Effects of submicron-MgO and nano-MgO on the expansion and microscopic properties of high-performance concrete

Abstract

MgO-series expansive agents can effectively compensate for the shrinkage and deformation of concrete structures. However, few experimental studies have been conducted on MgO expansive agents, particularly concerning the difference between and effects of submicron-MgO and nano-MgO in high-performance concrete (HPC) with a low water-cement ratio, thereby limiting their application in practical engineering. To clarify the expansion effect and expansion mechanism of MgO expansive agents in HPC, the effects of submicron-MgO and nano-MgO on the strength, toughness, and expansion characteristics of HPC were examined. The test results showed that submicron-MgO and nano-MgO continued to hydrate in the cement environment to produce Mg(OH)₂, thus improving the structural compactness and structural strength of HPC. Nano-MgO concrete was found to have more stable mechanical properties and better structural deformability than submicron-MgO concrete. This study provides effective data support and theoretical reference concerning the hydration expansion mechanisms and engineering applications of nano-expanded materials.

Keywords

submicron-MgO / nano-MgO / high-performance concrete / strength / toughness / expansion characteristics / microstructure

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