9525

9525, written properly as 95/25, is a grade of oxidised bitumen rather than a proprietary sealant. The numbers are its properties: a softening point around 95 degrees and a penetration around 25. It is unmodified, carrying no polymer or rubber, but it is air-blown in manufacture rather than raw. That makes it hard and rigid where N1 and N2 are designed to move, which is why its place is below the surface rather than on it. Our main use for it is sealing cable chases carrying airfield ground lighting cable, where a runway is being resurfaced and the chase will be buried under the new asphalt.

In our experience, 9525 works better than a surface-grade sealant for AGL chases because its rigidity and bitumen content protect the cable run through the full depth of the construction, where a flexible surface sealant would not hold up between layers.

Applications: sub-surface and inter-layer cable chases, AGL cable sealing, below-surface joints. A note on specifying it: 95/25 is a grade of oxidised bitumen, so there is no such standard as BS EN 9525. Oxidised bitumens sit under BS EN 13304, while hot applied joint sealants such as N1 and N2 sit under BS EN 14188-1.