Effects of steel slag aggregates on mechanical and electrical resistivity characteristics of high-performance fiber-reinforced concretes = Ảnh hưởng của xỉ thép đến đặc trưng cơ học và điện trở suất của bê tông cường độ cao gia cường cốt sợi

Abstract

This study investigated the effects of different contents of steel slag aggregates (SSAs) on the mechanical and electrical resistivity properties of high-performance fiber-reinforced concrete (HPFRC). SSAs with a spherical shape and 0.4 mm in maximum diameter were used instead of 0, 30, 50, and 100% content of sand. 2 vol% short smooth steel fibers (0.2 mm in diameter and 13 mm in length) were added to reinforce the high performance concretes with water percement of 0.2. Two types of steel wire meshes were embedded in samples with a space of 20 mm to measure the electrical resistance of HPFRCs. The test results indicated that the flowability of HPFRC clearly increased from 210 to 270 mm as SSA content (instead of sand) increased from 0 to 100%. The HPFRC with 50% SSA produced the highest compressive strength of 125 MPa. The electrical resistivity of HPFRCs significantly decreased with increasing SSA content. The polarization effect can be ignored after 15 to 20 minutes of direct current measurement for HPFRC matrices with SSAs. In addition, the smaller mesh size of embedded electrodes improved the contacting conduction between electrodes and matrices and decreased the contacting conduction as well as the electrical resistivity of HPFRCs. The microstructure image surrounding fibers was captured and analyzed. A conductive pathway model was proposed based on the microstructure and functional fillers to explain the electrically conductive network in HPFRCs.