Study On Thermal And Mechanical Behaviors Of Hollow Glass Microsphere Reinforced Cement Composites

At present, cement based material is the most widely used building material, because ofits good water resistance, excellent machinability and remarkable economy. However, cementbased material belongs to brittle material. Its tensile bending strength and ultimate strain islow, and the impact strength is poor, so, sudden and uncontrollable damages may happen inbuildings, and cause huge economic losses and environmental pollution. Besides, thecement-based materials have worse thermal resistance property in extreme high-temperatureenvironment. Thus, how to develop high strength, high durability, high cracking resistance ofhigh performance concrete has been main research goal of researchers around the world.In this study, high-performance hollow glass microsphere extracted from industrial wastefly ash is used as filler to develop high performance cement-based composite. Hollow glassmicrosphere is a kind of new fillers for composites and has excellent thermal and mechanicalproperties. This thesis mainly focuses on the computational experimental analysis of hollowglass microsphere reinforced cement, and then establishes the corresponding composite model.the sensitivity analysis is also conducted to investigate the influence of microstructuresincluding filler volume content,filler material property, wall thickness of filler, dispersepattern of filler, and so on, on the equivalent thermal and mechanical properties of composite.Accordingly, one can design the high durability and crack resistance of cement basecomposite materials. The major studies of this thesis are:(1) The establishment of finite element model of composite. Compositecomputational mechanics is a method coupling advanced numerical method andmicrostructure of composite by solving representative volume element (RVE) of composite.Here, the RVE of hollow glass microsphere reinforced cement is established and is solved byfinite element method. The equivalent thermal conductivity of composite is evaluated as afunction of microsphere size, wall thickness and thermal conductivity.(2) Macro experiments. In different condition of beads materialperformance,size,distribution and the volume ratio (such as adding amount), macroscopicexperimental mainly study the beads adding quantity of cement mortar water, slurry rheological property, strength performance of composite materials (including tension andcompression, bending, stick relay), stability, setting time, the influence of fire resistance,sound insulation performance.(3) Microstructure experiment. In order to have the further understanding of the beadreinforced cement mortar characteristics and failure mechanism, the microstructure of thecomposite beads of different material, size, distribution and the volume ratio (adding amount),and other factors, on the material microstructure were observed under the scanning electronmicroscopy (SEM), a mesoscopic loading experiment, then observe the changes of beads andthe surrounding mortar interface bonding strength and failure process.