Concrete carriageways are typically classified into two main types: reinforced and unreinforced. While reinforced pavements utilize mesh reinforcement to manage cracking, the question arises as to how unreinforced pavements control cracking without such reinforcement.
The answer lies in the design features of unreinforced concrete pavements. According to Highways Standard Drawing No. H1109, these pavements incorporate regularly spaced grooves, approximately 3mm wide and one-third to one-fourth of the slab thickness deep. These grooves serve a dual purpose.
Firstly, they are designed to be too narrow for stones to fall into when cracks open due to concrete contraction, preventing debris from accumulating and potentially causing damage.
Secondly, the groove acts as a “potential crack-inducing device.” Due to its reduced cross-sectional area, it becomes a plane of weakness where shrinkage and thermal contraction-induced cracks are likely to initiate. As these cracks form at the base of the groove, they are concealed beneath the surface, maintaining the visual appeal of the unreinforced concrete pavement.
In essence, unreinforced concrete pavements utilize strategically placed grooves to preemptively control cracking, ensuring both structural integrity and aesthetic appeal.