Improvement of basalt fiber dispersion and its effect on mechanical characteristics of oil well cement

Abstract

The surface of basalt fiber (BF) is smooth, inert, and easy to agglutinate, which makes it unable to play its performance advantage in oil well cement. Therefore, this study adopted a coating method to modify the basalt fiber surface to improve its application performance in oil well cement. Phenolic epoxy resin was used as raw material, modified by methacrylic acid and Coupling agent KH-570, and then cetyltrimethylammonium chloride was added to obtain a hydrophilic cationic coating agent, which was coated on BF surface to obtain modified basalt fiber (MBF). Compared with traditional etching modification, this work will not damage fiber’s body structure and maintain its own excellent mechanical characteristics. FTIR, XPS, and EDS were used to examine the chemical composition of MBF. The dispersion calculation method and image analysis approach were used to assess the dispersibility of the fiber. The results show that the dispersion of MBF is 27.2% higher than that before modification, and the distribution coefficient is increased by 73%. In addition, the effect of MBF on mechanical characteristics of oil well cement was also investigated. According to the findings, MBF cement had compressive and flexural strengths that were, respectively, 15.9% and 13.5% stronger than it was before modification, and the optimal dosage was increased from 1% to 2%. Combined with the analysis of the microscope, SEM, and fiber monofilament pull-out test of cement stone, it was shown that the modification of BF surface coating increases its dispersibility in the cement matrix, and the fiber's dispersibility to stress was enhanced. At the same time, the modification of BF increased its surface roughness, which also strengthened the bonding performance between fiber and cement, and enhanced mechanical characteristics of oil well cement. The successful modification of basalt fiber surface improves its application effect in well cementing and broadens its application range. In the future, basalt fiber can be considered to further expand its application in concrete, fiber composite materials and other fields.