Preparation and Mechanism Study of Biochar based Mortar Composite Materials

Abstract

This study investigated the mechanical properties and hydration mechanism of cement-based composites incorporating rice husk biochar (RB) and corn straw biochar (CB) under standard curing conditions of 28 days. The compressive strength, flexural strength, and total calcium hydroxide generated during hydration of the cement-based composites were studied using simultaneous thermal analysis (TG-DTG), X-ray diffraction (XRD), mercury intrusion porosimetry (MIP), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). The results showed that when the incorporation of RB and CB was 4%, both the compressive and flexural strengths were significantly improved. The incorporation of RB and CB did not generate new hydration products or change the total amount of calcium hydroxide generated during hydration. On the contrary, refining the internal pore structure of the cement significantly improved the mechanical properties of the cement-based materials. These findings indicate that biochar materials prepared from agricultural and forestry waste represent a valuable new development strategy for improving the performance of cement-based materials.