Variety of soil is available in abundance in nature and each type of soil exhibits different engineering properties. Also, the same soil exhibits different properties in dry and wet conditions or static and dynamic conditions. The shear modulus in static and that in dynamic conditions varies largely. The properties of the soil can be altered by providing geo-membrane in the soil (Yegian M.K. and KadakalU.). The cost of soil is meager and needs no maintenance. Knowing these facts, clean river sand was tried as base isolation material and experiments were conducted on a RCC frame model having raft foundation. The results observed during experiments are encouraging and the base isolation effects are observed. Frequencies obtained from the experiment and analysis are in good agreement.

Keywords: Base isolation, Shear modulus, Kobe motion, Modulus reduction.