Research On Resistivity And Anti-corrosion Properties Of Reinforced Concrete Grounding Material

The grounding of equipment or substation is an important subject in power system.Although many new materials,such as copper clad steel and hot-dip galvanized steel,are used in the actual production,there are still plenty of original flat steels and angle steels used as grounding material in many areas by the reason of economic restriction.If it is in the corrosive soil and environment,the ground material will be destroyed in a short time and lost its value,even causes threat to equipment and personal safety.Concrete,as a cheap building material,is mainly researched in this study to protect the earthing metal,by wrapped in a prefabricated form around the earthing metal.Due to the high resistivity of the concrete,it is considered adding additives and admixtures to adjust the resistivity.And also the processing,transportation and landfill of the finished product is necessary,the mechanical strength should be taken into account.After a reasonable concrete formulation is found,the corrosion resistance of the material to the metal is tested,in order to achieve a low resistivity and a good corrosion resistance.Also providing a reference for protecting earthing metals with the concrete material.This paper mainly studies the influence of the production process,inorganic salt,bentonite and corrosion inhibitor on the resistivity and mechanical strength of concrete materials,and tests the anti-corrosion effect of four corrosion inhibitors on carbon steel specimens by weight method.Then,based on the results of tests,a reasonable additive species and quantity is set,an orthonormal experiment to determine the final formula and an electrochemical corrosion test are carried out.The test results show that:(1)The resistivity and mechanical strength of concrete are related to the species and amount of inorganic salt and corrosion inhibitor and the amount of bentonite.Meanwhile,foamed concrete is not in accordance with the grounding requirement in mechanical strength,water retention and thermal conductivity except for some advantages in the water absorption rate.Therefore,1%of KCI and NaCl,and 20%of bentonite substitution is set to be the initial formula choice.(2)The anti-corrosion effect of four inorganic corrosion inhibitors for carbon steel is verified in the corrosion test.According to the performance,Na5P3O10 and Na2MoO4 are selected as the corrosion inhibitor additives.(3)Based on the orthogonal test data,the final formula for concrete is determined,which is the amount of the bentonite,inorganic salt,Na5P3O10 and Na2MoO4 are 22%,0.75%,0.375%,and 0,5%respectively.(4)After a 150-day embedded test in the soil of 15%humidity,the concrete resistivity of above formula reaches 0.3k? cm,and still has room to drop.And in a certain corrosion environment,the corrosion rate of carbon steel specimens is 0.0057 mm/a,proving a good anti-corrosion effect of the concrete.