Impacts of the Longitudinal Joint Location on Slab Stresses

Longitudinal joints in concrete pavements historically have been located along the edges of lane lines, a condition that results in applied loads being located at the most critical points (e.g., edges and corners of slabs). With increasing use of light?colored silicone sealants that contrast less with the concrete surface color, the innovation of thinner sawcut blades that also make the joints less visually prominent, and a realization that joints in the middle of a driving lane are not problematic (through the adoption of thin concrete overlays with shorter joint spacings and other short?slab design methodologies), locating longitudinal joints at the edges of lane lines might lead to an underoptimized design. For example, a typical geometric design of a 2?lane roadway with 12 ft (3.7 m) wide lanes and 6 ft (1.8 m) shoulders on either side could be designed such that only two longitudinal joints are used, evenly spaced at 12 ft (3.7 m), rather than the conventional three longitudinal joints. Such an arrangement reduces stresses and deflection under the same applied loads because edge loads are turned into interior loads. Other benefits, such as easier access to longitudinal joints for future maintenance, also exist. This paper presents finite element analysis to support this concept and examples of the application of mid-lane alternate longitudinal joint layouts in the USA and Australia.