A GRANULAR MATERIAL DUE TO CONTAMINATION WITH A CLAY SOIL

Abstract

The presence of cohesive soils, especially those with high plasticity, negatively impacts the mechanical properties of granular materials, posing a risk to the stability and durability of road structures. The studied granular material was subjected to physical and mechanical tests, confirming its suitability for use in subbases. It was verified to be non-plastic, with a liquid limit below 25% and a CBR value above 30%. As a contaminant, a high-plasticity silty clay soil was used, classified according to the AASHTO methodology as type A-7-6, characterized by its low CBR value and high plasticity. The methodology involved mixing the granular material with different proportions of cohesive soil and evaluating its strength through CBR tests. Two contamination levels were established, varying the amount of cohesive soil as the independent variable and considering the CBR value as the dependent variable. The results showed that increasing the proportion of cohesive soil in the mixtures raises the amount of fine particles retained on the No. 40 sieve, thereby increasing the material’s plasticity. This leads to a significant reduction in CBR values, implying a loss in load-bearing capacity. In conclusion, contamination by cohesive soils, particularly those with high plasticity, reduces the load-bearing capacity of granular materials, affecting pavement durability. Therefore, it is essential to control such contamination to ensure the proper performance of structural layers.