A concrete lid for an in-ground utilities box includes a plastic reinforcement structure filled with concrete. The plastic reinforcement structure includes one or more plastic sidewalls that protect the edges of the lid from damage. The upper and lower surfaces of the lid are exposed concrete (with the exception of the upper and lower edges of the one or more plastic sidewalls). The one or more plastic sidewalls laterally surround a plastic reinforcement grid, which is centrally located between the upper and lower edges of the one or more plastic sidewalls. The one or more plastic sidewalls can be integrally formed with the plastic reinforcement grid. The plastic reinforcement grid reinforces the concrete lid, eliminating the need for separate reinforcement material. Support struts can be used to support the plastic reinforcement grid while wet concrete is being poured into the plastic reinforcing structure.