Dissertation > Industrial Technology > Chemical Industry > Silicate > Cement Industry > Cement products

Study on the Preparation and Properties of the Grounding Module of Conductive Cement Composites

Author ShiJianHua
Tutor ZhaoRen
School University of North
Course Weapons systems and the use of engineering
Keywords Conductive cement Polystyrene Basalt fiber Grounding module Polyvinylpyrrolidone
CLC TQ172.7
Type PhD thesis
Year 2014
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The electrostatic protection is particular important in the process of production and theusing of explosive and ammunition, and also in the building for militaryproduction, conductive rubber as antistatic materials is widely used. Military conductiverubber is of high production costs, and only under a certain pressure can the conductiveparticles contacting each other, and in this way the conductive rubber expresses goodconductivity. Cement materials are widely used in the buildings of military production plants,if the cement which has certain conductivity is used in the plant ground, working tables andsome non-bared walls, it can not only improve the antistatic ability effectively, but also canreduce the construction cost greatly. Making a cement material of obvious ground effect, gooddurability, no pollution, being economic and light has become the common concern issue toscientific workers. For solving this problem, theoretical research, science experiments andnumerical analysis were all used in this paper to study the preparation principle, process andconductivity, heat mechanism of foam graphite-cement conductive composites. Through alot of tests, the factors that have effect on electrical conductivity and physical properties ofcement were studied, the method of preparing foam graphite-cement conductive compositesand the best mixture ratio were also obtained.Due to the addition of graphite, the intensity of the cement matrix greatly decrease,therefore, it’s necessary to add some fiber to increase the strength of the cement matrix. Thebasalt fiber with good physical and mechanical performance was selected in the paper. Thestrength, crack resistance and toughness of the cement product will be dramaticallyenhanced by adding basalt fiber into the cement mortar. In order to reduce the density of theconductive cement, two methods were chosen. One is to add the polystyrene particles intothe conductive cement; the other is to deal with the graphite-cement slurry using thephysical foaming method and hydrogen peroxide chemical foaming method. So, in thepaper, first, the dense graphite-cement conductive ground module was prepared with graphite as conductive phase, cement as cementing materials, and the influence of differentgraphite content on the mechanics performance and electrical performance of the compoundmaterial was studied. Then, the polystyrene particles and basalt fiber were added into thegraphite-cement slurry to reduce the density and enhance the strength of the specimen. Thebest size and amount of the polystyrene particles and basalt fiber were determined. Third,the preparation technology for high performance, light quality conductive cement groundmaterial by physical foaming method was studied. Last, the light quality conductive cementground module was prepared by hydrogen peroxide chemical foaming method usingpolyvinyl alcohol, sodium dodecyl sulfate and polyethylene pyrrolidone as stable foamagent. The resistivity, compressive strength, flexural strength and dry density werecompared. The main results and conclusions are as follows:1The effect of adding different content of graphite on the resistivity, compressivestrength, flexural strength and dry density of cement base composite materials was studied.The results show that:1) The electrical conductivity of graphite-cement composite material is related to thegraphite content. The more the graphite content, the greater the conductivity, but thegraphite content will affect the strength of the material, so the graphite content also cannotadd too much in order to keep the strength.2) With the increase of graphite content, the resistivity and dry density of the densegraphite-cement conductive composites is significantly reduced, but also causes materialcompressive strength and flexural strength reduced. When the graphite content is50%, theprepared conductive cement ground material has good mechanical properties and electricalproperties.2The effect of adding different polystyrene particle and basalt fiber on mechanicalproperty and electrical property of the conductive cement was investigated under fixing50%graphite. The results show that, when the graphite content is50%, the physicalproperty of the conductive cement with mixed1~2mm polystyrene particles and2.5%basalt fiber is the best. 3The setting time of graphite-conductive cement ground sample by physical foamingmethod is long. The internal hole with the same size is small, the spherical degree is high, theconnectivity rate between bubble holes is low, and the intensity is high.4The resistivity, compressive strength, flexural strength and dry density of the graphite-conductive cement composite material prepared by hydrogen peroxide chemical foamingmethod are varied with the doped polymer variety.Under the condition of graphite, content is50%. When using polyvinylpyrrolidone asstable foam agent, the getting stomata is tiny. The pore size distribution is uniform whichcan reduce the stress concentration, increase mechanical property of the material. At thesame experimental conditions, the setting time and bubble stability time of the graphite-conductive cement composite material prepared by the polyvinyl alcohol and sodiumdodecyl sulfate are not synchronized, that lead to bubbles burst after growing up and reducethe mechanical property and electrical property.

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