Study On Impact Resistance Of Nano-silicon Dioxide-PVA Fiber Reinforced Mortar

In the new era,higher requirements for the strength,toughness and durability of new engineering materials was put forward for the rapid development of ocean engineering structural infrastructure construction,which reflects the urgent need to build new land-sea channels in western China,and is in line with the national strategy of"carbon neutrality"and"maritime power".At present,the concrete material has some defects such as low bending-tension strength and high brittleness.At the same time,its porous material characteristics lead to the problem of insufficient erosion resistance,which is a technical bottleneck in the design and research and development of building materials,which to some extent limits the development of Marine military protection structure engineering.The research and application of cement-based materials,especially on chloride erosion of islands and reefs construction in the South China Sea,has always been a hot issue in the engineering field,With the development of the concept of composite materials,research progress at home and abroad shows that adding reinforced materials can improve the performance of cement-based materials,and improve their durability and impact resistance,which provides a new direction to remedy the defects of cement-based materials.Among many fibers,PVA fiber can prevent and inhibit the development of micro cracks because of its high elasticity and high modulus;Nano-Si O₂has good pozzolanic activity.Both of them can improve the strength of concrete,which has attracted much attention.Based on the study of composite materials performance enhancement method at home and abroad,this paper designed a composite cement mortar test,including context of mix Nano-Si O₂only,mix polyvinyl alcohol（PVA）fiber only,and mix both,mainly to carry out the basic mechanical properties of composite cement mortar,shock resistance,resistance to chloride ion erosion performance and shock resistance test after the chlorine salt erosion.By combining fiber reinforcement and nano-material modification,the law of fiber toughening and nano-modification synergistic strengthening of cement mortar properties under different types and dosage of composite materials is revealed.The specific work contents and results are as follows:（1）The compressive flexural strength test and impact resistance test of Nano-silicon dioxide-PVA fiber reinforced mortar with different dosage was carried out,in which the regular influence of Nano-silicon dioxide-PVA fiber reinforced mortar toughening on compressive flexural strength and impact resistance of cement mortar was comparatively analyzed.The result shows that the compressive strength,flexural strength and impact resistance of cement mortar can be improved from nano-filling modification and toughening of material body respectively.Both of them have the synergistic effect of fiber toughening and nano modification,which can significantly improve the compressive and flexural strength of cement mortar and enhance its impact resistance.（2）The chlorine-salt resistance test（RCM）of Nano-silicon dioxide-PVA fiber reinforced mortar with different dosage was carried out.The results show that with the increase of Nano-Si O₂content,the chloride diffusion coefficient of Nano-silicon dioxide-PVA fiber reinforced mortar decreases firstly and then increases.When Nano-Si O₂content is 1.8%,the chloride diffusion coefficient reaches the minimum value,decreasing by 37%.（3）The drop hammer impact test was carried out on Nano-silicon dioxide-PVA fiber reinforced mortar with different dosage after chloride salt erosion.The results show that both Nano-silicon dioxide-PVA fiber reinforced mortar can improve the impact resistance of cement mortar after chloride salt erosion.The impact resistance of Nano-silicon dioxide-PVA fiber reinforced mortar cement mortar increases first and then decreases before and after erosion.The impact resistance of Nano-silicon dioxide-PVA fiber reinforced mortar increases most obviously when Nano-Si O₂content is 1.8%.However,the effect of Nano-silicon dioxide-PVA fiber reinforced mortar on the impact resistance of cement mortar decreases obviously after erosion compared with before erosion.（4）In order to further reveal the influence of Nano-Si O₂and PVA fiber on the impact resistance of cement mortar,the impact resistance times obtained in this study was regarded as a random variable,and based on lognormal distribution and Weibull distribution models,the principle and method of probability and statistics were used to carry out a specific analysis.The impact life distribution of composite cement mortar is consistent with the above two models.Under a certain content of PVA fiber,there is a quadratic function relationship between the content of Nano-Si O₂and the impact times of cement mortar.Based on the correlation,a prediction model of impact times and impact energy consumption of composite cement mortar based on Nano-Si O₂content was proposed under different probability conditions.