Effects of Lao Cai graphite on the mechanical properties and electrical conductivity of high-performance concretes = Ảnh hưởng của graphite Lào Cai đến đặc trưng cơ học và tính dẫn điện của bê tông hạt mịn cường độ cao

Abstract

This study investigated the influence of graphite, sourced from Lao Cai, on the mechanical properties and electrical conductivity of high-strength fine-grained concrete (HSFGC). HSFGC specimens were produced with four graphite contents (0%, 1%, 5%, and 10% by cement weight) and tested for compressive strength, flexural strength, and electrical resistivity. The control sample (without graphite) exhibited a compressive strength of 98.21 MPa and a flexural strength of 15.28 MPa. As the graphite content increased from 0% to 10%, the compressive strength decreased by 7%, 28%, and 62%, while flexural strength declined by 11%, 25%, and 30%, respectively. Concurrently, the electrical resistivity markedly dropped from 805 kΩ-cm to 167 kΩ-cm, i.e., the electrical conductivity of HSFGCs significantly increased. The degradation in mechanical performance can be attributed to the soft nature, weak bonding capacity, and chemical inertness of graphite. However, the enhanced electrical conductivity was explained by the formation of an internal conductive network. These findings highlight the potential for developing smart concrete materials with integrated electrical conductivity, sensing, and energy storage capabilities, supporting the utilization of indigenous resources and promoting the advancement of smart infrastructure and cities in Vietnam.