Study On Properties And Mechanism Of NANO-CaCO₃in Fly Ash Concrete

Fly ash concrete has been widely research and application due to its excellentperformance.But its strength and elastic modulus is low in the early days.With thedevelopment of nano technology,the application of the characteristics of nanometermaterials in concrete and improve the shortage of the fly anh concrete is becomepossible.In this paper, thermal analysis, XRD, SEM and mercury intrusion analysis wereused, to study how nano-CaCO3influence of the hydration and microstructure of fly ashcementitious materies.Then,by the research on mechanical and durable properties tostudy how nano-CaCO3influence on it.Based on the micro and matro test,study on theproperties and mechanism of nano-CaCO3in fly ash concrete.The main contents and results are as follows:1, Study on the effect of nano-CaCO3on the hydration properties of fly ashcementitious materies.Found that the addition of nano-CaCO3can effectively increasethe Ca(OH)2,especially in the early ages.2, Study on the effect of nano-CaCO3on the impact of Ca(OH)2diffraction peakintensity as well as C3S.Found that the addition of nano-CaCO3can reduce the C3S,atthe same time improve of the Ca(OH)2.3, Analysis of the content of none evaporate water in the fly ash cementitiousmateries.The results shows that the addition of nano-CaCO3can improve the content ofnone evaporate water in the early ages,as well as in the later period.4, Reaserch on the effect of nano-CaCO3on the morphology by SEM.The resultsshows that nano-CaCO3can make the setcement more uniform.5, Analysis of the pore structure of nano-CaCO3in fly ash concrete.Found thatnano-CaCO3can refine the pore structure of fly ash cementitious materies.Made thepore size smaller,but has little effect on the porosity concrete.6, Study on the mechanics properties of nano-CaCO3in fly ash concrete.Theresults shows that nano-CaCO3can inprove the compressive strength and cleavagestrength, especially in the early period.7, Reaserch on the resistance to chloride ion permeability properties of nano-CaCO3in fly ash concrete.Found that nano-CaCO3can effectively improve the resistance to chloride ion permeability properties,and the pore structure has a certainrelevance to the resistance to chloride ion permeability properties.8,Reaserch on the effect of nano-CaCO3on the performance of resisrance tofrost.The results shows that nano-CaCO3can improve the freeze-thaw cycles,and thinkmainly of nano-CaCO3refined the pore structure to make the bubble spacing decrease.9, Reaserch on the resistance to carbonation properties of nano-CaCO3in fly ashconcrete. Found that nano-CaCO3can effectively reduce the carbonation depth.