Amorphous Carbon Powder for Performance Enhancement of Sulfur Mortar: Alternative Fabrication Method

This study focused on the characterization of sulfur-modified mortars made with amorphous carbon powder (ACP). To this end, modified paste samples were fabricated initially with different ACP content through a dry mixing method, considering varying mixing times. The reinforcement efficiency was evaluated through X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) analyses. Subsequently, the sulfur-modified mortar samples were prepared following the results of the paste assessment. A series of properties of modified and raw sulfur mortar samples, including mechanical performances and durability behaviors, were investigated. Microstructural investigation of the paste samples showed that the degree of modification increased by increasing the ACP content and reducing the mixing time. Results from mechanical measurements revealed that the addition of 20% ACP by weight of sulfur enhanced the compressive and flexural strengths of the mortar sample by up to 26% and 57%, respectively, which aligns with the outcomes from the helium porosimetry and ultrasonic pulse velocity (UPV) tests. The incorporation of ACP led to a significant reduction in the sorptivity and water absorption of the mortar samples by enhancing the hydrophobicity properties of the mortar. Durability assessments demonstrated that mortar samples containing ACP are less prone to corrosion damage compared with raw sulfur mortar. However, these positive effects were less pronounced in mortar samples including a large amount of ACP.