Land functions as a supporting medium for all living activities. The problem that is often encountered is the level of soil stability at each location is different, for this reason the following research is used to determine the parameters of stable soil density when soil structure composed of clay components added 10% of sand from the total weight of the specimen with different diameter variations using proctor testing. The density properties of clay soil after the addition of brantas sand with size variations passed the sieves number 8, 10, 16 and 20 amounting to 10% in perfect solid state the structure of the original soil specimens showed an γd value of 9.61 gr / cm3, in addition of sand 10% with a diameter passing through number 8 shows an γd value of 10.44, at number 10 shows a value of γd 11.77, at number 16 shows the value γd 10.97 and in number 20 shows a value of γd 11.55. the addition of sand to the expansionary structure with low stability can improve the level of stability of the soil structure. Moreover, the addition of sand with a no. 10 sieve diameter shows the value of dry volume density γd of 11.77, the value shows the above average density parameter - average of several other test objects.