Cement production produces a high amount of carbon dioxide, which has a negative impact on the environment. By utilizing waste products instead of cement, environmental degradation can be reduced. The current study was undertaken to study the mechanical and durability performance of concrete by replacing 7.5%, 10%, and 12.5% silica fume (SF) of cement weight. Additionally, coal bottom ash (CBA) was also substituted as fine aggregates with 10%, 20%, and 30%. Compressive strength and indirect tensile strength were the major parameters regarding mechanical properties, while corrosion analysis and sulfate attack were set for durability performance. Sixteen mixes were prepared including a control mix. Out of these, three mixes contained SF, three mixes contained CBA, and eight mixes contained both SF and CBA with 1:2:4 ratio at 0.5 w/b ratio. The results concluded that the addition of 12.5% SF and 30% CBA gives optimum compressive strength and tensile strength. Furthermore, using the SF and CBA reduces the workability of concrete. Furthermore, the use of these byproducts increased the durability in terms of corrosion and sulfate attack.

Interest in self-healing-crack technologies for cement-based materials has been growing, but research into such materials remains in the early stage of development and standardized methods for evaluating healing capacity have not yet been established. Therefore, this study proposes a test method to evaluate the self-healing capacity of cement-based materials in terms of their resistance to chloride penetration. For this purpose, the steady-state chloride migration test has been used to measure the diffusion coefficients of cracked mortar specimens containing crystalline, expansive, and swelling admixtures. The results of the present study show that the time to reach a quasi-steady-state decreased and the diffusion coefficients increased as the potential increased because of the potential drop inside the migration cell and self-healing that occurred during the test. Therefore, use of a high potential is recommended to minimize the test duration, as long as the temperature does not rise too much during the test. Using this test method, the self-healing capacity of the new self-healing technologies can be evaluated, and an index of self-healing capacity is proposed based on the rate of charged chloride ions passing through a crack.

This research is sought to characterize the stimulated autogenous healing of fiber-reinforced mortars that incorporate healing agents such as crystalline admixtures, expansive agents, and geomaterials. The effects of the healing materials on mechanical performance and water permeability were evaluated experimentally. Furthermore, microscopic and microstructural observations were conducted to investigate the characteristics and physical appearance of healing products within healed cracks. Test results are presented herein regarding index of strength recovery (ISR), index of damage recovery (IDR) and index of dissipation energy gain (IDEG) in relation to crack healing, and reduction of water flow rate. The self-healing capability of the mortars was greater in terms of resisting water flow rather than recovering mechanical performance likely because water flow depends on surface crack sealing, whereas mechanical performance depends on bonding capacity as well as full-depth healing of cracks; thus, mechanical performance may further be improved after longer healing duration.

The construction industry's rapid growth poses challenges tied to raw material depletion and increased greenhouse gas emissions. To address this, alternative materials like agricultural residues are gaining prominence due to their potential to reduce carbon emissions and waste generation. In this context this research optimizes the use of banana leaves ash as a partial cement substitution, focusing on durability, and identifying the ideal cement-to-ash ratio for sustainable concrete. For this purpose, concrete mixes were prepared with BLA replacing cement partially in different proportions i.e. (0 %, 5 %, 10 %, 15 %, & 20 %) and were analyzed for their physical, mechanical and Durability (Acid and Sulphate resistance) properties. Compressive strength, acid resistance and sulphate resistance testing continued for 90 days with the intervals of 7, 28 and 90 days. The results revealed that up to 10 % incorporation of BLA improved compressive strength by 10 %, while higher BLA proportions (up to 20 %) displayed superior performance in durability tests as compared to the conventional mix. The results reveal the potentials of banana leave ash to refine the concrete matrix by formation of addition C–S–H gel which leads towards a better performance specially in terms of durability aspect. Hence, banana leaf ash (BLA) is an efficient concrete ingredient, particularly up to 10 % of the mix. Beyond this threshold, it's still suitable for applications where extreme strength isn't the primary concern, because there may be a slight reduction in compressive strength.

Concrete is a popular building material all over the world, but because of different physiochemical processes, it is susceptible to crack development. One of the primary deterioration processes of reinforced concrete buildings is corrosion of steel bars within the concrete through these cracks. In this regard, a self-healing technique for crack repair would be the best solution to reduce the penetration of chloride ions inside concrete mass. In this study, a rapid chloride migration (RCM) test was conducted to determine the self-healing capacity of cracked mortar. With the help of the RCM test, the steady-state migration coefficient of cracked and uncracked specimens incorporating expansive and crystalline admixtures was calculated. Based on the rate of change of the chloride ion concentrations in the steady-state condition, the migration coefficient was calculated. Furthermore, bulk electrical conductivity tests were also conducted before and after the migration test to understand the self-healing behavior. It was evident from the test results that the self-healing of cracks was helpful to reduce the penetration of chloride ions and that it enhanced the ability of cracked mortar to restrict the chloride ingress. Using this test method, the self-healing capacity of the new self-healing technologies can be evaluated. The RCM test can be an acceptable technique to assess the self-healing ability of cement-based materials in a very short period, and the self-healing capacity can be characterized in terms of the decrease of chloride migration coefficients.