International Concrete Abstracts Portal

This study presents a comprehensive review of eco-friendly materials and advanced repair techniques for rehabilitating reinforced-concrete (RC) structures, emphasizing their role in promoting sustainability and enhancing performance. By evaluating fifty-five research programs conducted between 2001 and 2024, the study focuses on emerging materials such as geopolymers, natural fibers, and fiber-reinforced composites, highlighting their mechanical properties, environmental benefits, and potential for integration into traditional RC systems. The review is thematically organized into four areas: (1) Sustainability and Environmental Impacts, (2) Material Innovation and Properties, (3) Repair Techniques and Efficiency, and (4) Structural Performance. Key findings reveal that these materials not only reduce the carbon footprint of construction but also significantly improve structural durability, corrosion resistance, and long-term performance under varying environmental conditions. Specifically, geopolymer concretes exhibit low CO₂ emissions and superior bond strength; bamboo and flax fibers offer strong tensile capacity with renewable sourcing; and MICP techniques deliver self-healing functionality that reduces dependency on chemical-based crack sealants. Additionally, the use of recycled and bio-based materials further contributes to cost-efficiency and environmental resilience, fostering circular economy principles. By synthesizing findings across these domains, this study provides practical insights into how eco-friendly materials can simultaneously address environmental, structural, and economic challenges in RC repair. The study underscores the importance of adopting innovative repair methods that incorporate these sustainable materials to address modern civil engineering challenges, balancing infrastructure longevity, sustainability, and reduced environmental impact.

As global demand for concrete has been forecasted to keep rising, one of the approaches towards more sustainable constructions is the adoption of mix designs replacing conventional ones. The current study contains a comparison between concrete mixes that constitutes only Ordinary Portland Cement (OPC) and mixes incorporating 25% OPC with a 75% replacement by supplementary cementitious materials (SCM). The major experimental hypothesis circles around investigating whether it is effective to use thermal treatment under moderately elevated temperatures to enhance the physical and mechanical properties of concrete. Comparisons were performed using mechanical tests such as: compressive strength, tensile strength, flexural strength, and through several non-destructive physical experiments as well as microstructural investigation using SEM and EDS. In conclusion, the experimental results have shown a mostly positive influence observing significant enhancements after thermal treatment. However, treated concrete mixes that constitute only OPC seem to excel in overall performance compared to those incorporating SCM.

Engineered cementitious composites (ECC) represent a significantinnovation in construction materials due to their exceptionalflexibility, tensile strength, and durability, surpassing traditionalconcrete. This review systematically examines the composition,mechanical behavior, and real-world applications of ECC, with afocus on how fiber reinforcement, mineral additives, and micromechanical design improve its structural performances. The present study reports on the effects of various factors, including different types of mineral admixtures, aggregate sizes, fiber hybridization, and specimen dimensions. Key topics include ECC’s strain hardening properties, its sustainability, and its capacity to resist crack development, making it ideal for high-performance infrastructure projects. Additionally, the review discusses recentadvancements in ECC technology such as hybrid fiber reinforcementand the material’s growing use in seismic structures. The paper also addresses the primary obstacles, including high initial costs and the absence of standardized specifications, while proposing future research paths aimed at optimizing ECC’s efficiency and economic viability.

The production of carbonated aggregates from Class F fly ash(FA) is challenging due to its low calcium content, typically lessthan 10%. This study investigates the production of carbonatedalkali-activated aggregates using FA and calcium carbide sludge(CCS). Sodium hydroxide was used as an activator, and the effectsof autoclave treatment on the properties of these aggregates wereexamined. The optimal mixture, comprising 70% FA and 30%CCS, achieved a single aggregate strength of >5 MPa in autoclavecarbonated (AC) aggregates, comparable to the strength obtainedafter 14 days of water curing without-autoclave carbonated(WAC) aggregates. Both AC and WAC aggregates exhibited a bulkdensity of 790 to 805 kg/m3, and the CO2 uptake was 12.5% and13.3% in AC and WAC aggregates, respectively. Field-emissionscanning electron microscopy (FE-SEM) and Fourier-transforminfrared spectroscopy (FTIR) analysis indicated the formation ofcalcium-aluminum-silicate-hydrate (C-A-S-H) gel in non-carbonatedaggregates, while calcite and vaterite, along with sodiumaluminum-silicate-hydrate (N-A-S-H) gel, formed in carbonatedaggregates. Concrete incorporating AC and WAC aggregatesexhibited compressive strength of 39 and 38 MPa, with concretedensity of 2065 kg/m3 and 2085 kg/m3, respectively. Furthermore,AC and WAC aggregate concrete showed a reduction in CO2emissions of 18% and 31%, respectively, compared to autoclavenon-carbonated (ANC) aggregate concrete. These findings highlightthe potential of producing carbonated alkali-activated aggregatesfrom FA and CCS as sustainable materials for constructionapplications.

This experimental study investigates the influence of flexuralcracks and punching shear failure inclination on double-headedstud anchorage within the critical perimeter. The research alsoexplored the technical feasibility of using synthetic coarse aggregatesfrom bauxite residue as a sustainable alternative in structuralconcrete production. The results showed that the overall structuralintegrity is impaired at 40 to 50% due to flexural cracks at thecritical perimeter of 2d (30 degrees); however, the perimeter of1.2d (45 degrees) enhanced the shear reinforcement activationand shear strength up 15%, providing a balanced failure withinthe strengthening zone. Thus, a concrete anchoring capacity (CAC)method was proposed to calculate the contribution of doubleheadedstuds in serviceability and ultimate limit states. In addition,synthetic aggregates performed similarly to natural aggregates,offering environmental benefits such as reducing the carbon footprint and production stages.