The average internal cohesion function of two-dimensional (2d)-agglomerates formed by assemblage of fractal aggregates of masses i and j (the aggregates being previously obtained using the algorithms of the diffusion-limited aggregation processes) was determined on the basis of the frequency function P(v, i, j) of the number v of interaggregate connections forming the link. The agglomerate fragmentation threshold was set by choosing the number m of connections which may be broken. The amount of agglomerate sustaining break-up was found to be independent of the mass (i+j) of the final agglomerate and expressed by a Johnson–Mehl equation of the variable m. The porosity of platelets formed by the agglomeration of a great number of fractal aggregates was found to increase as a power law of the aggregate mass and this might explain the lower bending or flexural strength of platelets of large aggregates.