Abstract Traditional theoretical and experimental investigations of the mechanical behavior of particulate solids are restricted by the limited quantitative information about what actually happens inside particulate assemblies. This paper presents computer simulation results of the breakage of lactose agglomerates due to impact on a target plate using distinct element analysis. The agglomerates of interest here are generally weak and easy to disintegrate as no binder other than weak surface forces is holding the primary particles together. Particle interaction laws in the simulation code are based on theoretical contact mechanics, where adhesive interface energy determines the bond strength between individual particles of the assembly. Experimental investigations have been conducted to validate the computer simulation results, using a simple air-eductor where particles are accelerated to the required velocity by an air flow and impacted against a rigid target plate. Computer graphics of the simulation results of agglomerate breakdown are compared with the images obtained by high speed video recording of the impact events. A good agreement has been found between the simulation results and experimental measurements. Dynamic features and loading compliance of weak agglomerates are found to be distinctly different from those of high strength agglomerates and solid particles.