THE USE OF RESISTIVITY AND GROUND PENETRATING RADAR TECNIQUES IN THE DETERMINATION OF CLAY RESERVES FOR THE BRICK INDUSTRY

Typically every five years a brick manufacturing company will look at their clay reserves. There are numerous reasons for doing this. Some of the questions to be answered include: a) How much clay is there left? b) How is the material changing? c) Will the material on one side of the quarry shrink more than the material taken from another side of the quarry? d) How is the chemical composition of the raw material changing? e) What are the physical properties? f) Would the company invest X amount of dollars on a capital investment project if there is a reason to believe that there are only a few weeks left of clay reserves? g) Should the company look into expanding the limits of the quarry or look for another similar source of raw material? h) If expansion is possible, for how long would the company be able to operate?. Resistivity and Ground Penetrating Radar (GPR) techniques were used to help determine clay reserves. The resistivity technique is used particularly on materials that exhibit low resistivity. GPR techniques are not good to use on materials that exhibit low resistivity such as clay, but is very useful if applied on two or multiple surface layers that have noticeable different degrees of resistivity between each other. Although the illite-rich pit in study is fairly homogeneous, an area where the resistivity is relatively high was found. An analysis was performed to determine if the area consisted of: a) a large igneous rock such as granite; b) a concentrated amount of quartz or any other material with resistivity values above 2K ohm-m; c) percolating groundwater. Bore-log tests were conducted and analized which confirmed the data obtained and the analysis performed. GPR gave us an idea of the volume of sand needed to be extracted before mining the clay. The resistivity test provided us ore's depth information. If the rate of mining is known, then estimating the clay reserves is an easy task. The resistivity test provided a depth of penetration that GPR could not do on low resistivity materials. GPR is excellent when used on areas with distinguish differences in dielectric constant in between layers.