and enhances compressive strength, reaching an increase of about 20%. The optimal Pozzolana mixture achieved approximately 15% higher compressive strength than the control mix. Furthermore, Pozzolana improved durability characteristics, reducing water absorption and increasing ultrasonic pulse velocity of the concrete.
  Keywords: Pozzolana; lightweight; high strength; high temperature; freeze and thaw; self-compacting concrete; SCC; ultrasonic pulse velocity; UPV; experimental study.
  DOI: 10.1504/IJSTRUCTE.2026.10077979
   
  
• A study on modulus of elasticity and Poissons ratio of GGBFS-metakaolin-based geopolymer concrete  
  by Mohd. Nazim Raza, Syed Saifuddin, Qamar Sultana, Asma Sultana, Moahmmed Arif Hussain, Shaik Amaan, Mohammed Abraar 
  Abstract: Cement production contributes nearly 8% of global CO emissions, driving the need for sustainable alternatives. Geopolymer concrete (GPC) replaces cement with industrial by-products such as ground granulated blast furnace slag (GGFBS) and metakaolin, which provide silica and alumina for geopolymerisation. GPC also reduces water usage through sunlight, oven, or ambient curing. This study investigates the modulus of elasticity and Poissons ratio of GGFBS-metakaolin-based GPC in two phases. In the first phase, eight mixes were prepared with binder ratios of GG70-MK30 and GG80-MK20, maintaining 12M NaOH and varying coarse aggregate content (5080%). Tests on fresh and hardened concrete showed optimal performance for GG80-MK20 with 70% aggregates. In the second phase, a linear regression model was developed to predict both properties. Compared to previous studies with errors exceeding 20%, the proposed model achieved errors below 20% and is applicable for 10M and 12M GPC at 28 days.
  Keywords: geopolymer concrete; GPC; ground granulated blast furnace slag; GGBFS; metakaolin; modulus of elasticity; Poisson’s ratio; regression analysis.
  DOI: 10.1504/IJSTRUCTE.2026.10078011
   
  
• Analysis of bond characteristics between keramzit concrete and GFRP rebars with geometrical property variations using pull-out test.  
  by Sy-Quan Tu, Dang-Quang Ngo, Thuy-Chi Dang, The-Truyen Tran, Hoang-Quan Nguyen, Huy-Cuong Nguyen 
  Abstract: Among the properties of concrete members, the bond behaviour of the reinforcement to the surrounding concrete is an important parameter. In the case of lightweight concrete, many studies and specifications recommend a certain diminution of bond behaviour. It is noticed that the lightweight gravel as keramzit used instead of coarse aggregate in concrete has been gradually applied in construction works, significantly reducing the weight of the substructure and saving the costs related to the mounting as well as the foundation. Thus, many pull-out tests have been carried out on the lightweight concrete specimens with different rebar diameters and embedded lengths. Based on the obtained results, the effects of tested parameters on the bond strength and development length of GFRP rebar and lightweight concrete can be specified. The failure mode and bond mechanism of the experimental specimens are compared to the simulation results given by Atena 3D software, which helps to make many recommendations for design work.
  Keywords: development length; bond behaviour; lightweight concrete; LWC; keramzit gravel; GFRP rebar; pull-out tests.
  DOI: 10.1504/IJSTRUCTE.2026.10078205
   
  
• Development of robust mathematical models for sustainable polypropylene fibres reinforced geopolymer concrete  
  by Hamza Waheed, Kong Fah Tee 
  Abstract: Sustainable alternatives to ordinary Portland cement concrete have gained significant attention due to their potential to reduce CO2 emissions. Fly ash-based geopolymer concrete is a promising option; however, reliable strength prediction is essential for its wider application. This study develops mathematical models to predict the mechanical properties of polypropylene (PP) fibre-reinforced geopolymer concrete. Sixteen mixes were prepared with constant NaOH molarity (14 M) and sodium silicate-to-sodium hydroxide ratio (1.5), while varying alkaline activator-to-fly ash ratio (0.40.7) and PP fibre content (01.5%). A total of 48 cylinders and 48 prisms were tested. Linear, multi-linear, and non-linear (power and exponential) regression analyses were performed to relate compressive strength, tensile strength, and elastic modulus to mix parameters, with one-way ANOVA used to validate the models. Results indicate that non-linear models provide superior prediction accuracy for elastic modulus, and that AA/FA ratio and PP fibre content significantly influence mechanical performance.
  Keywords: geopolymer concrete; GPC; regression analysis; polypropylene fibres; mathematical modelling; compressive strength; tensile strength; elastic modulus; non-linear regression analysis.
  DOI: 10.1504/IJSTRUCTE.2026.10078228
   
  
• A comprehensive review of AI-driven techniques for modelling the mechanical and durability performance of high performance concrete  
  by Gaurav P. Gohil, Indrajit N. Patel 
  Abstract: High-performance concrete (HPC) is widely adopted for its superior compressive, flexural, and durability characteristics, yet its complex mix design makes performance prediction challenging. This review synthesises recent advances in artificial intelligence (AI), machine learning (ML) and deep learning (DL) techniques applied to HPC property prediction. The analysed studies considered key input variables such as cement content, water-to-binder ratio, aggregate proportions, mineral admixtures (fly ash, silica fume, slag), superplasticisers, and curing conditions. Comparative analysis of different AI models revealed that support vector machine (SVM) and M5P model tree achieved the best predictive accuracy for compressive strength, with performance values up to R2 = 0.9913 and RMSE = 2.158, significantly outperforming traditional regression methods (R2 < 0.70). In durability predictions, gradient boosted regression trees (GBRT) and deep neural networks (DNN) demonstrated high reliability, reaching R2 = 0.970 for carbonation depth and chloride penetration resistance. The novelty of this review lies in its integrated comparison of AI techniques for both mechanical and durability properties of HPC, highlighting the superiority of AI-driven approaches over conventional testing and pointing to future opportunities in hybrid models, explainable AI, and real-time monitoring to optimise next-generation HPC design.
  Keywords: high performance concrete; machine learning; artificial intelligence; deep learning; durability; prediction.
  DOI: 10.1504/IJSTRUCTE.2026.10078346
   
  
• Prediction of mechanical and durability properties of concrete incorporating PET and RHA using hybrid DBN and KNN integrated with QIEO technique  
  by Pololy Pradeep Kumar, Valikala Giridhar, Hanchate Sudarsana Rao 
  Abstract: The increasing need for sustainable construction materials has encouraged the use of polyethylene terephthalate (PET) and rice husk ash (RHA) during the production of concrete. However, incorporating these materials alters the concrete behaviour therefore making accurate prediction of mechanical and durability properties is important for reliable structural design and long-term performance assessment. This research presents a novel hybrid model that combines the strengths of deep belief network (DBN) and K-nearest neighbours (KNN) with quantum-inspired evolutionary optimisation (QIEO). The DBN enables nonlinear feature learning, KNN improves local prediction accuracy and QIEO optimises the parameters of the model for improved generalisation. The dataset is split into 60% training, 20% testing and 20% validation. The DBN-KNN-QIEO model outperforms other models by obtaining an R2 of 0.9985, MAE of 0.001, RMSE of 0.0026, and an MAPE of 0.01. The results highlight that the proposed model has strong potential for accurately predicting the concrete properties.
  Keywords: properties of concrete; polyethylene terephthalate; rice husk ash; RHA; deep learning model and optimisation.
  DOI: 10.1504/IJSTRUCTE.2026.10078479
   
  
• Analytical evaluation of CFRP repair techniques for prestressed concrete beams with varying strand losses  
  by Ahmed Nasr, Heba Shehata, Hany Abdalla, Khaled F. El-Kashif 
  Abstract: The deterioration of prestressed concrete bridges, caused by corrosion, long-term deflection, and vehicle impacts, demands reliable and durable repair solutions. This study evaluates the structural performance of prestressed concrete beams repaired with carbon fibre reinforced polymer (CFRP) systems, known for their high strength, corrosion resistance, and superior fatigue behaviour. Rectangular, I-, and box-section beams were analytically modelled to assess prestress losses and the effectiveness of subsequent repairs. A MATLAB program was developed to compute prestress losses under serviceability and ultimate limit states. Each beam was examined under four prestress loss ratios and strengthened using externally bonded, pre-tensioned, and post-tensioned CFRP strips. Results showed strong agreement between analytical predictions and expected practical behaviour. Among the techniques, pre-tensioned CFRP provided the greatest enhancement in flexural capacity and overall performance. The study offers useful guidance for optimising CFRP repair strategies in deteriorated prestressed bridge structures, contributing to safer and more sustainable rehabilitation practices.
  Keywords: bridge beam repair; carbon fibre-reinforced polymer; fabric-reinforced cementitious matrix; prestressed concrete; strengthening.
  DOI: 10.1504/IJSTRUCTE.2026.10078566
   
  
• Finite element analysis of a new type of prestressed total-prefabricated multifunctional concrete slabs  
  by Jun Zhao, Zhen Dai, Yang Peng, Jun Dong 
  Abstract: This study proposes a new prestressed fully assembled multifunctional concrete slab system, realising full dry assembly and integration of structural and enclosure functions, which solves the defects of traditional prefabricated buildings. The basic composition and key enclosure structure of the new system are proposed, and the working mechanism is analysed. The mechanical state under vertical load and horizontal load are analysed by FEM, and the influence of the number of wallboard and the number of layers on the mechanical characteristics are studied. Under vertical and horizontal load, the change of the number of layers and the number of wallboard in each layer affects the mechanics characteristic of the new system. Results show under vertical load, when the number of single-layer wallboard increases from 2 to 5, the stress concentration increases by 3.8%, 5.9% and 6.7% respectively, compared with the two wallboard. When the number of layers is less than the number of single-layer wallboard, the degree of stress concentration of the wallboard increases with the number of layers increases. Under horizontal load, when the number of wallboard of each layer changes, the stress state of wallboard of each layer is roughly the same. With the increase of the number of wallboard of each layer, the maximum vertical stress difference increases, and the growth tends to be stable, and the maximum difference does not exceed 25%.
  Keywords: prefabricated system; dry assembly; prestressed; multifunctional concrete slab.
  DOI: 10.1504/IJSTRUCTE.2026.10078780
   
  
• Review on the experimental and computational investigation of fly ash-based geopolymer brick  
  by Ghausul Azam Ansari, Anil Kumar Chhotu, Tabrej Alam, Md Arman, Rahul Kumar 
  Abstract: A shortage of building materials and improvements in construction waste has led to the development of new building materials as construction activity has expanded. As building activity has increased, new industrial materials have evolved as a result of advancements in construction waste and the availability of supplies. Moreover, clay and sand are often blended, moulded, dried, and burned in many steps to create the bricks used in traditional buildings. When compared to ordinary bricks, the production process for geopolymer bricks is less energy-intensive and costs less. For fly ash-based bricks to be made, sufficient fly ash must be mixed with an alkaline solution and additional material. An alkali silicate or hydroxide solution coupled with different aluminosilicate oxides triggers a polymerisation process that yields So-O-Al-O molecules. The mechanical and experimental performance investigations of geopolymer bricks are included in this article.
  Keywords: alkali activator; bricks; experimental; fly ash; geopolymer.
  DOI: 10.1504/IJSTRUCTE.2026.10078781
   
  
• Chloride ion penetrability and resistance to chloride ions of zeolite and steel fibre modified geopolymer concrete  
  by Jinu Mohan Mohanakumar, Jija Gibuslown Sujakumari, Shalu Ravi Filomina 
  Abstract: The increasing demand for concrete to support infrastructure development has raised concerns about its environmental impact. So, the usage of geopolymer concrete is very useful. The mechanical and durability properties are the main criteria for geopolymer concrete. The previous studies show that, zeolite will enhance the mechanical as well as durability properties. And also steel fibre reinforced concrete also enhances these properties. This study investigates using these materials in combination with micro steel fibres and zeolite to enhance geopolymer concretes performance and environmental friendliness. The research evaluates various parameters to improve geopolymer concretes fresh, hardened, and durable characteristics. The compressive enhanced 36.6% when zeolite of 7.5% and steel fibre of 1% is added. The study shows that, adding the combination of zeolite and micro-steel fibres will enhance the mechanical and durability properties.
  Keywords: geopolymer; zeolite; steel fibres; durability; RCPT; RMPT.
  DOI: 10.1504/IJSTRUCTE.2026.10078814
   
  
• Mechanical performance testing and GA-BP model prediction of open-hole rubber bearings  
  by Shaowei Jiang, Lixing Lu, Haode Cheng, Yingxiong Wu 
  Abstract: Open-hole rubber bearings exhibit heightened sensitivity to external loads due to their internal perforated structure. This paper systematically investigates the mechanical behaviour of open-hole rubber bearings through experimental analysis, numerical simulation, theoretical model refinement, and the development of a GA-BP-based predictive model. A rubber bearing with an open-hole ratio of 6.67% was designed, and vertical compression and horizontal shear tests were conducted. Through detailed numerical simulations, the effects of varying the open-hole ratio on the mechanical properties of the rubber bearings and the performance of stiffness prediction models were thoroughly analysed. The research indicates that the vertical hysteresis curves of open-hole rubber bearings are well-defined and exhibit a distinct bilinear characteristic in the skeleton curves. The open-hole design not only affects the overall stress distribution on the steel plates but also alters the distribution pattern of stress concentration zones. Vertical stiffness gradually decreases with an increase in the open-hole ratio, while horizontal stiffness shows a complex trend due to varying stress and shear strain conditions. Furthermore, the GA-BP neural network predictive model for stiffness of open-hole rubber bearings demonstrates strong generalisation ability and high prediction accuracy.
  Keywords: open-hole rubber bearing; plasticity ratio; horizontal stiffness; vertical stiffness; GA-BP neural network.
  DOI: 10.1504/IJSTRUCTE.2026.10078849