The Research On Bending Property And Modifying Mechanism Of Cement Based Composite

Organic material ( polyvinyl alcohol(PVA), vinyl versatate-acrylate copolymer emulsion etc.) and inorganic material( wollastonite powder and silica sol etc.) are added respectively as reinforcing phase. Their reinforcing effect is compared and studied. Molding process is studied to reveal its influence on flexural strength, elastic modulus and deflection. Modifying effect and reinforcing mechanism of these materials are studied. The result of those composite shows:1. Flexural strength of sample without reinforcement equals 16.3 MPa, 16% higher than its counterpart with 20MPa molding pressure. There is significant effect of molding pressure on size structure and density of samples.As a result it affects flexural strength apparently.2. The maximum of silica sol/cement composite is 115% higher than that of reference sample. Its deflection is 2 times of that of reference sample. Among reinforcing material whose main content is SiO₂, silica sol can enhance flexural strength and deflection though lessening the porosity, as is shown in SEM photographs. The mechanism of reinforcement is given and discussed. Wollastonite/cement composite has flexural strength twice as high as that of reference sample.The maximum deflection equals 0.25 mm. According to the model in this paper, favorable content of reinforcing material is 2%⁴.7%.3. There is limited effect to the reinforcement of polyester polyurethane. The modulus pours as its content and deflection hikes. The deflection can be bettered with a maximum deflection 7 mm. Flexural strength of PVA/cement composite(20MPa molding pressure) is 115% higher than that of reference sample,with deflection once to twice of reference sample's defelction,on the basis of absorption of the hydration stress. Vinyl versatate-acrylate copolymer emulsion mixure forms strengthened...