You may not be aware of it, but the joints in your concrete jobs may be shortening the life of your paving projects dramatically.
THE FAILURE MECHANISM AT WORK
To a great extent, concrete pavement is only as good as the base it rests on. Thus, any weakening of the base may put the slab in jeopardy. If water is allowed to reach the base, it can erode it and reduce the amount of support available for the concrete. Failures at panel corners usually occur first. There are three main reasons for this. First, the base is more likely to be weakened at a corner because it is exposed to water penetration from two fronts. Second, the stresses due to loading at a corner are resisted by only a limited area of the slab. Third, any curling of the concrete may actually lift the slab from the base, creating a subsurface void even before water has had a chance to cause erosion. Joints aren't the only locations where moisture can enter the base. Any uncontrolled cracks are potential spots for further deterioration to take place.
HOW TO AVOID FAILURES
By following a set of simple rules, you can minimize problems related to joints. The following list of precautions is worth remembering:
- Provide adequate slope for runoff.
- Use the right joint for the job.
- Avoid tee intersections of joints and long joint spacings.
- Ensure proper load transfer at control joints.
- Don't restrain horizontal movement at control joints.
- Seal joints properly.