Effect Of Polymer/nano Silica On Properties Of Cement-based Materials

For the study of hydrophilic and lipophilic nano SiO2 and nano SiO2 sol three different properties of nano materials and rubber,polyvinyl alcohol and waterborne epoxy resin three kinds of polymer materials of cement-based material mechanical properties and durability of modified iMPact test,research and test of cement-based material strength and resistance to chloride ion permeability and shrinkage performance.It provides the necessary experimental basis and accumulation for the wide application of nano materials and polymer materials in silicate cement based materials.Test the different characters of nano silicon oxide,polymer and different dosage of cement mortar in different age strength effect,the results show that the different characters of nano SiO2 can improve the strength of cement mortar,the nano SiO2 sol on cement mortar strength promotion effect is good,at the dosage of 1.5%3D,the compressive strength increased by 33%.Higher than the best amount of nano SiO2 20%and enhance the rate of hydrophilic lipophilic SiO2 increase rate of 11%.The hydrophilic SiO2 nanoparticles on the late strength promotion effect is good,when the hydrophilic nano SiO2 content is 1%,the compressive strength of 28d coMPared with the blank raised 22%,higher than the optimum dosage of nano SiO2 sol and enhance the rate of the 8.7%lipophilic nano SiO2 11.9%upgrade rate.Polyvinyl alcohol and polymer powder reduces the compressive strength,the compressive strength of 3d loss rate was above 20%,the strength of 28d maximum compressive strength loss rate was 35%and 31.4%,the flexural strength is enhanced by different degrees.The epoxy resin emulsion improves the mechanical strength of mortar at various ages,and the maximum lifting rate of 28d compressive strength and flexural strength is 20.6%and 32.5%.On the same water cement ratio and cement sand ratio under the condition of adding nano silica and polymer cement resistance to chloride ion permeability and shrinkage properties,the results show that the different characters of nano SiO2 can improve the resistance to chloride ion permeability of mortar,but the introduction of nano SiO2 slurry increases the shrinkage rate.The hydrophilic SiO2 nanoparticles on the anti permeability performance improvement effect is most obvious,followed by nano SiO2 sol,in its best dosage 1.5%,the electric flux test value is reduced by 24.7%coMPared with the blank,the electric flux decreased rate were higher than that of other two kinds of nano materials.At the same time,nano SiO2 sol on the shrinkage of the most obvious effect,when the content reached 1.5%,the shrinkage rate increased by 18.2%coMPared with the blank,the effect of lipophilic nano Si02 minimum,the maximum contraction rate increased by 6%coMPared with the blank.The polymer can also improve the chloride ion penetration resistance of mortar and improve the volume shrinkage of cement mortar.Among them,improve the performance of the most obvious effect against chloride ion penetration of polyvinyl alcohol,epoxy resin of polyvinyl alcohol 6h flux optimal content value was 28.9%lower than the blank.At the same time of polyvinyl alcohol on the performance of cement mortar to improve the inhibition of contraction effect is most obvious,the effect of rubber powder,polyvinyl alcohol,optimum dosage of 1.5%,the shrinkage rate decreased by 30.7%compared with the blank.Effect of nano silica composite polymer on cement performance.Experimental results show that the lipophilic nano SiO2 and rubber powder composite,nano SiO2 sol and PVA composite hydrophilic and nano SiO2 and water-based cation resin emulsion.Not only improves the strength loss caused by the introduction of the polymer,but also improved due to the introduction of nano SiO2 shrinkage increases,improve the anti crack performance of the material,and is conducive to the improvement of the cement base material resistance to chloride ion permeability.The use of XRD and SEM in hardened cement paste was studied.The results showed that the introduction of nano materials,resulting in the cement hydration product characteristic peak intensity increased,decreased peak characteristics of calcium hydroxide.The variation rule of the characteristic peak intensity of XRD hydration product with polymer paste.At the same time,it was observed by SEM observation that the internal structure of the nano material sample was more dense,and the hydration product combination was better.The polymer material specimen is found on the surface of calcium hydroxide is not the hair.It can be concluded that polymer can slow cement hydration and affect the structural density of the system.Nano SiO2 can not only promote cement hydration,but also dense structure.The microscopic analysis results provide reference basis for the influence of various modified materials on various properties.