Abstract: Based on experimental and theoretical analysis， new nano-concrete was made by adding different dosage of nano-SiO₂ and nano-CaCO₃ into ordinary concrete. The influence of nano-materials on the internal structure of concrete was analyzed by electron microscope observation. The impact of different nano-materials on the dry-shrinkage rate of concrete was compared through the dry-shrinkage tests， and the optimal dosage of nano-material was found. Results show that both nano-SiO₂ and nano-CaCO₃ can change the dry-shrinkage rate of the concrete， however， the changing rate of dry-shrinkage for concrete with nano-SiO₂ is more obvious than that with nano-CaCO₃. When the nano-SiO₂ content is 0.5% or when the nano-CaCO₃ content is 2.0%， the dry-shrinkage rate is the minimum. It is also found that there exists dynamic equilibrium relationship between the concrete shrinkage， the dense degree of concrete and the number of meniscus and internal humidity.

Key words: nano-concrete, internal structure, dry-shrinkage rate, dry-shrinkage mechanism, pore pressure