Agglomerates of glass ballotini adhered together by an epoxy resin binder have been prepared to investigate the effect of macro-voids and interparticle bond strength on the agglomerate breakage. A special novel preparation method is used to control the structure of the agglomerates by manipulating the number and size of large cavities introduced in the assembly, and the properties of the interparticle bonds. The packing density obtained by this agglomeration method is shown to be very reproducible, hence producing specimens of nearly identical characteristics. This provides a tool to evaluate the influence of structural properties and bond strength on the mechanical strength of agglomerates. The strength has been assessed by studying the breakage of agglomerates subjected to a single impact. The effects of the curing of the binder and the amount of glue on the agglomerate strength are reported. Very small changes in solid fraction, obtained by generating large cavities into the assembly, drastically affect the extent of breakage of the agglomerates upon impact.