High-Carbon Fly Ash in Manufacturing Conductive CLSM and Concrete

Three controlled low-strength material (CLSM) mixtures (100, 100S with sand, and 100SG with sand and stone) were made using 93, 32, and 22% high-carbon fly ash (12% loss on ignition) by mass of total solids, respectively. Three concrete mixtures [40, 50 with steel fibers, and 60 with taconite (an iron ore) pellets] were made, each containing high-carbon fly ash at 43% of total cementitious materials. The respective 28-day electrical resistivity values of water-cured, saturated CLSM mixtures 100, 100S, and 100SG were 0.5, 1.0, and 1.8 Ω-m (ohm-m), and the corresponding values of water-cured, saturated concrete mixtures 40, 50, and 60 were 41, 15, and 17 Ω-m . As the amount of cementitious paste (including high-carbon fly ash) increased, electrical resistivity of CLSM decreased. Electrical resistivity of concrete reduced by more than half upon inclusion of 3% steel fibers or upon replacement of natural crushed stone with taconite pellets. This study also shows that high-carbon fly ash can be used in manufacturing conductive CLSM and concrete. Such materials can be used for conducting electrical charge from lightening to the ground more safely.