Comportamiento de las arcillas del área metropolitana de Cúcuta sometidas a proceso de moldeo por extrusión.

The behaviour of clay materials located in the metropolitan area of San Jose de Cucuta when subjected to extrusion process is presented. The research was conducted using samples from the Leon geological formations (municipality of Cucuta) and Guayabo (municipality of El Zulia and Los Patios). We studied of the effect of raw materials (sand content and particle size) on the molding process, through the plasticity index, water absorption percent and the bending strength. The dimensions of the samples were: length 4cm, width 4 cm and 1 cm high. The drying process was carried out using forced circulation oven for 24 hours at 110 °C, while the baking is make through electric furnace at a maximum temperature of 1000 °C for 6 hours. It was found that the percentage of clay present in the samples of the two geological formations is similar(~ 61%), while the sand concentration and silt varied considerably according to the geological formation (Guayabo and Leon). We reported the average plasticity index (IP) for samples, being of 24,5% for Guayabo formation, and 29,5% for Leon formation. The bending strength and water absorption percent did not present significant change. The tests conducted on mixtures with variation of the sand concentration revealed that the most suitable for the formulation of ceramic pastes using minerals of the metropolitan area of San Jose de Cucuta area must be: the sandy fraction between 20 and 27%, 23 y 28% for the fraction of the slime and between 47 and 58% for the clay fraction, the plasticity index should be close to 22%. The mixtures these ranges can get good results for extrusion speed, adequate energy consumption and good quality of the manufactured product by molding extrusion process