Early-Age Performance of Graphene-Nanoplatelet-Modified High-Strength Concrete Cured by Electric Thermal Curing in Severe Cold Regions

Concrete structure construction with a high strength grade in cold regions is a significant problem that has elicited considerable research attention. In this work, we firstly prepared steel-fiber-reinforced high-strength concrete (HSC) at −20 °C for winter concrete construction in a cold region. Specifically, the combination of graphene nanoplatelet (GNP) incorporation and electric thermal (ET) curing could effectively improve the performance when preparing high-strength concrete (GNP-HSC) at −20 °C. The optimal amount of steel fiber added in this work was determined numerically and experimentally to be 2.5 vol%. The temperature development regularity of the ET-cured sample was also recorded during the whole curing process. Mechanical property results indicated that the combination of GNP incorporation and ET curing could effectively stimulate the strength formation of HSC samples to 91.2 MPa at early age, which is remarkable for concrete construction at −20 °C. Moreover, microstructural analyses (including XRD, TG and SEM analyses) were further conducted to verify the advantages of GNP incorporation and ET curing on the hydration products, hydration degree and microstructure of HSC samples. This work provides new insights into the application of GNP as a nanoscale material to improve the performance of HSC structures at extremely low temperatures.

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