Arrangement applied to modular block with wedge-like couplings

A system comprising:

• a plurality of hollow modular blocks composed of polymer, each modular block comprising:
• four walls, a top face and two internal cavities separated by a partition, and, on the top face, two quadratic projections extending above the top face are prominently juxtaposed each with a central bore for passage of tethers used in assembling, wherein the four walls have a common height each from a base thereof to a top thereof joined to the top face, and wherein the four walls comprise a first wall, a second wall adjacent and perpendicular to the first wall, a third wall adjacent and perpendicular to the second wall and parallel to the first wall, and a fourth wall adjacent and perpendicular to each of the third wall and first wall and parallel to the second wall;
• a vertical extension located along a vertical junction of an exterior of the first wall and an exterior of the second wall, the vertical extension projecting outwardly therefrom and completely extending the common height, wherein, in an assembled configuration, the second wall of a first modular block of the plurality of blocks is laterally joined with a side-adjacent block of the plurality of blocks such that the vertical extension of the first modular block prevents entry of residues inwardly thereof;
• a fillet completely extending the common height along the exterior of the second wall from the base of the second wall to the top of the second wall, the fillet having a trapezoidal horizontal cross section narrowing from the base of the second wall to the top of the second wall;
• and a recess completely extending the common height along an exterior of the fourth wall from the base of the fourth wall to the top of the fourth wall without defining an opening therethrough, the recess having a matching trapezoidal horizontal cross section narrowing from the base of the fourth wall to the top of the fourth wall.