High-conductivity cementitious composites suited for flooring applications: Effect of mixing methods and utilization rates of conductive materials

Abstract

The objective of this study is to develop cementitious electrostatic discharge composites suited for flooring applications with the lowest amount of conductive material using the most appropriate mixing method. For electrical conductivity, milled carbon fiber (MCF), carbon fiber (CF), and brass-coated steel fiber (SF) were incorporated into the cementitious matrices with ratios increasing from 0 to 1% at 0.1% intervals, by the total weight of the binder. To address the homogenous distribution of conductive materials, first (F), synchronous (S), and latter (L) admixing methods were used. Reaching high early strength was another aim of the study. Flow diameter, electrical resistance (ER), compressive strength measurements, and SEM/EDX analyses were performed. According to the experimental results, the ER has a decreasing trend with the increasing fiber ratio in the matrices. CF- and MCF-based mixtures are of adequate electrical performance (10–1000 kΩ) according to related standards after 180-day measurements. No clear percolation thresholds are available for SF- and MCF-based composites up to a 1% utilization rate. Adequate electrical performance can be obtained from CF-based composites at the percolation threshold of 0.6% when prepared by the synchronous admixing method and 0.3% by the latter admixing method. Considering the CF-based mixture incorporating 0.3% CF and prepared by the latter admixing method, the flow diameter is 39.75 cm, 1-day compressive strength is 38.1 MPa, and 180-day ER is 104.15 kΩ in the long term. In conclusion, it is possible to manufacture cementitious composites with significantly improved electrical performance suitable for flooring applications with low cost, high early strength, and good fluidity ready for on-site use.