Experimental study on the influence of aggregate morphology on concrete interfacial properties

Abstract

Aggregate is the basic component of concrete, and its shape and surface properties largely determine the mechanical properties and durability of concrete. In order to further study the mesoscopic influence of aggregate shape on concrete interfacial phase, this study focuses on two aggregate shapes, circular and polygonal, and the elastic modulus and hardness of interfacial phase of specimens with different aggregate shapes were obtained by nano-indentation technology, and the mesoscopic component partition was quantified. Based on Gaussian statistical theory, the distribution model of nanomechanical properties of each phase was established, and the influence of aggregate shape on mechanical properties was studied by SEM test. The results show that (1) The width of the interfacial zone of natural rounded aggregate (∼50 μm) is slightly smaller than that of polygonal aggregate (∼60 μm), and the modulus of elasticity and hardness of the interfacial zone corresponding to the rounded aggregate (e.g., interfacial transition zone (E,H) ∼ (23.65 GPa, 0.9 GPa)) are larger than that of the interfacial zone of polygonal aggregate (interfacial transition zone (E,H) ∼ (21.66 GPa, 0.73 GPa)), indicating that the micromechanical properties of the interfacial zone of the circular aggregate are better than those of the polygonal aggregate; (2) The hydration products in the transition zone of the interface of different shapes of aggregates are almost the same, indicating that the influence of the shape of aggregates on the performance of concrete is mainly due to its own geometric characteristics. Based on the findings of the study, the direction of future research can focus on modeling with further refinement of the influence of aggregate shape parameters, such as shape factor and surface roughness, on the performance of concrete, so as to facilitate more accurate prediction and regulation of the performance of concrete. This study provides theoretical references for the design of aggregate proportioning and the simulation technology of fine data values in actual projects, and also provides theoretical basis and technical support for the standardization and performance evaluation of concrete materials.