Investigation and Modification of Available Mechanistic–Empirical Procedures for Reflective Cracking in Asphalt Overlays of Concrete Pavements

Abstract

In recent decades, state, local, and federal use of asphalt concrete overlays to rehabilitate portland cement concrete pavements has increased significantly. This growth has increased the attention given to mechanistic– empirical modeling of reflective cracking. This paper describes recent research that assessed and modified the state of the art in mechanistic– empirical modeling of reflective cracking. The research reviewed the original Mechanistic–Empirical Pavement Design Guide model and the CalME reflective cracking model. The paper also details research in which the CalME model was modified to facilitate its integration into the design guide for pavement projects of composite asphalt concrete over portland cement concrete.

Performance Comparison of Break and Seat and Rubblization Rehabilitation Techniques for Reflection-Crack Mitigation: Case Study in Louisiana

“…From Figure 7 a , the break and seat techniques with different break patterns utilized in field project 1 were effective in improving ride quality of the pavement compared with the control technique. The seating activities performed on these sections were effective in providing strong support and uniform surface for the HMA overlay and, therefore, improved ride quality for these sections ( 1 , 14 ). The two reflection-crack mitigation techniques (break and seat, and rubblization) utilized in field project 2 were effective in improving the ride quality of the pavement section over time (see Figure 7 b ).…”

“…The three PCC slab-fracturing techniques differ by the magnitude of the fracturing load, the PCC pavement type (i.e., jointed, plain, or reinforced concrete) and the size of the fractured components. Crack and seat technique is typically used in jointed plain concretes ( 14 ). Crack and seat technique requires PCC slabs to be broken into pieces with sizes ranging from 12 in.…”

“…Drop hammers are commonly used for the cracking activity. After cracking, the fractured slabs are seated back by applying a 30 to 50 ton capacity rubber-tired roller ( 14 ). According to Khazanovich et al, seating is performed in the crack and seat as well as break and seat techniques to achieve three objectives: 1) eliminate voids and establish support between the broken slabs and the underlying material, 2) create a uniform surface to support the paving operation, and 3) identify soft spots for further treatment ( 14 ).…”

“…After cracking, the fractured slabs are seated back by applying a 30 to 50 ton capacity rubber-tired roller ( 14 ). According to Khazanovich et al, seating is performed in the crack and seat as well as break and seat techniques to achieve three objectives: 1) eliminate voids and establish support between the broken slabs and the underlying material, 2) create a uniform surface to support the paving operation, and 3) identify soft spots for further treatment ( 14 ). Researchers have demonstrated that pavement rehabilitation using the crack and seat technique can delay reflection-crack formation, especially in cases with adequate and uniform subgrade support ( 13 , 15 , 16 ).…”

“…The rubblization technique, though similar to the crack/break and seat method, produces much smaller fractured concrete pieces ( 14 ). It is considered the best rehabilitation technique among all the slab-fracturing methods ( 18 ).…”