Tailoring water absorption and mechanical properties of cementitious composites by varying the oxidation degree of graphene

In this study we present the synthesis and characterization of graphene oxide (GO) with distinct oxidation degrees, designated as ‘GO-1’ (less oxidized) and ‘GO-2’ (more oxidized), and their impact on water absorption and mechanical properties in cementitious composites. XRD analysis confirmed the complete oxidation phase in GO-2. Thermal analysis quantified oxygenated groups at 12% (m/m) for GO-1 and 35% (m/m) for GO-2. FTIR and Raman spectroscopy revealed heightened oxygenated group presence and increased structural disorder in GO-2, with a D/G intensity ratio of 1.12 for GO-2 compared to 0.98 for GO-1. SEM analysis confirmed large lamellar structures in GO-2. Incorporating GO-1 and GO-2 into cementitious composites resulted in significant changes in water absorption and mechanical properties. The composite with GO-1 reduced water absorption by 14%, while GO-2 increased it by 10%. Compressive strength for GO-1 reached 28 MPa, a 17% increase over GO-2 (24 MPa) and 3.7% higher than the control (27 MPa). Tensile strength for GO-1 was 3.0 MPa (7.1% higher than the control at 2.8 MPa), while GO-2 achieved 3.1 MPa, a 10.7% improvement over the control. Contact angle measurements further supported these trends, with GO-1 showing ~22% increase (indicating hydrophobicity) and GO-2 ~4% decrease (indicating hydrophilicity). These findings highlight the critical role of GO oxidation degree in tailoring cementitious composites for enhanced durability (reduced water absorption) or improved tensile strength, providing a pathway for optimizing material performance.