Experimental　approaches　in　concrete　technology　are　time-consuming,　laborious　and　thus　expensive.　Developments　in　computer　facilities　render　possible　nowadays　realistically　simulating　the　particulate　structure　and　microstructure　of　cementitious　materials.　For　that　purpose,　discrete　element　methods　(DEM)　are　required　because　of　more　correctly　simulating　particle　dispersion.　Dynamic　DEMs　like　Delft-produced　SPACE　and　HADES　were　developed　and　applied.　The　approaches　are　outlined　and　usage　is　illustrated　by　means　of　assessing　particle　size　effects　on　packing　density　of　aggregate.　Shape　simulation　is　accomplished　for　simple　shape　families　like　ellipsoids　and　polyhedra.　This　type　of　particles　is　used　so　far　for　the　simulation　of　structures　consisting　of　gravel,　crushed　rock　or　cement　particles.