Jun, 24 2026
Why Overlaying Cement-Stabilized Base Directly on Old Asphalt Triggers Catastrophic Pavement Failure?
This technical analysis exposes the structural risks of placing cement-stabilized bases directly over impermeable old asphalt pavements. It explains how this error triggers a “bathtub effect,” leading to severe mud pumping and shearing failure under dynamic water pressure, before presenting the SINOTO Synchronous Chip Sealer as the definitive solution. Introduction: The Fatal Dilemma in Road Rehabilitation When highway engineers are working on rehabilitating an existing, distressed asphalt pavement, one of the important decisions they must make is whether to completely mill and remove the asphalt pavement, or to pave directly over it. As an alternative to these options, an “apparently reliable” approach is sometimes suggested: to leave the existing, dense hot-mix asphalt (HMA) surface as is, spread a new, semirigid, cement-stabilized macadam (CSM) base over it, and overlay with a new asphalt wearing course. The structural design is inverted and seems to take advantage of the strength at hand and the new rigidity. History in the field, however, shows this to be a perilous situation. However, many of the roads rehabilitated in this manner have experienced catastrophic mud pumping, excessive potholes, and structural failure within two years. The problem is that one overlooked characteristic—the old asphalt surface is a very...
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