Study On Properties Of Carbon Nanotubes Reinforced Superfine Cement Grouting Materials

With the rise of the construction industry and the state's vigorous development of prefabricated buildings,the performance of grouting materials is required more and more by the industry.The cement base grouting materials are high in strength,good durability,wide source of material,and the lack of tensile strength and poor toughness,In order to overcome the problem of common fiber materials can't be applied to the grouting materials,In this paper,Carbon nanotubes(a nanoscale fiber)were selected as enhanced componentsto improve the properties of self-prepared ultrafine cement grouting materials,Utilization test method,The mix design,mechanical properties,flow properties and microscopic properties of carbon nanotube cement-based grouting materials were investi-gated,This article has mainly carried on the following aspects content:(1)Super-fine cement and quartz sand were choosed as raw materials,In determining the amount of each component admixtures and water-binder ratio,In the article,the "slurry to aggregate ratio method" based on the theory of slurry filling and inclusion was used to design the mix ratio of ultra-fine cement grouting materials,and the evaluation indexes are strength,flow performance and micro-characteristics,A super-fine cement grouting material with high strength,high fluidity,compact internal structure and good bonding property was prepared.(2)This paper taking the content and diameter of carbon nanotubes as variables,the effects of carbon nanotubes on the compressive and flexural properties of ultra-fine cement grouting materials were investigated,The test results show that,the addition of dispersant(PVP)will affect the mechanical properties of the grouting material;As the content of carbon nanotubes increase,the strength of grouting material increases first and then decreases,When the content of carbon nanotubes was 0.1-0.2%,it had the best enhancement effect on the grouting material.The highest flexural strength increased by 33.62%,and the highest compressive strength increased by 29.30%;The carbon nanotubes with smaller diameter have more obvious enhancement effect on the grouting material,while the larger diameter carbon nanotubes have less effect on the flexural strength.(3)The rheological properties of grouting materials were systematically studied and analyzed by using R/S rheometer from Brookfield,combined with the modified Binghammodel,the constitutive relation model of different grouting materials is presented.The study found that,Dispersant(PVP)has an adverse effect on the rheological properties of grouting materials;With the addition of carbon nanotubes,the yield stress,plastic viscosity and thixotropy of the grouting materials show a trend of gradual increase with the increase of the content of carbon nanotubes,It has an adverse effect on the rheological properties of grouting materials,However,the normal flow performance of the grouting material can be guaranteed under the appropriate content of carbon nanotubes;The effect of carbon nanotube diameter on yield stress is not obvious,the effect on plastic viscosity is more significant;The addition of carbon nanotubes obviously increased the area of thixotropic ring of grouting materials,In other words,the thixotropy of grouting material is obviously increased.(4)The lattice Boltzmann method was used to simulate the macroscopic flow behavior of grouting materials.It turns out,When the grouting material flows through the obstacle,an obvious yield area appears on the back of the obstacle;With the decrease of the size of the filling channel,the slurry velocity decreased significantly,and the filling depth decreased;When the grouting material flows at the complex boundary,the velocity at the boundary is almost zero due to viscous resistance.(5)In this paper,a variety of micro analysis techniques are used to investigate the micro characteristics of grouting materials,It is found that carbon nanotubes can play a good role in filling fiber matrix and filling,Thus the macroscopic mechanical properties of grouting materials are improved;Carbon nanotubes increase the compactness of the microstructure of the grouting material and have a certain influence on the hydration of the grouting materials.