Study On Properties, Mechanism And Application Of Nano-CaCO₃ In Cement-based Materials

On the purpose of applying nano particles to engineering construction, dispersion and applicability were studied when nano SiO2, nano-CaCO3 and nano-CaC03 intermediate were added in cement. The micromechanism of Nano particles was investigated. The properties of nano composite admixtures were studied which was produced with nano-CaCO3 intermediate and slag powder. In addition, the feasibility was studied when mineral admixer used as nano particles's carrier. A new testing method was introduced to study the mechanism of nano particles, the testing methods of XRD, SEM, surface hardness were adopted in this method. Consistency, compress strength, chloride permeability, anti-carbonation capability and frost resistance were further studied on concrete with nanomaterials for engineering construction.The testing results indicated that nano particles filled into the micro porous as nucleator in the cementitious materials accelerate the cement hydration and hardening process. At the same time, the particles also reduced crystal size of hydration products so that the compressive strength was greatly enhanced especially in the early age.The nano CaCO3 intermediate was used in this study for its relatively low price. The test results indicated that the intermediate was well-dispersed. The early age strength of concrete was greatly enhanced. Compared with other nano material, CaCO3 intermediate has the advantages of economic and well-dispersed, In addition, a nano composite admixtures producing method was proposed. The nano CaCO3 intermediate was used to make the slag powder as carrier of nano-CaCO3 intermediate. Both the early age strength and strength growth were improved with the use of proposed nano composite admixture. The performance, mechanical properties and durability of concrete were all effectively improved with nano composite admixtures.A new method was proposed to study the mechanism on cement-based materials with nano-CaCO3 intermediate. The cement pastes at early age were immersed into nano-CaCO3 fluid so that the interaction of hydration product of cement could be effectively eliminated.This study focused on the application of nano-CaCO3 in cement-based materials. The research results are also helpful for the application of other nano particles in engineering.