In Civil Engineering (Road work), How can unreinforced concrete pavement function without mesh reinforcement?

one should pay attention to the features of unreinforced concrete pavement. In accordance with Highways Standards, an approximately3mm wide groove with a depth of about one-third to one-fourth of slab thickness is designed with a regular spacing (normally5m). The grooves are designed to be too narrow for stones to fall into when the cracks are open due to concrete contraction. The sectional area in which the groove is located is a plane of weakness and thus this groove acts a potential crack-inducing device in which any potential cracks due to shrinkage and thermal contraction may form. Consequently, the cracks are formed at the base of the groove and thus it would not cause any unpleasant visual appearance on the exposed surface of unreinforced concrete pavement.