Investigation of electrical resistivity for fiber-reinforced coral aggregate concrete

Abstract

The application of fiber-reinforced coral aggregate concrete (FRCAC) holds importance in alleviating material scarcity for island and reef construction and in enhancing structural performance. Electrical resistivity, a nondestructive metric, can be employed to assess the comprehensive performance of FRCAC. Therefore, FRCAC was prepared by incorporating basalt fibers (BF), basalt fibers (MBF), and steel fibers (SF) into coral aggregate concrete in this study. The influence of fiber content, fiber addition form, curing time, and erosion time on the electrical resistivity of FRCAC (FRCAC-ER) was analyzed. Mechanistic analysis of the differences in FRCAC-ER was conducted by mercury intrusion porosimetry and scanning electron microscopy. A predictive model for FRCAC-ER was established using the multi-objective slime mold optimization support vector regression (MOSMA-SVR) algorithm. Results indicate that the optimal fiber content for single fiber incorporation is 0.05% for BF, 1.5% for MBF, and 1.5% for SF. The optimal content decreases to 1% when hybrid fibers (MBF+BF or SF+BF) are used. The microscopic analysis reveals that excessive fiber content increases porosity, reduces the proportion of harmless and less-harmful pores, and increases the proportion of more-harmful pores. Extending the curing time improves FRCAC-ER. At curing times of 3 and 7 days, FRCAC-ER reaches 70–75% and 80–85% of the 28-day resistivity, respectively. Seawater erosion reduces the erosion coefficient of FRCAC-ER, with a more pronounced decrease as the exposure time lengthens. The MOSMA-SVR predictive model for FRCAC-ER demonstrates superior predictive accuracy, model error distribution, and performance evaluation indicators compared with other models. The SF proportion and the water-binder ratio emerge as the most crucial ingredient parameters, exhibiting a negative correlation. A graphical user interface for FRCAC-ER has been developed to assist researchers in predicting and quantifying FRCAC-ER effectively. This research employs resistivity as a metric to gauge FRCAC performance and enhance its overall capabilities, thereby establishing a foundational framework for reef construction.