Abstract
Three kinds of nano-concrete, i.e., 2.0% nano-SiO2 doped, 2.0% nano-CaCO3 doped and 1.0% nano-SiO2-1.0% nano-CaCO3 co-doped concretes (NS, NC, NSC) were prepared for a study on static property and dynamic property under different strain rates (50–130 s−1) using HYY series hydraulic servo test system and Φ100 mm split Hopkinson pressure bar test system, and a comparison with plain concrete (PC) as well. The results have shown that under static load, as compared with PC, NC has both strength and elastic modulus increased obviously, while NS has strength decreased and elastic modulus increased, and under dynamic load, there is an obvious strain rate effect for the dynamic compressive strength, impact toughness, energy dissipation and impact failure mode of concrete. Under the same strain rate, the dynamic compressive strength, peak strain, impact toughness and energy dissipation of NC are significantly increased, while its dynamic elastic modulus is decreased. Compared with PC, NS has dynamic compressive strength, peak strain, impact toughness and energy dissipation decreased, and dynamic elastic modulus increased, NC has static and dynamic mechanical properties improved, NS has static and dynamic mechanical properties weakened, and NSC is between PC and NC in static and dynamic mechanical properties, but generally improved. Doped with nano-CaCO3, NC has compactness improved, weak areas reduced, and pore size distribution optimized, while doped with nano-SiO2, NS has obvious internal weak areas, with pore structure degraded.
Highlights
Three kinds of nano-concrete, i.e., 2.0% nano-SiO2 doped, 2.0% nano-CaCO3 doped and 1.0% nanoSiO2-1.0% nano-CaCO3 co-doped concretes (NS, NC, NSC) were prepared for a study on static property and dynamic property under different strain rates (50–130 s −1) using HYY series hydraulic servo test system and Φ100 mm split Hopkinson pressure bar test system, and a comparison with plain concrete (PC) as well
An appropriate amount of nano-SiO2 can improve the microstructure of concrete, increasing the compressive strength and elastic modulus of concrete[16]
Shaikh et al.[17] studied the effect of nano-SiO2 on the mechanical properties of recycled coarse aggregate concrete, and found that nano-SiO2 can improve the compressive strength of recycled coarse aggregate concrete, in other words, if concrete contains 25% recycled coarse aggregate and 2.0% nano-SiO2, its compressive strength could reach 92% of the normal compressive strength of concrete
Summary
Three kinds of nano-concrete, i.e., 2.0% nano-SiO2 doped, 2.0% nano-CaCO3 doped and 1.0% nanoSiO2-1.0% nano-CaCO3 co-doped concretes (NS, NC, NSC) were prepared for a study on static property and dynamic property under different strain rates (50–130 s −1) using HYY series hydraulic servo test system and Φ100 mm split Hopkinson pressure bar test system, and a comparison with plain concrete (PC) as well. Nano-SiO2 and nano-CaCO3 are used as materials for modification and high-performance water-reducing agent of polycarboxylates as dispersant of nanomaterial and water reducing agent of concrete for preparing 3 kinds of nano-concrete (NS, NC, NSC), which were nano-SiO2 doped, nano-CaCO3 doped, and nano-SiO2/nano-CaCO3 co-doped respectively. HYY series hydraulic servo test system and Φ100 mm split Hopkinson pressure bar (SHPB) test system were utilized to study the static and dynamic properties of the three kinds of nano-concrete under different strain rates, and have a comparison with plain concrete (PC) based on indexes of static mechanical performance like stress–strain curve, compressive strength, flexural strength, splitting tensile strength, elastic modulus, and indexes of dynamic mechanical performance like compressive strength, peak strain, dynamic modulus of elasticity, impact toughness, impact energy dissipation, and impact failure mode. The effects of nano-SiO2 and nano-CaCO3 on the static and dynamic mechanical properties of the concretes were analyzed, and relevant microscopic mechanism was explored by scanning electron microscopy and mercury injection test
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