This document describes the reference method for the determination of the lime fixation point (LFP) in soil treatment for earthworks. The test consists in measuring the lowest quantity of lime to be added in a soil suspension in water that will result in a pH value of the soil-lime mix suspension of 12,4, measured at 25 °C ± 1 °C. This test method cannot be used to provide information about soil reactivity with lime, or other performance values (mechanical characteristics of soil-lime mixes) applicable for improvement or stabilization purposes. Those performance tests will be conducted in a laboratory from a specific study, the lime dosage to be applied being indicated from this method.