Bestone®

Bremanger Quarry is located in the Hornelen Basin in Western Norway, a Devonian sedimentary basin about 400 million years old. Filled with sedimentary deposits from ancient river systems.

From sand fraction to Bestone®
In the Bremanger area, these deposits consisted mainly of sand fraction, which later formed the basis for the stone marketed by Bontrup under trade name Bestone®.

During the Caledonian mountain formation, these sandstone layers were buried at 10-15 km depth, where pressures were high and temperatures rose above 200°C. Due to prolonged compression, a low degree of metamorphism occurred. This led to the following:

• Almost all of the original pores disappeared;
• Particles fused tightly together;
• Clay minerals disappeared and transformed into muscovite, chlorite and epidote, among others;
• Microstructure and particle angularity were preserved.

The formed rock was then lifted and ultimately resurfaced due to tectonic forces. This explains the distinctive, cascading Norwegian landscape and makes that Bestone® is extractable at the surface today.

Compact, hard and wear-resistant
The metamorphosis created a compact, hard and wear-resistant rock. Crucially, the metamorphosis did not go too far: the rough microtexture was retained and no schist or gneiss was created, which means weak surfaces and foliation are absent.

Skid resistance remains high
This micro-roughness - and the fact that Bestone®is composed of a perfect balance of hard and softer minerals - ensures that the rough microtexture remains intact: the rock does not polish to a smooth surface, but always retains a rough surface. The result is an exceptionally uniform, hard and permanently slip-resistant meta-sandstone, the geological basis of Bestone®.

Bestone® is known for its consistent and predictable performance. Deep core drilling in Bremanger Quarry, investigated by SINTEF, shows that: "Bremanger stone is very homogeneous both in structural and lithologic appearance."

Highly consistent
Bestone® has now been tested thousands of times by dozens of laboratories and knowledge institutions, including Delft University of Technology. The results show very small deviations in all technical parameters - a rare level of consistency in natural stone.

Skid resistance (PSV) - for road safety
The excellent micro roughness and the absence of weak surfaces provide a high Polished Stone Value (PSV). The PSV-test determines the degree of skid resistance after polishing of the aggregates by traffic - a direct indicator of road safety.

Wear resistance
Bestone® is highly wear-resistant and can withstand heavy traffic. This is demonstrated by the Los Angeles (LA) test, which measures resistance to fragmentation. Similar tests are resistance to wear (Micro-Deval) and impact (SZ). On all tests, Bestone® scores exceptionally well due to its strong composition and dense structure.

Hardness
Bestone® has a compressive strength exceeding that of high-strength concrete. As a result, a skeleton built with Bestone® aggregates is strong enough to withstand the large forces of traffic.

Low porosity
Due to the metamorphosis, Bestone® has a dense structure and low porosity. As a result, the product is:

• Resistant to freeze-thaw cycles;
• Insensitive to salts and chemicals.

Skid resistance = safety
The safety of a road is directly linked to the skid resistance of the surface layer. A higher PSV-aggregate means better grip in wet conditions, while braking and during high speeds. Bestone® is among the world's best performing aggregates on PSV.

Wear resistance + low porosity = increased service life
The service life of asphalt courses is determined by wear and damage caused by the forces of nature. Bestone® is highly wear-resistant and insensitive to freeze-thaw, salts and chemicals. This results in:

• Less maintenance;
• Longer lifespan;
• Lower maintenance costs.

Double-layered Open Asphalt Concrete
The strength of Bestone® also makes it very suitable for (two-layer) Open Asphalt Concrete (ZOAB). This type of road surfacing prevents water splashing and reduces noise. This is why Bestone® has been the number one aggregate for highway surfacing in the Netherlands for decades, and why its use is growing rapidly in other countries. It is not without reason that the Netherlands has one of the safest and best-performing road networks in the world.

Bestone® combines a unique geological formation with exceptionally reliable technical properties. The rock is homogeneous, strong, wear-resistant, rigid and consistent. These are properties that make it the logical choice for high-quality and durable infrastructure.

'Bestone® - shaped by nature. Chosen for performance.'