Recent studies in the field of concrete materials show that the early cracking criteria in micro-size can occur as soon as the cement matrix becomes hardened. In many ways, these cracks can become macro-size and opened cracks resulting in significant issues for the durability and appearance of concrete structures as water leakage and corrosion. The technique of self-healing using bacteria has recently received attention for its potential applications. However, the effectiveness and the repeatability of this method over a long period have not been clarified. The information on both the survival and the number of bacteria after healing is limited. This paper aims to improve the self-healing ability and repeatability of concrete when using Bacillus subtilis natto. The experimental studies evaluate the effect of biomineralization with lightweight aggregate as the protecting-carrying vehicle, which can control the release of healing fluid through four cracking-healing cycles. The urease activity and the biomineralization of the bacteria with urea as the main carbon source were assessed and the effect of cracking age on the self-healing capacity, associated with the compressive strength improvement was studied. The results obtained from the optical microscope and SEM/EDS analysis indicated the existence of bacteria CaCO3 forming in concrete after four healing cycles. During long duration, bacterial concentration in concrete was determined by microscopic counting method. Based on experimental results, the restoration of the compressive strength confirmed the high self-healing ability of concrete when using bacteria in lightweight aggregate.

Scientists have been using microorganisms to improve soil strength and durability through a process called biocementation. This technique involves inducing mineral precipitation to form a cement-like material that enhances soil properties. Biocementation has been successful in various applications, including soil stabilization, erosion control, and groundwater remediation. Researchers are optimizing nutrient concentrations and ratios to create a favorable environment for microbial activity and promote efficient mineral formation. Different microorganisms have varying abilities to induce mineralization, and cycle treatments have shown promise in stimulating biomineralization processes. Biocementation is a sustainable and eco-friendly technique that can stabilize and immobilize contaminants in soil and groundwater, preventing the spread of pollutants. Despite these challenges, biocementation holds great potential for innovative soil improvement and environmental remediation. Recent studies, experiments, testing devices, and results from research groups in the world and Vietnam in recent years were reviewed to gain insight into this promising approach. Ongoing research aims to develop cost-efficient and sustainable methods for large-scale production and application of biocementing agents. Further research is needed to uncover the intricate mechanisms and identify optimal strategies for applications and environmental conditions.

This study explores the impact of weak acid salt agents (citrate and tartrate) in the mixture and various curing conditions on the properties of supersulfated cement (SSC) mortar. Compressive strength tests were conducted on prism-shaped samples measuring 4 × 4 × 16 cm. A comprehensive analysis of the phase assemblage of hardened products was carried out using X-ray diffraction (XRD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS). The results reveal the abundant formation of ettringite (E) and hydrotalcite (Ht) when weak acid salt agents are added, especially in chloride and sulfate-rich curing solutions, leading to a notable increase in compressive strength, up to 200% compared to the control sample. Furthermore, the study demonstrates a substantial improvement in early and overall strength under temperature-stimulated curing conditions, accelerating the hydration reaction of SSC. These findings provide deeper insights into the factors influencing SSC hardening and strength development, offering valuable information for enhancing the efficiency and utilization of SSC in the construction industry, aligning with the goals of sustainable development.

This review delves into the utilization of rock powder as a mineral-derived fertilizer to support soil remineralization in the context of sustainable agriculture. Soil remineralization has emerged as a key strategy for ensuring long-term soil fertility and reducing the dependency on synthetic fertilizers. This review critically assesses the methodological approaches applied in various studies, taking into account factors such as local rock mineralogy, soil conditions, crop types, and nutrient uptake by plants. The review covers a range of methods, including nutrient value analysis, assessment of nutrient release rates, crop cultivation experiments in both laboratory and field settings, and the resulting implications for soil remineralization. Additionally, we present findings from a preliminary study focusing on the nutrient content of basalt rock from Nghe-An Province, Vietnam. This experimental investigation is centered on the assessment of nutrient values in a specific porous basalt material, which has been processed into micro-nanometer particles using a high-energy ball mill, thereby enhancing nutrient release efficiency. The study employs a range of analytical techniques, including XRD, XRF, SEM/EDS, and ICP-MS, to quantify macro- and micro-nutrient compositions. While the basalt rock samples may exhibit limitations in providing macronutrients (such as K) compared to commercial azomite rock, they offer distinct advantages in furnishing secondary macronutrients (like Ca). This comprehensive analysis provides insights into the potential use of micronized basalt rock for soil remineralization.

Enhancing the durability of concrete by safeguarding it against cracking and environmental deterioration is paramount. While silicate-based densifiers have been instrumental in shielding concrete surfaces from wear and environmental factors, the surging popularity of lithium silicate solutions faces a significant impediment due to the high cost of lithium, mainly attributed to its predominant use in manufacturing lithium batteries. To address this substantial challenge, an intriguing approach involves blending lithium silicate with colloidal silica, potentially offering a cost-effective and efficient solution for concrete surface treatment. This study delves into the feasibility of utilizing lithium-stabilized colloidal silica as a silicate densifier, focusing on their preparation, characterization, and efficacy in lab-scale applications. The results demonstrate that lithium-stabilized colloidal silica can heighten surface hardness while concurrently reducing porosity. However, it is worth noting that this approach presents particular challenges, particularly regarding preparation and water resistance, when compared to surfaces treated solely with lithium silicate. Addressing these hurdles holds promise for optimizing and enhancing lithium-stabilized colloidal silica and advancing the concrete surface treatment field in future research endeavours.