2.3.2 Existing Pavement Condition
The condition of the pavement substrate plays an important role in the performance of sprayed seals. Particular concerns include embedment of the aggregate into softer materials, cracking, non‑uniform surface texture and permeability of the pavement surface.
Aggregate embedment can occur in poor quality or wet granular materials. Compaction and the uniform surface finish of granular materials are critical elements in the successful use of sprayed seals as initial treatments on granular pavements. Aggregate embedment can also be an issue when designing a reseal for flushed or bleeding bituminous surfaces, or over fresh asphalt or microsurfacing.
Pavement cracking can allow moisture into underlying materials causing loss of pavement strength, increased roughness and increased levels of patching and routine maintenance. Timely retreatment of sprayed seals on granular pavements, before extensive cracking and pavement deformation develops, is desirable and cost‑effective in terms of maintaining most rural road pavements. Even relatively poor quality granular materials can perform satisfactorily as road pavements if the moisture regime is well‑controlled.