The present study investigates the adhesion properties and coefficient of friction of various cementitious particles using atomic force microscopy (AFM). The cementitious materials studied are Portland cement (PC), fly ash (FA) and ground granulated blast furnace slag (GGBFS). AFM probes used were commercial silicon nitride tips and cementitious particles attached to the tips of AFM cantilevers. The adhesion force is determined from pull-off force measurements, which is then used to calculate effective Hamaker constants according to JKR or DMT contact models. The coeffi cient of friction is determined by sliding the tip of the AFM probes on another material and increasing the normal loads and friction forces. The results in dry air indicate that FA can have a high Hamaker constant; also when in contact with other cementitious materials. The results in fluid environments have showed high Hamaker constants for PC and FA. The results for the friction test in dry air indicate that the coeffi cient of friction of PC is lower than fly ashes, which is attributed to the asperities present on the particle surface. However, the coefficient of friction of PC becomes much higher in fluid environments.