Abstract 
. Nowadays, volume of the traffic as well as the load of the vehicles are becoming higher and heavier. That situation of course requires more strength of the base of the pavement. Some efforts have been done by road designers to improve the strength of the pavement especially on the base layer. Most improvement which has been done is stabilizing this layer with sand, cement, lime and even with asphalt. This paper presents laboratory evaluation on stabilizing of road base of the pavement using Oil Palm Fruit Ash (OPFASH), a waste material of palm oil industry. Using OPFASH is intended to reduce of using original portland cement (cement), the material most use for base stabilization, as stabilizing agent since the increasing of cement price. 1% to 4% with interval 1% by weight of both cement and OPFASH are added to the road base material. Laboratory experiments show that compressive strength of the road base using 2% cement and 2% OPFASH as well as 1% cement and 3% OPFASH almost have the same result as if using 4% cement and 0% OPFASH. This can be concluded that OPFASH can be used as road base material stabilization in road construction. 
Keywords: opfash, stabilize, road base, strength, pavement