Fundamental characteristics for ground-resistance reducing material using water-absorbent polymer

Abstract

As the number of communication facilities increases, the number of grounding points needed for the facilities increases. In the high ground-resistance areas with soils composed of volcanic ash or sand, it is difficult to achieve the specified ground resistance and, hence, a ground resistance-reducing material must be used. This paper proposes a method to reduce ground resistance using water-absorbent material. Also, a method is described for measuring ground resistance using a box-type metal container, where the influences from the walls and the bottom of the metal container are taken into account. The properties of the ground resistance-reducing material based on the water-absorbent material which was solidified by using epoxy resin has been investigated to find the condition where the ground resistance was lower than when a grounding electrode was used and the compressive strength of the material was higher than that of bentonite. As a result, it was found that, when the water-absorbing ratio was 1:2, the ratio of the weight of the water-absorbent material to that of epoxy resin should be between 0.3 and 1.7. It was found also that this ground-reducing material was as effective as a grounding electrode with respect to the buried depth and earth conductivity and that the ground resistance decreased exponentially with a buried radius (αr−0.37).