Design And Performance Study Of High Voltage Withstanded Cement-based Composites

Polymer cement concrete?PCC?can be used as a high voltage insulation with high insulation for polymer resin and high strength,high durability,high thermal conductivity for concrete.This topic studied compatibility method of polymer emulsion and cement systemically,aiming at high voltage capacity transmission requirements.An newly PCC materials with high strength and good insulation was manufactured in this manuscript.Detailed investigation on constitutes,structures and properties leads to following achievements:Through study the effect of Cement-Polymer emulsion composite slurry on PCC flow,mechanical and dielectric properties a design of slurry with expansion componnents was proposed.The optimized slurry component was determined by micro hardness and dielectric strength.Subsequently,based on these results a new PCC insulating layer material was obtained.The effect of polymer amount on the working,force and dielectric strength under different cement content was executed.And the three different formation of pouring type,compression type and centrifugal type was analysed respectively.It is observed that the more polymer,the lower performance on micro hardness and compressive test in all three types.Whereas,the dielectric properties increased to a maximum,then started to decrease.When polymer amount reached 10%,the pouring type viscosity lower than 2000m·Pa·s,28d compressive strength 27.8MPa,flexural strength 7.8MPa,HV value 58.3,dielectric strength6.3kV/mm;the compression type micro hardness 79.6,dielectric strength 16.5kV/mm;the centrifugal type HV value 27.9,dielectric strength 2.7kV/mm after 28days.Effects on the thermal stability property of PCC insulation materials?pouring type,compression type and centrifugal type?were investigated.It is found that the separation of free water and bound water in hardended composite slurry at temperature of 100-200?,and evaporated polymer at 200-550?.All PCC samples had 3 weigth loss peak at 100?,350?,720?,and centrifugal type was lowest.Thermal conductivity of compression type rose from0.95W/?m·K?at 25?to 1.2W/?m·K?at 75?.The regularity of materials compatibility and molding process on discharge voltage,dielectric constant and dielectric loss was studied.When polymer rate is 10%,the discharge voltage of compression,pouring and centrifugal type were 6.15kV,5.60kV,5.17kV respectively,the frequency dielectric constant and dielectric loss were 52.85,0.36 respectively,and electrical conductivity and resistivity reached at 2.33×10^-10,4.28×10⁹.The crystal phase and microstructure of PCC slurry was employed by SEM,XRD,FTIR,TGA.It is observed that the EP was more obvious than BA-St-MMA to delay SAC hydration ettringite formation of AFt and C₄A₃S,whereas not obviously in POC.The micro compactness of compression was better than pouring and centrifugal type.However,the bubble structure of pouring type and micro cracks of S,P provided a carrier channel and weakened its insulation performance,resulting in the degradation or loss of the insulation of the PCC material.This paper develops an new PCC insulation layer materials in laboratory 35kV transmission pipeline,ensure an mach between insulation and heat dissipation,solves the problem of bond between concrete and semi-conductive layer,provides an effective reference for its application as insulation materials.