Testing Cement Improved Residual Soil Layers: Fid-Bau Portal

Testing Cement Improved Residual Soil Layers

Veloso Marques, Sérgio Filipe / Consoli, Nilo Cesar / Almeida e Sousa, Jorge

Present research aims to carry out field and laboratory tests in a top cement improved residual soil layer. Regarding laboratory tests, the isolated influence of parameters such as cement percentage, porosity and water content will be studied after unconfined compression testing. Test results showed that the unconfined compressive strength ( $q_{u}$ ) increased along with the cement percentage and with the reduction of the porosity of the compacted mixture. It was still possible to verify that the water content had reduced influence on the unconfined compressive strength, which was basically dependent of porosity and amount of cement. The research also studied the behavior of plate load tests with different diameters (D) bearing on a treated layered system with different thickness (H) considering 5% of portland cement (determined after analysis of unconfined compression test results). Triaxial tests were also carried out in specimens retrieved from the cement treated layer, cone penetration tests (CPT) were done in the cement improved layer and the outcome shows a substantial increase in tip cone resistance comparatively with the natural soil. A finite-element analysis of the plate load tests was carried out using the elastic-perfectly plastic model with Drucker-Prager failure criterion that proved suitable for the simulation. After processing results of plate load tests bearing on the cemented layered system, it was verified that the applied pressure versus settlement to diameter ratio correlation is controlled by the H/D relation, in which this factor increase takes to a stiffer and stronger response.