A study was undertaken at the university of illinois to develop a mechanistic design approach for continuously reinforced concrete (crc) pavements to account for punchout distress. A mechanism relating to the loss of load transfer and the progressive development of punchout-related distress is presented. Analysis procedures, demonstrated to implement the mechanism as a rationally based thickness design procedure for crc pavement, suggest that the optimal crack interval is between 3 and 4 ft. Present crc design methodologies focus on limiting to certain design criteria cracking intervals, crack width, and stress in the reinforcements. Load transfer mechanisms have not been considered in the limiting design criteria and consequently arenot included in these design procedures. These methods attempted todetermine the design pavement thickness based on the combined effects of environmental and load-related stress on the final crack spacing, which must be limited to the design cracking criteria. However, past experience has indicated that a certain percentage of crack spacing usually falls below the specified minimum crack interval. Thesedata suggest a greater tendency for punchouts to develop within this lower range of crack spacing. How pavement thickness, percent reinforcement, and crack spacing may be considered with respect to pavement spalling and loss of load transfer in the process of punchout development are outlined. This paper appears in transportation research record no. 1286, Design and evaluation of rigid and flexible pavements 1990.
Abstract