Unsealed contraction joints in concrete pavement
For unreinforced concrete pavement, contraction joint is an approximately 3mm wide groove with a depth of about one-third to one-fourth of slab thickness and a regular spacing of usually 5m. Grooves are designed such that they are too narrow for stones to fall into when cracks are open because of the contraction of concrete. Groove location is l a plane of weakness and groove behaves as a potential crack-inducing device where any potential cracks because of shrinkage and thermal contraction can form will be confined to the base of groove. It would not cause any unpleasant visual appearance on the exposed surface of unreinforced concrete pavement.
The above-mentioned contraction joints can be designed as unsealed. These grooves are very narrow so that stones can barely get into these grooves even when joint undergoes contraction. Fine particles or grit entering into the groove are supposed to be sucked out by the passing vehicles. The joints can be self-cleansing and it may not be necessary to seal the joints for fear of attracting the accumulation of rubbish and dirt.