Study On The Mechanical Properties Of PVA Fiber Reinforced Magnesium Phosphate Cement-Bonded Particleboards

Cement-bonded particleboard is a kind of new-type engineering material composed of cement and wood materials,which synthesizes the advantages of cement based materials and woodiness material,and then shows high strength,durable,lightweight and environmentally friendly,it has great significance in promoting the sustainable development of civil engineering.Traditional production of cement-bonded particleboard choose Portland cement as the cementing materials,the hydration process will be affected by the woodiness material and the hardening is slow,which impedes the production efficiency of particleboard and causes poor mechanical performance.Magnesium phosphate cement is chosen as the cementing material in this study because of its fast hardening,and the main research is focused on the influence of PVA fiber on mechanical performance of cement-bonded particleboard,then the durability test is conducted in the final.The conclusion of this study can be drawn as follow:(1)When the magnesium to phosphate ratio of cement is 7,the compressive strength is the highest and condensation rate is fast,and wood shows good compatibility with magnesium phosphate cement,which means it is suitable for producing cement particle board.(2)PVA fiber can significantly improve the bending strength,tensile strength and fracture energy of magnesium phosphate cement particleboard,the brittle failure turns to better ductile failure,and shows good volume stability after 24 h immersion.(3)The strength of particleboard rise first and then decline with the raise of PVA fiber volume content,2% is the best fiber volume fraction,and bending strength of specimen increase by 30%.The strength of particleboard slightly decreases when fiber length is longer,but the fracture energy is significantly enhanced.Under the condition of same volume fraction,smaller diameter PVA fiber has better reinforced efficiency.(4)PVA fiber with oil treated has excellent reinforcing effect,most fibers are pulled out slowly from the cement matrix when delaying the propagation of crack,while PVA fiber without treatment ruptured during this process,which cause lower resistance to deformation and smaller fracture energy.(5)The strength and toughness of PVA fiber-reinforced magnesium phosphate cement particleboard will weaken after under the environment of high temperature,but its volume stability can meet the specification requirements.The bending strength of particleboard under the condition of 200℃ is 6.3 MPa,and failure will show obvious brittleness when the temperature is over 300℃.(6)The strength of PVA fiber-reinforced magnesium phosphate cement particleboard will decrease gradually with the increase of immersion time,significant decrease is observed in the early stages,and then held steady after 6 h with good toughness still maintained.The bending strength after 24 h immersion can meet the requirements of specifications,which proves its good resistance to water.