Fracture mechanics analysis for saw cutting requirements of concrete pavements

Concrete sawing operations are performed at predetermined locations within the first 24 h to prevent random cracking on jointed plain concrete pavements. In current construction procedures, the depth and timing of the saw are usually established by the contractor on the basis of experience. A study analyzed the effect of several concrete mixture proportions and constituents on the early-age fracture properties and their effect on saw cut timing and depth for concrete pavements with several slab geometries. Concrete pavement mixtures with different coarse aggregate size and cementitious content were evaluated to determine sensitivity of the measured fracture properties on saw cut model predictions. Finite element analysis was used to derive the geometric correction factors necessary to characterize the fracture properties of concrete based on the wedge splitting test configuration. A saw cut depth model previously proposed was modified to determine the timing and depth of notches on jointed plain concrete pavements. The theoretical analysis and practical example lead to the observation that if greater time is desired before saw cutting, the design should favor concrete materials with slower development of fracture properties. Thinner concrete pavements also require significantly deeper notch depth ratios relative to those of thicker slabs.