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This study developed an energy-efficient, sustainable, and economical method for capturing carbon dioxide using landfilled coal fly ash. The innovative approach processes captured carbon dioxide with supplementary additives and alkali activators to produce a new class of hydraulic cement. A total of eight cement formulations incorporating varying proportions of landfilled coal fly ash, calcium-containing industrial byproducts, and alkali activators were produced and experimentally tested. The study achieved significant CO₂ uptakes, reaching up to 8.35% by weight of the raw materials. Up to 99.98% immobilization efficiency of heavy metal (copper) was recorded along with a significant increase in the total dissolved solids and conductivity. FTIR spectroscopy confirmed CO₂ incorporation with notable peaks at 1400 cm− 1 and 1063 cm− 1, indicating carbonate species. SEM and EDS analyses revealed varied morphologies, with dense, interconnected particle networks in some of the cement formulations. Compressive strength tests showed all formulations exceeded the EPA’s minimum requirement of 0.34 MPa, with the highest strength reaching 38 MPa at 28 days. The findings of this study point to the viability of the production of mechanochemically processed hydraulic cements in CO₂ environment with effective carbon sequestration capability, marked heavy metals immobilization characteristics, and enhanced physical and mechanical attributes. [ABSTRACT FROM AUTHOR]

Field performance of recycled aggregate concrete (RAC) in pavement construction subjected to heavy traffic loads under aggressive weathering conditions was investigated. Test results of laboratory- cured specimens and cores drilled from pavement sections after 270 days of concrete age showed that the RAC mixes can show performance at par or even better than that of corresponding control (normal) concrete mixes. Later-age enhanced strength and durability attributes of RAC concrete suggest its suitability for use in concrete-based infrastructure such as pavement construction. The effect of the quality of parent concrete from which recycled aggregate has been obtained was observed to be significant on the performance of the resulting RAC mix. Use of RAC in pavement-concrete is estimated to result in major energy and environmental gains besides being a step forward in the direction of sustainable concrete construction. Large scale use of recycled aggregate in concrete pavement construction can significantly economize its construction. [ABSTRACT FROM AUTHOR]

Self-healing structures mimic the ability of biological structures (e.g. bone) to redistribute their structural mass in response to dynamic service loads and damaging effects. The self-healing features yield enhanced levels of structural efficiency and safety in dynamic service environments. In this study, the piezoelectric effect was used to convert the dynamic mechanical energy applied to the structure into electrical energy that, in turn, was used to drive electrochemical self-healing phenomena within a solid electrolyte. A theoretical framework was developed for self-healing materials, and experiments were conducted to verify the fundamental principles of the approach. The theoretical models confirmed that: (1) the piezoelectric effect can, within the geometric and mechanical constraints of actual structural systems, generate sufficient electric potential and charge (through harvesting the available mechanical energy) to enable electrochemical mass transport within a solid electrolyte; and (2) the redistribution of structural mass in dynamic service environments can occur within viable time frames. The fundamental principles of the new self-healing materials were validated through the demonstration of piezo-induced electrolytic phenomena in solid electrolytes and by verifying the gains in mechanical performance associated with such phenomena. [ABSTRACT FROM PUBLISHER]