Non dowel joint spacing for low volume roads in tropical climate - a case study in Sri Lanka

Abstract

Shrinkage and thermal stresses are the dominant contributors to develop tensile stresses in rigid pavements. As a result, cracks can be developed in pavement without vehicle loading. Providing lateral joints at appropriate spacing is one of the solutions to overcome the said stresses. Width of a joint will be wider at the time when curling and contraction strains are at the optimum strain. It is essential to consider daily temperature variation, shrinkage and curling together with the fatigue damage in determination of optimum joint spacing for concrete roads. Rigid pavements are usually exposed to solar radiation to a great extent and as a result thermal stresses are developed. This research propose a methodology to estimate the relevant deformation (width of the joint) of concrete due to its exposure to the solar radiation incorporate the temperature variation of the concrete slab by use of a 3D finite element model (FEM) approach. A laboratory scale slab was used to verify the results obtained from the FEM. Lateral deformations due to shrinkage effect were calculated according to the American Concrete Institute shrinkage model (ACI 209 R-92). Aggregate interlocking is an efficient load transfer mechanism for thin concrete pavements which are commonly used in rural roads. An Experiment was carried out to find a relationship between crack width of the interlocking joint and load transfer efficiency (LTE). From the obtained results, it was observed that LTE decreases non-linearly with the increase of crack width. According to the study, joint spacing of thin rigid pavements can be provided even beyond the specified values of American Concrete Pavement Association (ACPA) to maintain 60% of LTE.