This study comprehensively investigates the modification effects of tung oil incorporation in cement mortar by examining its effect on workability, mechanical properties, water absorption properties, phase compositions and microstructural characteristics. Results demonstrate that the increase in tung oil content initially increases the fluidity and consistency of cement mortar, but then decreases, while also continuously extending both the initial and final setting times. Moreover, while the incorporation of tung oil preserves the Bingham model of cement mortar, it substantially enhances both the yield stress and plastic viscosity. In terms of mechanical properties, the incorporation of tung oil reduces compressive and flexural strengths nonlinearly, exhibiting an initial increase followed by a decrease in the strength reduction rate with increasing tung oil content. In addition, tung oil significantly improves water absorption resistance by forming a waterproof layer through partial adhesion to capillary pores and microcracks in the hardened paste. Furthermore, tung oil encapsulation of cement particles and hydration products inhibits both cement hydration and pozzolanic reactions, consequently altering the hardened paste's microstructure. Specifically, increased tung oil content substantially reduces the most probable pore diameter, proportion of large pores, and pore surface fractal dimension ( D s), which can be attributed to tung oil refining pore size and reducing pore connectivity.
Pan et al. (Sun,) studied this question.