21/01/2026
Sealing chips of specific sizes, such as 19mm and 13.4mm, are critical components in the construction and long-term performance of sealed bituminous pavements (like chip seals or surface dressings).
When applied to a properly leveled pavement, these precisely graded aggregates serve three primary functions: they provide immediate skid resistance, shield the underlying binder from UV degradation and weather, and create a durable, load-distributing wearing course.
The correct chip size is selected based on traffic volume and desired texture depth. On a level substrate, chips embed uniformly into the bitumen binder, creating a consistent, interlocked matrix that resists ravelling and retains stability under traffic.
The effect of using uneven or oversized chips on a completed seal is profoundly negative. First, poor embedment occurs: oversized chips protrude excessively, failing to lock into the binder matrix. This leads to ravelling, where chips are easily dislodged by traffic, resulting in aggregate loss, binder exposure, and rapid surface deterioration.
Conversely, undersized or fine material can create a slick, fat surface.
Second, instability and chip loss are major issues, as uneven chips cannot properly interlock, making the surface susceptible to movement and stripping under vehicle forces. Third, increased vehicle wear and safety hazards arise; protruding chips cause excessive tire wear, while a loose, uneven surface drastically reduces skid resistance, especially when wet.
Finally, the seal's longevity is compromised, necessitating premature and costly maintenance.
In essence, the success of a sealed surface is entirely dependent on the interaction between a level pavement, the correct binder application rate, and the use of uniformly sized sealing chips. Deviation in chip size undermines the entire system, converting a cost-effective preservation treatment into a failed, hazardous, and wasteful investment.
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