Static Mechanical Properties of Concrete with Nanoparticles Cured Using Different Methods

This research examines the progression of mechanical properties in nanoconcrete under various high-temperature curing conditions. The compressive, flexural, and split tensile strength of plain concrete (PC), nano-SiO2 concrete (NSC), and nano-CaCO3 concrete (NCC) were examined under standard curing (SC), steam curing (StC), and hot water curing (HWC). The strength development mechanism of nanoconcrete under different curing methods was revealed using X-ray diffraction. The findings indicate that the optimal content of nano-SiO2 and nano-CaCO3 in concrete under the three curing methods is 2% and 1%, respectively. Nano-SiO2 contributes more significantly to the concrete’s mechanical properties than nano-CaCO3. HWC and StC greatly enhanced the concrete’s early mechanical properties, but high-temperature curing resulted in varying degrees of degradation in the later concrete’s mechanical properties, and HWC was more effective than StC. Nanoparticles can combine with high-temperature curing to impart higher concrete’s early mechanical properties while mitigating the decline of its later mechanical properties. The 56-day compressive strength of HWC-NSC20 and HWC-NCC10 could be restored to 107.28% and 103.54% of SC-PC, respectively, with nano-SiO2 showing a more significant repair effect. Both high-temperature curing and nanoparticles enhanced the hydration degree of C2S/C3S phases at 3 days. Delayed ettringite formation and incomplete cement hydration are the primary causes of the loss of later mechanical properties in hot water–cured concrete. The incorporation of nanoparticles partially repaired the degradation of later mechanical properties caused by high-temperature curing.