Usually, optimal percentages of additives used to improve the characteristics of soils, are determined by laboratory tests of different complexity. Then, these optimal combinations are used directly in the pavement structures, without analysis of time or scale differences between laboratory and field conditions. This paper presents the results of a full-scale accelerated pavement test on a base course that has been improved by using fly ash and an alkali activator. Initially, the main characteristics of the testing equipment are presented. The optimal amount of the different components was previously obtained by laboratory tests. The components were mixed, the material was extended and compacted in layers and a curing time was permitted. After that, a wheel loaded with a vertical hydraulic actuator, simulating a rear half-axis of a truck, passed on the top layer repeated times. During the test, vertical deformations of the surface were measured in several points along the track. Results after around 10000 loading repetitions were compared against simultaneous measurements on a non-treated material subjected to identical loading application, showing the advantages of the alkali activation in reducing deformability of base courses and the effect of variable natural wheatear conditions on both type of pavement structures.