Amir Mohammad Ramezanianpour

Replacing cement with supplementary cementitious materials (SCMs) is widely recognized as an effective strategy to reduce the environmental footprint of cement production. However, focusing solely on technical or environmental dimensions is insufficient for drawing comprehensive sustainability conclusions. A thorough evaluation requires integrating key sustainable development indicators across all life-cycle stages. Life Cycle Assessment (LCA) is a valuable tool that quantifies environmental impacts across all stages of a product’s life, including green concretes, which are often assessed from cradle to gate. This study examined the technical, economic, and environmental performance of self-consolidating concretes (SCCs) incorporating various SCMs, including silica fume (SF), ground granulated blast furnace slag (GS), metakaolin (MK), and pumice (PU), across 13 mix designs. The technical evaluation included measures of slump flow, compressive strength, and chloride migration, along with a service life prediction model to estimate long-term environmental impacts associated with each mix. Furthermore, an expert questionnaire was developed to prioritize the importance of these performance indicators from construction professionals’ perspectives. The results indicate that mixes containing 20% and 15% metakalolin or 15% silica fume demonstrated superior performance across combined technical, environmental, and economic criteria, as confirmed by expert evaluations. Compared to the control mixture, these mixes achieved CO₂ emission reductions of 94%, 93%, and 89% per cubic meter per service-year, respectively. Experts prioritized the highest weightage to the technical criterion (66%), followed by economic (21%) and environmental (13%) considerations.

Automation in crack and bug-hole detection through non-destructive evaluation methods remains a major challenge in Structural Health Monitoring. Typically, machine learning models are fed with original, grayscale, or binary formats of concrete images. Original images retain excessive color data, grayscale formats reduce color without preserving structural relevance, and binary images often lack sufficient detail for assessing damage type and severity. To overcome these limitations, multilevel colored image thresholding using meta-heuristic algorithms such as Particle Swarm Optimization, Genetic Algorithm, Jaya and Sine Cosine Algorithm—guided by Otsu’s objective function. This technique enhances the contrast, edges, and texture boundaries, which serve as crucial primitives for object recognition, compared to original images. Additionally, it increases pixel connectivity, thereby simplifying image analysis for deep learning and machine learning applications. In fact, this method reduces the number of colors by an average of 97.3%, significantly decreasing computational load, while maintaining a high Structural Similarity Index (SSIM) of 0.873. Experimental results demonstrate that the optimized images outperform the original, grayscale, and binary formats in both object detection performance and precise evaluation of damage severity and progression. This fusion of optimization and perceptual image representation presents a promising advancement for automated structural damage assessment.

Purpose: This review provides a holistic and critical examination of bacteria-based self-healing concrete, aiming to bridge the research gap between fundamental bio-mineralization mechanisms and their integrated effects on structural integrity, mechanical properties and long-term durability. Design/methodology/approach: A systematic literature review was performed, synthesizing findings from microstructural analyses and experimental studies. The methodology focused on key parameters governing performance, including bacterial strains, nutrient sources, encapsulation strategies and environmental conditions. Findings: Bacteria-induced calcite precipitation can seal cracks up to 0.97 mm, significantly enhancing structural integrity. At optimal concentrations (104−107 cfu/mL), select bacteria increase compressive strength by up to 32% and achieve gains of 14–29% in flexural and tensile strength at the optimal dosage. Advanced encapsulation techniques, crucial for microbial viability, facilitate significant durability gains, including up to a 50% reduction in permeability and a 45–55% decrease in chloride ion ingress. Despite these advantages, challenges related to cost, large-scale implementation and the environmental impact of ureolytic byproducts remain critical hurdles. Originality/value: By integrating multifaceted performance data, this review provides a comprehensive assessment of the potential and current limitations of bacteria-based self-healing concrete. It provides a unified framework to guide future research toward developing cost-effective, scalable encapsulation methods and ecologically sound self-healing concrete, accelerating its transition from laboratory validation to reliable field application.