Abstract
In this study, the effect of carbon nanotubes (CNTs) on the physical properties of cement composites was investigated. The mechanism of the change of autogenous shrinkage of CNTs-reinforced cement composites was also examined. In the experiments, ordinary Portland cement (OPC) and fly ash (FA) were used as binders, and 0.0, 0.1, 0.3, and 0.5% multi-walled CNTs (MWCNTs) were added to fabricate pastes. When the hydration heat was measured through isothermal calorimetry, it was found that CNTs accelerated the early age hydration of the pastes and that the hydration rate increased as the CNT content increased. The compressive strength was the highest when the CNT content was 0.1%. As the CNT content increased, the internal relative humidity (IRH) decreased and autogenous shrinkage showed a decreasing tendency. Through the analysis of the correlation between autogenous shrinkage and IRH, it was confirmed that the reduction in autogenous shrinkage due to the addition of CNTs resulted from the decrease in bulk strain.
Highlights
Carbon nanotubes (CNTs) are widely used owing to their mechanical, electrical, and thermal properties [1,2,3]
When the carbon nanotubes (CNTs) content increased to 0.5%, the initial setting time was reduced by 6 min and the final setting time by 10 min
Ordinary Portland cement (OPC) and fly ash (FA) were used as binders, and CNT-reinforced cement composites fabricated with different CNT contents were used
Summary
Carbon nanotubes (CNTs) are widely used owing to their mechanical, electrical, and thermal properties [1,2,3]. The electrical conductivity of CNTs is similar to that of metallic materials. Their yield strength ranges from 10 to 60 GPa, and their modulus of elasticity ranges from 0.3 to 1 TPa [4,5]. Several studies have been conducted in the field of construction to apply CNTs to cement composites [7]. Previous studies focused on the effects of CNTs on the mechanical properties of cement composites, such as compressive, flexural, and tensile strengths [7,8,9,10,11]. To use CNT-reinforced cement composites in the field, their hydration and shrinkage properties need to be investigated; several researchers have conducted studies on such properties
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