The recent earthquakes that hit Italy have shown that the built heritage is at risk not only because of inertial and kinematic stresses directly induced on the structure by shaking, but also because of possible soil liquefaction phenomena. The techniques generally used to mitigate the soil liquefaction susceptibility in the case of new constructions (vibro-compaction, dynamic compaction, etc.), are generally not suitable for existing buildings. Within a large European project (LIQUEFACT), the University of Napoli is studying innovative soil improvement techniques suitable for the mitigation of the soil liquefaction risk in densely urbanized areas. In this paper, the addition of fine content (laponite) is experimentally studied by means of different preliminary laboratory tests with the main goal to verify the injectability and effectiveness of the selected mixtures against liquefaction. The applicability of this technique has been verified by means of viscosity and permeability tests, while its effectiveness has been analyzed via cyclic triaxial tests. Experimental results show that the addition of an additive (SPP) to delay the mixture gelling time is necessary to assure the injectability of the tested laponite mixtures. The addition of fine content reduces the mobility of grains and modifies the pore pressure building up during cycling loads, leading to an increase of soil liquefaction resistance.
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